U.S. patent application number 15/424470 was filed with the patent office on 2017-05-25 for ion implantation apparatus and ion implantation method.
The applicant listed for this patent is SEN CORPORATION. Invention is credited to Tetsuya KUDO, Shiro NINOMIYA.
Application Number | 20170148633 15/424470 |
Document ID | / |
Family ID | 47335177 |
Filed Date | 2017-05-25 |
United States Patent
Application |
20170148633 |
Kind Code |
A1 |
NINOMIYA; Shiro ; et
al. |
May 25, 2017 |
ION IMPLANTATION APPARATUS AND ION IMPLANTATION METHOD
Abstract
An ion implantation method in which an ion beam is scanned in a
beam scanning direction and a wafer is mechanically scanned in a
direction perpendicular to the beam scanning direction, includes
setting a wafer rotation angle with respect to the ion beam so as
to be varied, wherein a set angle of the wafer rotation angle is
changed in a stepwise manner so as to implant ions into the wafer
at each set eagle, and wherein a wafer scanning region length is
set to be varied, and, at the same time, a beam scanning speed of
the ion beam is changed, in ion implantation at each set angle in a
plurality of ion implantation operations during one rotation of the
wafer, such that the ions are implanted into the wafer and dose
amount non-uniformity in a wafer surface in other semiconductor
manufacturing processes is corrected.
Inventors: |
NINOMIYA; Shiro; (Tokyo,
JP) ; KUDO; Tetsuya; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEN CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
47335177 |
Appl. No.: |
15/424470 |
Filed: |
February 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13495888 |
Jun 13, 2012 |
9601314 |
|
|
15424470 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 14/48 20130101;
H01L 21/26586 20130101; H01J 2237/20214 20130101; H01J 37/3171
20130101; C23C 14/54 20130101; H01J 2237/20228 20130101; H01J
2237/30483 20130101; H01J 2237/3171 20130101 |
International
Class: |
H01L 21/265 20060101
H01L021/265; C23C 14/54 20060101 C23C014/54; C23C 14/48 20060101
C23C014/48 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2011 |
JP |
2011-132216 |
Claims
1-10. (canceled)
11. An ion implantation method in which an ion beam is scanned in a
beam scanning direction and a wafer is mechanically scanned in a
direction perpendicular to the beam scanning direction so as to
implant ions into the wafer, the method comprising: setting a wafer
rotation angle with respect to the ion beam in a stepwise manner to
implant ions into the wafer at each of a set wafer rotation angles;
and implanting the ions into the wafer forming a central region in
the wafer overlapping a portion of a range where the wafer is
mechanically scanned to obtain a two dimensional ion implantation
amount in-surface distribution pattern, the central region
representing the maximum or the minimum ion implantation amount
corresponding to a defined relationship among a diameter of the
wafer, a wafer scanning region length, and a radius of the wafer,
wherein, when the central region represents the minimum ion
implantation amount and a plurality of ion implantation regions
that overlap as the wafer is rotated, the implanting comprises:
during a first step of the implanting, setting the wafer scanning
region length to be shorter than the radius of the wafer, during a
second step of the implanting, with the wafer being mechanically
scanned at each of the set of wafer rotation angles, and during a
third step of the implanting, continuously repeating the second
step for a full rotation of the wafer, wherein, when the central
region represents the maximum ion implantation amount and a
plurality of ion implantation regions that overlap as the wafer is
rotated, the implanting comprises: during a first step of the
implanting, setting the wafer scanning region length to be longer
than the radius of the wafer, during a second step of the
implanting, with the wafer being mechanically scanned at each of
the set of wafer rotation angles, and during a third step of the
implanting, continuously repeating the second step for a full
rotation of the wafer.
12. The ion implantation method according to claim 11, wherein the
beam scanning speed of the ion beam is substantially constant
during the second step of the implanting.
13. The ion implantation method according to claim 11, wherein the
wafer scanning region length is set to be continuously varied for
each specific angle with regard to the set of wafer rotation
angles.
14. The ion implantation method according to claim 11, wherein the
beam scanning speed of the ion beam is continuously set for each
specific angle with regard to the set of the wafer rotation
angles.
15. The ion implantation method according to claim 11, wherein two
control amounts of the degree of dose amount non-uniformity in the
wafer surface and a two-dimensional non-uniform shape pattern
thereof are controlled independently from each other by
simultaneously controlling two control parameters of the variable
setting of the wafer scanning region length and the setting in the
beam scanning speed of the ion beam.
16. The ion implantation method according to claim 15, wherein the
two-dimensional ion implantation amount in-surface distribution
pattern is realized by at least varying the wafer scanning region
length and a two-dimensional ion implantation amount in-surface
distribution is realized by varying the beam scanning speed of the
ion beam, thereby controlling the two control amounts of the degree
of dose amount non-uniformity in the wafer surface and the
two-dimensional non-uniform shape pattern independently of each
other.
17. The ion implantation method according to claim 11, wherein the
two-dimensional ion implantation amount in-surface distribution
where the ratio of the maximum ion implantation amount to the
minimum ion implantation amount in the wafer surface is five times
or more is realized by implanting ions into the wafer surface while
forming the central region into which the ions are not implanted in
ion implantation at each of the set angle of the wafer rotation
angles.
18. An ion implantation apparatus which includes a beam scanner
scanning an ion beam in a beam scanning direction and a mechanical
scanning system mechanically scanning a wafer in a direction
perpendicular to the beam scanning direction and implant ions into
the wafer, the ion implantation apparatus comprising: a rotation
device that is provided in the mechanical scanning system and
varies a wafer rotation angle with respect to the ion beam; and a
controller that has a function of controlling at least the beam
scanner and the mechanical scanning system, wherein the controller
is configured to: set a wafer rotation angle with respect to the
ion beam in a stepwise manner to implant ions into the wafer at
each of a set wafer rotation angles; and implant the ions into the
wafer forming a central region in the wafer overlapping a portion
of a range where the wafer is mechanically scanned to obtain a
two-dimensional ion implantation amount in-surface distribution
pattern, the central region representing the maximum or the minimum
ion implantation amount corresponding to a defined relationship
among a diameter of the wafer, a wafer scanning region length, and
a radius of the wafer, wherein, when the central region represents
the minimum ion implantation amount and a plurality of ion
implantation regions that overlap as the wafer is rotated, the
controller is configured to the ions into the wafer by: setting the
wafer scanning region length to be shorter than the radius of the
wafer during a first step of the implanting, during a second step
of the implanting, with the wafer being mechanically scanned at
each of the set of wafer rotation angles, and during a third step
of the implanting, continuously repeating the second step for a
full rotation of the wafer, wherein, when the central region
represents the maximum ion implantation amount and a plurality of
ion implantation regions that overlap as the wafer is rotated, the
controller is configured to the ions into the wafer: setting the
wafer scanning region length to be longer than the radius of the
wafer during a first step of the implanting, during a second step
of the implanting, with the wafer being mechanically scanned at
each of the set of wafer rotation angles, and during a third step
of the implanting, continuously repeating the second step for a
full rotation of the wafer.
