U.S. patent application number 14/941897 was filed with the patent office on 2016-03-10 for method and apparatus for surface processing of a substrate using an energetic particle beam.
This patent application is currently assigned to Veeco Instruments, Inc.. The applicant listed for this patent is Boris L. Druz, Roger P. Fremgen, Alan V. Hayes, Viktor Kanarov, Robert Krause, Ira Reiss, Piero Sferlazzo. Invention is credited to Boris L. Druz, Roger P. Fremgen, Alan V. Hayes, Viktor Kanarov, Robert Krause, Ira Reiss, Piero Sferlazzo.
Application Number | 20160071708 14/941897 |
Document ID | / |
Family ID | 40534495 |
Filed Date | 2016-03-10 |
United States Patent
Application |
20160071708 |
Kind Code |
A1 |
Druz; Boris L. ; et
al. |
March 10, 2016 |
METHOD AND APPARATUS FOR SURFACE PROCESSING OF A SUBSTRATE USING AN
ENERGETIC PARTICLE BEAM
Abstract
Method and apparatus for processing a substrate with an
energetic particle beam. Features on the substrate are oriented
relative to the energetic particle beam and the substrate is
scanned through the energetic particle beam. The substrate is
periodically indexed about its azimuthal axis of symmetry, while
shielded from exposure to the energetic particle beam, to reorient
the features relative to the major dimension of the beam.
Inventors: |
Druz; Boris L.; (Brooklyn,
NY) ; Sferlazzo; Piero; (Marblehead, MA) ;
Fremgen; Roger P.; (Northport, NY) ; Hayes; Alan
V.; (Plainview, NY) ; Kanarov; Viktor;
(Bellmore, NY) ; Krause; Robert; (Levittown,
NY) ; Reiss; Ira; (New City, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Druz; Boris L.
Sferlazzo; Piero
Fremgen; Roger P.
Hayes; Alan V.
Kanarov; Viktor
Krause; Robert
Reiss; Ira |
Brooklyn
Marblehead
Northport
Plainview
Bellmore
Levittown
New City |
NY
MA
NY
NY
NY
NY
NY |
US
US
US
US
US
US
US |
|
|
Assignee: |
Veeco Instruments, Inc.
Plainview
NY
|
Family ID: |
40534495 |
Appl. No.: |
14/941897 |
Filed: |
November 16, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12212844 |
Sep 18, 2008 |
9206500 |
|
|
14941897 |
|
|
|
|
10915745 |
Aug 11, 2004 |
7879201 |
|
|
12212844 |
|
|
|
|
60973312 |
Sep 18, 2007 |
|
|
|
60494281 |
Aug 11, 2003 |
|
|
|
Current U.S.
Class: |
204/298.04 |
Current CPC
Class: |
H01J 2237/045 20130101;
C23C 14/044 20130101; C23C 14/46 20130101; H01J 37/302 20130101;
H01J 2237/20221 20130101; C23C 14/221 20130101; H01J 2237/20214
20130101; H01J 37/20 20130101; H01J 37/32752 20130101; H01J 37/3441
20130101; H01J 2237/20207 20130101; H01J 2237/30472 20130101; H01J
2237/0245 20130101; H01J 37/3488 20130101; H01J 37/317 20130101;
H01J 37/3476 20130101; H01J 2237/3146 20130101 |
International
Class: |
H01J 37/34 20060101
H01J037/34; H01J 37/32 20060101 H01J037/32; C23C 14/46 20060101
C23C014/46 |
Claims
1. A system for processing a substrate with an energetic particle
beam, the system comprising: a source configured to emit the
energetic particle beam, said source having a major dimension, and
said source configured to distribute the beam with a substantially
uniform flux distribution across at least a portion of said major
dimension; a vacuum chamber containing said source and including a
treatment zone across which the beam impinges the substrate; and a
fixture disposed inside said vacuum chamber at a position spaced
from said source, said fixture includes a first stage configured to
hold the substrate and a second stage adapted to translate said
first stage relative to said source, said first stage configured to
index the substrate about an azimuthal axis to different angular
orientations, and said second stage capable of translating the
substrate through said treatment zone with each of said different
angular orientations and to a parking area outside of said
treatment zone in which said first stage is used to index the
substrate.
2. The system of claim 1 wherein said second stage is adapted to
translate the substrate linearly relative to said major dimension
of said source within said treatment zone.
3. The system of claim 1 wherein said second stage is adapted to
translate the substrate in an arc having a radius of curvature such
that a direction of movement within said treatment zone is
substantially perpendicular to said major dimension of said
source.
4. The system of claim 1 wherein said source is adapted to move
relative to the substrate in an arc substantially perpendicular to
said major dimension of said source for changing an average
incident angle of the ion beam relative to the substrate.
5. The system of claim 1 further comprising: a third stage
configured to tilt said first stage about a pivot axis aligned with
said major axis of said source so that said azimuthal axis is
inclined tilted relative to a direction of the energetic particle
beam to define an angle of incidence.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of Provisional
Application No. 60/973,312, filed Sep. 18, 2007, now expired. The
present application is a divisional of application Ser. No.
