U.S. patent application number 14/721752 was filed with the patent office on 2015-11-26 for ion implantation apparatus.
The applicant listed for this patent is Sumitomo Heavy Industries Ion Technology Co., Ltd.. Invention is credited to Yoshitaka Amano, Mitsuaki Kabasawa, Hiroshi Matsushita, Takanori Yagita.
Application Number | 20150340197 14/721752 |
Document ID | / |
Family ID | 54556565 |
Filed Date | 2015-11-26 |
United States Patent
Application |
20150340197 |
Kind Code |
A1 |
Matsushita; Hiroshi ; et
al. |
November 26, 2015 |
ION IMPLANTATION APPARATUS
Abstract
An ion implantation apparatus includes a scanning unit scanning
the ion beams in a horizontal direction perpendicular to the
reference trajectory and a downstream electrode device disposed
downstream of the scanning electrode device. The scanning electrode
device includes a pair of scanning electrodes disposed to face each
other in the horizontal direction with the reference trajectory
interposed therebetween. The downstream electrode device includes
an electrode body configured such that, with respect to an opening
width in a vertical direction perpendicular to both the reference
trajectory and the horizontal direction and/or an opening thickness
in a direction along the reference trajectory, the opening width
and/or the opening thickness in a central portion in which the
reference trajectory is disposed is different from the opening
width and/or the opening thickness in the vicinity of a position
facing the downstream end of the scanning electrode.
Inventors: |
Matsushita; Hiroshi; (Ehime,
JP) ; Kabasawa; Mitsuaki; (Ehime, JP) ; Amano;
Yoshitaka; (Ehime, JP) ; Yagita; Takanori;
(Ehime, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sumitomo Heavy Industries Ion Technology Co., Ltd. |
Tokyo |
|
JP |
|
|
Family ID: |
54556565 |
Appl. No.: |
14/721752 |
Filed: |
May 26, 2015 |
Current U.S.
Class: |
250/396R |
Current CPC
Class: |
H01J 37/08 20130101;
H01J 37/3171 20130101; H01J 37/1477 20130101; H01J 2237/30483
20130101 |
International
Class: |
H01J 37/147 20060101
H01J037/147; H01J 37/08 20060101 H01J037/08; H01J 37/317 20060101
H01J037/317 |
Foreign Application Data
Date |
Code |
Application Number |
May 26, 2014 |
JP |
2014-108008 |
Claims
1. An ion implantation apparatus including a scanning unit, the
scanning unit comprising: a scanning electrode device that allows a
deflecting electric field to act on an ion beam incident along a
reference trajectory and scans the ion beam in a horizontal
direction perpendicular to the reference trajectory, and a
downstream electrode device disposed downstream of the scanning
electrode device and provided with openings through which the ion
beam scanned in the horizontal direction passes, wherein the
scanning electrode device includes a pair of scanning electrodes
disposed to face each other in the horizontal direction with the
reference trajectory interposed therebetween, and the downstream
electrode device includes an electrode body configured such that,
with respect to an opening width in a vertical direction
perpendicular to both the reference trajectory and the horizontal
direction and/or an opening thickness in a direction along the
reference trajectory, the opening width and/or the opening
thickness in a central portion in which the reference trajectory is
disposed is different from the opening width and/or the opening
thickness in the vicinity of a position facing a downstream end of
the scanning electrode.
2. The ion implantation apparatus according to claim 1, wherein the
downstream electrode device is configured as an electrode lens that
corrects deflection aberration occurring in an ion beam emitted
from the scanning electrode device, as a result of scanning
deflection by the scanning electrode device.
3. The ion implantation apparatus according to claim 1, wherein the
downstream electrode device is configured as an electrode lens that
corrects deflection aberration occurring in an ion beam passing
through the vicinity of both scanning ends from among ion beams
emitted from the scanning electrode device, as a result of scanning
deflection by the scanning electrode device.
4. The ion implantation apparatus according to claim 1, wherein the
downstream electrode device includes a first downstream reference
voltage electrode disposed just downstream of the scanning
electrode device, and the opening of the first downstream reference
voltage electrode has an opening width such that the opening width
in the vertical direction in the vicinity of a position facing the
downstream end of the scanning electrode device is larger than the
opening width in the vertical direction in the central portion in
which the reference trajectory is disposed.
5. The ion implantation apparatus according to claim 4, wherein the
opening of the first downstream reference voltage electrode has an
opening width such that the opening width in the vertical direction
is uniform in the vicinity of the central portion, and the opening
width in the vertical direction gradually increases toward right
and left ends of the opening in the vicinity of a position facing
the downstream end of the scanning electrode.
6. The ion implantation apparatus according to claim 4, wherein the
downstream electrode device further includes a second downstream
reference voltage electrode disposed downstream of the first
downstream reference voltage electrode and a first downstream
intermediate electrode disposed between the first downstream
reference voltage electrode and the second downstream reference
voltage electrode, the first downstream intermediate electrode and
the second downstream reference voltage electrode respectively have
an opening for ion beam passage at a position which communicates
with the opening of the first downstream reference voltage
electrode, the first downstream intermediate electrode receives a
high voltage of which a potential is different from potentials of
the first downstream reference voltage electrode and the second
downstream reference voltage electrode, the first downstream
reference voltage electrode has a downstream surface facing the
first downstream intermediate electrode and perpendicular to the
reference trajectory, the first downstream intermediate electrode
has an upstream surface facing the first downstream reference
voltage electrode and perpendicular to the reference trajectory,
and the first downstream reference voltage electrode and the first
downstream intermediate electrode have a shape such that with
respect to a distance between the downstream surface of the first
downstream reference voltage electrode and the upstream surface of
the first downstream intermediate electrode, the distance in the
vicinity of a position facing the downstream end of the scanning
electrode is larger than the distance in the central portion in
which the reference trajectory is disposed.
7. The ion implantation apparatus according to claim 6, wherein the
first downstream reference voltage electrode and the first
downstream intermediate electrode are configured such that a
distance between the downstream surface of the first downstream
reference voltage electrode and the upstream surface of the first
downstream intermediate electrode gradually increases toward right
and left ends of the opening in the vicinity of a position facing
the downstream end of the scanning electrode.
8. The ion implantation apparatus according to claim 6, wherein the
upstream surface of the first downstream intermediate electrode has
a shape protruding toward the first downstream reference voltage
electrode in the vicinity of the central portion in which the
reference trajectory is disposed.
9. The ion implantation apparatus according to claim 6, wherein the
downstream surface of the first downstream reference voltage
electrode has a shape protruding toward the first downstream
intermediate electrode in the vicinity of the central portion in
which the reference trajectory is disposed.
10. The ion implantation apparatus according to claim 6, wherein
the opening of the first downstream intermediate electrode has an
opening width in the horizontal direction which is larger than an
opening width in the horizontal direction of the first downstream
reference voltage electrode, and an opening of the second
downstream reference voltage electrode has an opening width in the
horizontal direction which is larger than an opening width in the
horizontal direction of the first downstream intermediate
electrode.
11. The ion implantation apparatus according to claim 6, wherein
the downstream electrode device further includes a third downstream
reference voltage electrode disposed downstream of the second
downstream reference voltage electrode and a second downstream
intermediate electrode disposed between the second downstream
reference voltage electrode and the third downstream reference
voltage electrode, the second downstream intermediate electrode and
the third downstream reference voltage electrode respectively have
an opening for ion beam passage at a position which communicates
with the opening of the second downstream reference voltage
electrode, and the second downstream intermediate electrode
receives a high voltage of which a potential is different from
potentials of the second downstream reference voltage electrode and
the third downstream reference voltage electrode, and has a
function that suppresses intrusion of electrons into the scanning
electrode device.
12. The ion implantation apparatus according to claim 11, wherein
the first downstream intermediate electrode receives a high voltage
of which an absolute value is larger than an absolute value of a
potential of the second downstream intermediate electrode, and has
a function that allows an ion beam emitted from the scanning
electrode device to converge in the vertical direction and/or the
horizontal direction.
13. The ion implantation apparatus according to claim 1, wherein
the scanning unit further includes an upstream electrode device
configured by a plurality of electrode bodies provided upstream of
the scanning electrode device.
14. The ion implantation apparatus according to claim 13, wherein
the upstream electrode device is configured as an electrode lens
that has function of shaping or adjusting a profile of an ion beam
incident into the scanning electrode device.
15. The ion implantation apparatus according to claim 13, wherein
the upstream electrode device is configured as a suppression
electrode device having electron suppression function with respect
to an ion beam incident into the scanning electrode device.
16. The ion implantation apparatus according to claim 1, wherein
the scanning electrode device includes a pair of scanning
electrodes provided to face each other in the horizontal direction
with the reference trajectory interposed therebetween, and a pair
of beam transport correction electrodes provided to face each other
in the vertical direction with the reference trajectory interposed
therebetween, and the beam transport correction electrode is
configured as a correction electrode that has shaping function or
adjusting function with respect to a beam shape of an ion beam
passing through the scanning electrode device.
17. The ion implantation apparatus according to claim 13, wherein
the scanning electrode device includes a pair of scanning
electrodes provided to face each other in the horizontal direction
with the reference trajectory interposed therebetween, and a pair
of beam transport correction electrodes provided to face each other
in the vertical direction with the reference trajectory interposed
therebetween, and the downstream electrode device is configured as
an electrode lens that has shaping function or adjusting function
with respect to a beam shape of an ion beam emitted from the
scanning electrode device, in conjunction with the upstream
electrode device and the beam transport correction electrodes.
Description
RELATED APPLICATION
[0001] Priority is claimed to Japanese Patent Application No.
2014-108008, filed on May 26, 2014, the entire content of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an ion implantation
apparatus.
[0004] 2. Description of the Related Art
[0005] In a certain ion implantation apparatus, an ion source is
connected to a power supply thereof such that an ion beam having a
small amount of beam current is extracted from the ion source. In
this apparatus, the connection between the ion source and the power
supply may be modified such that an ion beam having a large amount
of beam current is extracted from the ion source.
[0006] Another ion implantation apparatus includes an ion source,
an acceleration tube, and an electric circuit connecting power
supplies thereof, so as to implant ions into a target at high ion
energy. The electric circuit is provided with a selector switch for
switching the connection so as to implant ions at low ion
energy.
[0007] Attempts to extend the operating range of the ion
implantation apparatus to some degree have been made as described
above. However, a realistic proposal to the extension of the
operating range beyond the existing categories is rare.
[0008] Generally, ion implantation apparatuses are classified into
three categories: a high-current ion implantation apparatus, a
medium-current ion implantation apparatus, and a high-energy ion
implantation apparatus. Since practical design requirements are
different for each category, an apparatus of one category and an
apparatus of another category may have significantly different
configurations in, for example, beamline. Therefore, in the use of
the ion implantation apparatus (for example, in a semiconductor
manufacturing process), it is considered that apparatuses of
different categories have no compatibility. That is, for particular
ion implantation processing, an apparatus of a particular category
is selected and used. Therefore, for a variety of ion implantation
processing, it is necessary to own various types of ion
implantation apparatuses.
SUMMARY OF THE INVENTION
[0009] An exemplary object of an aspect of the present invention is
to provide an ion implantation apparatus and an ion implantation
method which can be used in a wide range, for example, an ion
implantation apparatus which can serve as both a high-current ion
implantation apparatus and a medium-current ion implantation
apparatus, and an ion implantation method.
[0010] According to an aspect of the present invention, there is
provided an ion implantation apparatus including a scanning unit,
the scanning unit including a scanning electrode device that allows
a deflecting electric field to act on an ion beam incident along a
reference trajectory and scans the ion beam in a horizontal
direction perpendicular to the reference trajectory, and a
downstream electrode device disposed downstream of the scanning
electrode device and provided with openings through which the ion
beam scanned in the horizontal direction passes, wherein the
scanning electrode device includes a pair of scanning electrodes
disposed to face each other in the horizontal direction with the
reference trajectory interposed therebetween. The downstream
electrode device includes an electrode body configured such that,
with respect to an opening width in a vertical direction
perpendicular to both the reference trajectory and the horizontal
direction and/or an opening thickness in a direction along the
reference trajectory, the opening width and/or the opening
thickness in a central portion in which the reference trajectory is
disposed is different from the opening width and/or the opening
thickness in the vicinity of a position facing the downstream end
of the scanning electrode.
[0011] Also, while arbitrary combinations of the above components
or the components or representations of the present invention are
mutually substituted among methods, apparatuses, systems, and
programs, these are also effective as the aspects of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagram schematically illustrating ranges of an
energy and a dose amount in several types of typical ion
implantation apparatuses;
[0013] FIG. 2 is a diagram schematically illustrating an ion
implantation apparatus according to an embodiment of the present
invention;
[0014] FIG. 3 is a diagram schematically illustrating an ion
implantation apparatus according to an embodiment of the present
invention;
[0015] FIG. 4 is a flowchart illustrating an ion implantation
method according to an embodiment of the present invention;
[0016] FIG. 5A is a plan view illustrating a schematic
configuration of an ion implantation apparatus according to an
embodiment of the present invention, and FIG. 5B is a side view
illustrating a schematic configuration of an ion implantation
apparatus according to an embodiment of the present invention;
[0017] FIG. 6 is a diagram schematically illustrating a
configuration of a power supply of an ion implantation apparatus
according to an embodiment of the present invention;
[0018] FIG. 7 is a diagram schematically illustrating a
configuration of a power supply of an ion implantation apparatus
according to an embodiment of the present invention;
[0019] FIG. 8A is a diagram illustrating a voltage in an ion
implantation apparatus according to an embodiment of the present
invention, and FIG. 8B is a diagram illustrating an energy in an
ion implantation apparatus according to an embodiment of the
present invention;
[0020] FIG. 9A is a diagram illustrating a voltage in an ion
implantation apparatus according to an embodiment of the present
invention, and FIG. 9B is a diagram illustrating an energy in an
ion implantation apparatus according to an embodiment of the
present invention;
[0021] FIG. 10 is a flowchart illustrating an ion implantation
method according to an embodiment of the present invention;
[0022] FIG. 11 is a diagram schematically illustrating ranges of an
energy and a dose amount in an ion implantation apparatuses
according to an embodiment of the present invention;
[0023] FIG. 12 is a diagram schematically illustrating ranges of an
energy and a dose amount in an ion implantation apparatuses
according to an embodiment of the present invention;
[0024] FIG. 13 is a diagram describing the use of a typical ion
implantation apparatus;
[0025] FIG. 14 is a diagram describing the use of an ion
implantation apparatus according to an embodiment of the present
invention;
[0026] FIG. 15 is a perspective cross-sectional view illustrating a
configuration of a scanning unit included in anion implantation
apparatus according to an embodiment of the present invention;
[0027] FIGS. 16A and 16B are cross-sectional views schematically
illustrating a configuration of an upstream electrode device, a
scanning electrode device, and a downstream electrode device
illustrated in FIG. 15;
[0028] FIG. 17 is a diagram schematically illustrating a
configuration of a scanning electrode device;
[0029] FIGS. 18A and 18B are diagrams schematically illustrating a
shape of a first upstream reference voltage electrode;
[0030] FIGS. 19A and 19B are diagrams schematically illustrating
trajectories of ion beams passing through a first upstream
reference voltage electrode and a scanning electrode device
according to a comparative example;
[0031] FIGS. 20A and 20B are diagrams schematically illustrating
trajectories of ion beams passing through a first upstream
reference voltage electrode and a scanning electrode device
according to the comparative example;
[0032] FIGS. 21A and 21B are diagrams schematically illustrating
trajectories of ion beams passing through a first upstream
reference voltage electrode and a scanning electrode device
according to an embodiment of the present invention;
[0033] FIGS. 22A and 22B are diagrams schematically illustrating
trajectories of ion beams passing through a first upstream
reference voltage electrode and a scanning electrode device
according to an embodiment of the present invention;
[0034] FIGS. 23A and 23B are diagrams schematically illustrating
trajectories of ion beams passing through a first upstream
reference voltage electrode and a scanning electrode device
according to an embodiment of the present invention;
[0035] FIGS. 24A and 24B are diagrams schematically illustrating a
shape of a beam transport correction electrode according to a
modification;
[0036] FIG. 25 is a diagram schematically illustrating trajectories
of ion beams passing through a first upstream reference voltage
electrode and a scanning electrode device according to a
modification;
[0037] FIG. 26 is a diagram schematically illustrating trajectories
of ion beams passing through a first upstream reference voltage
electrode and a scanning electrode device according to a
modification;
[0038] FIGS. 27A and 27B are diagrams schematically illustrating a
shape of a first downstream reference voltage electrode;
[0039] FIG. 28 is a diagram schematically illustrating a structure
of a first downstream reference voltage electrode and a first
downstream intermediate electrode;
[0040] FIG. 29 is a diagram schematically illustrating trajectories
of ion beams passing through a first downstream reference voltage
electrode and a first downstream intermediate electrode according
to the comparative example;
[0041] FIG. 30 is a diagram schematically illustrating a shape of a
first downstream reference voltage electrode according to the
comparative example;
[0042] FIG. 31 is a diagram schematically illustrating trajectories
of ion beams passing through a scanning electrode device, a first
downstream reference voltage electrode, and a first downstream
intermediate electrode according to an embodiment of the present
invention;
[0043] FIG. 32 is a diagram schematically illustrating trajectories
of ion beams passing through a scanning electrode device, a first
downstream reference voltage electrode, and a downstream first
intermediate electrode according to an embodiment of the present
invention;
[0044] FIG. 33 is a diagram schematically illustrating a shape of a
first downstream reference voltage electrode and a first downstream
intermediate electrode according to a modification;
[0045] FIGS. 34A and 34B schematically illustrate a trajectory of
ion beams passing through an upstream electrode device and a
scanning electrode device according to an embodiment of the present
invention; and
[0046] FIGS. 35A, 35B, and 35C are diagrams schematically
illustrating a configuration of an upstream electrode device and a
scanning electrode device according to a modification.
DETAILED DESCRIPTION OF THE INVENTION
[0047] The invention will now be described by reference to the
preferred embodiments. This does not intend to limit the scope of
the present invention, but to exemplify the invention.
[0048] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings. Also, in the
description of the drawings, the same reference numerals are
assigned to the same components, and a redundant description
thereof is appropriately omitted. Also, the configurations
described below are exemplary, and do not limit the scope of the
present invention. For example, in the following, a semiconductor
wafer is described as an example of an object to which an ion
implantation is performed, but other materials or members may also
be used.
[0049] First, a description will be given of circumstances that led
to an embodiment of the present invention to be described below. An
ion implantation apparatus can select an ion species to be
implanted and set an energy and a dose amount thereof, based on
desired properties to be established within a workpiece. Generally,
ion implantation apparatuses are classified into several categories
according to the ranges of energy and dose amount of ions to be
implanted. As representative categories, there are a high-dose
high-current ion implantation apparatus (hereinafter, referred to
as HC), a medium-dose medium-current ion implantation apparatus
(hereinafter, referred to as MC), and a high-energy ion
implantation apparatus (hereinafter, referred to as HE).