19. The ion implantation apparatus according to claim 18, wherein
the beam scanning speed of the ion beam is substantially constant
during the second step of the implanting.
20. The ion implantation apparatus according to claim 19, wherein
the controller further performs uniform ion implantation for the
entire surface of the wafer with a reduced ion implantation amount
in addition to the adjustment of ion implantation amount
distribution in the wafer surface, thereby performing an additional
adjustment of ion implantation amount distribution in the wafer
surface.
21. The ion implantation method according to claim 11, wherein the
wafer scanning region length is smaller than the radius of the
wafer.
22. The ion implantation method according to claim 11, wherein the
wafer scanning region length is larger than the radius of the wafer
and smaller than the diameter of the wafer.
23. The ion implantation apparatus according to claim 19, wherein
the wafer scanning region length is smaller than the radius of the
wafer.
24. The ion implantation apparatus according to claim 19, wherein
the wafer scanning region length is larger than the radius of the
wafer and smaller than the diameter of the wafer.
25. The ion implantation method according to claim 11, wherein the
minimum ion implantation amount is non-zero.
26. The ion implantation method according to claim 11, further
comprising repeatedly performing the ion implantation method on the
wafer for at least a plurality of times, where the plurality of
times is determined based on the set wafer rotation angles that are
obtained by dividing 360 degrees of the wafer by n (n.gtoreq.2),
where n is a positive integer.
27. An ion implantation method in which an ion beam is scanned in a
beam scanning direction and a wafer is mechanically scanned in a
direction perpendicular to the beam scanning direction so as to
implant ions into the wafer, the method comprising: setting a wafer
rotation angle with respect to the ion beam in a stepwise manner to
implant ions into the wafer at each of a set wafer rotation angles;
and implanting the ions into the wafer forming a central region in
the wafer overlapping a portion of a range where the wafer is
mechanically scanned to obtain a two dimensional ion implantation
amount in-surface distribution pattern, the central region
representing the minimum ion implantation amount corresponding to a
defined relationship among a diameter of the wafer, a wafer
scanning region length, and a radius of the wafer, wherein, when
the central region represents the minimum ion implantation amount
and a plurality of ion implantation regions that overlap as the
wafer is rotated, the implanting comprises: during a first step of
the implanting, setting the wafer scanning region length to be
longer than the radius of the wafer, during a second step of the
implanting, simultaneously varying the wafer scanning region length
for regulating the range where the wafer is mechanically scanned,
and changing a beam scanning speed of the ion beam to be higher in
the central region than other positions of the wafer at each of the
set of wafer rotation angles, and during a third step of the
implanting, continuously repeating the second step for a full
rotation of the wafer.
Description
[0001] This application is based upon and claims the benefit of
priority from Japanese patent application No. 2011-132216, filed on
Jun. 14, 2011, the disclosure of which is incorporated herein in
its entirety by reference.
TECHNICAL FIELD
[0002] The present invention relates to an ion implantation
apparatus and an ion implantation method, and more particularly to
ion implantation amount control of the ion implantation
apparatus.
BACKGROUND ART
[0003] In a semiconductor manufacturing processes, a process for
implanting ions into a semiconductor wafer is performed in a
standard procedure for the purpose of varying conductivity, varying
a crystalline structure of the wafer, or the like. An apparatus
used in this process is called an ion implantation apparatus. The
ion implantation apparatus has a function of generating ions using
an ion source, and then forming an accelerated ion beam, and a
function of irradiating the entire surface of the semiconductor
wafer with the ion beam, through beam scanning, wafer scanning, or
a combination thereof.
[0004] In the semiconductor manufacturing processes, in order to
create semiconductor chips having the same performance across the
entire surface of the wafer, typically, it is necessary to form a
uniform condition in the wafer surface. In the ion implantation
broom, typically, the ion implantation apparatus is controlled such
that an ion implantation amount implanted over the entire region of
the wafer is made to be uniform.
[0005] In some semiconductor manufacturing processes, it is
difficult to obtain uniform conditions in the wafer surface in
principle. Particularly, in recent years, miniaturization of the
semiconductor chip has rapidly progressed, and as the difficulty in
obtaining uniform conditions in the wafer surface has increased,
the extent of non-uniformity also increases. If a uniform condition
is formed in the wafer surface in other processes under such
conditions, as a result, semiconductor chips having the same
performance in the entire wafer surface cannot be created. For
example, in the ion implantation process, when a typical ion
implantation is performed for the entire region of the wafer such
that an ion implantation amount in the surface is uniform,
electrical characteristics of resultant semiconductor chips are not
the seine as each other, and thus semiconductor chips having the
same performance cannot be created.
[0006] Therefore, in a case where a uniform condition cannot be
formed in the wafer surface in the other semiconductor
manufacturing processes, in order to handle dose amount
non-uniformity in the wafer surface, an intentional non-uniform
two-dimensional ion implantation amount in-surface distribution
(hereinafter, simply referred to as two-dimensional ion
implantation amount in-surface distribution by omitting
"intentional non-uniform" in some cases) may be created in the
process of irradiating the entire wafer with an ion beam using the
ion implantation apparatus, and the dose amount non-uniformity in
the wafer surface may be corrected in the other semiconductor
manufacturing processes. At this time, it is important to employ an
ion implantation apparatus and an ion implantation method having a
function capable of handling both the size of the dose amount
non-uniformity in the wafer surface and a two-dimensional
non-uniform shape pattern thereof in the other semiconductor
manufacturing processes.
[0007] As an example of the method of creating a two-dimensional
icon implantation amount in-surface distribution in the wafer
surface, there has been proposed a method of controlling a scanning
speed by an on beam and a scanning speed (mechanical scanning
speed) by a semiconductor wafer (refer to Japanese Unexamined
Patent Publication No. 2003-86530).
[0008] In an ion implantation method disclosed in Japanese
Unexamined Patent Publication No. 2003-80500, only a scanning speed
by an ion beam and a scanning speed by a semiconductor wafer are
controlled. In this case, a control range of the scanning speed is
restricted, and thereby a large-scale two-dimensional ion
implantation amount in-surface distribution where a ratio of the
maximum ion implantation amount to the minimum ion implantation
amount in the wafer surface is five times or more cannot be
realized.
