U.S. patent application number 13/883539 was filed with the patent office on 2013-08-29 for ion milling device.
This patent application is currently assigned to HITACHI HIGH-TECHNOLOGIES CORPORATION. The applicant listed for this patent is Toru Iwaya, Atsushi Kamino, Asako Kaneko, Hirobumi Muto, Hisayuki Takasu. Invention is credited to Toru Iwaya, Atsushi Kamino, Asako Kaneko, Hirobumi Muto, Hisayuki Takasu.
Application Number | 20130220806 13/883539 |
Document ID | / |
Family ID | 46024529 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130220806 |
Kind Code |
A1 |
Iwaya; Toru ; et
al. |
August 29, 2013 |
ION MILLING DEVICE
Abstract
An ion milling device of the present invention is provided with
a tilt stage (8) which is disposed in a vacuum chamber (15) and has
a tilt axis parallel to a first axis orthogonal to an ion beam, a
drive mechanism (9, 51) which has a rotation axis and a tilt axis
parallel to a second axis orthogonal to the first axis and rotates
or tilts a sample (3), and a switching unit which enables switching
between a state in which the ion beam is applied while the sample
is rotated or swung while the tilt stage is tilted, and a state in
which the ion beams is applied while the tilt stage is brought into
an untilted state and the sample is swung. Consequently, the ion
milling device capable of performing cross-section processing and
flat processing of the sample in the same vacuum chamber is
implemented.
Inventors: |
Iwaya; Toru; (Hitachinaka,
JP) ; Muto; Hirobumi; (Hitachinaka, JP) ;
Takasu; Hisayuki; (Oarai, JP) ; Kamino; Atsushi;
(Naka, JP) ; Kaneko; Asako; (Hitachinaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Iwaya; Toru
Muto; Hirobumi
Takasu; Hisayuki
Kamino; Atsushi
Kaneko; Asako |
Hitachinaka
Hitachinaka
Oarai
Naka
Hitachinaka |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
HITACHI HIGH-TECHNOLOGIES
CORPORATION
Tokyo
JP
|
Family ID: |
46024529 |
Appl. No.: |
13/883539 |
Filed: |
November 2, 2011 |
PCT Filed: |
November 2, 2011 |
PCT NO: |
PCT/JP2011/075306 |
371 Date: |
May 3, 2013 |
Current U.S.
Class: |
204/298.32 ;
204/298.36 |
Current CPC
Class: |
H01J 37/20 20130101;
H01J 37/304 20130101; H01J 2237/20207 20130101; H01J 37/3007
20130101; H01J 37/3005 20130101; H01J 2237/20214 20130101; H01J
2237/26 20130101; H01J 37/3053 20130101 |
Class at
Publication: |
204/298.32 ;
204/298.36 |
International
Class: |
H01J 37/20 20060101
H01J037/20; H01J 37/30 20060101 H01J037/30; H01J 37/305 20060101
H01J037/305 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2010 |
JP |
2010-248022 |
Claims
1. An ion milling device including: an ion source for irradiating a
sample with an ion beam; and a tilt stage disposed inside a vacuum
chamber and having a tilt axis parallel with a first axis
orthogonal to the ion beam, characterized in that the ion milling
device comprises: a support table, disposed on the tilt stage, for
supporting a sample holding member for holding the sample; a drive
mechanism for rotating or tilting the support table, the drive
mechanism having a rotation axis and a tilt axis which are parallel
with a second axis orthogonal to the first axis; and a switching
unit for switching a state of the ion milling device between a
state where the ion beam is irradiated while the tilt stage is
tilted and the support table is rotated or swung and a state where
the ion beam is irradiated while the tilt stage is not tilted and
the support table is swung.
2. The ion milling device according to claim 1, wherein the ion
milling device comprises a mechanism to displace the axis of the
ion beam and the rotation axis of the support table from each
other.
3. The ion milling device according to claim 2, wherein the sample
holding member includes a shielding part for blocking part of the
ion beam and having a surface positioned in parallel with the
second axis, and the sample holding member is configured to be
attachable and detachable to and from the support table.
4. The ion milling device according to claim 2, wherein the ion
milling device comprises a control device for switching the state
of the ion milling device between the state where the ion beam is
irradiated with the tilt stage being tilted and the support table
being rotated or swung and the state where the ion beam is
irradiated with the tilt stage not being tilted and the support
table being swung, in accordance with the switching of the
switching unit.
5. The ion milling device according to claim 1, wherein the vacuum
chamber is provided with an observation window.
6. The ion milling device according to claim 5, wherein the
observation window is provided in a ceiling surface of the vacuum
chamber.
7. The ion milling device according to claim 6, wherein the ion
source is placed in a surface different from the ceiling surface of
the vacuum chamber.
8. The ion milling device according to claim 5, wherein a shutter
movable to a space between an ion beam irradiation position for the
sample and the observation window is provided.
9. The ion milling device according to claim 1, wherein the vacuum
chamber is provided with an optical microscope or electron
microscope.
10. The ion milling device according to claim 9, wherein the
optical microscope or electron microscope is provided in a ceiling
surface of the vacuum chamber.
11. The ion milling device according to claim 10, wherein the ion
source is placed in a surface different from the ceiling surface of
the vacuum chamber.
12. The ion milling device according to claim 9, wherein a shutter
movable to a space between an ion beam irradiation position for the
sample and the optical microscope or electron microscope.
13. An ion milling device including: an ion source, attached to a
vacuum chamber, for irradiating a sample with an ion beam; and a
tilt stage having a tilt axis in a direction perpendicular to an
irradiation direction of an ion beam emitted from the ion source,
wherein the ion milling device comprises: a rotor placed on the
sample stage and having a rotation tilt axis orthogonal to the tilt
axis; and an opening for processing observation provided in a wall
surface of the vacuum chamber in a direction orthogonal to a plane
formed by the tilt axis and an irradiation path of the ion
beam.