[0050] FIG. 1 schematically illustrates the energy ranges and the
dose ranges of a typical serial-type high-dose high-current ion
implantation apparatus HC, a serial-type medium-dose medium-current
ion implantation apparatus MC, and a serial-type high-energy ion
implantation apparatus HE. In FIG. 1, a horizontal axis represents
the dose, and a vertical axis represents the energy. The dose is
the number of ions (atoms) implanted per unit area (for example,
cm.sup.2), and the total amount of implanted material is provided
by a time integral of ion current. The ion current provided by the
ion implantation is generally expressed as mA or .mu.A. The dose is
also referred to as an implantation amount or a dose amount. In
FIG. 1, the energy and dose ranges of the HC, the MC, and the HE
are indicated by symbols A, B, and C, respectively. These are a set
range of implantation conditions required according to implantation
conditions (also called a recipe) for each implantation, and
represent practically reasonable apparatus configuration categories
matched with the implantation conditions (recipe), considering
practically allowable productivity. Each of the illustrated ranges
represents an implantation condition (recipe) range that can be
processed by the apparatus of each category. The dose amount
represents an approximate value when a realistic processing time is
assumed.
[0051] The HC is used for ion implantation in a relatively low
energy range of about 0.1 to 100 keV and in a high dose range of
about 1.times.10.sup.14 to 1.times.10.sup.17 atoms/cm.sup.2. The MC
is used for ion implantation in a medium energy range of about 3 to
500 keV and in a medium dose range of about 1.times.10.sup.11 to
1.times.10.sup.14 atoms/cm.sup.2. The HE is used for ion
implantation in a relatively high energy range of about 100 keV to
5 MeV and in a relatively low dose range of about 1.times.10.sup.10
to 1.times.10.sup.13 atoms/cm.sup.2. In this way, the broad ranges
of the implantation conditions having about five digits for the
energy range and about seven digits for the dose ranges are shared
by the HC, the MC, and the HE. However, these energy ranges or dose
ranges are a representative example, and are not strict. Also, the
way of providing the implantation conditions is not limited to the
dose and the energy, but is various. The implantation conditions
may be set by a beam current value (representing an area integral
beam amount of a beam cross-sectional profile by a current), a
throughput, implantation uniformity, and the like.
[0052] Since the implantation conditions for ion implantation
processing include particular values of energy and dose, the
implantation conditions can be expressed as individual points in
FIG. 1. For example, an implantation condition a has values of a
high energy and a low dose. The implantation condition a is in the
operating range of the MC and is also in the operating range of the
HE. The ion implantation can be processed accordingly using the MC
or the HE. An implantation condition b is a medium energy/dose and
the ion implantation can be processed by one of the HC, MC, and HE.
An implantation condition c is a medium energy/dose and the ion
implantation can be processed by the HC or the MC. An implantation
condition d is a low energy/a high dose and can be processed by
only the HC.
[0053] The ion implantation apparatus is an equipment essential to
the production of semiconductor devices, and the improvement of
performance and productivity thereof has an important meaning to a
device maker. The device maker selects an apparatus, which is
capable of realizing implantation characteristics necessary for a
device to be manufactured, among a plurality of ion implantation
apparatus categories. At this time, the device maker determines the
number of apparatuses of the category, considering various
circumstances such as the realization of the best manufacturing
efficiency, the cost of ownership of the apparatus, and the
like.
[0054] It is assumed that an apparatus of a certain category is
used at a high operating rate and an apparatus of another category
has a relatively sufficient processing capacity. At this time, if
the former apparatus cannot be replaced with the latter apparatus
in order to obtain a desired device because implantation
characteristics are strictly different for each category, the
failure of the former apparatus cause a bottleneck on production
processes, and thus overall productivity is impaired. Such trouble
may be avoided to some extent by assuming a failure rate and the
like in advance and determining a number configuration based on
that.
[0055] When a manufacturing device is changed due to a change in
demand or a technical advance and the number configuration of
necessary apparatuses is changed, apparatuses become lacking or a
non-operating apparatus occurs and thus an operating efficiency of
the apparatuses may be reduced. Such trouble may be avoided to some
extent by predicting the trend of future products and reflecting
the predicted trend to the number configuration.
[0056] Even though the apparatus can be replaced with an apparatus
of another category, the failure of the apparatus or the change of
the manufacturing device may reduce the production efficiency or
lead to wasted investment for the device maker. For example, in
some cases, a manufacturing process having been mainly processed
till now by a medium-current ion implantation apparatus is
processed by a high-current ion implantation apparatus due to the
change of the manufacturing device. If doing so, the processing
capacity of the high-current ion implantation apparatus becomes
lacking, and the processing capacity of the medium-current ion
implantation apparatus becomes surplus. If it is expected that the
state after the change will not change for a long period of time,
the operating efficiency of the apparatus can be improved by taking
measures of purchasing a new high-current ion implantation
apparatus and selling the medium-current ion implantation apparatus
having been owned. However, when a process is frequently changed,
or such a change is difficult to predict, a trouble may be caused
in production.
[0057] In practice, a process having already been performed in an
ion implantation apparatus of a certain category in order to
manufacture a certain device cannot be immediately used in an ion
implantation apparatus of another category. This is because a
process of matching device characteristics on the ion implantation
apparatus is required. That is, device characteristics obtained by
performing a process with the same ion species, energy, and dose
amount in the new ion implantation apparatus may be significantly
different from device characteristics obtained in the previous ion
implantation apparatus. Various conditions other than the ion
species, the energy, and the dose amount, for example, a beam
current density (that is, a dose rate), an implantation angle, or
an overspray method of an implantation region, also affect the
device characteristics. Generally, when the categories are
different, apparatus configurations also are different. Therefore,
even though the ion species, the energy, and the dose amount are
specified, it is impossible to automatically match the other
conditions affecting the device characteristics. These conditions
depend on implantation methods. Examples of the implantation
methods include a method of relative movement between a beam and a
workpiece (for example, a scanning beam, a ribbon beam, a
two-dimensional wafer scanning, or the like), a batch type and a
serial type to be described below.
[0058] In addition, rough classification of the high-dose
high-current ion implantation apparatus and the high-energy ion
implantation apparatus into a batch type and the medium-dose
medium-current ion implantation apparatus into a serial type also
increases a difference between the apparatuses. The batch type is a
method of processing a plurality of wafers at one time, and these
wafers are disposed on, for example, the circumference. The serial
type is a method of processing wafers one by one and is also called
a single wafer type. Also, in some cases, the high-dose
high-current ion implantation apparatus and the high-energy ion
implantation apparatus are configured as the serial type.
[0059] Also, a beamline of the batch-type high-dose high-current
ion implantation apparatus is typically made shorter than that of
the serial-type medium-dose medium-current ion implantation
apparatus by a request on beamline design according to high-dose
high-current beam characteristics. This is done for suppressing
beam loss caused by divergence of ion beams in a low energy/high
beam current condition in the design of the high-dose high-current
beamline. In particular, this is done for reducing a tendency to
expand outward in a radial direction, so-called a beam blow-up,
because ions forming the beam include charged particles repelling
each other. The necessity for such design is more remarkable when
the high-dose high-current ion implantation apparatus is the batch
type than when that is the serial type.
[0060] The beamline of the serial-type medium-dose medium-current
ion implantation apparatus is made relatively long for ion beam
acceleration or beam forming. In the serial-type medium-dose
medium-current ion implantation apparatus, ions having considerable
momentum are moving at high speed. The momentum of the ions
increases while the ions pass through one or several of
acceleration gaps added to the beamline. Also, in order to modify a
trajectory of particles having considerable momentum, a focusing
portion needs to be relatively long enough to fully apply a
focusing power.
[0061] Since the high-energy ion implantation apparatus adopts a
linear acceleration method or a tandem acceleration method, it is
essentially different from an acceleration method of the high-dose
high-current ion implantation apparatus or the medium-dose
medium-current ion implantation apparatus. This essential
difference is equally applied when the high-energy ion implantation
apparatus is the serial type or the batch type.
[0062] As such, the ion implantation apparatuses HC, MC and HE are
recognized as completely different apparatuses because the beamline
types or the implantation methods are different according to
categories. A difference in configuration between apparatuses of
different categories is recognized as inevitable. Among the
different types of apparatuses such as HC, MC and HE, process
compatibility considering the influence on the device
characteristics is not guaranteed.
[0063] Therefore, it is preferable that the ion implantation
apparatus has a broader energy range and/or dose range than the
apparatus of the existing category. In particular, it is desirable
to provide an ion implantation apparatus capable of implantation in
a broad range of energy and dose amount including at least two
existing categories, without changing the type of the implantation
apparatus.
[0064] Also, in recent years, the mainstream is that all
implantation apparatuses adopt the serial type. It is therefore
desirable to provide an ion implantation apparatus that has a
serial-type configuration and also has a broad energy range and/or
dose range.
[0065] Also, the HE uses an essentially different acceleration
method, and the HC and the MC are common in that ion beams are
accelerated or decelerated by a DC voltage. Therefore, there is a
probability that the HC and the MC can share the beamline. It is
therefore desirable to provide an ion implantation apparatus that
can serve as both the HC and the MC.
[0066] The apparatus capable of operating at a broad range helps to
improve productivity or operating efficiency in view of device
makers.
[0067] Also, the medium-current ion implantation apparatus MC can
operate in a high energy range and a low dose range as compared
with the high-current ion implantation apparatus HC. Therefore, in
this application, the medium-current ion implantation apparatus MC
is also referred to as a low-current ion implantation apparatus.
Likewise, regarding the medium-current ion implantation apparatus
MC, the energy and the dose are also referred to as high energy and
low dose, respectively. Alternatively, regarding the high-current
ion implantation apparatus HC, the energy and the dose are also
referred to as low energy and high dose, respectively. However,
these expressions in this application are not intended to
restrictively indicate only the energy range and the dose range of
the medium-current ion implantation apparatus MC, but may mean "a
high (or low) energy (or dose) range" literally according to the
context.
[0068] FIG. 2 is a diagram schematically illustrating an ion
implantation apparatus 100 according to an embodiment of the
present invention. The ion implantation apparatus 100 is configured
to perform ion implantation processing on a surface of a workpiece
W according to given ion implantation conditions. The ion
implantation conditions include, for example, an ion species to be
implanted into the workpiece W, an ion dose amount, and ion energy.
The workpiece W is, for example, a substrate, or, for example, a
wafer. Therefore, in the following, the workpiece W is also
referred to as a substrate W for convenience of description. This
is not intended to limit a target of the implantation processing to
a particular object.
[0069] The ion implantation apparatus 100 includes an ion source
102, a beamline device 104, and an implantation processing chamber
106. Also, the ion implantation apparatus 100 includes a vacuum
exhaust system (not illustrated) for providing desired vacuum
environments to the ion source 102, the beamline device 104, and
the implantation processing chamber 106.
[0070] The ion source 102 is configured to generate ions to be
implanted into the substrate W. The ion source 102 provides the
beamline device 104 with an ion beam B1 accelerated and extracted
from the ion source 102 by an extraction electrode unit 118 that is
an example of a component for adjusting a beam current.
Hereinafter, this may be also referred to as an initial ion beam
B1.
[0071] The beamline device 104 is configured to transport ions from
the ion source 102 to the implantation processing chamber 106. The
beamline device 104 provides a beamline for transporting the ion
beam. The beamline is a passage of the ion beam and may be also
said as a path of beam trajectory. The beamline device 104 performs
operations including deflection, acceleration, deceleration,
shaping, and scanning, with respect to the initial ion beam B1,
thereby forming an ion beam B2. Hereinafter, this may be also
referred to as an implantation ion beam B2. The beamline device 104
includes a plurality of beamline components arranged for such beam
operations. In this manner, the beamline device 104 provides the
implantation processing chamber 106 with the implantation ion beam
B2.
[0072] The implantation ion beam B2 has a beam irradiation region
105 in the plane perpendicular to a beam transport direction (or a
direction along a beam trajectory) of the beamline device 104.
Generally, the beam irradiation region 105 has a width including
the width of the substrate W. For example, when the beamline device
104 includes a beam scanning device scanning a spot-shaped ion
beam, the beam irradiation region 105 is an elongated irradiation
region extending over a scanning range along a longitudinal
direction perpendicular to the beam transport direction. Also,
likewise, when the beamline device 104 includes a ribbon beam
generator, the beam irradiation region 105 is an elongated
irradiation region extending in a longitudinal direction
perpendicular to the beam transport direction. However, the
elongated irradiation region is a cross-section of a corresponding
ribbon beam. The elongated irradiation region is longer than the
width (diameter when the substrate W is circular) of the substrate
W in a longitudinal direction.
[0073] The implantation processing chamber 106 includes a workpiece
holder 107 holding the substrate W such that the substrate W
receives the implantation ion beam B2. The workpiece holder 107 is
configured to move the substrate W in a direction perpendicular to
the beam transport direction of the beamline device 104 and the
longitudinal direction of the beam irradiation region 105. That is,
the workpiece holder 107 provides a mechanical scan of the
substrate W. In this application, the mechanical scan is the same
as reciprocating motion. Also, the "perpendicular direction" is not
limited to only a strict right angle. For example, when the
implantation is performed in a state in which the substrate W is
inclined in a vertical direction, the "perpendicular direction" may
include such an inclined angle.
[0074] The implantation processing chamber 106 is configured as a
serial-type implantation processing chamber. Therefore, the
workpiece holder 107 typically holds one sheet of the substrate W.
However, like the batch type, the workpiece holder 107 may include
a support holding a plurality of (for example, small) substrates,
and may be configured to mechanically scan the plurality of
substrates by linearly reciprocating the support. In another
embodiment, the implantation processing chamber 106 may be
configured as a batch-type implantation processing chamber. In this
case, for example, the workpiece holder 107 may include a rotating
disk that rotatably holds a plurality of substrates W on the
circumference of the disk. The rotating disk may be configured to
provide a mechanical scanning.
[0075] FIG. 3 illustrates an example of the beam irradiation region
105 and the relevant mechanical scanning. The ion implantation
apparatus 100 is configured to perform ion implantation by a hybrid
scanning method using both one-dimensional beam scanning S.sub.B of
the spot-shaped ion beam B2 and one-dimensional mechanical scanning
S.sub.M of the substrate W. On the side of the workpiece holder
107, a beam measurement device 130 (for example, Faraday cup) is
provided to overlap the beam irradiation region 105, and the
measurement result may be provided to a control unit 116.
[0076] In this manner, the beamline device 104 is configured to
supply the implantation processing chamber 106 with the
implantation ion beam B2 having the beam irradiation region 105.
The beam implantation region 105 is formed to irradiate the
implantation ion beam B2 across the substrate W in cooperation with
the mechanical scanning of the substrate W. Therefore, ions can be
implanted into the substrate W by the relative movement of the
substrate W and the ion beam.
[0077] In another embodiment, the ion implantation apparatus 100 is
configured to perform ion implantation by a ribbon beam+wafer
scanning method using both the ribbon-shaped ion beam B2 and the
one-dimensional mechanical scanning of the substrate W. The
horizontal width of the ribbon beam is expanded while maintaining
uniformity, and the substrate W is scanned so as to intersect with
the ribbon beam. In a further embodiment, the ion implantation
apparatus 100 may be configured to perform ion implantation by a
method of two-dimensionally mechanically scanning the substrate W
in a state in which the beam trajectory of the spot-shaped ion beam
B2 is fixed.
[0078] Also, the ion implantation apparatus 100 is not limited to a
particular implantation method for implanting ions across a broad
region on the substrate W. An implantation method using no
mechanical scanning is also possible. For example, the ion
implantation apparatus 100 may be configured to perform ion
implantation by a two-dimensional beam scanning method of
two-dimensionally scanning the substrate W with the spot-shaped ion
beam B2. Alternatively, the ion implantation apparatus 100 may be
configured to perform ion implantation by a large-size beam method
using the two-dimensionally expanded ion beam B2. The large-size
beam is expanded to make a beam size equal to or larger than a
substrate size while maintaining uniformity, and can process the
entire substrate at one time.
[0079] Although details will be described below, the ion
implantation apparatus 100 may be operated under a first beamline
setting S1 for high-dose implantation or a second beamline setting
S2 for low-dose implantation. Therefore, the beamline device 104
has the first beamline setting S1 or the second beamline setting S2
during operations. The two settings are determined to generate the
ion beams for different ion implantation conditions under the
common implantation method. Thus, in the first beamline setting S1
and the second beamline setting S2, the beam center trajectories
being the reference of the ion beams B1 and B2 are identical to
each other. The beam irradiation regions 105 are also identical to
each other in the first beamline setting S1 and the second beamline
setting S2.
[0080] The beam center trajectory being the reference refers to a
beam trajectory when beam is not scanned in the beam scanning
method. Also, in the case of the ribbon beam, the beam center
trajectory being the reference corresponds to a locus of a
geometric center of a beam cross-section.
[0081] The beamline device 104 may be divided into a beamline
upstream part on the ion source 102 side and a beamline downstream
part on the implantation processing chamber 106 side. In the
beamline upstream part, for example, a mass spectrometer 108
including a mass analysis magnet and a mass analysis slit is
provided. The mass spectrometer 108 performs mass spectrometry on
the initial ion beam B1 and provides only necessary ion species to
the beamline downstream part. In the beamline downstream part, for
example, a beam irradiation region determination unit 110 is
provided to determine the beam irradiation region 105 of the
implantation ion beam B2.
[0082] The beam irradiation region determination unit 110 is
configured to emit the ion beam having the beam irradiation region
105 (for example, the implantation ion beam B2) by applying either
(or both) of an electric field and a magnetic field to the incident
ion beam (for example, the initial ion beam B1). In an embodiment,
the beam irradiation region determination unit 110 includes abeam
scanning device and a beam parallelizing device. Examples of the
beamline components will be described below with reference to FIG.
5.
[0083] Also, it should be understood that the division into the
upstream part and the downstream part, as above-described, is
mentioned for conveniently describing a relative position
relationship of the components in the beamline device 104.
Therefore, for example, a component in the beamline downstream part
may be disposed at a place closer to the ion source 102 than the
position described above. The opposite holds true as well.
Therefore, in an embodiment, the beam irradiation region
determination unit 110 may include a ribbon beam generator and a
beam parallelizing device, and the ribbon beam generator may
include the mass spectrometer 108.
[0084] The beamline device 104 includes an energy adjustment system
112 and a beam current adjustment system 114. The energy adjustment
system 112 is configured to adjust implantation energy to the
substrate W. The beam current adjustment system 114 is configured
to adjust the beam current in a broad range so as to change a dose
amount implanted into the substrate W in a broad range. The beam
current adjustment system 114 is provided to adjust the beam
current of the ion beam quantitatively (rather than qualitatively).
In an embodiment, the adjustment of the ion source 102 can be also
used to adjust the beam current. In this case, the beam current
adjustment system 114 may be considered to include the ion source
102. Details of the energy adjustment system 112 and the beam
current adjustment system 114 will be described below.
[0085] Also, the ion implantation apparatus 100 includes a control
unit 116 for controlling all or part of the ion implantation
apparatus 100 (for example, all or part of the beamline device
104). The control unit 116 is configured to select any one from a
plurality of beamline settings including the first beamline setting
S1 and the second beamline setting S2, and operate the beamline
device 104 under the selected beamline setting. Specifically, the
control unit 116 sets the energy adjustment system 112 and the beam
current adjustment system 114 according to the selected beamline
setting, and controls the energy adjustment system 112 and the beam
current adjustment system 114. Also, the control unit 116 may be a
dedicated controller for controlling the energy adjustment system
112 and the beam current adjustment system 114.