[0009] In addition, since the ion implantation method disclosed in
Japanese Unexamined Patent Publication No. 2003-86530 is aimed at
creating regions having different ion implantation amounts on a
wafer, patterns of ion implantation amounts which can be
implemented in a wafer surface era restricted, and thus it does not
have a function of creating a two-dimensional ion implantation
amount in-surface distribution capable of handling a
two-dimensional non-uniform shape pattern in other semiconductor
manufacturing processes.
[0010] It is desirable to realize a two-dimensional ion
implantation amount in.-surface distribution where a ratio of the
maximum ion implantation amount to the minimum ion implantation
amount in the wafer surface is of a large scale.
[0011] Specific objects of the present invention are to realize the
following.
[0012] 1. To realize a large-scale two-dimensional ion implantation
amount in-surface distribution where a ratio of the maximum ion
implantation amount to the minimum ion implantation amount in the
wafer surface is five times or more.
[0013] 2. To provide a function capable of handling the degree of
dose amount non-uniformity in a wafer surface in other
semiconductor manufacturing processes.
[0014] 3. To provide a function capable of handling a
two-dimensional non-uniform shape pattern of dose amount
non-uniformity in a wafer surface in other semiconductor
manufacturing processes.
[0015] 4. To control the function capable of handling the degree of
dose amount non-uniformity in a wafer surface and the function
capable of handling a two-dimensional nonuniform shape pattern
independently from each other. For example, even if the degree of
dose amount non-uniformity in a wafer surface is the same, a
two-dimensional non-uniform shape pattern thereof can be varied,
and, conversely, even if a two-dimensional non-uniform shape
pattern is the same, the degree of dose amount non-uniformity in
the wafer surface can be varied.
[0016] The present invention is applied to an apparatus which scans
an ion beam in a beam scanning direction, mechanically scans a
wafer in a direction substantially perpendicular to the beam
scanning direction, and implants ions into the wafer.
[0017] According to an aspect of the present invention, an ion
implantation method is provided, in the ion implantation method, an
ion beam is scanned in a beam scanning direction and a wafer is
mechanically scanned in a direction perpendicular to the beam
scanning direction so as to implant ions into the wafer. The method
comprises setting a wafer rotation angle with respect to the ion
beam so as to be varied. A set angle of the wafer rotation angle is
changed in a stepwise manner so as to implant ions into the wafer
at each set angle. A wafer scanning region length for regulating a
range where the wafer is mechanically scanned is set to be varied,
and, at the same time, a beam scanning speed of the ion beam is
changed, in ion implantation at each set angle in a plurality of
ion implantation operations during one rotation of the wafer, such
that the ions are implanted into the wafer and dose amount
non-uniformity in a wafer surface in ether semiconductor
manufacturing processes is corrected.
[0018] According to another aspect of the present invention, an ion
implantation method is provided. In the ion implantation method, an
ion beam is scanned in a beam scanning direction and a wafer is
mechanically scanned in a direction perpendicular to the beam
scanning direction so as to implant ions into the wafer. The method
comprises setting a wafer rotation angle with respect to the ion
beam so as to be varied and setting a wafer scanning region length
for regulating a range where the wafer is mechanically scanned so
as to be varied, ion implantation is performed multiple times for a
partial region surface from one end side of the wafer to the set
wafer scanning region length during one rotation of the wafer at an
angle used as a reference of the wafer rotation angle and one or
more set angles changed from the angle used as a reference. A
combination of variable setting of the wafer scanning region length
and change control of the beam scanning speed of the ion beam in
ion implantation at each set angle is performed such that the ions
are implanted into the wafer and dose amount non-uniformity in a
wafer surface in other semiconductor manufacturing processes is
corrected.
[0019] According to still another aspect of the present invention,
an ion implantation apparatus includes a beam scanner scanning an
ion beam in a beam scanning direction and a mechanical scanning
system mechanically scanning a water in a direction perpendicular
to the beam scanning direction and implant ions into the wafer. The
apparatus comprises a rotation device that is provided in the
mechanical scanning system and varies a wafer rotation angle with
respect to the on beam and a controller that has a function of
controlling at least the beam scanner and the mechanical scanning
system.
[0020] The controller controls the rotation device such that a set
angle of the wafer rotation angle with respect to the ion beam is
changed in a stepwise manner so as to implant lone into the wafer
at each set angle, controls the mechanical scanning system such
that a wafer scanning region length for regulating a range where
the wafer is mechanically scanned is set to be varied, and, at the
same time, controls the beam scanner such that a beam scanning
speed of the ion beam is changed, in ion implantation at each set
angle in a plurality of ion implantation operations during one
rotation of the wafer, such that the ions are implanted into the
wafer and a dose amount in a direction where the wafer is
mechanically scanned is controlled, thereby performing an
adjustment of ion implantation amount distribution in a wafer
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a plan view illustrating a schematic configuration
of an example of the ion implantation apparatus to which the
present invention is applicable.
[0022] FIG. 2 is a side view illustrating, by enlargement, a
schematic configuration of an example of the wafer periphery of the
ion implantation apparatus shown in FIG. 1.
[0023] FIG. 3 is a diagram illustrating an ion beam scanning method
and a wafer scanning method.
[0024] FIG. 4 is a diagram illustrating ion implantation for
realizing dose amount uniformity in a wafer surface which is
performed in the related art.
[0025] FIG. 5 is a diagram illustrating control of a wafer scanning
region length for mechanically scanning a wafer according to an
embodiment of the present invention.
[0026] FIGS. 6A to 6C are diagrams illustrating an ion implantation
method of irradiating a wafer with an ion beam while simultaneously
controlling a wafer scanning region length for mechanically
scanning a wafer and a beam scanning speed in a beam scanning
direction according to an embodiment of the present invention.
[0027] FIG. 7 is a diagram illustrating variability of the wafer
scanning region length for mechanically scanning a wafer according
to an embodiment of the present invention.
[0028] FIGS. 8A and 8B are diagrams illustrating an ion
implantation scheme of repeatedly performing the ion implantation
method of simultaneously controlling the wafer scanning region
length and the beam scanning speed multiple times while changing a
wafer rotation angle with respect to an ion beam according to an
embodiment of the present invention.
[0029] FIGS. 9A to 9E are diagrams illustrating an ion implantation
scheme of repeatedly performing the ion implantation method of
varying only the wafer scanning region length for mechanically
scanning a wafer multiple times while changing a wafer rotation
angle with respect to an ion beam according to an embodiment of the
present invention.