14. The ion milling device according to claim 13, wherein the ion
milling device comprises a center displacing mechanism for
displacing a center of a position of the sample on the sample
stage.
15. The ion milling device according to claim 13, wherein the ion
milling device comprises a sample-mask unit on the rotor, and the
sample-mask unit has a shielding part having an ion-beam shielding
surface parallel with the rotation tilt axis.
16. The ion milling device according to claim 13, wherein a mode of
the device is switched between cross-section milling and flat
surface milling depending on a distance between the ion beam source
and the sample.
17. The ion milling device according to claim 13, wherein an
optical microscope is disposed on an upper portion of the opening
for processing observation.
18. The ion milling device according to claim 13, wherein a column
of an electron microscope is disposed on a portion of the opening
for processing observation.
Description
TECHNICAL FIELD
[0001] The present invention relates to an ion milling device and
an ion milling method for fabricating a sample to be observed by
using a scanning electron microscope (SEM), a transmission electron
microscope (TEM), or the like.
BACKGROUND ART
[0002] An ion milling device is a device for polishing a surface or
cross section of a metal, glass, ceramic, or the like by
irradiating the surface or cross section with an argon ion beam,
and is favorable as a pre-processing device for observation of a
surface or cross section of a sample using an electron
microscope.
[0003] In the conventional cross-sectional observation of a sample
using an electron microscope, a vicinity of a part to be observed
is first cut by using a diamond cutter, a jigsaw, or the like, for
example. Then, after the cut surface is mechanically polished, the
sample is placed on a sample table for an electron microscope and
the image of the cut surface is observed.
[0004] The mechanical polishing has a problem that, when a soft
sample such as of a polymer material or aluminum is polished, the
surface to be observed is crushed or deeply scratched by particles
of an abrasive compound. Moreover, the mechanical polishing also
has problems that it is difficult to polish a hard sample such as
of glass or a ceramic and that it is extremely difficult to perform
cross-section processing on a composite material in which a soft
material and a hard material are stacked.
[0005] On the other hand, ion milling has advantageous effects of
being capable of processing a soft sample without crushing the
profile of the surface, of being capable of polishing a hard sample
and a composite material, and of being capable of easily obtaining
a cross section in a mirror state.
[0006] Patent Literature 1 describes a sample fabricating device
including: ion beam irradiating means, disposed in a vacuum
chamber, for irradiating a sample with an ion beam; a tilt stage
disposed in the vacuum chamber and having a tilt axis in a
direction substantially perpendicular to the ion beam; a sample
holder, disposed on the tilt stage, for holding the sample; and a
shielding member, located on the tilt stage, for blocking part of
the ion beam for irradiating the sample, the sample fabricating
device being configured to process a sample with the ion beam while
changing a tilt angle of the tilt stage.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: JP-A-2005-91094
SUMMARY OF INVENTION
Technical Problem
[0008] The sample fabricating device disclosed in Patent Literature
1 is an ion milling device for cross-section processing
(cross-section milling). Meanwhile, there is an ion milling device
for flat surface milling, which processes a surface of a sample
with an ion beam while rotating the sample. Although processing a
sample by irradiating the sample with an ion beam in a similar
manner as described above, these devices need to be used separately
because of their different movements of a sample at the time of
irradiation with an ion beam.
[0009] Hereinafter, an ion milling device intended to perform both
cross-section processing and flat surface processing in the same
vacuum chamber will be described.
Solution to Problem
[0010] As an aspect for achieving the above-described object, there
is proposed an ion milling device including: an ion source for
irradiating a sample with an ion beam; and a tilt stage disposed
inside a vacuum chamber and having a tilt axis parallel with a
first axis orthogonal to the ion beam, in which the ion milling
device includes a support table, disposed on the tilt stage, for
supporting a sample holding member for holding the sample; a drive
mechanism for rotating or tilting the support table, the drive
mechanism having a rotation axis and a tilt axis which are parallel
with a second axis orthogonal to the first axis; and a switching
unit for switching a state of the ion milling device between a
state where the ion beam is irradiated while the tilt stage is
tilted and the support table is rotated or swung and a state where
the ion beam is irradiated while the tilt stage is not tilted and
the support table is swung.
Advantageous Effect of Invention
[0011] According to the above-described configuration, it is
possible to perform both of the cross-section milling and the flat
surface milling with a single device.
[0012] Other objects, characteristics, and advantages of the
present invention will be clarified from the following description
of embodiments of the present invention regarding the attached
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic configuration view of an ion milling
device.
[0014] FIG. 2 is a schematic configuration view of a sample-mask
unit.
[0015] FIG. 3 is a view showing another example of the sample-mask
unit.
[0016] FIG. 4 is an explanatory view showing a method of placing a
cross section of a sample and a mask in parallel with each
other.
[0017] FIG. 5 is a view showing a state where the sample unit base
is pulled out and a sample-mask-unit slightly moving mechanism on
which the sample-mask unit is placed has been detached.
[0018] FIG. 6 is a view showing how a sample-mask-unit slightly
moving mechanism on which a sample-mask unit is placed is mounted
on a separately provided optical microscope.
[0019] FIG. 7 a view showing a state where the sample-mask-unit
slightly moving mechanism on which the sample-mask unit is placed
is mounted on the optical microscope.
[0020] FIG. 8 is an explanatory view showing a method of aligning
the center of an argon ion beam and a portion of the sample to be
subjected to cross-section polishing.
[0021] FIG. 9 is an explanatory view showing a method of polishing
a cross section of a sample by ion milling.
[0022] FIG. 10 is a schematic configuration view of the ion milling
device.
[0023] FIG. 11 is a configuration view of the sample-mask-unit
slightly moving mechanism on which the sample-mask unit is placed
and the sample unit base.