[0086] The control unit 116 is configured to select a beamline
setting suitable for given ion implantation conditions among the
plurality of beamline settings including the first beamline setting
S1 and the second beamline setting S2. The first beamline setting
S1 is suitable for transport of a high-current beam for high-dose
implantation into the substrate W. Therefore, for example, the
control unit 116 selects the first beamline setting S1 when a
desired ion dose amount implanted into the substrate W is in the
range of about 1.times.10.sup.14 to 1.times.10.sup.17
atoms/cm.sup.2. Also, the second beamline setting S2 is suitable
for transport of a low-current beam for low-dose implantation into
the substrate. Therefore, for example, the control unit 116 selects
the second beamline setting S2 when a desired ion dose amount
implanted into the substrate W is in the range of about
1.times.10.sup.11 to 1.times.10.sup.14 atoms/cm.sup.2. Details of
the beamline settings will be described below.
[0087] The energy adjustment system 112 includes a plurality of
energy adjustment elements arranged along the beamline device 104.
The plurality of energy adjustment elements is disposed at fixed
positions on the beamline device 104. As illustrated in FIG. 2, the
energy adjustment system 112 includes, for example, three
adjustment elements, specifically, an upstream adjustment element
118, an intermediate adjustment element 120, and a downstream
adjustment element 122. Each of these adjustment elements includes
one or more electrodes configured to exert an electric field for
accelerating or decelerating the initial ion beam B1 and/or the
implantation ion beam B2.
[0088] The upstream adjustment element 118 is provided in the
upstream part of the beamline device 104, for example, the most
upstream part of the beamline device 104. The upstream adjustment
element 118 includes, for example, an extraction electrode system
for extracting the initial ion beam B1 from the ion source 102 to
the beamline device 104. The intermediate adjustment element 120 is
installed in the middle portion of the beamline device 104 and
includes, for example, an electrostatic beam parallelizing device.
The downstream adjustment element 122 is provided in the downstream
part of the beamline device 104 and includes, for example, an
acceleration/deceleration column. The downstream adjustment element
122 may include an angular energy filter (AEF) disposed in the
downstream of the acceleration/deceleration column.
[0089] Also, the energy adjustment system 112 includes a power
supply system for the above-described energy adjustment elements.
This will be described below with reference to FIGS. 6 and 7. Also,
the plurality of energy adjustment elements may be provided in any
number anywhere on the beamline device 104, which is not limited to
the illustrated arrangement. Also, the energy adjustment system 112
may include only one energy adjustment element.
[0090] The beam current adjustment system 114 is provided in the
upstream part of the beamline device 104, and includes a beam
current adjustment element 124 for adjusting the beam current of
the initial ion beam B1. The beam current adjustment element 124 is
configured to block at least a portion of the initial ion beam B1
when the initial ion beam B1 passes through the beam current
adjustment element 124. In an embodiment, the beam current
adjustment system 114 may include a plurality of current adjustment
elements 124 arranged along the beamline device 104. Also, the beam
current adjustment system 114 may be provided in the downstream
part of the beamline device 104.
[0091] The beam current adjustment element 124 includes a movable
portion for adjusting a passage region of the ion beam
cross-section perpendicular to the beam transport direction of the
beamline device 104. According to the movable portion, the beam
current adjustment element 124 constitutes a beam limiting device
having a variable-width slit or a variable-shape opening for
limiting a portion of the initial ion beam B1. Also, the beam
current adjustment system 114 includes a driving device for
continuously or discontinuously adjusting the movable portion of
the beam current adjustment element 124.
[0092] Additionally or alternatively, the beam current adjustment
element 124 may include a plurality of adjustment members (for
example, adjustment aperture) each having a plurality of beam
passage regions having different areas and/or shapes. The beam
current adjustment element 124 may be configured to switch the
adjustment member disposed on the beam trajectory among the
plurality of adjustment members. In this manner, the beam current
adjustment element 124 may be configured to adjust the beam current
stepwise.
[0093] As illustrated, the beam current adjustment element 124 is a
beamline component separate from the plurality of energy adjustment
elements of the energy adjustment system 112. By separately
installing the beam current adjustment element and the energy
adjustment element, the beam current adjustment and the energy
adjustment may be individually performed. This may increase the
degree of freedom in the setting of the beam current range and the
energy range in the individual beamline settings.
[0094] The first beamline setting S1 includes a first energy
setting for the energy adjustment system 112 and a first beam
current setting for the beam current adjustment system 114. The
second beamline setting S2 includes a second energy setting for the
energy adjustment system 112 and a second beam current setting for
the beam current adjustment system 114. The first beamline setting
S1 is directed to the low-energy and high-dose ion implantation,
and the second beamline setting S2 is directed to the high-energy
and low-dose ion implantation.
[0095] Therefore, the first energy setting is determined to be
suitable for the transport of the low-energy beam as compared with
the second energy setting. Also, the second beam current setting is
determined to reduce the beam current of the ion beam as compared
with the first beam current setting. By combining the beam current
adjustment and the irradiation time adjustment of the implantation
ion beam B2, a desired dose amount can be implanted into the
substrate W.
[0096] The first energy setting includes a first power supply
connection setting that determines the connection between the
energy adjustment system 112 and the power supply system thereof.
The second energy setting includes a second power supply connection
setting that determines the connection between the energy
adjustment system 112 and the power supply system thereof. The
power supply connection settings are determined such that the
intermediate adjustment element 120 and/or the downstream
adjustment element 122 generate an electric field for helping the
beam transport. For example, the beam parallelizing device and/or
the acceleration/deceleration column, as a whole, are configured to
decelerate the implantation ion beam B2 under the first energy
setting and accelerate the implantation ion beam B2 under the
second energy setting. Due to the power supply connection settings,
a voltage adjustment range of each adjustment element of the energy
adjustment system 112 is determined. In the adjustment range, a
voltage of the power supply corresponding to each adjustment
element can be adjusted to provide a desired implantation energy to
the implantation ion beam B2.
[0097] The first beam current setting includes a first opening
setting that determines the ion beam passage region of the beam
current adjustment element 124. The second beam current setting
includes a second opening setting that determines the ion beam
passage region of the beam current adjustment element 124. The
second opening setting is determined such that the ion beam passage
region is small as compared with the first opening setting. The
opening settings determine, for example, the movable range of the
movable portion of the beam current adjustment element 124.
Alternatively, the opening settings may determine the adjustment
member to be used. In this manner, the ion beam passage region
corresponding to the desired beam current within the adjustment
range determined by the opening settings may be set to the beam
current adjustment element 124. The ion beam passage region can be
adjusted such that a desired dose amount is implanted into the
substrate W within a processing time permitted to the ion
implantation processing.
[0098] Thus, the beamline device 104 has a first energy adjustment
range under the first beamline setting S1 and has a second energy
adjustment range under the second beamline setting S2. In order to
enable a broad range of the adjustment, the first energy adjustment
range has a portion overlapping the second energy adjustment range.
That is, two adjustment ranges overlap each other in at least the
ends thereof. The overlapping portion may be a straight-line in the
diagram schematically illustrating range of an energy and dose of
ion implantation apparatuses. In this case, two adjustment ranges
contact each other. In another embodiment, the first energy
adjustment range may be separated from the second energy adjustment
range.
[0099] Likewise, the beamline device 104 has a first dose
adjustment range under the first beamline setting S1 and has a
second dose adjustment range under the second beamline setting S2.
The first dose adjustment range has a portion overlapping the
second dose adjustment range. That is, two adjustment ranges
overlap each other in at least the ends thereof. The overlapping
portion may be a straight-line in the diagram schematically
illustrating range of an energy and dose of ion implantation
apparatuses. In this case, two adjustment ranges contact each
other. In another embodiment, the first dose adjustment range may
be separated from the second dose adjustment range.
[0100] In this manner, the beamline device 104 is operated in a
first operation mode under the first beamline setting S1. The first
operation mode may be referred to as a low-energy mode (or a
high-dose mode). Also, the beamline device 104 is operated in a
second operation mode under the second beamline setting S2. The
second operation mode may be referred to as a high-energy mode (or
a low-dose mode). The first beamline setting S1 can be also
referred to as a first implantation setting configuration suitable
for the transport of a low-energy/high-current beam for the
high-dose implantation into the workpiece W. The second beamline
setting S2 can be also referred to as a second implantation setting
configuration suitable for the transport of a
high-energy/low-current beam for the low-dose implantation into the
workpiece W.
[0101] An operator of the ion implantation apparatus 100 can switch
the beamline settings before a certain ion implantation processing
is performed, depending on the implantation conditions of the
processing. Therefore, the broad range from the low-energy (or
high-dose) to the high-energy (or low-dose) can be processed by one
ion implantation apparatus.
[0102] Also, the ion implantation apparatus 100 corresponds to the
broad range of the implantation conditions in the same implantation
method. That is, the ion implantation apparatus 100 processes
abroad range with substantially the same beamline device 104. Also,
the ion implantation apparatus 100 has the serial-type
configuration that is recently becoming the mainstream. Therefore,
although details will be described below, the ion implantation
apparatus 100 is suitable for use as a shared unit of the existing
ion implantation apparatuses (for example, HC and MC).
[0103] The beamline device 104 can also be considered to include
abeam control device for controlling the ion beam, a beam
conditioning device for conditioning the ion beam, and a beam
shaping device for shaping the ion beam. The beamline device 104
supplies the ion beam having the beam irradiation region 105
exceeding the width of the workpiece W in the implantation
processing chamber 106 by using the beam control device, the beam
conditioning device, and the beam shaping device. In the ion
implantation apparatus 100, the beam control device, the beam
conditioning device, and the beam shaping device may have the same
hardware configuration in the first beamline setting S1 and the
second beamline setting S2. In this case, the beam control device,
the beam conditioning device, and the beam shaping device may be
disposed with the same layout in the first beamline setting S1 and
the second beamline setting S2. Therefore, the ion implantation
apparatus 100 may have the same installation floor area (so-called
footprint) in the first beamline setting S1 and the second beamline
setting S2.
[0104] The beam center trajectory being the reference is a beam
trajectory that is a locus of geometric center of the beam
cross-section without beam scanning in the beam scanning method.
Also, in the case of the ribbon beam that is a stationary beam, the
beam center trajectory being the reference corresponds to a locus
of a geometric center of the beam cross-section, regardless of a
change in the beam cross-sectional shape in the implantation ion
beam B2 of the downstream part.
[0105] The beam control device may include the control unit 116.
The beam conditioning device may include the beam irradiation
region determination unit 110. The beam conditioning device may
include an energy filter or a deflection element. The beam shaping
device may include a first XY convergence lens 206, a second XY
convergence lens 208, and a Y convergence lens 210, which are to be
described below.
[0106] It can be considered that, in the case of the beam scanning
method, the initial ion beam B1 takes a single beam trajectory in
the upstream part of the beamline device 104, and in the downstream
part the implantation ion beam B2 takes a plurality of beam
trajectories due to the beam scanning and parallelizing with
reference to the beam center trajectory being the reference.
However, in the case of the ribbon beam, it becomes a beam
irradiation zone because the beam cross-sectional shape of the
single beam trajectory is changed and the beam width is widened.
Thus, the beam trajectory is also single. According to this view,
the beam irradiation region 105 may be also referred to as an ion
beam trajectory zone. Therefore, in the ion implantation apparatus
100, the implantation ion beam B2 has the same ion beam trajectory
zone in the first beamline setting S1 and the second beamline
setting S2.
[0107] FIG. 4 is a flowchart illustrating an ion implantation
method according to an embodiment of the present invention. This
ion implantation method is suitable for use in the ion implantation
apparatus 100. This method is performed by the control unit 116. As
illustrated in FIG. 4, this method includes a beamline setting
selecting step (S10) and an ion implantation step (S20).
[0108] The control unit 116 selects a beamline setting suitable
forgiven ion implantation conditions among a plurality of beamline
settings (S10). As described above, the plurality of beamline
settings includes a first beamline setting S1 suitable for
transport of a high-current beam for high-dose implantation into a
workpiece, and a second beamline setting S2 suitable for transport
of a low-current beam for low-dose implantation into a workpiece.
For example, the control unit 116 selects the first beamline
setting S1 when a desired ion dose amount implanted into a
substrate W exceeds a threshold value, and selects the second
beamline setting S2 when the desired ion dose amount is smaller
than the threshold value. Also, as described below, the plurality
of beamline settings (or implantation setting configurations) may
include a third beamline setting (or third implantation setting
configuration) and/or a fourth beamline setting (or fourth
implantation setting configuration).
[0109] When the first beamline setting S1 is selected, the control
unit 116 sets the energy adjustment system 112 by using the first
energy setting. The energy adjustment system 112 and the power
supply thereof are connected according to a first power supply
connection setting. Also, the control unit 116 sets the beam
current adjustment system. 114 by using the first beam current
setting. Therefore, the ion beam passage region (or adjustment
range thereof) is set according to the first opening setting.
Likewise, when the second beamline setting S2 is selected, the
control unit 116 sets the energy adjustment system 112 by using the
second energy setting, and sets the beam current adjustment system
114 by using the second beam current setting.
[0110] The selecting process step may include a process step of
adjusting the beamline device 104 in the adjustment range according
to the selected beamline setting. In the adjusting process step,
each adjustment element of the beamline device 104 is adjusted
within a corresponding adjustment range so as to generate the ion
beam of a desired implantation condition. For example, the control
unit 116 determines a voltage of a power supply corresponding to
each adjustment element of the energy adjustment system 112 so as
to obtain a desired implantation energy. Also, the control unit 116
determines the ion beam passage region of the beam current
adjustment element 124 so as to obtain a desired implantation dose
amount.
[0111] In this manner, the control unit 116 operates the ion
implantation apparatus 100 under the selected beamline setting
(S20). The implantation ion beam B2 having the beam irradiation
region 105 is generated and supplied to the substrate W. The
implantation ion beam B2 scans the entire substrate W in
cooperation with the mechanical scanning of the substrate W (or
with the beam alone). As a result, ions are implanted into the
substrate W at the energy and dose amount of the desired ion
implantation conditions.
[0112] The serial-type high-dose high-current ion implantation
apparatus, which is being used in device production, currently
adopts a hybrid scanning method, a two-dimensional mechanical
scanning method, and a ribbon beam+wafer scanning method. However,
the two-dimensional mechanical scanning method has a limitation in
increase of a scanning speed due to a load of mechanical driving
mechanism of the mechanical scanning, and thus, the two-dimensional
mechanical scanning method disadvantageously cannot suppress
implantation non-uniformity sufficiently. Also, in the ribbon
beam+wafer scanning method, uniformity is easily degraded when the
beam size is expanded in a horizontal direction. Therefore, in
particular, there are problems in the uniformity and the identity
of beam angle in the low-dose condition (low beam current
condition). However, when the obtained implantation result is
within an allowable range, the ion implantation apparatus of the
present invention may be configured by the two-dimensional
mechanical scanning method or the ribbon beam+wafer scanning
method.
[0113] On the other hand, the hybrid scanning method can achieve
excellent uniformity in the beam scanning direction by adjusting
the bean scanning speed at high accuracy. Also, by performing the
beam scanning at a sufficient high speed, implantation
non-uniformity in the wafer scanning direction can be sufficiently
suppressed. Therefore, the hybrid scanning method is considered as
optimal over a broad range of the dose condition.
[0114] FIG. 5A is a plan view illustrating a schematic
configuration of an ion implantation apparatus 200 according to an
embodiment of the present invention, and FIG. 5B is a side view
illustrating a schematic configuration of an ion implantation
apparatus 200 according to an embodiment of the present invention.
The ion implantation apparatus 200 is an embodiment when the hybrid
scanning method is applied to the ion implantation apparatus 100
illustrated in FIG. 2. Also, like the ion implantation apparatus
100 illustrated in FIG. 2, the ion implantation apparatus 200 is a
serial-type apparatus.
[0115] As illustrated, the ion implantation apparatus 200 includes
a plurality of beamline components. The beamline upstream part of
the ion implantation apparatus 200 includes, in order from the
upstream side, an ion source 201, a mass analysis magnet 202, a
beam dump 203, a resolving aperture 204, a current suppression
mechanism 205, a first XY convergence lens 206, a beam current
measurement device 207, and a second XY convergence lens 208. An
extraction electrode 218 (see FIGS. 6 and 7) for extracting ions
from the ion source 201 is provided between the ion source 201 and
the mass analysis magnet 202.
[0116] A scanner 209 is provided between the beamline upstream part
and the beamline downstream part. The beamline downstream part
includes, in order from the upstream side, a Y convergence lens
210, a beam parallelizing mechanism 211, an AD (Accel/Decel) column
212, and an energy filter 213. A wafer 214 is disposed in the most
downstream part of the beamline downstream part. The beamline
components from the ion source 201 to the beam parallelizing
mechanism 211 are accommodated in a terminal 216.
[0117] The current suppression mechanism 205 is an example of the
above-described beam current adjustment system 114. The current
suppression mechanism 205 is provided for switching a low-dose mode
and a high-dose mode. The current suppression mechanism 205
includes, for example, a continuously variable aperture (CVA). The
CVA is an aperture capable of adjusting an opening size by a
driving mechanism. Therefore, the current suppression mechanism 205
is configured to operate in a relatively small opening size
adjustment range in the low-dose mode, and operate in a relatively
large opening size adjustment range in the high-dose mode. In an
embodiment, in addition or alternative to the current suppression
mechanism 205, a plurality of resolving apertures 204 having
different opening widths may be configured to operate with
different settings in the low-dose mode and the high-dose mode.
[0118] The current suppression mechanism 205 serves to help beam
adjustment under the low beam current condition by limiting an ion
beam amount arriving at the downstream. The current suppression
mechanism 205 is provided in the beamline upstream part (that is,
from the ion extraction from the ion source 201 to the upstream
side of the scanner 209). Therefore, the beam current adjustment
range can be increased. Also, the current suppression mechanism 205
may be provided in the beamline downstream part.
[0119] The beam current measurement device 207 is, for example, a
movable flag Faraday.
[0120] The first XY convergence lens 206, the second XY convergence
lens 208, and the Y convergence lens 210 constitute the beam
shaping device for adjusting the beam shape in the vertical and
horizontal directions (beam cross-section in an XY plane). As such,
the beam shaping device includes a plurality of lenses arranged
along the beamline between the mass analysis magnet 202 and the
beam parallelizing mechanism 211. The beam shaping device can use
the convergence/divergence effect of these lenses in order to
appropriately transport the ion beam up to the downstream in a
broad range of energy/beam current condition. That is, the ion beam
can be appropriately transported to the wafer 214 in any condition
of low energy/low beam current, low energy/high beam current, high
energy/low beam current, and high energy/high beam current.
[0121] The first XY convergence lens 206 is, for example, a Q lens.
The second XY convergence lens 208 is, for example, an XY-direction
einzel lens. The Y convergence lens 210 is, for example, a
Y-direction einzel lens or Q lens. Each of the first XY convergence
lens 206, the second XY convergence lens 208, and the Y convergence
lens 210 may be a single lens or a group of lenses. In this manner,
the beam shaping device is designed to appropriately control the
ion beam from the low energy/high beam current condition having a
beam self-divergence problem caused by a large beam potential to
the high energy/low beam current having a beam cross-sectional
shape control problem caused by a small beam potential.