[0030] FIGS. 10A to 10E are diagrams illustrating, an ion
implantation scheme of repeatedly performing the ion implantation
method of varying only the wafer scanning region length for
mechanically scanning a wafer multiple times while changing a wafer
rotation angle with respect to an ion beam according to an
embodiment of the present invention.
[0031] FIGS. 11A to 11E are diagrams illustrating an ion
implantation scheme of performing the ion implantation method of
simultaneously controlling the wafer scanning region length and the
beam scanning speed each time a wafer rotation angle with respect
to an ion beam is changed and of repeatedly performing the ion
implantation method multiple times according to an embodiment of
the present invention.
[0032] FIGS. 12A to 12E are diagrams illustrating an ion
implantation scheme of performing the ion implantation method of
simultaneously controlling the wafer scanning region length and the
beam scanning speed each time a wafer rotation angle with respect
to an ion beam is changed and of repeatedly performing the ion
implantation method multiple times according to an embodiment of
the present invention.
[0033] FIGS. 13A to 13E are diagrams illustrating an ion
implantation scheme of performing the ion implantation method of
simultaneously controlling the wafer scanning region length and the
beam scanning speed each time a wafer rotation angle with respect
to en ion beam is changed and of repeatedly performing it multiple
times according to an embodiment of the present invention.
[0034] FIG. 14 is a diagram illustrating an example of the
large-scale two-dimensional ion implantation amount in-surface
distribution where a ratio of the maximum ion implantation amount
to the minimum on implantation amount in the wafer surface is five
times or more, which has been actually obtained according to the
embodiment of the present invention.
[0035] FIG. 15 is a diagram illustrating an example of the ion
implantation amount distribution indicating that two control
amounts of dose amount non-uniformity in a wafer surface and a
two-dimensional non-uniform shape pattern thereof can be controlled
independently from each other, which has been actually obtained
according to the embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Here, a schematic configuration of the ion implantation
apparatus to which the present invention is applicable will be
described with reference to FIG. 1. In the ion implantation
apparatus to which the present invention is applicable, a mass
spectrometry magnet device 3, a mass spectrometry silt 4, a beam
scanner 5, and a wafer treatment chamber (ion implantation chamber)
(not shown) are disposed in this order along a beam line such that
an ion beam extracted from an ion source 1 by an extraction
electrode 2 pass through the beam line reaching to a wafer 7. In
the wafer treatment chamber, a mechanical scanning device having a
mechanism including a holder 8 holding the wafer 7 is disposed. The
ion beam extracted from the ion source 1 are guided to the wafer 7
on the holder 8 disposed at an ion implantation position of the
wafer treatment chamber along the beam line.
[0037] The ion beam becomes parallel by a function of a parallel
lens 6 after being scanned by the beam scanner 5 in the beam
scanning direction, and then are guided to the wafer 7. In the ion
implantation apparatus according to the embodiment of the present
invention, the wafer 7 is mechanically scanned in a direction which
is substantially perpendicular to the ion beam scanning direction,
and thereby ions are implanted into the wafer 7. In FIG. 1, the
wafer 7 may be scanned in the perpendicular direction to the
figure.
[0038] FIG. 2 is a side view illustrating, by enlargement, a
schematic configuration of an example of the wafer periphery of the
ion implantation apparatus shown in FIG. 1. In FIG. 2, the ion beam
is scanned on the surface perpendicular to the figure and is
applied to the wafer 7 held on the holder 8. The holder 8 is
reciprocally driven in the arrow A direction in FIG. 2 by a lifting
device 10, and, as a result, the wafer 7 held on the holder 8 is
also reciprocally driven in the arrow A direction in FIG. 2. In
other words, the ion beam is scanned in the beam scanning
direction, and the wafer 7 is mechanically scanned in the direction
substantially perpendicular to the beam scanning direction, thereby
implanting ions into the entire surface of the wafer 7.
[0039] In addition, the ion implantation apparatus is provided with
a rotation device 9 which rotates the holder 8 in the arrow B
direction. As a result, the wafer 7 held on the holder 8 is also
rotated with respect to the ion beam. In ether words, the wafer 7
is rotated with respect to a central axis thereof as a center. The
lifting device 10 reciprocally drives not only the wafer 7 and the
holder 8 but also the rotation device 9 in the arrow A direction in
FIG. 2.
[0040] Here, an ion beam scanning method and a wafer scanning
method will be described with reference to FIG. 3. In FIG. 3, only
the scanned wafer 7, the scanned ion beam, and the lifting device
10 are shown, and the holder and the rotation device are not shown.
In this example, the ion beam is scanned in the transverse
direction, and the wafer 7 is scanned in the longitudinal
direction. As shown in FIG. 3, in a typical ion implantation
apparatus, the scanning region of the ion beam exceeds the wafer
diameter, and a region where the wafer 7 is mechanically scanned is
controlled such that the wafer 7 dots across the ion beam
irradiation region (the region indicated by the solid line as the
scanned ion beam).
[0041] Although a control system of the ion implantation apparatus
is not shown, control of a mechanical scanning device including the
rotation device 9 and the lifting device and, for example, control
of a beam scanning speed in the beam scanner 5 are performed by a
controller (not shown). For this reason, various measurement
devices such as a sensor detecting a rotation angle of the rotation
device 9, a sensor detecting a lifting position and a lifting speed
of the lifting device 10, and a sensor measuring ion beam in the
wafer treatment chamber, are installed, and the controller executes
a control operation using results measured by the measurement
devices.
[0042] The ion implantation apparatus according to the embodiment
of the present invention is, as described above, an apparatus which
scans the ion beam in the beam scanning direction, mechanically
scans the wafer in the direction substantially perpendicular to the
beam scanning direction, and implants one into the wafer, but if an
ion implantation amount implanted into the wafer is to be
considered, a relative movement between the ion beam and the wafer
is problematic. Therefore, for convenience of understanding,
assuming that the wafer is static, an implantation region of the
ion and a beam scanning speed may be considered relatively.
[0043] FIG. 4 is a diagram illustrating ion implantation for
realizing dose amount uniformity in the wafer surface which is
performed in the related art. In FIG. 4, it can be seen that the
ion implantation region extends over the entire surface of the
wafer 7 in the transverse direction as well as in the longitudinal
direction. In other words, the convenient ion beam implantation
region range includes the wafer shape.
[0044] In standard ion implantation for realizing dose amount
uniformity in the wafer surface performed in the related art, in
order to secure ion implantation amount uniformity in the
transverse direction on the wafer, scanning speed of the ion beam
is maintained to be nearly constant. In addition, in order to
maintain uniformity in the longitudinal direction on the wafer, a
scanning speed of the wafer, that is, a mechanical scanning speed
is maintained to be nearly constant.