[0024] FIG. 12 is a configuration view of the sample-mask-unit
slightly moving mechanism on which the sample-mask unit is placed
and a sample unit base using a shaft coupling.
[0025] FIG. 13 is a view showing how the sample-mask-unit slightly
moving mechanism on which the sample-mask unit is placed is mounted
on a separately provided optical microscope.
[0026] FIG. 14 is a configuration view of a rotating and tilting
mechanism and a center displacing mechanism.
[0027] FIG. 15 is a configuration view of a rotating and tilting
mechanism and a center displacing mechanism (using a shaft
coupling).
[0028] FIG. 16 is a configuration view of a sample surface unit and
the sample unit base.
[0029] FIG. 17 is a schematic configuration view of an ion milling
device on which an optical microscope is mounted.
[0030] FIG. 18 is a schematic configuration view of the ion milling
device on which an electron microscope is mounted.
[0031] FIG. 19 is a view for explaining a relation between a line
of the ion beam and the rotation tilt axis of the rotating and
tilting mechanism during the cross-section milling.
[0032] FIG. 20 is a view for explaining a relation between a line
of the ion beam and the rotation tilt axis of the rotating and
tilting mechanism during the flat surface milling.
[0033] FIG. 21 is a view showing an overview of an operation panel
of the ion milling device.
[0034] FIG. 22 is a view for explaining an overview of a control
device of the ion milling device.
[0035] FIG. 23 is a flowchart showing a procedure of setting a
processing mode and processing condition.
DESCRIPTION OF EMBODIMENTS
[0036] In a cross-section milling device (device for forming a
smooth surface in a sample by milling the sample via a mask), a
sample stage and a unit for holding a sample are placed on the same
rotation tilt axis (which means they have the same movement). For
this reason, a processing observation window is placed on the same
axial direction as that of the sample stage. Accordingly, when the
sample stage is located on a front surface of the device, the
processing observation window is located on the front surface or a
rear surface of the device, which makes it difficult to place and
operate an observation device (microscope). In addition, flat
surface milling (which smoothly flattens a surface perpendicular to
an axis of an ion beam (which means the tilt angle of the sample
stage is 90 degrees)) cannot be enabled by only replacing a
rotating and tilting mechanism of the cross-section milling device
with a rotating mechanism; accordingly milling devices respectively
for cross-section and flat surface milling are required.
[0037] In this embodiment, description will be given of an ion
milling device characterized in that it facilitates observation of
an observation surface processed mainly by milling and further of
performing both of the cross-section milling and the flat surface
milling.
[0038] In this embodiment, as an example of the ion milling device,
description will be given of an ion milling device including: an
ion beam source, attached to a vacuum chamber, for irradiating a
sample with an ion beam; a sample-mask unit including a sample
holder for fixing the sample, a mask (shielding part) for shielding
part of the sample fixed to the sample holder, a sample rotating
mechanism for rotating the sample holder, and a mask position
adjusting unit for adjusting a shielding positional relation
between the mask and the sample; a sample-mask-unit slightly moving
mechanism capable of driving the sample-mask unit in the X-axis and
Y-axis directions perpendicular to the ion beam; a sample unit base
capable of placing the sample-mask-unit slightly moving mechanism
in the vacuum chamber; and an optical microscope for observing the
shielding positional relation between the mask and the sample,
characterized in that a fixation part of the sample-mask unit or
the sample-mask-unit slightly moving mechanism to be fixed to the
sample unit base is a rear portion of the sample-mask unit or the
sample-mask-unit slightly moving mechanism, a rotation part is
provided on the sample unit base, the sample stage, the ion beam
source, and the processing observation window are mounted
respectively on a front surface, a right or left side surface, and
an upper surface of the vacuum chamber, and a shutter is provided
between the sample and the processing observation window.
[0039] In addition, description will be given of the ion milling
device characterized in that the rotating and tilting mechanism for
the sample includes a rotating function, the ion milling device
includes a tilting mechanism having a tilt axis in a direction
perpendicular to a rotation axis of the sample, and a center
displacing mechanism for the axis of the ion beam and the rotation
axis of the sample (in the case where the tilt angle of the stage
is 90 degrees) is provided.
[0040] The above-described configuration facilitates the
observation of an observation surface processed by milling and
makes it possible to perform both of the cross-section milling and
the flat surface milling.
[0041] Hereinafter, the embodiment will be described on the basis
of the drawings.
[0042] This embodiment will be described by giving as an example an
ion milling device equipped with an ion source for irradiation with
an argon ion beam. However, the ion beam is not limited to the
argon ion beam and various types of ion beams are applicable.
[0043] FIG. 1 shows a configuration of the ion milling device. An
ion source 1 and a sample stage 8 are provided on an upper surface
and a front surface of a vacuum chamber 15, respectively.
[0044] A sample-mask-unit slightly moving mechanism 4 is mounted on
a sample unit base 5. The mounting method is to cause a lower
surface (on the opposite side to a mask surface to be irradiated
with the ion beam) of the sample-mask-unit slightly moving
mechanism 4 and an upper surface of the sample unit base 5 to come
into contact with each other, and be screwed. The sample unit base
5 is configured to be rotatable and tiltable at any angle to the
optical axis of the ion beam. The direction and tilt angle of the
rotation and tilt of the sample unit base 5 is controlled by the
sample stage 8. Rotating and tilting the sample stage 8 allows a
sample 3 placed on the sample-mask-unit slightly moving mechanism 4
to be set at a predetermined angle to the optical axis of the ion
beam. Moreover, the rotation tilt axis of the sample stage 8 and
the upper surface of the sample (lower surface of the mask) are
positioned at the same level, thereby forming an efficient and
smooth processing plane. In addition, the sample-mask-unit slightly
moving mechanism 4 is configured to be movable to the front, rear,
left, and right in directions perpendicular to the optical axis of
the ion beam, that is, in the X direction and the Y direction.