[0122] The energy filter 213 is, for example, an angular energy
filter (AEF) having a deflection electrode or a deflection
electromagnet, or both of the defection electrode and the
deflection electromagnet.
[0123] The ions generated in the ion source 201 are accelerated
with an extraction electric field (not illustrated). The
accelerated ions are deflected in the mass analysis magnet 202. In
this manner, only ions having a predetermined energy and a
mass-to-charge ratio pass through the resolving aperture 204.
Subsequently, the ions are guided to the scanner 209 through the
current suppression mechanism (CVA) 205, the first XY convergence
lens 206, and the second XY convergence lens 208.
[0124] The scanner 209 reciprocally scans the ion beam in a
horizontal direction (which may be a vertical direction or an
oblique direction) by applying either (or both) of a periodic
electric field and a periodic magnetic field. Due to the scanner
209, the ion beam is adjusted such that the ion beam is uniformly
implanted in a horizontal direction on the wafer 214. The traveling
direction of the ion beam 215 with which the scanner 209 scans can
be parallelized by the beam parallelizing mechanism 211 using the
application of either (or both) of the electric field and the
magnetic field. Thereafter, the ion beam 215 is accelerated or
decelerated to have a predetermined energy in the AD column 212 by
applying the electric field. The ion beam 215 exiting the AD column
212 reaches the final implantation energy (in the low-energy mode,
the energy may be adjusted to be higher than the implantation
energy, and the ion beam may be deflected while decelerating in the
energy filter). The energy filter 213 in the downstream of the AD
column 212 deflects the ion beam 215 to the wafer 214 by the
application of either (or both) of the electric field and the
magnetic field with the deflection electrode or the deflection
electromagnet. Thus, a contamination with energy other than target
energy is eliminated. In this manner, the purified ion beam 215 is
implanted into the wafer 214.
[0125] Also, the beam dump 203 is disposed between the mass
analysis magnet 202 and the resolving aperture 204. The beam dump
203 deflects the ion beam by applying the electric field when
necessary. Therefore, the beam dump 203 can control the arrival of
the ion beam at the downstream at high speed.
[0126] Next, the low-energy mode and the high-energy mode in the
ion implantation apparatus 200 illustrated in FIG. 5 will be
described with reference to the configuration system diagram of the
high-voltage power supply system 230 illustrated in FIGS. 6 and 7.
FIG. 6 illustrates a power supply switching state of the low-energy
mode, and FIG. 7 illustrates a power supply switching state of the
high-energy mode. FIGS. 6 and 7 illustrate main components related
to the energy adjustment of the ion beam among the beamline
components illustrated in FIG. 5. In FIGS. 6 and 7, the ion beam
215 is indicated by an arrow.
[0127] As illustrated in FIGS. 6 and 7, the beam parallelizing
mechanism 211 (see FIG. 5) includes a double P lens 220. The double
P lens 220 includes a first voltage gap 221 and a second voltage
gap 222 disposed spaced apart from each other along the ion
movement direction. The first voltage gap 221 is disposed in the
upstream, and the second voltage gap 222 is disposed in the
downstream.
[0128] The first voltage gap 221 is formed between a pair of
electrodes 223 and 224. The second voltage gap 222 is formed
between another pair of electrodes 225 and 226 disposed in the
downstream of the electrodes 223 and 224. The first voltage gap 221
and the electrodes 223 and 224 forming the gap 221 have a convex
shape toward the upstream side. Conversely, the second voltage gap
222 and the electrodes 225 and 226 forming the gap 222 have a
convex shape toward the downstream side. Also, for convenience of
description, these electrodes may be also referred to as a first P
lens upstream electrode 223, a first P lens downstream electrode
224, a second P lens upstream electrode 225, and a second P lens
downstream electrode 226 below.
[0129] The double P lens 220 parallelizes the incident ion beam
before emission and adjusts the energy of the ion beam by a
combination of the electric fields applied to the first voltage gap
221 and the second voltage gap 222. That is, the double P lens 220
accelerates or decelerates the ion beam by the electric fields of
the first voltage gap 221 and the second voltage gap 222.
[0130] Also, the ion implantation apparatus 200 includes a
high-voltage power supply system 230 including a power supply for
the beamline components. The high-voltage power supply system 230
includes a first power supply unit 231, a second power supply unit
232, a third power supply unit 233, a fourth power supply unit 234,
and a fifth power supply unit 235. As illustrated, the high-voltage
power supply system 230 includes a connection circuit for
connecting the first to fifth power supply units 231 to 235 to the
ion implantation apparatus 200.
[0131] The first power supply unit 231 includes a first power
supply 241 and a first switch 251. The first power supply 241 is
provided between the ion source 201 and the first switch 251, and
is a DC power supply that provides the ion source 201 with a
positive voltage. The first switch 251 connects the first power
supply 241 to a ground 217 in the low-energy mode (see FIG. 6), and
connects the first power supply 241 to a terminal 216 in the
high-energy mode (see FIG. 7). Therefore, the first power supply
241 provides a voltage V.sub.HV to the ion source 201 in the
low-energy mode on the basis of a ground potential. This provides
the total ion energy as it is. On the other hand, the first power
supply 241 provides a voltage V.sub.HV to the ion source 201 in the
high-energy mode on the basis of a terminal potential.
[0132] The second power supply unit 232 includes a second power
supply 242 and a second switch 252. The second power supply 242 is
provided between the terminal 216 and the ground 217, and is a DC
power supply that provides the terminal 216 with one of positive
and negative voltages by the switching of the second switch 252.
The second switch 252 connects a negative electrode of the second
power supply 242 to the terminal 216 in the low-energy mode (see
FIG. 6), and connects a positive electrode of the second power
supply 242 to the terminal 216 in the high-energy mode (see FIG.
7). Therefore, the second power supply 242 provides a voltage
V.sub.T (VT<0) to the terminal 216 in the low-energy mode on the
basis of the ground potential. On the other hand, the second power
supply 242 provides a voltage V.sub.T (V.sub.T>0) to the
terminal 216 in the high-energy mode on the basis of the ground
potential.
[0133] Therefore, an extraction voltage V.sub.EXT of the extraction
electrode 218 is V.sub.EXT=V.sub.HV-V.sub.T in the low-energy mode,
and is V.sub.EXT=V.sub.HV in the high-energy mode. When a charge of
an ion is q, the final energy is qV.sub.HV in the low-energy mode,
and is q(V.sub.HV+V.sub.T) in the high-energy mode.
[0134] The third power supply unit 233 includes a third power
supply 243 and a third switch 253. The third power supply 243 is
provided between the terminal 216 and the double P lens 220. The
third power supply 243 includes a first P lens power supply 243-1
and a second P lens power supply 243-2. The first P lens power
supply 243-1 is a DC power supply that provides a voltage V.sub.AP
to the first P lens downstream electrode 224 and the second P lens
upstream electrode 225 on the basis of the terminal potential. The
second P lens power supply 243-2 is a DC power supply that provides
a voltage V.sub.DP to a destination through the third switch 253 on
the basis of the terminal potential. The third switch 253 is
provided between the terminal 216 and the double P lens 220 to
connect one of the first P lens power supply 243-1 and the second P
lens power supply 243-2 to the second P lens downstream electrode
226 by the switching. Also, the first P lens upstream electrode 223
is connected to the terminal 216.
[0135] The third switch 253 connects the second P lens power supply
243-2 to the second P lens downstream electrode 226 in the
low-energy mode (see FIG. 6), and connects the first P lens power
supply 243-1 to the second P lens downstream electrode 226 in the
high-energy mode (see FIG. 7). Therefore, the third power supply
243 provides a voltage V.sub.DP to the second P lens downstream
electrode 226 in the low-energy mode on the basis of the terminal
potential. On the other hand, the third power supply 243 provides a
voltage V.sub.AP to the second P lens downstream electrode 226 in
the high-energy mode on the basis of the terminal potential.
[0136] The fourth power supply unit 234 includes a fourth power
supply 244 and a fourth switch 254. The fourth power supply 244 is
provided between the fourth switch 254 and the ground 217 and is a
DC power supply that provides a negative voltage to an exit (that
is, the downstream end) of the AD column 212. The fourth switch 254
connects the fourth power supply 244 to the exit of the AD column
212 in the low-energy mode (see FIG. 6), and connects the exit of
the AD column 212 to the ground 217 in the high-energy mode (see
FIG. 7). Therefore, the fourth power supply 244 provides a voltage
V.sub.ad to the exit of the AD column 212 in the low-energy mode on
the basis of the ground potential. On the other hand, the fourth
power supply 244 is not used in the high-energy mode.
[0137] The fifth power supply unit 235 includes a fifth power
supply 245 and a fifth switch 255. The fifth power supply 245 is
provided between the fifth switch 255 and the ground 217. The fifth
power supply 245 is provided for the energy filter (AEF) 213. The
fifth switch 255 is provided for switching the operation modes of
the energy filter 213. The energy filter 213 is operated in a
so-called offset mode in the low-energy mode, and is operated in a
normal mode in the high-energy mode. The offset mode is an
operation mode of the AEF in which an average value of the positive
electrode and the negative electrode is a negative potential. The
beam convergence effect of the offset mode can prevent beam loss
caused by the beam divergence in the AEF. The normal mode is an
operation mode of the AEF in which an average value of the positive
electrode and the negative electrode is the ground potential.
[0138] The ground potential is provided to the wafer 214.
[0139] FIG. 8A illustrates an example of a voltage applied to each
portion of the ion implantation apparatus 200 in the low-energy
mode, and FIG. 8B illustrates an example of energy of the ion in
each portion of the ion implantation apparatus 200 in the
low-energy mode. FIG. 9A illustrates an example of a voltage
applied to each portion of the ion implantation apparatus 200 in
the high-energy mode, and FIG. 9B illustrates an example of energy
of the ion in each portion of the ion implantation apparatus 200 in
the high-energy mode. The vertical axes in FIGS. 8A and 9A
represent the voltage, and the vertical axes in FIGS. 8B and 9B
represent the energy. In the horizontal axes of the respective
drawings, locations in the ion implantation apparatus 200 are
represented by symbols a to g. The symbols a, b, c, d, e, f, and P
represent the ion source 201, the terminal 216, the acceleration P
lens (first P lens downstream electrode 224), the deceleration P
lens (second P lens downstream electrode 226), the exit of the AD
column 212, the energy filter 213, and the wafer 214,
respectively.
[0140] The double P lens 220 has a configuration that uses the
acceleration P lens c alone, or uses the deceleration P lens d
alone, or uses both of the acceleration P lens c and the
deceleration P lens d, when necessary according to the implantation
condition. In the configuration that uses both of the acceleration
P lens c and the deceleration P lens d, the double P lens 220 can
be configured to change the distribution of the acceleration and
deceleration effects by using both of the acceleration effect and
the deceleration effect. In this case, the double P lens 220 can be
configured such that a difference between the incident beam energy
to the double P lens 220 and the exit beam energy from the double P
lens 220 is used to accelerate or decelerate the beam.
Alternatively, the double P lens 220 can be configured such that
the difference between the incident beam energy and the exit beam
energy becomes zero, and thus, the beam is neither accelerated nor
decelerated.
[0141] As an example, as illustrated, in the low-energy mode, the
double P lens 220 is configured to decelerate the ion beam in the
deceleration P lens d, accelerate the ion beam in the acceleration
P lens c to some extent when necessary, and thereby the ion beam is
decelerated as a whole. On the other hand, in the high-energy mode,
the double P lens 220 is configured to accelerate the ion beam only
in the acceleration P lens c. Also, in the high-energy mode, the
double P lens 220 may be configured to decelerate the ion beam in
the deceleration P lens d to some extent when necessary, as long as
the ion beam is accelerated as a whole.
[0142] Since the high-voltage power supply system 230 is configured
as above, the voltages applied to several regions on the beamline
can be changed by the switching of the power supply. Also, the
voltage application paths in some regions can also be changed. By
using these, it is possible to switch the low-energy mode and the
high-energy mode in the same beamline.
[0143] In the low-energy mode, the potential V.sub.HV of the ion
source 201 is directly applied on the basis of the ground
potential. Therefore, a high-accuracy voltage application to the
source unit is possible, and the accuracy of energy setting can be
increased during the ion implantation at low energy. Also, by
setting the terminal voltage V.sub.T, the P lens voltage V.sub.DP,
the AD column exit voltage V.sub.ad, and the energy filter voltage
V.sub.bias to negative, it is possible to transport the ions to the
energy filter at a relatively high energy. Therefore, the transport
efficiency of the ion beam can be improved, and the high current
can be obtained.
[0144] Also, in the low-energy mode, the deceleration P lens is
employed to facilitate the ion beam transport in the high-energy
state. This helps the low-energy mode coexist with the high-energy
mode in the same beamline. Also, in the low-energy mode, an
expanded beam by design is generated by adjusting the
convergence/divergence elements of the beamline in order to
transport the beam such that the self-divergence of the beam is
minimized. This also helps the low-energy mode coexist with the
high-energy mode in the same beamline.
[0145] In the high-energy mode, the potential of the ion source 201
is the sum of the acceleration extraction voltage V.sub.HV and the
terminal potential V.sub.T. This can enable the application of the
high voltage to the source unit, and accelerate ions at high
energy.
[0146] FIG. 10 is a flowchart illustrating an ion implantation
method according to an embodiment of the present invention. This
method may be performed by, for example, the beam control device
for the ion implantation apparatus. As illustrated in FIG. 10,
first, the implantation recipe is selected (S100). The control
device reads the recipe condition (S102), and selects the beamline
setting according to the recipe condition (S104). The ion beam
adjusting process is performed under the selected beamline setting.
The adjusting process includes a beam emission and adjustment
(S106) and an obtained beam checking (S108). In this manner, the
preparing process for the ion implantation is ended. Next, the
wafer is loaded (S110), the ion implantation is performed (S112),
and the wafer is unloaded (S114). Steps 110 to 114 may be repeated
until the desired number of wafers are processed.
[0147] FIG. 11 schematically illustrates a range D of energy and
dose amount that is realized by the ion implantation apparatus 200.
Like in FIG. 1, FIG. 11 illustrates the range of energy and dose
amount that can be processed in the actually allowable
productivity. For comparison, ranges A, B and C of energy and dose
amount of the HC, the MC, and the HE illustrated in FIG. 1 are
illustrated in FIG. 11.
[0148] As illustrated in FIG. 11, it can be seen that the ion
implantation apparatus 200 includes all the operation ranges of the
existing apparatuses HC and MC. Therefore, the ion implantation
apparatus 200 is a novel apparatus beyond the existing framework.
Even one novel ion implantation apparatus can serve as the two
existing types of categories HC and MC while maintaining the same
beamline and the implantation method. Therefore, this apparatus may
be referred to as HCMC.
[0149] Therefore, according to the present embodiment, it is
possible to provide the HCMC in which the serial-type high-dose
high-current ion implantation apparatus and the serial-type
medium-dose medium-current ion implantation apparatus are
configured as a single apparatus. The HCMC can perform the
implantation in a broad range of energy condition and dose
condition by changing the voltage applying method in the low-energy
condition and the high-energy condition and changing the beam
current from high current to low current in the CVA.
[0150] Also, the HCMC-type ion implantation apparatus may not
include all the implantation condition ranges of the existing HC
and MC. Considering the tradeoff of the device manufacturing cost
and the implantation performance, it may be thought to provide an
apparatus having a range E (see FIG. 12) narrower than the range D
illustrated in FIG. 11. In this case, the ion implantation
apparatus having excellent practicality can be provided as long as
it covers the ion implantation conditions required for the device
maker.
[0151] The improvement in the operation efficiency of the apparatus
realized by the HCMC in the device manufacturing process will be
described. For example, as illustrated in FIG. 13, it is assumed
that a device maker uses six HCs and four MCs in order to process a
manufacturing process X (that is, this device maker owns only the
existing apparatuses HC and MC). Thereafter, the device maker
changes the process X to a process Y according to a change in a
manufacturing device. As a result, the device maker needs eight HCs
and two MCs. The maker needs to install two more HCs, and thus, the
increase in investment and the lead time are required. At the same
time, two MCs are not operated, and thus, the maker unnecessarily
owns these. As described above, since the HC and the MC are
generally different in the implantation method, it is difficult to
convert the non-operating MCs to newly necessary HCs.
[0152] Next, as illustrated in FIG. 14, it is considered that the
device maker uses six HCs, two MCs, and two HCMCs in order to
process the process X. In this case, even when the process X is
changed to the process Y according to the change in the
manufacturing device, the HCMC can be operated as the HC because
the HCMC is the process shared machine of the HC and the MC.
Therefore, additional equipment installation and non-operation are
unnecessary.
[0153] As such, there is a great merit when the device maker owns a
certain number of HCMCs. This is because the process change of HC
and the MC can be absorbed by the HCMC. Also, when some apparatuses
cannot be used due to malfunction or maintenance, the HCMC can also
be used as the HC or the MC. Therefore, by owning the HCMC, the
overall operating rate of the apparatus can be significantly
improved.
[0154] Also, ultimately, it can be considered that all apparatuses
are provided with HCMCs. However, in many cases, it is practical
that part of the apparatuses are provided with HCMCs considering a
price difference between the HCMC and the HC (or MC) or the
utilization of the already owned HC or MC.
[0155] Also, when a type of the existing ion implantation apparatus
is replaced with other apparatuses having different methods of
implanting ions into the wafer in order for an ion implantation
process to be performed, it may be difficult to match the
implantation characteristics. This is because a beam divergence
angle or a beam density may be different even though the energy and
dose are matched in two types of ion implantation apparatuses for
the ion implantation process. However, the HCMC can process the
high-dose high-current ion implantation condition and the
medium-dose medium-current ion implantation condition on the same
beamline (the same ion beam trajectory). In this way the HCMC can
separately use the high-dose high-current ion implantation
condition and the medium-dose medium-current ion implantation
condition. Therefore, it is expected to facilitate the matching
because the change in the implantation characteristics followed by
the replacement of the apparatus is sufficiently suppressed.
[0156] The HCMC is the shared machine of the HC and the MC and can
also process the implantation condition out of the operation range
of the existing HC or the MC. As illustrated in FIG. 11, the HCMC
is a new apparatus that can also process the high energy/high dose
implantation (right upper region F in the range D) and low
energy/low dose implantation (left lower region G in the range D).
Therefore, in addition or alternative to the first beamline setting
S1 and the second beamline setting S2 described above, in an
embodiment, the ion implantation apparatus may include a third
beamline setting for high energy/high dose implantation and/or a
fourth beamline setting for low energy/low dose implantation.
[0157] As described above, in the present embodiment, the beamlines
of the serial-type high-dose high-current ion implantation
apparatus and the serial-type medium-dose medium-current ion
implantation apparatus are matched and shared. Moreover, a
structure for switching the beamline configuration is constructed.
In this manner, the implantation processing is possible over a
broad range of energy and beam current regions on the same beamline
(the same ion beam trajectory and the same implantation
method).