[0045] As an example of the method of creating an intentional
non-uniform two-dimensional ion implantation amount in-surface
distribution in a wafer surface (as described above, hereinafter,
simply referred to as two-dimensional ion implantation amount
in-surface distribution by omitting "intentional non-uniform"), a
method of controlling a scanning speed of ion beam and a scanning
speed of a semiconductor wafer may be considered. However, in this
ease, since a control range of each scanning speed is restricted, a
large-scale two-dimensional ion implantation amount in-surface
distribution where a ratio of the maximum ion implantation amount
to the minimum ion implantation amount in the wafer surface is five
times or more, which is intended to be realized by certain
embodiments of the present invention, cannot be realized.
[0046] In certain embodiments of the present invention, an ion
implantation method is used in which a wafer is irradiated with ion
beam while simultaneously controlling a wafer scanning region
length for regulating a range where the wafer is mechanically
scanned and a beam scanning speed in the beam scanning direction,
and, first, with reference to FIG. 5, control of the wafer scanning
region length for scanning the wafer 7 according to an embodiment
of the present invention will be described. In FIG. 5, only the
scanned wafer 7, the scanned ion beam and the Ming device 10 are
shown, and the holder and the rotation device are not shown, in
this example, the ion beam is scanned in the transverse direction
and the wafer is scanned in the longitudinal direction.
[0047] As described in FIG. 3, in a typical ion implantation
apparatus, the ion beam irradiation region exceeds the wafer
diameter, and a region where the wafer 7 is mechanically scanned is
controlled such that the wafer 7 cuts across the ion beam
irradiation region. In contrast, in certain embodiments of the
present invention, the ion beam irradiation region exceeds the
wafer diameter in the same manner as the typical ion implantation
apparatus, but the region where the wafer 7 is mechanically scanned
is controlled such that the wafer 7 does not completely cut across
the ion beam irradiation region. FIG. 5 shows that when the wafer 7
arrives at the lowermost position indicated by the two-dot chain
line, the wafer 7 does not completely cut across the ion beam
irradiation region. However, this is an example, and when the wafer
7 arrives at the uppermost position indicated by the two-dot chain
line different from it, the wafer 7 may not completely cut across
the ion beam irradiation region, or the wafer 7 may not completely
cut across the ion beam irradiation region in either the wafer
uppermost position or the wafer lowermost position.
[0048] Here, with reference to FIGS. 6A to 6C, a description will
be made of en ion implantation method of irradiating the wafer 7
with the ion beam while simultaneously controlling a wafer scanning
region length for mechanically scanning the wafer 7 and a beam
scanning speed in the beam scanning direction. As described in FIG.
4, if are ion implantation amount implanted into the wafer 7 is to
be considered, for convenience of understanding, assuming that the
wafer 7 stops, the ion beam irradiation region and the beam
scanning speed may be considered relatively. Therefore, in FIG. 6A
as well, for convenience of understanding, the wafer 7 is shown as
if it stops.
[0049] As described in FIG. 6, in certain embodiments of the
present invention, the wafer scanning region length for scanning
the wafer 7 is configured to be continuously changed. Therefore, in
FIG. 6A, the ion beam irradiation region extends over the entire
surface of the wafer in the transverse direction, but ion
implantation is performed only up to the middle part of the wafer 7
in the longitudinal direction. In other words, a range of the
convenient ion beam irradiation region does not include the wafer
shape. In addition, as is clear from FIG. 6B, the beam scanning
speed V of the ion beam can be controlled so as to be continuously
varied in the transverse direction of the wafer. In FIG. 6A, the
wafer scanning region length is shown so as to exceed the wafer
center, but this is an example and the wafer scanning region length
may not exceed the wafer center. Further, as is clear from FIG. 6B,
the beam scanning speed V may be controlled (set) so as to become a
valley type (indicated by C1, C2 and C5) at the central region of
the wafer (the central region of the beam scanning range),
conversely, may be controlled (set) so as to be a mountain type
(C4) at the central region of the wafer, or may be controlled (set)
such that a,plurality of valleys and mountains (C3) exist from the
end of the wafer to the central region of the wafer or so as to
become asymmetric.
[0050] Here, with reference to FIG. 6C, a relationship between the
beam scanning speed V and the on implantation amount D will be
described. When the beam scanning speed V is high, the ion
implantation amount D implanted in a corresponding ion beam
irradiation region for the unit time decreases in reverse
proportion to the beam scanning speed V. In certain embodiments of
the present invention, the beam scanning speed is actually
controlled, but a purpose thereof is control of an ion implantation
amount, and, hereinafter, discussion will be performed using the
ion implantation amount unless particularly clearly indicated.
[0051] Next, with reference to FIG. 7, a description will be made
of the wafer scanning region length for mechanically scanning the
wafer 7. In certain embodiments of the present invention, the wafer
scanning region length for mechanically scanning the wafer 7 can be
set to be varied. In other words, the wafer scanning region length
for scanning the wafer 7 may be set to be smaller than the wafer
radius, or may be set to be larger than the wafer radius and
smaller than the wafer diameter.
[0052] In the ion implantation method according to en embodiment of
the present invention, since the wafer scanning region length for
mechanically scanning the wafer is changed, there is a region into
which ions are not implanted in the longitudinal direction of the
wafer and a region into which ions are implanted in this step.
Based on this great difference between ion implantation amounts in
the two regions, as described later in detail, after executing an
implantation method which is repeatedly performed multiple times
while continuously changing a wafer rotation angle with respect to
the ion beam. It is possible to realize a large-scale
two-dimensional ion implantation amount in-surface distribution
where a ratio of the maximum ion implantation amount to the minimum
ion implantation amount is five times or more. In addition, in the
region into which ions are implanted a distribution can be
intentionally generated in the ion implantation amounts depending
on a position in the transverse direction of the wafer in response
to the change in the beam scanning speed. Based on this
distribution as described later in detail, alter executing an
implantation method which is repeatedly performed multiple times
while continuously changing a wafer rotation angle with respect to
the ion beam, it is possible to control two control amounts of the
degree of the dose amount non-uniformity in a wafer surface and a
two-dimensional non-uniform shape pattern thereof independently
from each other.
[0053] Next, certain embodiments of the present invention employs
an implantation method in which an ion implantation where the wafer
scanning region length and the beam scanning speed are
simultaneously controlled is performed each time a wafer rotation
angle with respect to the ion beam is changed and this is
repeatedly performed multiple times during one rotation of the
wafer.