[0045] The sample unit base 5 is disposed via the sample stage 8
(rotating mechanism) mounted on a flange 10 serving part of a
container wall of the vacuum chamber 15. The sample unit base 5 is
configured to be pulled out of the vacuum chamber when the vacuum
chamber 15 is opened into an atmospheric state by pulling out the
flange 10 along a linear guide 11. In this way, a sample-stage
pulling out mechanism is configured.
[0046] A main body of a sample-mask unit 21 will be described on
the basis of FIG. 2. Part (a) and Part (b) of FIG. 2 are a plan
view and a side view, respectively. In the embodiment, a main body
configured integrally of at least a sample holder 23, the rotating
mechanism for the sample holder 23, a mask 2, and a finely
adjusting mechanism for the mask 2 is referred to as the
sample-mask unit (main body) 21. In FIG. 2, a sample-holder rotary
ring 22 and a sample-holder rotary screw 28 are included as the
rotating mechanism for the sample holder 23, so that the sample
holder is rotatable vertically with respect to the optical axis of
the ion beam. The sample-holder rotary ring 22 is configured to be
rotated by rotating the sample-holder rotary screw 28, and to be
reversely rotated back by a spring pressure of a spring 29.
[0047] The sample-mask unit 21 has a mechanism capable of finely
adjusting the position and rotation angle of the mask, and is
attachable to and detachable from the sample-mask-unit slightly
moving mechanism 4. In this embodiment, the sample-mask unit 21 and
the sample-mask-unit slightly moving mechanism 4 are two
components, but may be configured as a single component (In the
embodiment, the sample-mask unit and the sample-mask-unit slightly
moving mechanism are described separately for the sake of
understanding).
[0048] The mask 2 is fixed to a mask holder 25 with a mask fixing
screw 27. The mask holder 25 is moved along a linear guide 24 by
operating a mask finely adjusting mechanism (that is, a mask
position adjusting unit) 26, so that the positions of the sample 3
and the mask 2 are finely adjusted. The sample holder 23 is
inserted into and fixed to the sample-holder rotary ring 22 from a
lower side. The sample 3 is bonded and fixed to the sample holder
23. The position of the sample holder 23 in a height direction is
adjusted with a sample-holder-position controlling mechanism 30,
thereby bring the sample holder 23 into close contact with the mask
2.
[0049] FIG. 3 shows another example of the sample-mask unit 21.
This example uses a sample-holder fixing metal fitting 35 and the
other configurations are basically the same as those of the example
shown in FIG. 2. Part (a) of FIG. 3 shows a state where the sample
holder 23 to which the sample 3 is fixed is mounted in the
sample-mask unit 21 while Part (b) of FIG. 3 shows a state where
the sample holder 23 to which the sample 3 is fixed is removed out
of the sample-mask unit 21.
[0050] FIG. 4 is an explanatory view showing a method of placing a
cross section of the sample and the mask in parallel with each
other. The sample-holder rotary screw 28 is rotated to perform
position adjustment in an X1 direction, followed by performing fine
adjustment under the microscope as described later to place the
cross section of the sample 3 and the ridge line of the mask 2 in
parallel with each other. In this event, the setting is performed
by rotating the mask finely adjusting mechanism 26 such that the
cross section of the sample 3 slightly protrudes, for example
protrudes by approximately 50 .mu.m, from the mask.
[0051] FIG. 5 shows a configuration of a sample-stage pulling out
mechanism 60. The sample-stage pulling out mechanism 60 includes
the linear guide 11 and the flange 10 fixedly attached to the
linear guide 11. The sample unit base 5 fixedly attached to the
sample stage mounted on the flange 10 is pulled out of the vacuum
chamber 15 along the linear guide 11. In conjunction with this
operation, the sample-mask-unit slightly moving mechanism 4 with
the sample-mask unit 21 is placed is placed on the sample unit base
5, in other words, the mask 2, the sample holder 23, and the sample
3 are integrally pulled out of the vacuum chamber 15.
[0052] In the embodiment, the sample-mask-unit slightly moving
mechanism 4, on which the sample-mask unit 21 is placed, has such a
configuration as to be detachably fixed to the sample unit base 5.
Accordingly, once the sample-mask-unit slightly moving mechanism 4,
on which the sample-mask unit 21 is placed, is pulled out of the
vacuum chamber 15, the sample-mask-unit slightly moving mechanism
4, on which the sample-mask unit 21 is placed, is made detachable
from the sample unit base 5 (detachment standby of the sample-mask
unit 21).
[0053] FIG. 5 shows a state where the sample-mask-unit slightly
moving mechanism 4, on which the sample-mask unit 21 is placed, has
been detached from such a detachable state. This detachment is
performed manually or with an appropriate tool.
[0054] On the other hand, an optical microscope 40 for observing
the shielding positional relation between the mask 2 and the sample
3 is configured as a separate body from the vacuum chamber 15 as
shown in FIG. 6, and can be disposed at any position. In addition,
the optical microscope 40 includes a known magnifying lens 12 and a
magnifying-lens slightly moving mechanism 13. Further, the optical
microscope 40 is provided with a fixation table 42 on an
observation table 41 such that the detached sample-mask-unit
slightly moving mechanism 4, on which the sample-mask unit 21 is
placed, can be placed on the fixation table 42. The
sample-mask-unit slightly moving mechanism 4, on which the
sample-mask unit 21 is placed, is placed on the fixation table 42
at a determined position that is reproducible by shafts and holes
for positioning.
[0055] FIG. 7 shows a state where the sample-mask-unit slightly
moving mechanism 4, on which the sample-mask unit 21 is placed, is
fixed on the fixation table 42.