[0158] The present invention has been described based on the
embodiments. The present invention is not limited to the
embodiments, and it can be understood by those skilled in the art
that designs can be modified in various ways, various modifications
can be made, and such modifications fall within the scope of the
present invention.
[0159] In addition or alternative to the above-described
configurations, the quantitative adjustment of the beam current by
the beam current adjustment system can be configured in various
ways. For example, when the beam current adjustment system includes
a variable-width aperture arranged on the beamline, the
variable-width aperture may be disposed at any arbitrary position.
Therefore, the variable-width aperture may be disposed between the
ion source and the mass analysis magnet, between the mass analysis
magnet and the mass analysis slit, between the mass analysis slit
and the beam shaping device, between the beam shaping device and
the beam control device, between the beam control device and the
beam conditioning device, between the respective elements of the
beam conditioning device, and/or between the beam conditioning
device and the workpiece. The variable-width aperture may be the
mass analysis slit.
[0160] The beam current adjustment may be configured to adjust the
amount of ion beam passing through the aperture by arranging the
divergence/convergence lens system before and/or after a
fixed-width aperture. The fixed-width aperture may be the mass
analysis slit.
[0161] The beam current adjustment may be performed using an energy
slit opening width variable (and/or a beamline end opening width
variable slit apparatus). The beam current adjustment may be
performed using an analyzer magnet (mass analysis magnet) and/or a
steerer magnet (trajectory modification magnet). The dose amount
adjustment may be accompanied by an expansion of the variable range
of mechanical scan speed (for example, from ultra-low speed to
ultra-high speed) and/or a change in the number of times of the
mechanical scanning.
[0162] The beam current adjustment may be performed by the
adjustment of the ion source (for example, amount of gas or arc
current). The beam current adjustment may be performed by the
exchange of the ion source. In this case, the ions source for MC
and the ion source for HC may be selectively used. The beam current
adjustment may be performed by the gap adjustment of the extraction
electrode of the ion source. The beam current adjustment may be
performed by providing the CVA immediately downstream of the ion
source.
[0163] The beam current adjustment may be performed according to
the change in the vertical width of the ribbon beam. The dose
amount adjustment may be performed according to the change in the
scanning speed during the two-dimensional mechanical scanning.
[0164] The beamline device may include a plurality of beamline
components configured to operate under only one of the first
beamline setting and the second beamline setting, and thus, the ion
implantation apparatus may be configured as a high-current ion
implantation apparatus or a medium-current ion implantation
apparatus. That is, with the HCMC as a platform, for example, by
exchanging some beamline components, or changing the power supply
configuration, the serial-type high-dose dedicated ion implantation
apparatus or the serial-type medium-dose dedicated ion implantation
apparatus can be produced from the serial-type high-dose
medium-dose wide-use ion implantation apparatus. Since it is
expected to manufacture each dedicated apparatus at lower cost than
the wide-use apparatus, it can contribute to reducing the
manufacturing costs for the device maker.
[0165] In the MC, implantation at higher energy may be achieved by
using multivalent ions such as divalent ions or trivalent ions.
However, in the typical ion source (thermionic emission type ion
source), the generation efficiency of multivalent ions is much
lower than the generation efficiency of monovalent ions. Therefore,
practical dose implantation in the high-energy range is actually
difficult. When a multivalent ion enhancement source, such as an RF
ion source, is employed as the ion source, tetravalent or
pentavalent ions can be obtained. Therefore, more ion beams can be
obtained in the higher energy condition.
[0166] Therefore, by employing the multivalent ion enhancement
source, such as the RF ion source, as the ion source, the HCMC can
operate as the serial-type high energy ion implantation apparatus
(HE). Therefore, a portion of the implantation condition that has
been processed by only the serial-type high energy/low-dose ion
implantation apparatus can be processed by the HCMC (the range of
the MC illustrated in FIG. 8 may be expanded to include at least a
portion of the range C).
[0167] Hereinafter, several aspects of the present invention will
be described.
[0168] An ion implantation apparatus according to an embodiment
includes: an ion source for generating ions and extracting the ions
as an ion beam; an implantation processing chamber for implanting
the ions into a workpiece; and a beamline device for providing a
beamline to transport the ion beam from the ion source to the
implantation processing chamber, wherein the beamline device
supplies the ion beam having a beam irradiation region exceeding
the width of the workpiece in the implantation processing chamber,
the implantation processing chamber includes a mechanical scanning
device for mechanically scanning the workpiece with respect to the
beam irradiation region, the beamline device is operated under one
of a plurality of implantation setting configurations according to
an implantation condition, the plurality of implantation setting
configurations including a first implantation setting configuration
suitable for transport of a low energy/high current beam for
high-dose implantation into the workpiece, and a second
implantation setting configuration suitable for transport of a high
energy/low current beam for low-dose implantation into the
workpiece, and the beamline device is configured such that a same
beam center trajectory being a reference in the beamline is
provided from the ion source to the implantation processing chamber
in the first implantation setting configuration and the second
implantation setting configuration.
[0169] An ion implantation apparatus according to an embodiment
includes: an ion source for generating ions and extracting the ions
as an ion beam; an implantation processing chamber for implanting
the ions into a workpiece; and a beamline device for providing a
beamline to transport the ion beam from the ion source to the
implantation processing chamber, wherein the ion implantation
apparatus is configured to irradiate the workpiece with the ion
beam in cooperation with mechanical scanning of the workpiece, the
beamline device is operated under one of a plurality of
implantation setting configurations according to an implantation
condition, the plurality of implantation setting configurations
including a first implantation setting configuration suitable for
transport of a low energy/high current beam for high-dose
implantation into the workpiece, and a second implantation setting
configuration suitable for transport of a high energy/low current
beam for low-dose implantation into the workpiece, and the beamline
device is configured such that a same beam center trajectory being
a reference in the beamline is provided from the ion source to the
implantation processing chamber in the first implantation setting
configuration and the second implantation setting
configuration.
[0170] The beamline device may take the same implantation method in
the first implantation setting configuration and the second
implantation setting configuration. The beam irradiation region may
be equal in the first implantation setting configuration and the
second implantation setting configuration.
[0171] The beamline apparatus may include a beam conditioning
device for conditioning the ion beam, and a beam shaping device for
shaping the ion beam. The beam conditioning device and the beam
shaping device in the beamline device may be disposed in the same
layout in the first implantation setting configuration and the
second implantation setting configuration. The beam implantation
apparatus may have the same installation floor area in the first
implantation setting configuration and the second implantation
setting configuration.
[0172] The beamline device may include a beam current adjustment
system for adjusting the total amount of beam current of the ion
beam. The first implantation setting configuration may include a
first beam current setting for the beam current adjustment system,
the second implantation setting configuration may include a second
beam current setting for the beam current adjustment system, and
the second beam current setting may be determined to make the beam
current of the ion beam smaller than that of the first beam current
setting.
[0173] The beam current adjustment system may be configured to
block at least a portion of the ion beam when passing through an
adjustment element. The beam current adjustment system may include
a variable-width aperture arranged on the beamline. The beam
current adjustment system may include a beamline end opening width
variable slit device. The ion source may be configured to adjust
the total amount of beam current of the ion beam. The ion source
may include an extraction electrode for extracting the ion beam,
and the total amount of beam current of the ion beam may be
adjusted by adjusting an opening of the extraction electrode.
[0174] The beamline device may include an energy adjustment system
for adjusting an implantation energy of the ions into the
workpiece. The first implantation setting configuration may include
a first energy setting for the energy adjustment system, the second
implantation setting configuration may include a second energy
setting for the energy adjustment system, the first energy setting
may be suitable for transport of a lower energy beam as compared
with the second energy setting.
[0175] The energy adjustment system may include a beam
parallelizing device for parallelizing the ion beam. The beam
parallelizing device may be configured to decelerate, or decelerate
and accelerate the ion beam under the first implantation setting
configuration, and accelerate, or accelerate and decelerate the ion
beam under the second implantation setting configuration. The beam
parallelizing device may include an acceleration lens for
accelerating the ion beam, and a deceleration lens for decelerating
the ion beam, and may be configured to modify a distribution of
acceleration and deceleration, and the beam parallelizing device
may be configured to mainly decelerate the ion beam under the first
implantation setting configuration, and mainly accelerate the ion
beam under the second implantation setting configuration.
[0176] The beamline device may include a beam current adjustment
system for adjusting the total amount of beam current of the ion
beam, and an energy adjustment system for adjusting an implantation
energy of the ions into the workpiece, and may adjust the total
amount of the beam current and the implantation energy individually
or simultaneously. The beam current adjustment system and the
energy adjustment system may be separate beamline components.
[0177] The ion implantation apparatus may include a control unit
configured to manually or automatically select one implantation
setting configuration suitable for a given ion implantation
condition among the plurality of implantation setting
configurations including the first implantation setting
configuration and the second implantation setting
configuration.
[0178] The control unit may select the first implantation setting
configuration when a desired ion dose amount implanted into the
workpiece is in the range of about 1.times.10.sup.14 to
1.times.10.sup.17 atoms/cm.sup.2, and may select the second
implantation setting configuration when a desired ion dose amount
implanted into the workpiece is in the range of about
1.times.10.sup.11 to 1.times.10.sup.14 atoms/cm.sup.2.
[0179] The beamline device may have a first energy adjustment range
under the first implantation setting configuration, and may have a
second energy adjustment range under the second implantation
setting configuration, and the first energy adjustment range and
the second energy adjustment range may have a partially overlapped
range.
[0180] The beamline device may have a first dose adjustment range
under the first implantation setting configuration, and may have a
second dose adjustment range under the second implantation setting
configuration, and the first dose adjustment range and the second
dose adjustment range may have a partially overlapped range.
[0181] The beamline device may include a beam scanning device for
providing scanning of the ion beam to form an elongated irradiation
region extending in a longitudinal direction perpendicular to a
beam transport direction. The implantation processing chamber may
include a workpiece holder configured to provide mechanical
scanning of the workpiece in a direction perpendicular to the
longitudinal direction and the beam transport direction.
[0182] The beamline device may include a ribbon beam generator for
generating a ribbon beam having an elongated irradiation region
extending in a longitudinal direction perpendicular to a beam
transport direction. The implantation processing chamber may
include a workpiece holder configured to provide mechanical
scanning of the workpiece in a direction perpendicular to the
longitudinal direction and the beam transport direction.
[0183] The implantation processing chamber may include a workpiece
holder configured to provide mechanical scanning of the workpiece
in two directions perpendicular to each other in a plane
perpendicular to the beam transport direction.
[0184] The beamline device may be configured to be selectable from
a plurality of beamline components configured to be operated under
only one of the first implantation setting configuration and the
second implantation setting configuration, and the ion implantation
apparatus may be configured as a high-current dedicated ion
implantation apparatus or a medium-current dedicated ion
implantation apparatus.
[0185] An ion implantation method according to an embodiment
includes: selecting one implantation setting configuration, with
respect to a beamline device, which is suitable for a given ion
implantation condition among a plurality of implantation setting
configurations including a first implantation setting configuration
suitable for transport of a low energy/high current beam for
high-dose implantation into a workpiece, and a second implantation
setting configuration suitable for transport of a high energy/low
current beam for low-dose implantation into the workpiece;
transporting an ion beam along a beam center trajectory being a
reference in a beamline from an ion source to an implantation
processing chamber by using the beamline device under the selected
implantation setting configuration; and irradiating the workpiece
with the ion beam in cooperation with mechanical scanning of the
workpiece, wherein the beam center trajectory being the reference
is equal in the first implantation setting configuration and the
second implantation setting configuration.
[0186] The transporting may include adjusting an implantation dose
amount into the workpiece by adjusting the total amount of beam
current of the ion beam. The implantation dose amount may be
adjusted in a first dose adjustment range under the first
implantation setting configuration, and may be adjusted in a second
dose adjustment range under the second implantation setting
configuration, the second dose adjustment range including a dose
range smaller than the first dose adjustment range.
[0187] The transporting may include adjusting the implantation
energy into the workpiece. The implantation energy may be adjusted
in a first energy adjustment range under the first implantation
setting configuration, and may be adjusted in a second energy
adjustment range under the second implantation setting
configuration, the second energy adjustment range including an
energy range higher than the first energy adjustment range.
[0188] 1. An ion implantation apparatus according to an embodiment
has the same beam trajectory and the same implantation method and
has a broad energy range by switching a connection of a power
supply for deceleration as a whole and a connection of a power
supply for acceleration as a whole.
[0189] 2. An ion implantation apparatus according to an embodiment
has the same beam trajectory and the same implantation method and
has a broad beam current range by including a device for cutting a
portion of beam in a beamline upstream part in a beamline capable
of obtaining a high current.
[0190] 3. An ion implantation apparatus according to an embodiment
may have the same beam trajectory and the same implantation method
and have a broad energy range and a broad beam current range by
including both of the features of the embodiment 1 and the
embodiment 2.
[0191] An ion implantation apparatus according to an embodiment may
be an apparatus that combines a beam scanning and a mechanical
wafer scanning as the same implantation method in the embodiments 1
to 3. An ion implantation apparatus according to an embodiment may
be an apparatus that combines a ribbon-shaped beam and a mechanical
wafer scanning as the same implantation method in the embodiments 1
to 3. An ion implantation apparatus according to an embodiment may
be an apparatus that combines a two-dimensional mechanical wafer
scanning as the same implantation method in the embodiments 1 to
3.
[0192] 4. An ion implantation apparatus according to an embodiment
is configured to freely select/switch a high-dose high-current ion
implantation and a medium-dose medium-current ion implantation by
configuring a high-dose high-current ion implantation beamline
component and a medium-dose medium-current ion implantation
beamline component in parallel on the same beamline (the same ion
beam trajectory and the same implantation method), and covers a
very broad energy range from low energy to high energy and a very
broad dose range from a low dose to a high dose.
[0193] 5. In the embodiment 4, each beamline component shared in
the high dose use and the medium dose use and each beamline
component individually switched in the high dose/medium dose use
may be configured on the same beamline.
[0194] 6. In the embodiment 4 or 5, in order to adjust the beam
current amount in a broad range, a beam limiting device (vertical
or horizontal variable-width slit, or rectangular or circular
variable opening) for physically cutting a portion of beam in a
beamline upstream part may be provided.
[0195] 7. In any one of the embodiments 4 to 6, a switch controller
control device may be provided to select a high-dose high-current
ion implantation and a medium-dose medium-current ion implantation,
based on a desired ion dose amount implanted into the
workpiece.
[0196] 8. In the embodiment 7, the switch controller is configured
to operate the beamline in a medium-dose acceleration
(extraction)/acceleration (P lens)/acceleration or deceleration (AD
column) mode when a desired ion dose amount implanted into the
workpiece is in the medium-dose medium-current range of about
1.times.10.sup.11 to 1.times.10.sup.14 atoms/cm.sup.2, and operate
the beamline in a high-dose acceleration (extraction)/deceleration
(P lens)/deceleration (AD column) mode when a desired ion dose
amount implanted into the workpiece is in the high-dose
high-current range of about 1.times.10.sup.14 to 1.times.10.sup.17
atoms/cm.sup.2.
[0197] 9. In any one of the embodiments 4 to 8, an apparatus for
implanting ions of relatively high energy by using an acceleration
mode and an apparatus for implanting ions of relatively low energy
by using a deceleration mode may have a mutually overlapped energy
range.
[0198] 10. In any one of the embodiments 4 to 8, an apparatus for
implanting ions of relatively high energy by using an acceleration
mode and an apparatus for implanting ions of relatively low energy
by using a deceleration mode may have a mutually overlapped dose
range.
[0199] 11. In any one of the embodiments 4 to 6, by limiting the
beamline components, the ion implantation apparatus may easily be
changed to a high-dose high-current dedicated ion implantation
apparatus or a medium-dose medium-current dedicated ion
implantation apparatus.
[0200] 12. In anyone of the embodiments 4 to 11, the beamline
configuration may combine a beam scanning and a mechanical
substrate scanning.
[0201] 13. In anyone of the embodiments 4 to 11, the beamline
configuration may combine a mechanical substrate scanning and a
ribbon-shaped beam having a width equal to or greater than a width
of a substrate (or wafer or workpiece).
[0202] 14. In anyone of the embodiments 4 to 11, the beamline
configuration may include a mechanical substrate scanning in a
two-dimensional direction.
[0203] FIG. 15 is a perspective cross-sectional view illustrating a
configuration of a scanning unit 1000 included in an ion
implantation apparatus according to an embodiment of the present
invention. The ion implantation apparatus includes the scanning
unit 1000 that includes an upstream electrode device 300, a
scanning electrode device 400, and a downstream electrode device
500. The upstream electrode device 300, the scanning electrode
device 400, and the downstream electrode device 500 which are
illustrated in the present drawing have a vertically and
horizontally symmetric shape with respect to a reference trajectory
of an ion beam B which is incident into the scanning unit 1000. In
the present drawing, a lower half configuration thereof is only
illustrated in order to facilitate understanding.
[0204] The upstream electrode device 300 is disposed just upstream
of the scanning electrode device 400, and shapes a profile of an
ion beam which is incident into the scanning electrode device 400.
The upstream electrode device 300 is configured by a plurality of
electrode bodies, and includes a first upstream reference voltage
electrode 310, an upstream intermediate electrode 330, and a second
upstream reference voltage electrode 350. The upstream electrode
device 300 can be used as, for example, the second XY focusing lens
208 of the ion implantation apparatus 200 illustrated in FIGS. 5A
and 5B.
[0205] The scanning electrode device 400 allows a deflecting
electric field to act on the ion beam incident into the scanning
electrode device 400 and provides periodical scanning of the ion
beam in a horizontal direction (x direction). The scanning
electrode device 400 includes a pair of scanning electrodes 410R
and 410L (hereinafter, also collectively referred to as a scanning
electrode 410) that allow a deflecting electric field to act on the
ion beam and a beam transport correction electrode 450. The beam
transport correction electrode 450 is provided to suppress a
so-called "zero field effect", in which when the deflecting
electric field applied by the scanning electrodes 410R and 410L
becomes zero, the diameter of the ion beam is reduced as compared
to a case in which the deflected filed is applied. A pair of beam
transport correction electrodes 450 are provided, which face each
other in a vertical direction (y direction). In this drawing, there
is illustrated only a lower correction electrode 450B disposed in
the lower side. The scanning electrode device 400 can be used as,
for example, the scanner 209 of the ion implantation apparatus 200
illustrated in FIGS. 5A and 5B.
[0206] The downstream electrode device 500 is disposed just
downstream of the scanning electrode device 400, and shapes a
profile of an ion beam scanned by the scanning electrode device
400. The downstream electrode device 500 is configured by a
plurality of electrode bodies, and includes a first downstream
reference voltage electrode 510, a first downstream intermediate
electrode 530, a second downstream reference voltage electrode 550,
a second downstream intermediate electrode 570, and a third
downstream reference voltage electrode 590. The downstream
electrode device 500 can be used as, for example, the Y focusing
lens 210 of the ion implantation apparatus 200 illustrated in FIGS.
5A and 5B.