[0054] This implantation method will be described with reference to
FIGS. 8A and 8B. In the ion implantation apparatus according to an
embodiment of the present invention, as described in FIG. 2, the
holder 8 is intermittently rotated at a set angle by the rotation
device 9 rotating the holder a, and, as a result, the wafer 7 held
on the holder 8 can be intermittently rotated with respect to the
ion beam at the set angle. However, if an ion implantation amount
implanted into the wafer 7 is to be considered, a relative movement
between the ion beam and the wafer 7 is problematic. Therefore, for
convenience of understanding, assuming that the wafer 7 stops, the
ion beam irradiation region may be considered to be rotated. In
FIGS. 8A and 8B, the wafer 7 is shown so as to stop.
[0055] As described in FIGS. 6A to 6C since certain embodiments of
the present invention employ an implantation method of implanting
ions into the wafer 7 while simultaneously controlling a wafer
scanning region length for mechanically scanning the wafer 7 end an
ion beam scanning speed, as a result, when the first implantation
operation finishes, a region 12 into which ions are not implanted
and a region 13 into which ions are implanted occur in the wafer 7.
Here, an ion implantation amount in-surface distribution 11 occurs
in the region 13 into which ions are implanted by control of the
beam scanning speed according to certain embodiments of the present
invention. In certain embodiments of the present invention, the
implantation method is used in which a wafer rotation angle with
respect to the ion beam is continuously changed, the
above-described implantation operation is performed after the
rotation stops, and this is repeatedly performed multiple times
during one rotation of the wafer. Here, the multiple times are
defined by set angles obtained by dividing 360 degrees of the wafer
by n with the number of 2 to n times (where n is a positive
integer). FIG. 8B shows an example of the second implantation
operation. A region 14 into which ions are implanted in the first
implantation operation is indicated by being hatched with the
diagonal lines. In the second implantation operation as well, in
the same manner as the first implantation operation, since there is
use of the implantation method of implanting ions into the wafer 7
while simultaneously controlling a wafer scanning region length for
mechanically scanning the wafer 7 and a beam scanning speed, a
region into which ions are net implanted in the implantation
operation and a region, having an implantation amount in-surface
distribution, into which ions are implanted also occur in the wafer
7 in the second implantation operation. Since rotation angles of
the wafer 7 with respect to the ion beam are varied in the first
implantation operation and the second implantation operation
(rotation in the counterclockwise direction in FIG. 8B), the region
into which ions are not implanted in the wafer decreases. In
addition, the ion implantation amount in-surface distribution is
further formed in the region into which ions are implanted.
[0056] In certain embodiments of the present invention, although,
in the continuously performed implantation operation, the wafer
scanning region length for mechanically scanning the wafer is set
to be continuously varied for each specific rotation angle, the
same wafer scanning region length may be used. In addition,
although the beam scanning speed in the beam scanning direction is
also controlled so as to be continuously varied for each specific
rotation angle, the same beam scanning speed pattern may be
used.
[0057] By repeatedly performing the implantation operation multiple
times, it is possible to realize a two-dimensional ion implantation
amount in-surface distribution in the wafer surface while
implanting ions into the entire surface region in the wafer
surface. Since the wafer scanning region length for mechanically
scanning the wafer 7 is controlled in certain embodiments of the
present invention, it is possible to realize an intentional
large-scale two-dimensional ion implantation amount in-surface
distribution where a ratio of the maximum ion implantation amount
to the minimum ion implantation amount in the wafer surface
increases. Specifically, it is possible to realize a large-scale
two-dimensional ion implantation amount in-surface distribution
where a ratio of the maximum ion implantation amount to the minimum
ion implantation amount is five times or more.
[0058] In order to describe the ion implantation method according
to certain embodiments of the present invention more in detail,
first, with reference to FIGS. 9A to 9E and 10A to 10E, a
description will be made of an implantation method in which only
the wafer scanning region length for mechanically scanning the
wafer 7 is varied while rotating the wafer 7. In addition,
hereinafter, in the description referring to FIGS. 9A to 9E, 10A to
10E, 11A to 11E, 12A to 12E, and 13A to 13E, A to D in the
respective figures show results that an implantation operation
where the wafer 7 is rotated by 90 degrees (set angle) in the
clockwise direction and ions are implanted after the rotation stops
is repeatedly performed four times, and E in the respective figures
shows results that an implantation operation where the wafer 7 is
rotated by 45 degrees (set angle) and ions are implanted after the
rotation stops is repeatedly performed eight times. However, these
are shown for convenience of the description and are not aimed at
limitation, in addition, in the description referring to FIGS. 9A
to 9E, 10A to 10E, 11A to 11E, 12A to 12E, and 13A to 13E, the
wafer scanning region length for mechanically scanning the wafer is
shown so as to be constant regardless of a wafer rotation angle,
but this is shown for convenience of the description and is not
aimed at limitation. Further, in the description referring to FIGS.
9A to 9E, 10A to 10E, 11A to 11E, 12A to 12E, and 13A to 13E, the
beam scanning speed pattern in the beam scanning direction is shown
so as to be constant regardless of a wafer rotation angle, but this
is also shown for convenience of the description and is not aimed
at limitation.
[0059] FIGS. 9A to 9E show an implantation method in which the
wafer scanning region length for mechanically scanning the wafer 7
is set to be larger than the wafer radius and smaller than the
wafer diameter, and only the wafer scanning region length is
varied. In this case, as can be seen from FIGS. 9A to 9D, the
implantation operation is continuously performed while rotating the
wafer 7 by 90 degrees in the clockwise direction, and thereby the
region where ions are not implanted into the wafer 7 decreases. An
ion implantation amount distribution in the wafer surface when a
series of implantation operations performed while rotating the
wafer 7 by the set angle finish is the same as in FIG. 9E. Here, it
is noted that, when only the wafer scanning region length is
changed as in FIGS. 9A to 9E, since one kind of variable is
changed, the degree of dose amount non-uniformity in the wafer
surface and a two-dimensional non-uniform shape pattern thereof
have a certain relationship.
[0060] This circumstance is also the same for a case using an
implantation method in which, as shown in FIGS. 10A to 10E, the
wafer scanning region length for mechanically scanning the wafer 7
is set to be smaller than the wafer radius and only the wafer
scanning region length is varied. In other words, FIGS. 10A to 10E
are the same as FIGS. 9A to 9E except that the wafer scanning
region length is set to be smeller than the wafer radius.
[0061] To summarize, as in the ion implantation method shown in
FIGS. 9A to 9E and 10A to 10E, since one kind of variable is
changed if only the wafer scanning region length is changed, the
degree of dose amount non-uniformity in the wafer surface and a
two-dimensional non-uniform shape pattern thereof are correlated
with each other and thus cannot freely move from each other. The
degree of dose amount non-uniformity in the wafer surface end the
two-dimensional non-uniform shape pattern thereof are important
factors in non-uniformity in the wafer surface in other
semiconductor manufacturing processes, and if each requirement
cannot be satisfied independently, this is not compatible with a
purpose of correcting the dose amount non-uniformity in the wafer
surface in the other semiconductor manufacturing processes.