[0056] FIG. 8 is an explanatory view showing a method of aligning a
portion of the sample 3 desired to be subjected to cross-sectional
polishing with the center of the ion beam. A mark formed by
irradiation with the ion beam with a photosensitive paper or the
like being attached to the sample holder 23, that is, the center of
the beam and the center of the magnifying lens are aligned with
each other by driving the magnifying lens in the X2 and Y2
directions by the magnifying-lens slightly moving mechanism 13. The
sample-mask-unit slightly moving mechanism 4, on which the
sample-mask unit main body 21 loaded with the sample 3 as shown in
FIG. 3 is placed, is placed on the fixation table 42. The position
of the fixation table 42 in the X3 and Y3 directions is adjusted to
be aligned with the center of the magnifying lens, thereby aligning
the center of the ion beam with the portion desired to be subjected
to cross-sectional polishing.
[0057] As described above, when the shielding positional relation
between the mask 2 and the sample 3 is adjusted, the
sample-mask-unit slightly moving mechanism 4, on which the
sample-mask unit 21 is placed, is detached from the sample unit
base 5 and mounted on the fixation table 42 of the optical
microscope 40, and the shielding positional relation of the mask 2
relative to the sample 3 is adjusted by the mask position adjusting
unit (mask finely adjusting mechanism).
[0058] FIG. 9 is an explanatory view showing a method of
mirror-polishing the cross section of the sample 3 with the ion
beam. Irradiating the sample 3 with an argon ion beam can remove a
portion of the sample 3 not covered with the mask 2 along the mask
2 in a depth direction and can mirror-polish the surface of the
cross section of the sample 3.
[0059] In this way, the sample-mask-unit slightly moving mechanism
4, on which the sample-mask unit 21 including the mask 2 having the
adjusted shielding positional relation relative to the sample is
placed, is returned to and mounted on the sample unit base 5 at the
time of the ion milling.
[0060] As described above, an ion milling method is configured, in
which at the time of adjusting the shielding positional relation
between the mask 2 and the sample 3, the sample-mask-unit slightly
moving mechanism 4 on which the sample-mask unit 21 is placed is
removed from the sample unit base 5 and mounted on the fixation
table 42 of the optical microscope 40 and the shielding positional
relation of the mask relative to the sample 3 is adjusted, and at
the time of ion milling, the sample-mask-unit slightly moving
mechanism 4, on which the sample-mask unit 21 including the mask 2
having the adjusted shielding positional relation relative to the
sample is placed, is returned into the vacuum chamber 15 and
mounted on the sample unit base 5.
[0061] The ion milling device as illustrated in FIG. 1 can perform
the cross-section milling processing but cannot perform the flat
surface milling processing. For this reason, in this embodiment, an
ion milling device capable of both types of processing will be
described.
[0062] FIG. 10 shows a configuration of an ion milling device that
can perform both of the cross-section milling processing and the
flat surface milling processing. A processing observation window 7,
an ion source, and a sample stage are mounted respectively on an
upper surface, a left side surface (may alternatively be a right
side surface), and a front surface of a vacuum chamber 15, and a
shutter 101 is provided between a sample and the processing
observation window 7. The shutter 101 is provided to prevent
sputtered particles from being deposited on the processing
observation window 7. The vacuum chamber 15 generally has a box
shape forming a space to form a vacuum atmosphere or a shape
similar to the box shape. The observation window is provided above
the box (in a direction opposite to that in which the gravitational
field is directed in an environment with gravity) while the ion
source is provided on a side wall surface of the box (a surface
adjacent to the upper surface of the box and in a direction
perpendicular to the direction in which the gravitational field is
directed). In other words, the processing observation window is
provided on the wall surface of the vacuum chamber in a direction
orthogonal to a plane including the tilt axis of the sample stage
and the irradiation path of the ion beam. Note that an optical
microscope or an electron microscope may be provided in an opening
for the processing observation window instead of providing a window
capable of being vacuum-sealed, as will be described later.
[0063] The sample unit base 5 is provided with a rotor 9 on which a
sample holding member (member for holding a sample including the
sample-mask-unit slightly moving mechanism 4) can be mounted. The
rotor 9 functions as a support table for supporting the sample
holding member. As shown in FIG. 11, the sample unit base 5 is
formed of the rotor 9, gears 50, and bearings 51. As shown in FIG.
11, the sample-mask-unit slightly moving mechanism 4 has a mask
unit fixation part (including a screw) 52 provided on a rear
surface of the sample-mask-unit slightly moving mechanism 4. A
method of mounting the sample-mask-unit slightly moving mechanism 4
onto the sample unit base 5 is to cause a fixation surface (rear
surface) of the sample-mask-unit slightly moving mechanism 4 and an
upper surface of the rotor 9 of the sample unit base 5 to come into
contact with each other, and be screwed by using the mask unit
fixation part 52. The sample unit base 5 is not rotated or tilted,
and configured such that the rotor 9 mounted on the sample unit
base 5 enables rotation and tilt at any angle to the optical axis
of the ion beam irradiated from the side surface of the vacuum
chamber 15. The direction and tilt angle of the rotation and tilt
are controlled by the sample stage 8.
[0064] Here, the method of rotating and tilting the rotor 9 of the
sample unit base 5 may be either one shown in FIG. 11 or one (using
a shaft coupling 53 shown in FIG. 12. Rotating and tilting the
rotor 9 of the sample unit base 5 can set the sample 3 placed on
the sample-mask-unit slightly moving mechanism 4 at a predetermined
angle to the optical axis of the ion beam. Further, the rotation
axis of the rotor 9 of the sample unit base 5 and the upper surface
of the sample (the lower surface of the mask) are positioned at the
same level, thereby forming an efficient and smooth processing
plane. In addition, the sample-mask-unit slightly moving mechanism
4 is configured to be movable to the front, rear, left, and right
in a direction perpendicular to the optical axis of the ion beam,
that is, in the X direction and the Y direction.