[0207] FIGS. 16A and 16B are cross-sectional views schematically
illustrating a configuration of the scanning unit 1000 illustrated
in FIG. 15. FIG. 16A illustrates a horizontal direction
cross-section (xz-plane cross-section) including a reference
trajectory Z when it is assumed that the reference trajectory Z of
an ion beam extends in a z direction. FIG. 16B illustrates a
vertical direction cross-section (yz-plane cross-section) including
the reference trajectory Z. Hereinafter, the scanning electrode
device 400, the upstream electrode device 300, and the downstream
electrode device 500 in the scanning unit 1000 will be described in
order with reference to the present drawings.
[0208] FIG. 17 is a diagram schematically illustrating the scanning
electrode device 400, which illustrates X-X cross-section of FIG.
16A. The pair of scanning electrodes 410R and 410L are provided to
face each other in a horizontal direction (x direction) with
respect to the reference trajectory Z of the ion beam B. The
scanning electrodes 410R and 410L respectively include electrode
inner surfaces 412R and 412L each having a substantially concave
shape. By using an electrode having a substantially concave shape,
it is possible to deflect the ion beam B having a
horizontally-elongated cross-sectional shape uniformly at the same
angle. Also, the cross-sectional shape of the ion beam B as
indicated by a dashed line schematically illustrates a shape in the
vicinity of an inlet 402 of the scanning electrode device 400
illustrated in FIGS. 16A and 16B.
[0209] As illustrated in FIG. 16A, the scanning electrodes 410R and
410L have a folding-fan shape such that a distance between the
right electrode inner surface 412R and the left electrode inner
surface 412L increases toward a downstream direction. Therefore, it
is possible to deflect the ion beam B, which is deflected to be
close to one of the right scanning electrode 410R and the left
scanning electrode 410L, uniformly at the same angle in the
vicinity of an outlet 404 of the scanning electrode device 400.
[0210] The pair of beam transport correction electrodes 450A and
450B (hereinafter, also collectively referred to as a beam
transport correction electrode 450) are provided to face each other
in a vertical direction (y direction) with respect to the reference
trajectory Z of the ion beam B. The beam transport correction
electrode 450 is formed of a plate-shaped member having a thickness
d in a horizontal direction (x direction). It is preferable that
the thickness d of the beam transport correction electrode 450 is
thick enough to have a strength to stand alone and is thin enough
to limit an effect due to the beam transport correction electrode
450 to the vicinity of the reference trajectory Z. The reason for
this is that the "zero field effect" which is intended to be
suppressed by the beam transport correction electrode 450 occurs
when the deflecting electric field becomes zero, and the ion beam
travels along the reference trajectory Z. A positive bias voltage
of about several kV to 20 kV is applied to the beam transport
correction electrode 450, for example, a voltage of about +10 kV is
applied to the beam transport correction electrode 450.
[0211] Each of the beam transport correction electrodes 450A and
450B includes a straight portion 452 extending from the inlet 402
of the scanning electrode device 400 to the outlet 404, and a beam
transport correction inlet electrode body 454 protruding from the
straight portion 452 toward the reference trajectory Z in a
vertical direction. The straight portion 452 mainly has a function
of suppressing occurrence of the zero field effect with respect to
the entire scanning electrode device 400. On the other hand, the
beam transport correction inlet electrode body 454 mainly has a
function of allowing ion beams passing through the vicinity of the
reference trajectory Z to vertically converge substantially at the
inlet 402 of the scanning electrode device 400.
[0212] The beam transport correction inlet electrode body 454 is
provided in the vicinity of the inlet 402 of the scanning electrode
device 400. As illustrated in FIG. 16B, the beam transport
correction inlet electrode body 454 is provided such that a length
L.sub.b in a z direction is equal to or smaller than one third of a
total length L.sub.a of the beam transport correction electrode 450
including the straight portion 452. It is preferable that the
length L.sub.b of the beam transport correction inlet electrode
body 454 is in a range from about one fourth to about one fifth of
the total length L.sub.a of the beam transport correction electrode
450. Accordingly, it is possible to limit the effect of the
vertical focusing by the beam transport correction inlet electrode
body 454 to the vicinity of the inlet 402 of the scanning electrode
device 400. Also, by thinning the thickness d of the beam transport
correction inlet electrode body 454, the effect of the vertical
focusing is limited to ions passing through the vicinity of the
reference trajectory Z, and influence on the ions passing through
the outer side than the reference trajectory Z is suppressed.
[0213] As illustrated in FIG. 17, the beam transport correction
inlet electrode body 454 is provided such that an end 454a is
adjacent to the ion beam B. In this case, a distance h.sub.0
between the reference trajectory Z and the end 454a needs to be
adjusted to a distance enough to reduce influence on a deflecting
electric field generated by the scanning electrode 410 and, at the
same time, to allow influence due to the beam transport correction
inlet electrode body 454 to act on the vicinity of the reference
trajectory Z. It is preferable that the distance h.sub.0 between
the reference trajectory Z and the end 454a is about several times
a diameter D.sub.y in a vertical direction of the ion beam B, for
example, the distance h.sub.0 may be in a range from about three
times to about four times the diameter D.sub.y.
[0214] Returning to FIGS. 16A and 16B, the upstream electrode
device 300 will be described below.
[0215] Electrodes that constitute the upstream electrode device 300
are arranged in the order of the first upstream reference voltage
electrode 310, the upstream intermediate electrode 330, and the
second upstream reference voltage electrode 350 from the inlet 402
of the scanning electrode device 400 toward an upstream
direction.
[0216] The first upstream reference voltage electrode 310, the
upstream intermediate electrode 330, and the second upstream
reference voltage electrode 350 respectively include openings 312,
332, and 352 for ion beam passage. The ion beam B incident into the
upstream electrode device 300 has a horizontally-elongated flat
shape, and the openings 312, 332 and 352 of the electrodes
constituting the upstream electrode device 300 have a
horizontally-elongated rectangular cross-sectional shape. For
example, the shape of the opening 312 of the first upstream
reference voltage electrode 310 is illustrated in FIG. 18A which
will be described below.
[0217] The first upstream reference voltage electrode 310 and the
second upstream reference voltage electrode 350 generally have a
ground potential. Therefore, the first upstream reference voltage
electrode 310 and the second upstream reference voltage electrode
350 can be also referred to as a first upstream ground electrode
and a second upstream ground electrode. Also, instead of the ground
potential, other potential being a reference voltage may be applied
to the first upstream reference voltage electrode 310 and the
second upstream reference voltage electrode 350.
[0218] A high negative voltage is applied to the upstream
intermediate electrode 330 disposed between the first upstream
reference voltage electrode 310 and the second upstream reference
voltage electrode 350. Therefore, the upstream intermediate
electrode 330 functions as a suppression electrode that suppresses
intrusion of electrons into the scanning electrode device 400.
Also, by providing reference voltage electrodes both upstream and
downstream of the upstream intermediate electrode 330, an electron
shielding effect due to the suppression electrode is enhanced.
Therefore, the upstream electrode device 300 can be referred to as
a suppression electrode device having electron suppression action
with respect to the ion beam incident on the scanning electrode
device 400.
[0219] As another embodiment, a voltage higher than a voltage
needed as the suppression voltage can be applied to the upstream
intermediate electrode 330. For example, a negative voltage of tens
of kV is applied to the upstream intermediate electrode 330. For
example, a voltage of about -30 kV to about -50 kV is applied to
the upstream intermediate electrode 330. Therefore, the upstream
electrode device 300 functions as an einzel lens. Thus, the
upstream intermediate electrode 330 can be also referred to as an
einzel lens electrode. Accordingly, the upstream electrode device
300 allows an ion beam passing through the upstream electrode
device 300 to converge in a vertical direction and/or a horizontal
direction, and shapes the ion beam B incident into the scanning
electrode device 400. As a result, the upstream electrode device
300 is configured as an electrode lens that has function of shaping
or adjusting a profile of the ion beam incident into the scanning
electrode device 400.
[0220] An upstream surface 330a of the upstream intermediate
electrode 330 has an arcuate shape to have a convex curved surface.
Also, a downstream surface 350b of the second upstream reference
voltage electrode 350 has an arcuate shape to have a concave curved
surface corresponding to the upstream surface 330a of the upstream
intermediate electrode 330. Therefore, an ion beam passing through
the upstream electrode device 300 converges in a horizontal
direction. Also, the upstream electrode device 300 may have a shape
such that the ion beam passing through the upstream electrode
device 300 converges in a vertical direction, or may have a shape
such that the ion beam converges in both a horizontal direction and
a vertical direction.
[0221] FIGS. 18A and 18B are diagrams schematically illustrating a
shape of the first upstream reference voltage electrode 310. FIG.
18A illustrates an appearance of the downstream surface 310b of the
first upstream reference voltage electrode 310, and FIG. 18B
illustrates a cross-section taken along line X-X of FIG. 18A. As
illustrated, the opening 312 of the first upstream reference
voltage electrode 310 has a horizontally-elongated rectangular
shape. The opening 312 is surrounded by four sides of an upper side
314, a lower side 315, a right side 316, and a left side 317.
[0222] The first upstream reference voltage electrode 310 has a
pair of aberration correctors 324 protruding from the downstream
surface 310b toward the scanning electrode device 400. The pair of
aberration correctors 324 are provided on upside and downside of
the opening 312 with the opening 312 interposed therebetween in a
vertical direction. The aberration correctors 324 have, for
example, a shape such that sides facing each other in a vertical
direction with the opening 312 interposed therebetween form a
triangle shape or a trapezoidal shape.
[0223] By providing the aberration correctors 324, the upper side
314 and the lower side 315 of the opening 312 has a shape such that
a central portion 320 thereof protrudes toward the scanning
electrode device 400. As a result, in the upper side 314 and the
lower side 315 of the first upstream reference voltage electrode
310, a thickness w.sub.1 of the central portion 320 in a z
direction is larger than a thickness w.sub.2 of a circumjacent
portion 322. Also, the central portion 320 is a position
corresponding to the reference trajectory Z, and the circumjacent
portion 322 is a position located away from the central portion 320
in a horizontal direction, and a position close to the right side
316 or the left side 317.
[0224] The aberration corrector 324 partially shields a deflecting
electric field generated by the scanning electrode device 400, and
reduces aberration occurring due to provision of the beam transport
correction electrode 450 having the beam transport correction inlet
electrode body 454. Hereinafter, by referring to a first upstream
reference voltage electrode and a scanning electrode device
according to a comparative example, effects due to provision of the
aberration corrector 324 to the first upstream reference voltage
electrode 310 will be represented along with effects of the beam
transport correction electrode 450 having the beam transport
correction inlet electrode body 454.
[0225] FIGS. 19A and 19B are diagrams schematically illustrating
trajectories of ion beams passing through a first upstream
reference voltage electrode 1310 and a scanning electrode device
1400 according to the comparative example. The first upstream
reference voltage electrode 1310 according to the comparative
example does not include the aberration corrector 324, and has an
opening shape such that thicknesses of a central portion and a
circumjacent portion in a z direction along a trajectory of an ion
beam are the same as each other. Also, the scanning electrode
device 1400 according to the comparative example is provided with a
beam transport correction electrode 1450 including no beam
transport correction inlet electrode body protruding toward a beam
trajectory.
[0226] FIGS. 19A and 19B illustrate trajectories in a case in which
a current value of a transported ion beam is relatively low, and a
state in which a transported ion beam is hard to divergence due to
a negligible space charge effect. Therefore, the trajectories of
the transported ion beams substantially trace the trajectories
intended in the design. Both when an ion beam passing along the
reference trajectory, and even when an ion beam passing outside of
the reference trajectory, the ion beams are deflected at the
substantially same angle due to the deflecting electric field
applied by the scanning electrode. Therefore, as illustrated in
FIG. 19A, ion beams passing along the central trajectory F1 and ion
beams passing along the left outer trajectory E1 and the right
outer trajectory G1 with respect to the central trajectory F1 are
deflected at the substantially same angle. Also, as illustrated in
FIG. 19B, ion beams passing along the upper outer trajectory J1 and
the lower outer trajectory K1 with respect to the central
trajectory are transported while hardly diverging in a vertical
direction at all, due to the negligible space charge effect.
[0227] Here, the "space charge effect" means to a phenomenon in
which, with respect to an ion beam including many ions with
positive charge, a diameter of the ion beam is expanded in a
horizontal direction, in a vertical direction, or in both
directions due to a repulsive force acting between adjacent ions.
In a case in which a current value of an ion beam is low, since a
spatial charge density of ions included in the ion beam is also low
and a distance between adjacent ions is spaced apart from each
other, the repulsive force hardly occurs. On the other hand, in a
case in which a current value of an ion beam is high, since a
spatial charge density of ions included in the ion beam is also
high and adjacent ions is close to each other, a relatively strong
repulsive force occurs, which is resulted in a state in which a
beam diameter is likely to be easily expanded. Therefore, in order
to appropriately transport a high current ion beam, there is a need
to design a beamline in consideration of the space charge
effect.
[0228] A beam trajectory in a case in which a current value of a
transported ion beam is relatively high will be described below. In
this case, it is assumed that trajectories E1, F1, G1, J1 and K1 of
an ion beam illustrated in FIGS. 19A and 19B are designed
trajectories being references. The designed trajectories may be
trajectories for which influence of the space charge effect that
needs to be taken into account in the case of transport of a high
current ion beam is compensated, and may be ideal trajectories
which correspond to a target in transport of a high current
beam.
[0229] FIGS. 20A and 20B are diagrams schematically illustrating
trajectories of ion beams passing through the first upstream
reference voltage electrode 1310 and the scanning electrode device
1400 according to the comparative example. In the present drawings,
there are illustrated trajectories in a case in which a current
value of a transported ion beam is relatively high in the same
device configuration as FIGS. 19A and 19B, and in a state in which
the beam diverges due to the space charge effect in both a
horizontal direction and a vertical direction.
[0230] As illustrated in FIG. 20A, an ion beam passing along a
central trajectory F2 passes along a trajectory substantially
identical to the designed trajectory F1 whereas ion beams passing
along a right outer trajectory E2 and a left outer trajectory G2
pass along trajectories slightly deviated to outside from the
designed trajectories E1 and G1. Also, as illustrated FIG. 20B, ion
beams passing along an upper outer trajectory J2 and a lower outer
trajectory K2 greatly diverge in a vertical direction with respect
to designed trajectories J1 and K1. An ion beam incident into the
scanning electrode device 1400 strongly converges in a vertical
direction and has a beam cross-sectional shape which is expanded in
a horizontal direction, based on which it is considered that the
space charge effect acts strongly in a vertical direction.
[0231] When a diameter of the beam emitted from the scanning
electrode device 1400 is expanded greatly in a vertical direction
as described above, this affects devices downstream from the
scanning electrode device 1400. For example, when it is tried to
transport an ion beam having a wide beam diameter as it is, there
is a need to expand openings for ion beam passage which are
provided in various electrodes, resulting in a requirement to
increase a size of electrodes disposed downstream. Also, when the
electrodes are sized up, capacities of power supplies that apply
high voltage to electrodes need to be increased. This results in an
increase in the size of the entire apparatus and therefore, a cost
for the apparatus increases.
[0232] Therefore, according to the present embodiment, the beam
transport correction inlet electrode body 454 protruding toward a
reference trajectory is provided in the beam transport correction
electrode 450, thereby causing an ion beam to converge in a
vertical direction in the vicinity of the inlet of the scanning
electrode device 400. FIGS. 21A and 21B are diagrams schematically
illustrating trajectories of ion beams passing through a first
upstream reference voltage electrode 1310 and a scanning electrode
device 400 according to an embodiment of the present invention. The
first upstream reference voltage electrode 1310 has the same
configuration as the above-described comparative example, but the
scanning electrode device 400 is different from that of the
comparative example in that the beam transport correction electrode
450 has the beam transport correction inlet electrode body 454.
[0233] As illustrated in FIG. 21B, by providing the beam transport
correction inlet electrode body 454, it is possible to cause a beam
to converge in a vertical direction in the inlet 402 of the
scanning electrode device 400. Therefore, in the present
embodiment, ion beams passing along the upper outer and lower outer
trajectories J3 and K3 is suppressed so as not to diverge in a
vertical direction, compared to the trajectories J2 and K2
according to the comparative example. Thus, it is possible to
prevent influence due to the phenomenon that the ion beam emitted
from the scanning electrode device 400 is expanded in a vertical
direction.
[0234] On the other hand, as illustrated in FIG. 21A, an ion beam
passing along a central trajectory F3 which is close to the beam
transport correction inlet electrode body 454 is deviated from the
designed trajectory F1 due to influence of the beam transport
correction inlet electrode body 454. The reason for this is that,
due to presence of the beam transport correction inlet electrode
body 454, distortion occurs in a deflecting electric field near the
beam transport correction inlet electrode body 454, and an ion
passing along a trajectory is relatively strongly deflected as the
trajectory is closer to the beam transport correction inlet
electrode body 454. As a result, aberration occurs in the vicinity
of the reference trajectory of an ion beam and a beam quality of an
ion beam passing through the scanning electrode device 400 is
degraded.
[0235] In the present embodiment, by providing the aberration
corrector 324 in the central portion 320 of the first upstream
reference voltage electrode 310, the influence of aberration
occurring in the vicinity of a reference trajectory of an ion beam
is suppressed. FIGS. 22A and 22B are diagrams schematically
illustrating trajectories of ion beams passing through a first
upstream reference voltage electrode 310 and a scanning electrode
device 400 according to an embodiment of the present invention. As
illustrated, the aberration corrector 324 is provided to protrude
toward the beam transport correction inlet electrode body 454. The
aberration corrector 324 has an effect that partially shields a
deflecting electric field generated by the scanning electrode
device 400 in the vicinity of the aberration corrector 324. As a
result, with respect to an ion beam passing along the central
trajectory F4, a deflecting electric field is partially shielded by
the aberration corrector 324 and a substantial distance over which
the deflecting electric field acts is shortened. Therefore,
influence is suppressed, in which an ion passing along a trajectory
is relatively strongly deflected as the ion is closer to the beam
transport correction inlet electrode body 454. Thus, by providing
the aberration corrector 324, it is possible to suppress the
influence of aberration occurring in the vicinity of a reference
trajectory of an ion beam and improve a beam quality. The upstream
electrode device 300 may be configured as an electrode lens that
has function of shaping or adjusting a profile of the ion beam
incident on the scanning electrode device 400, in conjunction with
the beam transport correction electrode 450.
[0236] FIGS. 23A and 23B are diagrams schematically illustrating
trajectories of ion beams passing through an upstream electrode
device 300 and a scanning electrode device 400 according to an
embodiment of the present invention. The present drawings
illustrate a configuration in which the upstream intermediate
electrode 330 and the second upstream reference voltage electrode
350 are added upstream of the first upstream reference voltage
electrode 310. As described above, by applying a high voltage
higher than the suppression voltage to the upstream intermediate
electrode 330, the upstream electrode device 300 functions as an
einzel lens. That is, the upstream electrode device 300 allows an
ion beam to converge in a horizontal direction before allowing the
ion beam to be incident into the scanning electrode device 400. As
illustrated in FIG. 23A, this allows ion beams passing along
trajectories E5 and G5 on the right outside and the left outside of
a center trajectory to converge in a horizontal direction, compared
to the trajectories E4 and G4 with no einzel lens.