Therefore, if only the wafer scanning region length is changed, it
is not possible to realize a two-dimensional ion implantation
amount in-surface distribution with large-scale non-uniformity,
which is to be realized by certain embodiments of the present
invention, for the purpose of correcting dose amount non-uniformity
in the wafer surface in the other semiconductor manufacturing
processes.
[0062] Here, since certain embodiments of the present invention
employ the implantation method of implanting ions into the wafer 7
while simultaneously controlling a wafer scanning region length for
mechanically scanning the wafer 7 and a beam scanning speed in the
beam scanning direction, in the implantation method shown in FIGS.
8A and 8B, two control amounts of the size of dose amount
non-uniformity in the wafer surface and the two-dimensional
non-uniform shape pattern thereof can be controlled individually
and independently. Therefore, it can be compatible with the purpose
of correcting dose amount non-uniformity in the wafer surface in
the other semiconductor manufacturing processes, which is to be
realized by certain embodiments of the present invention.
Hereinafter, a description will be made thereof for better
understanding.
[0063] FIGS. 11A to 11E show an implantation method in which the
wafer scanning region length for mechanically scanning the wafer 7
is set to be larger than the wafer radius end smaller than the
wafer diameter, the wafer scanning region length is varied, and a
beam scanning speed of the central region of the beam scanning
range is lower than at other positions, according to an embodiment
of the present invention. As described alcove, the ion implantation
amount D is inversely proportional to the beam scanning speed V.
Therefore, in the on implantation in FIG. 11A, a region 12 into
which ions are not implanted and a region 13 into which ions are
implanted occur in the wafer 7, and an ion implantation amount
in-surface distribution occurs in the region 13 into which ions are
implanted such that the ion implantation amount D increases in the
central region of the beam scanning range by the control of the
beam scanning speed V. The same implantation operation is performed
each time the wafer 7 is rotated, and thereby the region into which
ions are not implanted in the wafer 7 gradually decreases. As
described above, FIGS. 11A to 11D show results that the wafer 7 is
sequentially rotated by go degrees in the clockwise direction and
four ion implantations in total are performed, and FIG. 11E shows
an ion implantation amount distribution in the wafer surface after
the ion implantation is performed while rotating the wafer 7 by 45
degrees eight times.
[0064] FIGS. 12A to 12E show an implantation method in which the
wafer scanning region length for mechanically scanning the wafer 71
set to be larger than the wafer radius and smaller than the wafer
diameter, the wafer scanning region length is varied, end a beam
scanning speed of the central region of the beam scanning range is
higher than at other positions, according to an embodiment of the
present invention. As described above, the ion implantation amount
is inversely proportional to the beam scanning speed. Therefore, in
the ion implantation in FIG. 12A, a region 12 into which ions are
not implanted and a region 13 into which ions are implanted occur
in the wafer 7, and an ion implantation amount in-surface
distribution occurs in the region 13 into which ions are implanted
such that the ion implantation amount decreases in the central
region of the beam scanning range by the control of the beam
scanning speed. In FIGS. 12A to 12E, the wafer scanning region
length for mechanically scanning the wafer 7 is the same as that in
FIGS. 11A to 11E, in FIGS. 11E and 12E, the light and shade in the
wafer surface depending on presence or absence of hatching, broken
lines and dots indicates that a dose amount in the wafer surface is
non-uniform, that is, dose amount non-uniformity in the wafer
surface, and a pattern formed by such light and shade indicates a
two-dimensional non-uniform shape pattern. Therefore, as can be
clearly seen from FIGS. 11E and 12E, even if the wafer scanning
region length for mechanically scanning the water 7 is the same,
the two control amounts of the degree of dose amount non-uniformity
in the wafer surface and the two-dimensional nonuniform shape
pattern thereof can be controlled individually and independently.
That is to say, since certain embodiments of the present invention
employ the implantation method of implanting ions into the wafer 7
while simultaneously controlling a wafer scanning region length for
mechanically scanning the wafer 7 and a beam scanning speed in the
beam scanning direction, the two control amounts of the degree of
dose amount non-uniformity in the wafer surface and the
two-dimensional non-uniform shape pattern thereof can be controlled
individually and independently.
[0065] In FIGS. 11A to 11E and FIGS. 12A to 12E, although the
implantation method where a beam scanning speed of the central
region of the beam scanning range is lower than at other positions
is compared with the implantation method where it is higher than at
other position, a changing method of the beam scanning speed is not
limited thereto. In other words, a changing method of the beam
scanning speed may be in a form where a set speed thereof increases
or decreases in a stepwise manner, or randomly increases or
decreases. In addition, as described in FIG. 6B, the number of
valleys end mountains of the beam scanning speed may be changed.
Further, a pattern of the beam scanning speed may be generally
changed.
[0066] FIGS. 13A to 13E show an implantation method in which the
wafer scanning region length for mechanically scanning the wafer 7
is set to be smaller than the wafer radius, the wafer scanning
region length is varied, and a beam scanning speed of the central
region of the beam scanning range is lower than at other positions,
according to en embodiment of the present invention. Here, for
comparison, the beam scanning speed in FIGS. 11A to 11E and FIGS.
13A to 13E is the same. As can be clearly seen from FIGS. 11E and
13E, even if the beam scanning speed is the same, the two control
amounts of the degree of dose amount non-uniformity in the wafer
surface and the two-dimensional non-uniform shape pattern thereof
can be controlled individually and independently. As described
above, since certain embodiments of the present invention employ
the implantation method of implanting ions into the wafer 7 while
simultaneously controlling a wafer scanning region length for
mechanically scanning the wafer 7 and an ion beam scanning speed in
the beam scanning direction, the two control amounts of the degree
of dose amount non-uniformity in the wafer surface and the
two-dimensional non-uniform shape pattern thereof can be controlled
individually and independently, which is also proved from the
comparison of FIGS. 11A to 11E with FIGS. 13A to 14E.
[0067] As shown in FIGS. 13A to 13E, when the wafer scanning region
length for mechanically scanning the wafer 7 is set to be smaller
than the wafer radius, the region into which ions are not implanted
occurs at the central region of the wafer after repeatedly
performing the implantation operation multiple times while changing
a wafer rotation angle with respect to the ion beam. A series of
implantation operations may finish as a region with no ion
implantation amount by regarding this region may be regarded as a
case where the minimum ion implantation amount is zero, or, as
necessary, a minute adjustment of the ion implantation amount
distribution in the wafer surface may be performed by further
performing uniform ion implantation for the entire surface of the
wafer with a small ion implantation amount.