[0065] The placement onto the optical microscope 40, which is a
separate body from the device, may be achieved by a method using a
lower surface of the sample-mask-unit slightly moving mechanism 4,
instead of using the mask unit fixation part 52 of the sample-mask
unit 21 or the sample-mask-unit slightly moving mechanism 4, which
is used for the placement onto the sample unit base 5 as shown in
FIG. 13.
[0066] The point different from the example of FIG. 6 is that the
magnifying-lens slightly moving mechanism 13 for adjusting the
center of the beam and the center of the magnifying lens is
implemented on the fixation table 42 side. Either of this example
or the example of FIG. 6 may be employed for the magnifying-lens
slightly moving mechanism 13. The other operations are performed in
the same manner as those of FIG. 6.
[0067] In the ion milling device illustrated in FIG. 10, the
rotating and tilting mechanism for the sample is provided with a
rotating function while a tilting mechanism having a rotation tilt
axis perpendicular to the axis of the ion beam is provided, as
illustrated in FIG. 14. Further, a center displacing mechanism is
provided for displacing the axis of the ion beam and the rotation
axis of the sample-mask-unit slightly moving mechanism 4 from each
other when the tilt angle is set at 90 degrees as shown in FIG. 14.
Here, as shown in FIG. 15, a system using a shaft coupling may be
employed. However, the shaft coupling, when used, needs to be
placed in the rotating and tilting unit as shown in FIG. 15 while
the center displacing mechanism needs to be placed in a lower
portion of the rotor of the sample unit base 5. Having the function
of rotating a sample and being configured to determine the incident
angle and the amount of displacement of the center of the ion beam
as shown in FIG. 14 and FIG. 15, the ion milling device is capable
of also performing flat surface milling (smoothly processing a
surface perpendicular to the axis of the ion beam (when the tilt
angle of the sample stage is 90 degrees) while being the
cross-section milling (device forming a smooth surface by milling a
sample via a mask).
[0068] Note that since the distance between the ion source and the
sample needs to be changed depending on the performance of the ion
source for the cross-section milling and the flat surface milling,
a mechanism capable of moving the ion source or the sample stage in
the direction of the axis of the ion beam is provided. Therefore,
the distance between the ion source and the sample is determined
depending on the ion source when each of the cross-section milling
and the flat surface milling is performed. For this reason, the
device has a function of switching its mode between the
cross-section milling mode and the flat surface milling mode (for
example, rotation and tilt or rotation) by recognizing the
cross-section milling or the flat surface milling from the position
of the sample stage loaded with the sample or the position of the
ion source.
[0069] Here, the reason why two different types of processing are
made possible will be described further in detail. Hereinafter, the
principle that enables the device illustrated in the embodiment to
perform both of the cross-section milling processing and the flat
surface milling processing will be described in detail. FIG. 19 is
a view showing a relation between the irradiation direction of the
ion beam and the rotation axis or tilt axis (hereinafter, simply
referred to as the rotation axis) of each rotating mechanism or
tilting mechanism (hereinafter, simply referred to as the rotating
mechanism) in the cross-section milling. FIG. 20 is a view showing
a relation between the irradiation direction of the ion beam and
each rotation axis in the flat surface milling.
[0070] In FIG. 19, an axis 1901 represented by a dashed line is
parallel with an axis represented by an alternate long and short
dashed line in a diagram on the upper side of FIG. 10, and is also
parallel with the rotation axis of the rotor 9 illustrated in FIG.
11, for example. Further, an axis 1902 represented by an alternate
long and two short dashes line is parallel with the rotation axis
of the sample stage 8. Moreover, an axis 1903 represented by an
alternate long and short dashed line indicates the irradiation
direction of the ion beam emitted from the ion source 1. In
addition, the axis 1901 is parallel with a surface, irradiated with
the ion beam, of the mask 2.
[0071] In addition, the axes 1901, 1902, and 1903 are orthogonal to
one another. In the case of this example, the axis 1901, the axis
1902, and the axis 1903 are arranged in parallel with the z-axis,
the y-axis, and the x-axis, respectively.
[0072] In the cross-section milling, a swing drive with the
rotation axis parallel with the axis 1901 being set as a rotation
center is performed so that a line should not be formed along the
path of the ion beam on the cross section of the sample 3. At this
time, the mask surface is parallel with the axis 1901. On the other
hand, in the flat surface milling, as illustrated in FIG. 20, the
sample 1904 is driven to tilt at a predetermined angle or swing
within a predetermined angle range by the sample stage 8, and the
sample 1904 is rotated about an axis parallel with a tilt axis 1905
of the axis 1901 set as the rotation axis.
[0073] As described above, the device of this embodiment is capable
of rotation drive, or rotation drive about the tilt, or swing drive
of a second rotation axis (the axis 1901 or the axis 1905
(including the case of performing swing operation) on the sample
stage having a first rotation axis (axis parallel with the axis
1902). Specifically, the device illustrated in FIG. 10 is
characterized in that the device performs the swing drive for the
cross-section milling and the rotation or swing drive of the sample
for the flat surface milling by using the rotating mechanism
mounted on the sample stage 8 and performs the tilt for the flat
surface milling by using the rotating mechanism which tilts the
sample stage 8 itself. Note that the axis 1905 indicates the center
of rotation of the drive mechanism in FIG. 20, but in the flat
surface milling, rotation is performed with the center of the
sample being displaced from the axis 1905 in order to perform the
flat surface processing on a wide region of the sample.
[0074] FIG. 21 is a view showing an example of an operation panel
for switching the mode between the cross-section milling processing
and the flat surface milling processing and for setting the
operation conditions of the stage and the like. On a processing
mode setting part 2101, buttons for selecting the flat surface
milling (Flat) or the cross-section milling (Cross-section) are
disposed, enabling alternative selection of either one of them. In
addition, on a stage operation conditions setting part 2102,
buttons for selecting tilt operation (Tilt) or swing operation
(Swing) are disposed, enabling alternative selection of either one
of them. The stage operation conditions setting part 2102 is
further provided with setting parts for setting the tilt angle or
the angle range of the swing operation (Angle) and the periodic
speed (Speed) in the case of the swing operation. Further, a
rotating table operation conditions setting part 2103 is provided
with setting parts for setting the swing angle (Angle) and the
periodic speed (Speed) of the swing operation by the rotating
table.