[0237] FIGS. 24A and 24B are diagrams schematically illustrating a
shape of a beam transport correction electrode 450 according to a
modification. In the above-described embodiment, the beam transport
correction electrode 450 includes the straight portion 452
extending from the inlet 402 of the scanning electrode device 400
to the outlet 404. As illustrated in FIG. 24A, in the beam
transport correction electrode 450 according to one modification, a
length of the straight portion 452 may be shortened and the beam
transport correction electrode 450 may be provided only upstream of
the scanning electrode device 400. Also, as illustrated in FIG.
24B, in the beam transport correction electrode 450 according to
another modification, the straight portion 452 may not be provided,
and the beam transport correction electrode 450 may be configured
by only the beam transport correction inlet electrode body 454
disposed near the inlet 402 of the scanning electrode device 400.
According to the modifications, it is also possible to allow an ion
beam to converge in a vertical direction in the vicinity of the
inlet 402 of the scanning electrode device 400 and, at the same
time, obtain an effect that suppresses occurrence of the zero field
effect, like the above-described embodiment.
[0238] FIG. 25 is a diagram schematically illustrating trajectories
of ion beams passing through the first upstream reference voltage
electrode 1310 and the scanning electrode device 400 according to
another modification. In the above-described embodiment, as
illustrated in FIG. 21A, there has been described a case in which
an ion beam passing along the central trajectory F3 close to the
beam transport correction inlet electrode body 454 is strongly
deflected by the influence of the beam transport correction inlet
electrode body 454. On the other hand, in the present modification,
there is provided a case in which an ion beam passing along a
central trajectory F6 close to the beam transport correction inlet
electrode body 454 is relatively weakly deflected by the influence
of the beam transport correction inlet electrode body 454.
Depending on a shape or arrangement of the beam transport
correction inlet electrode body 454 as illustrated, a deflection
strength may be weakened in the vicinity of the reference
trajectory, caused by a distribution of a deflecting electric field
is disturbed due to presence of the beam transport correction inlet
electrode body 454. Even in this case, since aberration occurs in
the vicinity of the reference trajectory of an ion beam, a beam
quality of an ion beam passing through the scanning electrode
device 400 is degraded.
[0239] In the present embodiment, by providing the aberration
corrector 326 having a concave shape in the central portion 320 of
the first upstream reference voltage electrode 310, the influence
of aberration occurring in the vicinity of a reference trajectory
of an ion beam is suppressed. FIG. 26 is a diagram schematically
illustrating trajectories of ion beams passing through the first
upstream reference voltage electrode 310 and the scanning electrode
device 400 according to a modification. As illustrated, the
aberration corrector 326 is provided such that the central portion
320 is recessed with respect to the beam transport correction inlet
electrode body 454, and includes a shape such that the downstream
surface 310b is concave with respect to the scanning electrode
device 400. In other words, an opening shape is formed such that a
thickness w.sub.11 of the central portion 320 of the first upstream
reference voltage electrode 310 in a z direction is smaller than a
thickness w.sub.12 of the circumjacent portion 322 in a z
direction.
[0240] The aberration corrector 326 has an effect that expands an
area over which a deflecting electric field generated by the
scanning electrode device 400 acts, and with respect to the ion
beam passing along the central trajectory F7, a distance over which
the deflecting electric field acts becomes longer. Therefore,
influence is suppressed, in which an ion passing along a trajectory
is relatively weakly deflected as the ion is closer to the beam
transport correction inlet electrode body 454. Thus, according to
the present modification, by providing the aberration corrector 326
having a concave shape, it is possible to suppress the influence of
aberration occurring in the vicinity of a reference trajectory of
an ion beam and improve a beam quality.
[0241] Also, the first upstream reference voltage electrode 310
with the aberration correctors 324 and 326 may be used for other
purposes in addition a purpose to reduce the influence of
aberration occurring due to the beam transport correction inlet
electrode body 454 of the beam transport correction electrode 450.
For example, even in a case in which the beam transport correction
inlet electrode body 454 is not provided in the vicinity of the
inlet 402 of the scanning electrode device 400, when aberration
occurs in an ion beam passing along the vicinity of a reference
trajectory, the aberration corrector 324 or 326 may be provided for
the purpose of reducing the influence of the aberration. For
example, in a case in which a deflection amount of an ion beam
incident into the scanning electrode device 400 along the reference
trajectory is relatively large, the aberration corrector 324 having
a convex shape may be provided in the first upstream reference
voltage electrode 310. On the other hand, in a case in which a
deflection amount of an ion beam incident into the scanning
electrode device 400 along the reference trajectory is relatively
small, the aberration corrector 326 having a concave shape may be
provided in the first upstream reference voltage electrode 310.
Also, since the amount of aberration which is corrected by the
aberration corrector 324 or 326 can be adjusted by shapes of
aberration corrector 324 or 326, shapes of aberration corrector 324
or 326 may be determined depending on a correction amount as
required.
[0242] Next, returning to FIGS. 16A and 16B, the downstream
electrode device 500 will be described below. Electrodes that
constituting the downstream electrode device 500 are arranged in
the order of a first downstream reference voltage electrode 510, a
first downstream intermediate electrode 530, a second downstream
reference voltage electrode 550, a second downstream intermediate
electrode 570, and a third downstream reference voltage electrode
590 from the outlet 404 of the scanning electrode device 400 toward
a downstream direction.
[0243] The first downstream reference voltage electrode 510, the
first downstream intermediate electrode 530, the second downstream
reference voltage electrode 550, the second downstream intermediate
electrode 570, and the third downstream reference voltage electrode
590 respectively include openings 512, 532, 552, 572 and 592 for
ion beam passage. In the downstream electrode device 500, since an
ion beam emitted from the scanning electrode device 400 is scanned
by the scanning electrode device 400 in a horizontal direction, the
openings 512, 532, 552, 572 and 592 of the electrodes have a
horizontally-elongated shape.
[0244] In each of the electrodes constituting the downstream
electrode device 500, the opening is formed such that an opening
width thereof in a horizontal direction is expanded wide as the
electrode disposed downstream. For example, an opening width
w.sub.4 of the first downstream intermediate electrode 530 in a
horizontal direction is larger than an opening width w.sub.3 of the
first downstream reference voltage electrode 510 in a horizontal
direction. In addition, an opening width w.sub.5 of the second
downstream reference voltage electrode 550 in a horizontal
direction is larger than an opening width w.sub.4 of the first
downstream intermediate electrode 530 in a horizontal
direction.
[0245] Except for the opening 512 of the first downstream reference
voltage electrode 510, the openings 532, 552, 572 and 592 have a
horizontally-elongated rectangular cross-sectional shape. On the
other hand, the opening 512 of the first downstream reference
voltage electrode 510 has, as illustrated in FIG. 27A (described
below), a cross-sectional shape of which opening widths of right
and left ends are expanded in a vertical direction (y
direction).
[0246] The first downstream reference voltage electrode 510, the
second downstream reference voltage electrode 550, and the third
downstream reference voltage electrode 590 generally have a ground
potential. Therefore, the first downstream reference voltage
electrode 510, the second downstream reference voltage electrode
550, and the third downstream reference voltage electrode 590 can
also be referred to as a first downstream ground electrode, a
second downstream ground electrode, and a third downstream ground
electrode, respectively. Also, instead of the ground potential,
other potential being a reference voltage may be applied to each of
the first downstream reference voltage electrode 510, the second
downstream reference voltage electrode 550, and the third
downstream reference voltage electrode 590.
[0247] A positive high voltage of tens of kV is applied to the
first downstream intermediate electrode 530 disposed between the
first downstream reference voltage electrode 510 and the second
downstream reference voltage electrode 550, for example, a voltage
of about +30 to about +50 kV is applied thereto. Therefore, the
first downstream reference voltage electrode 510, the first
downstream intermediate electrode 530, and the second downstream
reference voltage electrode 550 function as an einzel lens. Thus,
the first downstream intermediate electrode 530 may be also
referred to as an einzel lens electrode. Therefore, the first
downstream reference voltage electrode 510, the first downstream
intermediate electrode 530, and the second downstream reference
voltage electrode 550 allow an ion beam passing through the
downstream electrode device 500 to converge in a vertical direction
and/or a horizontal direction, and shapes the ion beam passing
through the downstream electrode device 500. As a result, the
downstream electrode device 500 is configured as an electrode lens
that has function of shaping or adjusting a profile of the ion beam
emitted from the scanning electrode device 400.
[0248] Also, a negative high voltage of about several kV is applied
to the second downstream intermediate electrode 570 disposed
between the second downstream reference voltage electrode 550 and
the third downstream reference voltage electrode 590, for example,
a voltage of about -1 kV to about -10 kV is applied thereto.
Therefore, the second downstream intermediate electrode 570
functions as a suppression electrode that suppresses intrusion of
electrons into the scanning electrode device 400. Also, by
providing reference voltage electrodes both upstream and downstream
of the second downstream intermediate electrode 570, an electron
shielding effect due to the suppression electrode is enhanced.
Therefore, the downstream electrode device 500 can also be referred
to as a suppression electrode device having electron suppression
function with respect to the ion beam emitted from the scanning
electrode device 400.
[0249] FIGS. 27A and 27B are diagrams schematically illustrating a
shape of the first downstream reference voltage electrode 510. FIG.
27A illustrates an appearance of a downstream surface 510b of a
first downstream reference voltage electrode 510, in which a
position of a scanning electrode 410 disposed upstream of the first
downstream reference voltage electrode 510 is indicated by a dashed
line. FIG. 27B illustrates X-X line cross section of FIG. 27A. As
illustrated, an opening 512 of the first downstream reference
voltage electrode 510 substantially has a horizontally-elongated
rectangular shape, of which an opening width in a vertical
direction is expanded in the vicinity of both right and left
ends.
[0250] In the opening 512 of the first downstream reference voltage
electrode 510, an opening width h.sub.2 of circumjacent portions
522R and 522L in a vertical direction is larger than an opening
width h.sub.1 of a central portion 520 corresponding to a reference
trajectory Z in a vertical direction. Also, while the opening width
in a vertical direction in a central area X1 near the central
portion 520 is uniform at h.sub.1, and the opening width in a
vertical direction in a circumjacent area X2 near the circumjacent
regions 522R and 522L increases as closer to left and right ends.
In this case, the circumjacent area X2 is a position facing a
downstream end of the scanning electrode 410, that is a position
facing downstream ends 422R and 422L of the electrode inner
surfaces 412R and 412L of the scanning electrode 410.
[0251] Unlike in a position spaced apart from the electrode inner
surfaces 412R and 412L at a certain distance, electric field
distribution is distorted in the vicinity of the downstream ends
422R and 422L of the scanning electrode 410. The reason for this is
that the electric field distribution is more disturbed in the
vicinity of the ends of the electrodes, as compared to in the
vicinity of a center of the electrode surface. Therefore, an ion
beam passing through the vicinity of the downstream ends 422R and
422L of the scanning electrode 410 is affected by the distorted
deflecting electric field, causing convergence in an unintended
direction. According to the present embodiment, in the circumjacent
area X2 being a position facing the downstream ends 422R and 422L
of the scanning electrode 410, the influence of the distorted
deflecting electric field is reduced by expanding the opening width
of the opening 512 of the first downstream reference voltage
electrode 510 in a vertical direction.
[0252] FIG. 28 is a diagram schematically illustrating a
configuration of a first downstream reference voltage electrode 510
and a first downstream intermediate electrode 530. The first
downstream intermediate electrode 530 has an upstream surface 530a
which is perpendicular to a reference trajectory Z and has a shape
such that the upstream surface 530a protrudes toward the first
downstream reference voltage electrode 510 in the vicinity of the
central portion 540 at which the reference trajectory Z is
disposed. Also, the first downstream intermediate electrode 530 has
an upper side 534, a lower side 535, a right side 536, and a left
side 537 which surround the opening 532, and has a shape such that
the central portion 540 of the upper side 534 and lower side 535
protrude toward the first downstream reference voltage electrode
510. Therefore, in the first downstream intermediate electrode 530,
a thickness of the opening 532 in a z direction along the reference
trajectory Z, that is, a thickness w.sub.7 of the central portion
540 is larger than a thickness w.sub.8 of circumjacent portions
542R and 542L. Also, in the opening 532 of the first downstream
intermediate electrode 530, the thickness w.sub.7 in a z direction
is uniform in the central area X1, and the thickness in a z
direction gradually decreases in the circumjacent area X2, and, the
thickness w.sub.8 becomes smaller than that in the central area X1,
outside the circumjacent area X2.
[0253] On the other hand, the downstream surface 510b of the first
downstream reference voltage electrode 510 has a flat surface,
while the downstream surface 510b is perpendicular to the reference
trajectory Z. That is, in the opening 512 of the first downstream
reference voltage electrode 510, a thickness w.sub.6 in a z
direction is uniform in both the central area X1 and the
circumjacent area X2. Therefore, as to a distance between the
downstream surface 510b of the first downstream reference voltage
electrode 510 and the upstream surface 530a of the first downstream
intermediate electrode 530, the distance L.sub.1 is small in the
central area X1, the distance is gradually expanded in the
circumjacent area X2, and the distance L.sub.2 becomes large
outside the circumjacent area X2.
[0254] In the present embodiment, by making slope in a gap between
the first downstream reference voltage electrode 510 and the first
downstream intermediate electrode 530 in the circumjacent area X2,
the influence of aberration is reduced, aberration occurring due to
the fact that the opening width of the opening 512 of the first
downstream reference voltage electrode 510 is expanded in a
vertical direction in the circumjacent area X2. The downstream
electrode device 500 may be configured as an electrode lens that
corrects deflection aberration occurring in an ion beam emitted
from the scanning electrode device 400. In particular, the
downstream electrode device 500 may correct deflection aberration
occurring in an ion beam passing through the vicinity of the
downstream ends 422 of the scanning electrode 410, from among all
ion beams emitted from the scanning electrode device 400.
[0255] Hereinafter, effects caused by expanding the opening 512 of
the first downstream reference voltage electrode 510 in a vertical
direction in the circumjacent area X2 will be described while
referring to the scanning electrode device, the first downstream
reference voltage electrode and the first downstream intermediate
electrode according to the comparative example. Subsequently, in
the circumjacent area X2, an effect occurring due to the fact that
slope is made in the gap between the first downstream reference
voltage electrode 510 and the first downstream intermediate
electrode 530 will be described.
[0256] FIG. 29 is a diagram schematically illustrating trajectories
of ion beams passing through the scanning electrode device 400, the
first downstream reference voltage electrode 1510, and the first
downstream intermediate electrode 1530 according to the comparative
example. FIG. 30 is a diagram schematically illustrating a shape of
the first downstream reference voltage electrode 1510 according to
the comparative example. As illustrated in FIG. 30, a shape of an
opening 1512 of the first downstream reference voltage electrode
1510 according to the comparative example is a rectangular shape,
in which an opening width h.sub.1 in a vertical direction is
uniform at a central portion 1520 and circumjacent portions 1522R
and 1522L. Also, as illustrated in FIG. 29, the central portion of
the first downstream intermediate electrode 1530 according to the
comparative example does not protrude toward the first downstream
reference voltage electrode 1510, and a gap between the first
downstream reference voltage electrode 1510 and the first
downstream intermediate electrode 1530 is uniform.
[0257] In FIG. 29, ion beam trajectories E1 and G1 indicated by
dashed lines represent a case in which a beam diameter D.sub.x1 in
a horizontal direction is small, and ion beam trajectories E2 and
G2 indicated by solid lines represent a case in which a beam
diameter D.sub.x2 in a horizontal direction is large. In a case in
which a current value of an ion beam is relatively low, since the
influence of beam divergence due to the space charge effect is
small, it is easy to transport an ion beam with a high beam
quality, of which a cross-sectional ion distribution is uniform
even in the case of reducing the beam diameter D.sub.x1 as
indicated by the dashed lines. However, in a case in which a
current value of an ion beam is high, a beam easily diverges due to
the space charge effect, and therefore, it is difficult to
transport an ion beam with the beam diameter D.sub.x1 that is small
as indicated by the dashed lines. Therefore, it is required to
adjust the beam diameter D.sub.x2 that is large as indicated by the
solid lines in order to transport a high current ion beam.
[0258] When it is tried to transport an ion beam having the large
beam diameter D.sub.x2 with using a device designed to transport an
ion beam having the small beam diameter D.sub.x1, an ion passing
through the outer side of a beam trajectory is brought close to
openings end of electrodes. Since the electric field distributions
in the vicinities of the opening ends of the electrodes are more
disturbed, as compared to a center of the opening, an ion beam
passing through the vicinities of the opening ends may be deflected
in an unintended direction, and/or converges in an unintended
state. For example, in the case of deflecting an ion beam in a
right direction, an ion beam passing along a right outer trajectory
G2 passes through a point Q close to a downstream end 422R of a
right scanning electrode 410R and an upstream end 1516a of a right
side 1516 of the first downstream reference voltage electrode 1510.
At the point Q, disturbance in electric field distribution is large
and the ion beam easily converges in a vertical direction (y
direction) as compared to a point P through which an ion beam
passing along a left outer trajectory E2 passes. Then, only an ion
beam passing along the right outer trajectory G2 greatly converges
in a vertical direction, and therefore, aberration occurs.
Thereafter, a beam quality of a transported ion beam is
degraded.
[0259] It may be considered that it is possible to prevent such a
phenomenon from occurring by preventing an ion beam passing along
an outer trajectory from passing through the vicinities of the
openings of the electrodes. However, it is required to enlarge the
openings for ion beam passage which are provided in various
electrodes in order to prevent an ion beam from passing through the
vicinities of the opening edges of the electrodes, causing a
requirement to increase sizes of electrodes disposed downstream. In
addition, when the electrodes are increased in size, capacities of
a power supplies that apply a high voltages to electrodes also need
to be increased. This results in an increase in the size of the
entire apparatus and therefore, a cost for the apparatus
increases.
[0260] Therefore, in the present embodiment, the influence of the
above-described aberration is reduced by using the first downstream
reference voltage electrode 510 having an increased opening width
in a vertical direction in the circumjacent areas corresponding to
a position facing the downstream end 422 of the scanning electrode
410. FIG. 31 is a diagram schematically illustrating trajectories
of ion beams passing through the scanning electrode device 400, the
first downstream reference voltage electrode 510, and the first
downstream intermediate electrode 1530 according to an embodiment
of the present invention. The first downstream reference voltage
electrode 510 has a shape in which an opening width of the
circumjacent portion 522 in a vertical direction is expanded, and
therefore, it is possible to reduce vertical convergence occurring
when an ion beam passing along the right outer trajectory G3 passes
through the point Q.
[0261] However, when the opening width of the circumjacent portion
522 of the first downstream reference voltage electrode 510 in
vertical direction is expanded, this may cause occurrence of other
aberration. When the opening shape of the first downstream
reference voltage electrode 510 is changed, similarity of the shape
is diminished with respect to the opening shape of the first
downstream intermediate electrode 530. Therefore, disturbance in
electric field distribution occurs between the first downstream
reference voltage electrode 510 and the first downstream
intermediate electrode 530. In particular, when a high voltage is
applied to the first downstream intermediate electrode 530 in order
to allow the first downstream intermediate electrode 530 to
function as an einzel lens electrode, disturbance in electric field
distribution becomes remarkable, and only an ion beam passing
through the vicinity of the circumjacent portion 522 of the first
downstream reference voltage electrode 510 converges in a
horizontal direction, thereby other aberration occurring.