[0068] Since certain embodiments of the present invention employ
the implantation method of implanting ions into the wafer 7 while
simultaneously controlling a wafer scanning region length for
mechanically scanning the wafer 7 and a beam scanning speed in the
beam scanning direction, the two control amounts of the degree of
dose amount non-uniformity in the wafer surface and the
two-dimensional non-uniform shape pattern thereof can be controlled
individually and independently; however, as a third control factor,
a dose amount distribution in a direction where the wafer is
mechanically scanned is further controlled, and thereby a minute
adjustment of the ion implantation amount distribution in the wafer
surface may be performed. In this case, the dose amount
distribution in the direction where the wafer is mechanically
scanned may be controlled by controlling a mechanical scanning
speed for mechanically scanning the wafer 7, the dose amount
distribution in the direction where the wafer is mechanically
scanned may be controlled by changing and controlling a cycle of
the beam scanning, or the dose amount distribution in the direction
where the wafer is mechanically scanned may be controlled by
intermittently omitting the time during which the wafer is
irradiated with the ion beam.
[0069] To summarize once more, since certain embodiments of the
present invention employ the implantation method of implanting ions
into the wafer 7 while simultaneously controlling a wafer scanning
region length for mechanically scanning the wafer 7 and a beam
scanning speed in the beam scanning direction, the two control
amounts of the degree of dose amount non-uniformity in the wafer
surface and the two-dimensional non-uniform shape pattern thereof
can be controlled individually and independently. Therefore, it is
compatible with the purpose of correcting dose amount
non-uniformity in the wafer surface in the other semiconductor
manufacturing processes, which is to be realized by certain
embodiments of the present invention.
[0070] Of course, as described above, the reason why a large-scale
two-dimensional ion implantation amount in-surface distribution
where a ratio of the maximum ion implantation amount to the minimum
ion implantation amount in the wafer surface is five times or more
can be realized is that the wafer scanning region length for
mechanically scanning the wafer 7 is mainly changed. Therefore, it
may be regarded that a broad (or rough) two-dimensional ion
implantation amount in-surface distribution pattern is realized by
varying the wafer scanning region length for mechanically scanning
the wafer 7, and a detailed two-dimensional ion implantation amount
in-surface distribution is realized by varying the beam scanning
speed in the beam scanning direction.
[0071] As described above, when the entire surface of the wafer is
irradiated with ion beams, ion implantation is possible such that a
large-scale two-dimensional ion implantation amount in-surface
distribution where a ratio of the maximum ion implantation amount
to the minimum ion implantation amount in the wafer surface is five
times or more can be realized for the purpose of correcting dose
amount non-uniformity in the wafer surface in other semiconductor
manufacturing processes.
[0072] Hereinafter, an example which has been actually realized
according to certain embodiments of the present invention will be
described.
[0073] FIG. 14 shows an example of the ion implantation amount
in-surface distribution which has been actually obtained according
to the embodiment of the present invention. In this example, as a
measured numerical value is smaller, an actual ion implantation
amount increases in reverse proportion to the numerical value. In
the example shown in FIG. 14, an ion implantation amount at the
central region of the wafer is small, and an ion implantation
amount is large at the end (or edge) region of the wafer. FIG. 14
shows 15a indicating a measured numerical value of the
two-dimensional in-surface distribution in the wafer in a
two-dimensional manner, and 15b and 15c indicating measured
numerical distributions in two directions perpendicular to each
other in the wafer surface.
[0074] As is clearly shown in FIG. 14, a ratio of the maximum value
and the minimum value of the measured numerical values exceeds five
times. As described above, since the measured numerical value is
inversely proportional to the actual ion implantation amount, it is
shown that a ratio of the maximum ion implantation amount to the
minimum ion implantation amount in the actual wafer surface is five
times or more in the example shown in FIG. 14. FIG. 14 shows an
example but it can be seen that a large-scale two-dimensional ion
implantation amount in-surface distribution where a ratio of the
maximum ion implantation amount to the minimum ion implantation
amount in the wafer surface is five times or more can be
realized.
[0075] With reference to FIG. 16, an example of the ion
implantation amount distribution which has been actually obtained
according to the embodiment of the present invention will be
described, in FIG. 15, plots 16a, 16b and 16c of measured numerical
values on certain straight lines of the wafer are shown, in the
same manner as FIG. 14, in this example as wail, as a measured
numerical value is smaller, an actual on implantation amount
increases in reverse proportion to the numerical value. In the
example shown in FIG. 15 as well, an ion implantation amount at the
central region of the wafer is email, and an ion implantation
amount is large at the end (or edge) region of the wafer.
[0076] The plots 16a, 16b and 16c in FIG. 15 indicate an example of
the implantation operation where an implantation method of
variously changing a beam scanning speed while the wafer scanning
region length for mechanically scanning the wafer 7 is the same is
repeatedly performed multiple times while varying a wafer rotation
angles with respect to the ion beam. As is clear from FIG. 15, in a
case where the degree of dose amount non-uniformity in the wafer
surface is the same, a two-dimensional non-uniform shape pattern
thereof can varied.
[0077] FIG. 15 shows an example where two control amounts of the
degree of dose amount non,uniformity in the wafer surface and the
two-dimensional non-uniform shape pattern thereof can be controlled
individually and independently. As described with reference to
FIGS. 11A to 13E, even in a case where a two-dimensional
non-uniform shape pattern is the same in contrast to the
circumstance shown in FIG. 16, needless to say, it is possible to
vary the degree of the dose amount non-uniformity in the wafer
surface.
[0078] In addition, generally, it can be said that FIG. 15 shows an
example where a broad (or rough) two-dimensional ion implantation
amount in-surface distribution pattern is realized by varying the
wafer scanning region length for mechanically scanning the wafer 7,
and a detailed two-dimensional ion implantation amount in-surface
distribution is realized by varying the beam scanning speed in the
beam scanning direction.
[0079] As described above, according to certain embodiments of the
present invention, when the ion beam is applied to the entire
surface of the wafer, it is actually shown that a large-scale
two-dimensional ion implantation amount in-surface distribution can
be realized for the purpose of correcting dose amount
non-uniformity in the wafer surface in other semiconductor
manufacturing processes.
[0080] Although at least one exemplary embodiment has been
described hitherto, the description is only an example and is not
intended to limit the scope of the invention.
[0081] It should be understood that the invention is not limited to
the above-described embodiment, but may be modified into various
forms on the basis of the spirit of the invention. Additionally,
the modifications are included in the scope of the invention.
* * * * *