[0075] In the operation panel illustrated in FIG. 21, selection of
an input window is enabled by a select key (Select) and selection
of a numerical value is enabled by "Up" and "Down" buttons, for the
setting parts requiring input of a numerical value. Further, an
enter key (Enter) allows a numerical value thus selected to be
registered. The stage referred to here is, for example, the sample
stage 8 in FIG. 10 while the rotating table referred to here is,
for example, the rotor 9 in FIG. 11.
[0076] The cross-section milling processing requires the swing
drive of the rotating table, but does not require the swing drive
of the sample stage. For this reason, a control device of the
milling device is preferably configured such that selecting the
cross-section milling processing (selecting the Cross-section
button) prohibits or invalidates setting in the stage operation
conditions setting part 2102. On the other hand, tilting the sample
stage 8 at the time of the cross-section milling may cause a
portion irrelevant to the processing target to be irradiated with
the ion beam or may cause the cross section of the sample to be
processed obliquely. For this reason, with the cross-section
milling processing being selected, if the sample stage 8 is in a
tilt state, irradiation with the ion beam may be controlled to be
not allowed or an error message may be generated to warn the
operator. Alternatively, such a control that the tilt angle of the
sample stage 8 is automatically set at zero may be employed.
[0077] On the other hand, the flat surface milling processing uses
both of the tilting of the sample stage 8 and the rotation or swing
of the rotating table, and thus, inputs of both of the stage
operation conditions setting part 2102 and the rotating table
operation conditions setting part 2103 need to be validated.
[0078] In the device of the embodiment, the rotor 9 is caused to
perform both of the swing drive in the cross-section milling and
the rotation drive in the flat surface milling, thereby making it
possible to perform two different types of milling processing with
the single milling device.
[0079] Note that, in the device illustrated in FIG. 10, the ion
source 1 is disposed on a lateral side of the vacuum chamber 15.
This is because this configuration makes it possible to stabilize
the stage when the tilt stage is not tilted (for example, in the
cross-section milling). Performing the cross-section processing
with the tilt stage being not tilted requires irradiation with the
ion beam from a lateral side, and accordingly, the ion source 1 is
disposed on the lateral side of the vacuum chamber 15. In addition,
in conjunction with this configuration, the processing observation
window for checking the processed cross section is placed on the
upper side of the vacuum chamber 15. Such configuration makes it
possible to check the processed cross section in the cross-section
milling and to check the processed surface in the flat surface
milling through the single observation window.
[0080] FIG. 22 is a view showing an example of a control device of
the ion milling device illustrated in FIG. 10. A switching unit
2201 corresponds to the operation panel of FIG. 21, and information
on selection made in the switching unit 2201 is transmitted to a
calculating unit 2207 via an input interface 2205 provided in a
control device 2202. In the calculating unit 2207, a control signal
generating unit 2209 reads out a control signal from a control
signal storing unit 2208 on the basis of an input signal, and
transmits the control signal to an output interface 2206. Drive
mechanisms 2203, 2204 perform drive under conditions selected in
the switching unit 2201, on the basis of the received control
signal.
[0081] The drive mechanism 2203 is a drive mechanism for driving
the tilt stage and the drive mechanism 2204 is a drive mechanism
for driving the rotating table mounted on the tilt stage. Note
that, although in this embodiment, selection of which one of the
cross-section milling processing and the flat surface milling
processing is performed is made by selecting the processing mode in
the switching unit 2201, the present invention is not limited to
this configuration. For example, a sensor for recognizing the shape
of the sample stage may be provided to automatically select the
processing mode. In this case, the sensor and a calculating device
for recognizing the sensor information correspond to the switching
unit.
[0082] In addition, the device may be configured such that the
selection of the processing mode in the switching unit and the
state of the device are compared, and if the selection or the state
of the device is not appropriate, an error message is generated to
warn the operator not to perform processing based on the erroneous
conditions.
[0083] FIG. 23 is a flowchart showing a determination procedure of
comparing the processing mode and the state of the device and of
generating a message for leading the operator to perform correct
device settings. First, the processing mode is selected on the
operation panel as shown in FIG. 21 while the power of the device
is on (Step 2301). Then, the control signal generating unit 2209 of
the calculating unit 2207 determines which processing mode is
selected (Step 2302), and determines whether or not a sample holder
suitable for the processing mode has been placed on the sample
stage (the determination is made at Step 2303 when the
cross-section processing is selected or at Step 2304 when the flat
surface processing is selected).
[0084] The determination on whether or not a predetermined sample
holder has been placed is implemented by including in the vacuum
chamber a sensor (sensor unit 2210) for determining the difference
between the sample holders and whether or not the sample holder has
been placed. When the sensor generates a signal indicating that the
sample holder itself has not been placed or indicating that a
sample holder unsuitable for the set processing mode has been
placed, a device state monitoring unit 2211 incorporated in the
calculating unit 2207 transmits a predetermined signal to a display
unit 2212, which thus generates an error message (Step 2305). The
error message may be made as "Err" displayed on the display unit of
the operation panel illustrated in FIG. 21, or may be displayed by
using another display means or warning generator.
[0085] Next, when the cross-section milling is selected at Step
2302, it is determined whether or not the tilt angle of the sample
stage 8 is zero (Step 2306). When the tilt angle is not zero, an
error message is generated. The generation of such message makes it
possible to notice that the state of the stage is not appropriately
set for the cross-section milling and thus suppresses the
possibility of performing erroneous processing. After the tilt
angle of the stage is confirmed to be appropriately set at Step
2307, the determination procedure proceeds to a state enabling the
conditions for the swing drive of the rotating table to be inputted
(Step 2307).