[0262] Therefore, in the present embodiment, occurrence of the
above-described other aberration is suppressed by making slope in a
distance between the first downstream reference voltage electrode
510 and the first downstream intermediate electrode 530 in the
circumjacent areas corresponding to a position facing the
downstream end 422 of the scanning electrode 410. FIG. 32 is a
diagram schematically illustrating trajectories of ion beams
passing through the scanning electrode device 400, the first
downstream reference voltage electrode 510, and the first
downstream intermediate electrode 530 according to an embodiment of
the present invention. As illustrated, the first downstream
intermediate electrode 530 has a shape in which, with respect to a
distance between the first downstream reference voltage electrode
510 and the first downstream intermediate electrode 530, a distance
L.sub.2 in the circumjacent portion 542 is longer than a distance
L.sub.1 in the central portion 540 of the first downstream
intermediate electrode 530. Therefore, slopes are made such that
the distance between the first downstream reference voltage
electrode 510 and the first downstream intermediate electrode 530
gradually lengthens toward right and left ends thereof at a
position facing the circumjacent portion 522 of the first
downstream reference voltage electrode 510. As a result, it is
possible to reduce horizontal convergence occurring in the vicinity
of the circumjacent portion 522 of the first downstream reference
voltage electrode 510, and suppress degradation of a beam quality
with respect to an ion beam passing along the right outer
trajectory G4.
[0263] FIG. 33 is a diagram schematically illustrating a shape of a
first downstream reference voltage electrode 510 and a first
downstream intermediate electrode 530 according to a modification.
In the first downstream reference voltage electrode 510 and the
first downstream intermediate electrode 530 according to the
above-described embodiments, the distance L.sub.1 in the central
area X1 and the distance L.sub.2 outside the circumjacent area X2
become different from each other due to protrusion of the upstream
surface 530a of the first downstream intermediate electrode 530
toward the first downstream reference voltage electrode 510. On the
other hand, according to the present modification, the distance
L.sub.1 in the central area X1 is shorten and the distance L.sub.2
outside the circumjacent area X2 is lengthened due to protrusion of
the downstream surface 510b of the first downstream reference
voltage electrode 510 toward the first downstream intermediate
electrode 530. Therefore, in the first downstream reference voltage
electrode 510 according to the present modification, a thickness
w.sub.6 of the circumjacent portion 522 in z direction is small and
a thickness w.sub.9 in the central portion 520 is large. Also,
among four sides surrounding the opening 512, the central portion
520 of the upper side and the lower side has a shape protruding
toward the first downstream intermediate electrode 530. Therefore,
like the above-described embodiment, it is possible to reduce
horizontal aberration occurring in an ion beam passing through the
circumjacent area X2.
[0264] FIGS. 34A and 34B schematically illustrate a trajectory of
ion beams passing through an upstream electrode device 600 and a
scanning electrode device 400 according to another embodiment of
the present invention. Unlike the upstream electrode device 300
according to the embodiment or the modification which have been
described, in the upstream electrode device 600 according to the
present embodiment, a concave portion or a convex portion is not
provided in a first upstream reference voltage electrode 610. Also,
a thickness w.sub.10 of an opening of the first upstream reference
voltage electrode 610 in a z direction is large as compared to the
first upstream reference voltage electrode 310 according to the
embodiment or the modification which have been described.
Hereinafter, a description for the upstream electrode device 600 is
given focusing on a difference between the upstream electrode
device 600 and the upstream electrode device 300 according to the
above-described embodiment.
[0265] The upstream electrode device 600 is arranged for a purpose
to support a role of the beam transport correction inlet electrode
body 454 by allowing an ion beam before being incident into the
scanning electrode device 400 to converge in a vertical direction,
in a case the effect of vertical convergence by the beam transport
correction inlet electrode body 454 of the beam transport
correction electrode 450 is not sufficient. That is, the upstream
electrode device 600 has a role as a beam focusing portion provided
upstream of the scanning electrode device 400. A high voltage that
is about several times higher than the suppression voltage required
for electron shielding is applied to an upstream intermediate
electrode 630 of the upstream electrode device 600 in order to
enhance the effect of vertical convergence.
[0266] In this case, when a high voltage is applied to the upstream
intermediate electrode 630, this may affect a deflecting electric
field generated by the scanning electrode device 400. Therefore, in
order to sufficiently shield the einzel field generated by the
upstream intermediate electrode 630, the thickness w.sub.10 of the
first upstream reference voltage electrode 610 in a z direction is
thickened. In order to enhance the effect that shields the einzel
field, it is preferable that the thickness w.sub.10 of the first
upstream reference voltage electrode 610 in a z direction is
similar to the opening width h.sub.10 of the first upstream
reference voltage electrode 610 in the vertical direction, or is
larger than the opening width h.sub.10. As a result, it is possible
to relieve the influence on the deflecting electric field generated
by the scanning electrode device 400 and allow an ion beam incident
into the scanning electrode device 400 to converge in the vertical
direction in advance. Accordingly, it is possible to suppress the
vertical divergence of the ion beam emitted from the scanning
electrode device 400.
[0267] FIGS. 35A, 35B, and 35C are diagrams schematically
illustrating a configuration of an upstream electrode device 600
and a scanning electrode device 400 according to other
modifications. According to the modifications, it may be possible
to provide a horizontal convergence function, by shaping electrode
surfaces of electrodes that constitute the upstream electrode
device 600 to have arcuate shapes.
[0268] As illustrated in FIG. 35A, it may be possible to form a
first focusing lens having a concave surface corresponding to a
downstream surface 650b of the second upstream reference voltage
electrode 650 and a convex surface corresponding to an upstream
surface 630a of the upstream intermediate electrode 630, and a
second focusing lens having a convex surface corresponding to a
downstream surface 630b of the upstream intermediate electrode 630
and a concave surface corresponding to an upstream surface 610a of
the first upstream reference voltage electrode 610.
[0269] As illustrated in FIG. 35B, it may be possible to form a
focusing lens having a concave surface corresponding to a
downstream surface 650b of the second upstream reference voltage
electrode 650 and a convex surface corresponding to an upstream
surface 630a of the upstream intermediate electrode 630, and a
non-lens element having flat surfaces corresponding to the
downstream surface 630b of the upstream intermediate electrode 630
and the upstream surface 610a of the first upstream reference
voltage electrode 610.
[0270] As illustrated in FIG. 35C, it may be possible to form a
focusing lens having a concave surface corresponding to a
downstream surface 650b of the second upstream reference voltage
electrode 650 and a convex surface corresponding to an upstream
surface 630a of the upstream intermediate electrode 630, and to
form a defocusing lens having a concave surface corresponding to
the downstream surface 630b of the upstream intermediate electrode
630 and a convex surface corresponding to the upstream surface 610a
of the first upstream reference voltage electrode 610.
[0271] Hereinafter, several aspects of the present invention will
be described.
[0272] 1-1. An ion implantation apparatus according to an
embodiment includes a scanning unit, the scanning unit including a
scanning electrode device that allows a deflecting electric field
to act on an ion beam incident along a reference trajectory and
scans the ion beam in a horizontal direction perpendicular to the
reference trajectory, and an upstream electrode device configured
by a plurality of electrode bodies provided upstream of the
scanning electrode device.
[0273] The scanning electrode device includes a pair of scanning
electrodes provided to face each other in the horizontal direction
with the reference trajectory interposed therebetween, and a pair
of beam transport correction electrodes provided to face each other
in a vertical direction perpendicular to the horizontal direction
with the reference trajectory interposed therebetween.
[0274] Each of the pair of beam transport correction electrodes
includes a beam transport correction inlet electrode body
protruding toward the reference trajectory in the vertical
direction in the vicinity of an inlet of the scanning electrode
device.
[0275] 1-2. Each of the beam transport correction electrode may
have a straight portion extending from the inlet of the scanning
electrode device to an outlet thereof, and
[0276] each of the beam transport correction inlet electrode bodies
may be provided to protrude from the straight portion toward the
reference trajectory in the vicinity of the inlet of the scanning
electrode device.
[0277] 1-3. Each of the beam transport correction inlet electrode
bodies may have a plate-like member of which a thickness direction
is identical to the horizontal direction.
[0278] 1-4. The upstream electrode device may include a first
upstream reference voltage electrode disposed just upstream of the
scanning electrode device and having an opening through which an
ion beam passes.
[0279] The first upstream reference voltage electrode may include a
downstream surface that faces the scanning electrode device and is
perpendicular to the reference trajectory, and a pair of aberration
correctors provided in the downstream surface such that the opening
is interposed therebetween in the vertical direction and has a
shape protruding toward or recessed from the scanning electrode
device on the downstream surface, and
[0280] the opening may have a thickness in a direction along the
reference trajectory in which the thickness in a central portion
disposed in the vicinity of the reference trajectory is different
from the thickness of a circumjacent portion located away from the
central portion in the horizontal direction by providing the pair
of aberration correctors.
[0281] 1-5. Each of the pair of the aberration correctors may have
a shape protruding toward the scanning electrode device such that
sides facing each other in a vertical direction with the opening
interposed therebetween form a triangle shape or a trapezoid shape,
and
[0282] the thickness of the opening in a direction along the
reference trajectory may be determined such that the thickness in
the central portion is larger than that in the circumjacent
portion.
[0283] 1-6. The upstream electrode device may further include a
beam focusing portion that allows an ion beam incident into the
scanning electrode device to converge in the vertical direction
and/or the horizontal direction.
[0284] 1-7. The upstream electrode device may include a second
upstream reference voltage electrode disposed upstream of the first
upstream reference voltage electrode and an upstream intermediate
electrode disposed between the first upstream reference voltage
electrode and the second upstream reference voltage electrode.
[0285] The upstream intermediate electrode and the second upstream
reference voltage electrode may respectively have an opening for
ion beam passage at a position which communicates with the first
upstream reference voltage electrode, and
[0286] the upstream intermediate electrode may receive a high
voltage which is different from potentials of the first upstream
reference voltage electrode and the second upstream reference
voltage electrode and have a function that allows an ion beam
incident into the scanning electrode device to converge in the
vertical direction and/or the horizontal direction.
[0287] 1-8. The upstream electrode device may be configured as an
electrode lens that has function of shaping or adjusting a profile
of an ion beam incident into the scanning electrode device.
[0288] 1-9. The upstream electrode device may be configured as an
electrode lens that has function of shaping or adjusting a profile
of an ion beam incident into the scanning electrode device, in
conjunction with the pair of beam transport correction
electrodes.
[0289] 1-10. The upstream electrode device may be configured as a
suppression electrode device that has electron suppression function
with respect to an ion beam incident into the scanning electrode
device.
[0290] 1-11. The scanning unit may further include a downstream
electrode device configured by a plurality of electrode bodies
disposed downstream of the scanning electrode device.
[0291] 1-12. The downstream electrode device may be configured as
an electrode lens that has function of shaping or adjusting a
profile of an ion beam emitted from the scanning electrode
device.
[0292] 1-13. The downstream electrode device may be configured as
an electrode lens that has function of shaping or adjusting a
profile of an ion beam emitted from the scanning electrode device,
in conjunction with the beam transport correction electrode.
[0293] 1-14. The downstream electrode device may be configured as a
suppression electrode device that has electron suppression function
with respect to the ion beam emitted from the scanning electrode
device.
[0294] 1-15. Pair of the beam transport correction electrodes may
be configured as correction electrodes that have function of
shaping or adjusting a profile of an ion beam passing through the
scanning electrode device.
[0295] 1-16. An ion implantation apparatus according to an
embodiment includes a scanning unit, the scanning unit including a
scanning electrode device that allows a deflecting electric field
to act on an ion beam incident along a reference trajectory and
scans the ion beam in a horizontal direction perpendicular to the
reference trajectory, and an upstream electrode device configured
by a plurality of electrode bodies provided upstream of the
scanning electrode device.
[0296] The upstream electrode device may include a first upstream
reference voltage electrode disposed just upstream of the scanning
electrode device and having an opening through which an ion beam
passes,
[0297] the first upstream reference voltage electrode may include a
downstream surface that faces the scanning electrode device and is
perpendicular to the reference trajectory, and a pair of aberration
correctors provided in the downstream surface such that the opening
is interposed therebetween in a vertical direction perpendicular to
the horizontal direction and has a shape protruding toward or
recessed from the scanning electrode device on the downstream
surface, and
[0298] the opening may have a thickness in a direction along the
reference trajectory in which the thickness in a central portion
disposed in the vicinity of the reference trajectory is different
from the thickness of a circumjacent portion located away from the
central portion in the horizontal direction by providing the pair
of aberration correctors.
[0299] 2-1. An ion implantation apparatus according to an
embodiment includes a scanning unit, the scanning unit including a
scanning electrode device that allows a deflecting electric field
to act on an ion beam incident along a reference trajectory and
scans the ion beam in a horizontal direction perpendicular to the
reference trajectory, and a downstream electrode device disposed
downstream of the scanning electrode device and provided with
openings through which the ion beam scanned in the horizontal
direction passes.
[0300] The scanning electrode device has a pair of scanning
electrode provided to face each other in the horizontal direction
with the reference trajectory disposed therebetween, and
[0301] the downstream electrode device includes an electrode body
configured such that, with respect to an opening width in a
vertical direction perpendicular to both the reference trajectory
and the horizontal direction and/or an opening thickness in a
direction along the reference trajectory, the opening width and/or
the opening thickness in a central portion in which the reference
trajectory is disposed is different from the opening width and/or
the opening thickness in the vicinity of a position facing the
downstream end of the scanning electrode.
[0302] 2-2. The downstream electrode device may be configured as an
electrode lens that corrects deflected aberration occurring in an
ion beam emitted from the scanning electrode device, as a result of
scanning deflection by the scanning electrode device.
[0303] 2-3. The downstream electrode device may be configured as an
electrode lens that corrects deflected aberration occurring in an
ion beam passing through the vicinity of both scanning ends from
among ion beams emitted from the scanning electrode device, as a
result of scanning deflection due to the scanning electrode
device.
[0304] 2-4. The downstream electrode device may include a first
downstream reference voltage electrode disposed just downstream of
the scanning electrode device, and
[0305] the opening of the first downstream reference voltage
electrode may have an opening width in which the opening width in
the vertical direction in the vicinity of a position facing the
downstream end of the scanning electrode device is larger than the
opening width in the vertical direction in the central portion in
which the reference trajectory is disposed.
[0306] 2-5. The opening of the first downstream reference voltage
electrode may have an opening width such that the opening width in
the vertical direction is uniform in the vicinity of the central
portion and the opening width in the vertical direction increases
toward right and left ends of the opening in the vicinity of a
position facing the downstream end of the scanning electrode.
[0307] 2-6. The downstream electrode device may further include a
second downstream reference voltage electrode disposed downstream
of the first downstream reference voltage electrode and a first
downstream intermediate electrode disposed between the first
downstream reference voltage electrode and the second downstream
reference voltage electrode.
[0308] The first downstream intermediate electrode and the second
downstream reference voltage electrode may respectively have an
opening for ion beam passage at a position which communicates with
the first downstream reference voltage electrode,
[0309] the first downstream intermediate electrode may receive a
high voltage of which a potential is different from that of the
first downstream reference voltage electrode and the second
downstream reference voltage electrode,
[0310] the first downstream reference voltage electrode may have a
downstream surface facing the first downstream intermediate
electrode and perpendicular to the reference trajectory,
[0311] the first downstream intermediate electrode may have an
upstream surface facing the first downstream reference voltage
electrode and perpendicular to the reference trajectory, and
[0312] the first downstream reference voltage electrode and the
first downstream intermediate electrode may have a shape such that
with respect to a distance between the downstream surface of the
first downstream reference voltage electrode and the upstream
surface of the first downstream intermediate electrode, the
distance in the vicinity of a position facing the downstream end of
the scanning electrode is larger than the distance in the central
portion in which the reference trajectory is disposed.
[0313] 2-7. The first downstream reference voltage electrode and
the first downstream intermediate electrode may be configured such
that the distance between the downstream surface of the first
downstream reference voltage electrode and the upstream surface of
the first downstream intermediate electrode gradually increases
toward right and left ends of the opening in the vicinity of a
position facing the downstream end of the scanning electrode.
[0314] 2-8. The upstream surface of the first downstream
intermediate electrode may have a shape protruding toward the first
downstream reference voltage electrode in the vicinity of the
central portion in which the reference trajectory is disposed.
[0315] 2-9. The downstream surface of the first downstream
reference voltage electrode may have a shape protruding toward the
first downstream intermediate electrode in the vicinity of the
central portion in which the reference trajectory is disposed.
[0316] 2-10. The opening of the first downstream intermediate
electrode may have an opening width in the horizontal direction
which is larger than an opening width in the horizontal direction
of the first downstream reference voltage electrode, and
[0317] the opening of the second downstream reference voltage
electrode may have an opening width in the horizontal direction
which is larger than an opening width in the horizontal direction
of the first downstream intermediate electrode.
[0318] 2-11. The downstream electrode device may further include a
third downstream reference voltage electrode disposed downstream of
the second downstream reference voltage electrode and a second
downstream intermediate electrode disposed between the second
downstream reference voltage electrode and the third downstream
reference voltage electrode,
[0319] the second downstream intermediate electrode and the third
downstream reference voltage electrode may respectively have an
opening for ion beam passage at a position which communicates with
the second downstream reference voltage electrode, and
[0320] the second downstream intermediate electrode may receive a
high voltage of which a potential is different from a potential of
the second downstream reference voltage electrode and the third
downstream reference voltage electrode and have a function that
suppresses intrusion of electrons into the scanning electrode
device.
[0321] 2-12. The first downstream intermediate electrode may
receive a high voltage of which an absolute value is larger than a
potential of the second downstream intermediate electrode, and have
a function that allows an ion beam emitted from the scanning
electrode device to converge in the vertical direction and/or the
horizontal direction.
[0322] 2-13. The scanning unit may further include an upstream
electrode device configured by a plurality of electrode bodies
provided upstream of the scanning electrode device.
[0323] 2-14. The upstream electrode device may have function of
shaping or adjusting a profile of an ion beam incident into the
scanning electrode device.
[0324] 2-15. The upstream electrode device may be configured as a
suppression electrode device having electron suppression function
with respect to an ion beam incident into the scanning electrode
device.
[0325] 2-16. The scanning electrode device may include a pair of
scanning electrodes provided to face each other in the horizontal
direction with the reference trajectory interposed therebetween,
and a pair of beam transport correction electrodes provided to face
each other in the vertical direction with the reference trajectory
interposed therebetween, and
[0326] the beam transport correction electrode is configured as a
correction electrode that have a shaping function or an adjusting
function with respect to a beam shape of an ion beam passing
through the scanning electrode device.
[0327] 2-17. The scanning electrode device may include a pair of
scanning electrodes provided to face each other in the horizontal
direction with the reference trajectory interposed therebetween,
and a pair of beam transport correction electrodes provided to face
each other in the vertical direction with the reference trajectory
interposed therebetween, and
[0328] the downstream electrode device is configured as an
electrode lens that have a shaping function or an adjusting
function with respect to a beam shape of an ion beam passing
through the scanning electrode device in conjunction with the
upstream electrode device and the beam transport correction
electrode.
* * * * *