[0086] On the other hand, when the flat surface milling is selected
at Step 2302, the determination process proceeds to a state
enabling the conditions for both of the tilt stage and the rotating
stage to be set (Step 2308) because of the necessity to drive both
stages.
[0087] After the above-described procedure, it is further
determined whether or not the other conditions to be set (current
of the ion beam, processing time, and the like) are set (Step
2309), and the processing is started (Step 2310).
[0088] Performing the processing after the above-described
procedure eliminates occurrence of wrong selection in the device
capable of performing two types of processing, and allows easy
setting of the processing conditions. Moreover, when the stage is
tilted (if the tilt angle is not 0.degree.) at Step 2306, the tilt
stage may be controlled to fall automatically into a non-tilt
state.
[0089] As described above, finding the setting information of the
processing mode, the type of the mounted holder, and the state of
the device as well as comparing these pieces of information makes
it possible to easily determine whether or not the current setting
state is appropriate, and to thus prevent processing based on
erroneous settings from occurring.
[0090] In addition, as described above, the distance between the
ion source and the sample needs to be changed depending on the
performance of the ion source for the cross-section milling and the
flat surface milling. For this reason, the device may be configured
such that the processing mode is automatically switched depending
on the setting of the position of the sample stage. Moreover, the
device may be configured such that an error message is generated
when the setting of the position of the sample stage and the
selection of the processing mode conflict with each other. In this
case as well, performing the setting after the procedure as
illustrated in FIG. 23 makes it possible to prevent erroneous
settings. Further, the device may be provided with a control
mechanism that automatically controls the position of the sample
stage depending on the selection of the processing mode.
[0091] Since the sample-mask-unit slightly moving mechanism 4 on
which the sample-mask unit 21 is mounted is detachable from the
device body, a sample surface unit can be attached to the device
after the sample-mask-unit slightly moving mechanism 4 is removed
from the device. Performing the flat surface milling with the
sample surface unit being placed minimizes the milling processing
other than the sample and almost eliminates damaging of the sample
unit.
[0092] Moreover, placing an optical microscope 57, as in FIG. 17,
on the upper portion of the processing observation window of the
ion milling device illustrated in FIG. 10 and the like allows the
progress of the milling processing to be checked. This makes it
possible terminate the processing and to take out the sample when
the processing is completed up to a desired processing range, and
thereby contributes to an improvement in throughput.
[0093] Furthermore, an electron microscope 58 may be placed as
illustrated in FIG. 18 in place of the optical microscope 57
illustrated in FIG. 17. The electron microscope 58 is used for
checking the progress of the processing during performing the
milling processing on the sample with the ion beam. The method of
using the electron microscope 58 is to temporarily stop the milling
processing, open the shutter for contamination prevention, and then
perform observation using the electron microscope 58. When a
desired processing range has not been obtained yet, the electron
beam irradiation is terminated, the shutter for contamination
prevention is closed, and then, the milling processing is started
again by irradiation with the ion beam. When a desired processing
range has been obtained, the magnification is increased to a
required level and a required image is captured.
[0094] The device is configured such that sample-mask-unit slightly
moving mechanism 4 or the sample surface unit is removed from the
device, the sample is mounted on a sample unit for the electron
microscope, and then, the sample unit is attached to the device. In
this way, the device can be used as a normal electron microscope as
well.
[0095] According to the ion milling device illustrated in the
embodiment, it is possible to obtain an ion milling device in which
the processing observation window 7, the ion source 1, and the
sample stage 8 are placed on the upper surface, the left side
surface (or the right side surface), and the front surface of the
vacuum chamber 15, respectively. This facilitates both of the
placement and the observation of the processed surface observation
device. Furthermore, this makes it possible to perform both of the
cross-section milling and the flat surface milling with the single
device.
[0096] Recently, it has increasingly become important to perform
the cross-sectional observation on a composite material with an
electron microscope, particularly in the field of semiconductor
devices. Along with this, an increasing importance is placed on the
mirror-polishing of a cross section of a composite material. This
embodiment makes it possible to perform both of the cross-section
milling and the flat surface milling with a single device.
Furthermore, placing an observation device on an upper portion of a
vacuum chamber significantly improves the operability.
[0097] Although the above description has been made regarding the
embodiments, the present invention is not limited to these
embodiments, and it is apparent to those skilled in the art that
various changes and modifications may be made within the spirit of
the present invention and the scope of the attached claims.
REFERENCE SIGNS LIST
[0098] 1 ion source [0099] 2 mask [0100] 3 sample [0101] 4
sample-mask-unit slightly moving mechanism [0102] 5 sample unit
base [0103] 6 vacuum exhaust system [0104] 7 processing observation
window [0105] 8 sample stage [0106] 9 rotor [0107] 10 flange [0108]
11, 24 linear guide [0109] 12 magnifying lens [0110] 13
magnifying-lens slightly moving mechanism [0111] 15 vacuum chamber
[0112] 21 sample-mask unit [0113] 22 sample-holder rotary ring
[0114] 23 sample holder
[0115] 25 mask holder [0116] 26 mask finely adjusting mechanism
[0117] 27 mask fixing screw [0118] 28 sample-holder rotary screw
[0119] 30 sample-holder-position controlling mechanism [0120] 35
sample-holder fixing metal fitting [0121] 40, 57 optical microscope
[0122] 41 observation table [0123] 42 fixation table [0124] 50 gear
[0125] 51 bearing [0126] 52 mask unit fixation part [0127] 53 shaft
coupling [0128] 54 linear motion device [0129] 55 motor [0130] 56
sample surface unit [0131] 58 electron microscope [0132] 60
sample-stage pulling out mechanism
* * * * *