12/212,844, filed Sep. 18, 2008, which is a continuation-in-part of
application Ser. No. 10/915,745, filed Aug. 11, 2004, now U.S. Pat.
No. 7,879,201 issued Feb. 1, 2011, which claims the benefit of
Provisional Application No. 60/494,281, filed Aug. 11, 2003, now
expired. The disclosure of each of these documents is hereby
incorporated by reference herein in its entirety.
BACKGROUND
[0002] This invention relates generally to materials processing
and, more particularly, to apparatus and methods for processing or
treating the surface of a substrate with an energetic particle
beam.
[0003] Sputter deposition and ion beam deposition (IBD) are
familiar methods for depositing thin film materials. These
deposition processes require deposition on substrates with
particular topographical features that affect the distribution and
properties of deposited material across the substrate. For example,
lift-off deposition processes in which thin films are deposited
over a pattern of photoresist features are used in many important
thin film device fabrication processes.
[0004] IBD is particularly well suited for lift-off deposition
processes due to some unique advantages of the process, including
low process pressures and directional deposition. As a result, the
lift-off step is extremely clean and repeatable down to critical
dimensions less than 0.5 microns. Primarily because of these
advantages, IBD has become the dominant method for depositing
stabilization layers for thin film magnetic heads as a lift-off
step is required subsequent to the deposition of the stabilizing
material. In addition to good lift-off properties, IBD films have
extremely good magnetic properties. The substrate may be tilted to
different angles to optimize the properties of the IBD deposited
film and rotated to average out non-uniformities introduced by the
tilting.
[0005] With reference to FIG. 1, an IBD system generally includes a
deposition gun 10 that directs an energized beam 12 of ions to a
target 14 of material to be deposited. The ion beam 12 sputters
material from a finite, well-confined source region on the target
14 to generate a beam 16 of sputtered target material. A substrate
18 is held on a fixture 20 and positioned so that the beam 16
impinges the substrate 18. The target 14 is approximately the size
of substrate 18, which is located the equivalent of a few substrate
diameters away from the target 14. The fixture 20 is configured to
tilt the normal to the surface of substrate 18 at an angle .theta.
relative to the direction of the deposition flux 16 and to
continuously rotate the substrate 18 about the surface normal.
[0006] The divergence angle of the beam 16 depends on the
geometrical relationship between the target 14 and substrate 18.
One contribution to the divergence angle arises because the ion
beam 12 is focused on the target 14 to prevent ion beam sputtering
of nearby components in the process chamber. Another contribution
to the divergence angle originates from the target-to-substrate
distances that are limited due to the deposition rate
reduction.
[0007] Beam divergence in IBD systems cause asymmetrical shadowing
of the substrate surface by the features projecting from the
substrate surface, such as the features characterizing a
photoresist pattern. This causes the deposited material to have an
asymmetric deposition profile relative to the features, which
reduces the area over which lift-off is acceptable and reduces
magnetic property uniformity.
[0008] The substrate may be oriented relative to the flux direction
so that its surface normal is aligned with the line of sight
between substrate and the deposition flux source region on the
sputter target, which is typically the center of the target, and
rotated about its centerline. Under these circumstances, the
substrate is not shadowed by the feature on the inboard or
radially-innermost side of the feature. In contrast, the substrate
will always be shadowed by the feature on the outboard or
radially-outermost side of the feature. The degree of shadowing on
the outboard side increases with increasing radial separation
between the feature and the substrate centerline and also with
increasing divergence of the deposition flux. The resulting
deposition profile is highly asymmetrical.
[0009] Tilting the surface normal with respect to the line of sight
between the target and the substrate during deposition improves the
symmetry of the deposition profile by reducing the substrate
shadowing on the outboard side of features. However, the nature of
the substrate shadowing on the outboard and inboard sides of the
feature depends on the azimuthal position of the feature as the
substrate is rotated, as described below.
[0010] FIGS. 2A and 2B illustrate the shadow cast on a substrate 21
by the inboard side and the outboard side of a feature 26
projecting from substrate 21 at a location between the substrate
center and peripheral edge. FIG. 2A shows the feature 26 with the
substrate 21 oriented at a first azimuthal angle and tilted
relative to a target 28 of an IBD system. The outboard side of the
feature 26 shadows the substrate 21 over a distance 24. The inboard
side of the feature 26 does not shadow the substrate 21. FIG. 2B
shows feature 26 with the substrate 21 oriented at a second
azimuthal angle that locates feature 26 at an angular position
diametrically opposite to the position at the first azimuthal
angle. The inboard side of the feature 26 shadows the substrate 21
over a distance 22, which is a smaller distance than distance 24.
The outboard side of the feature 26 does not shadow the substrate
21 at the second azimuthal angle.
[0011] Despite substrate tilting, the shadowing of the substrate 21
over distance 24 on the outboard side of the feature 26 differs
from the shadowing of the substrate 21 over distance 22 by the
inboard side. In particular, the profile of the deposited material
will differ on the inboard and outboard sides of the feature 26
adjacent to the sidewalls of feature 26. Specifically, the longer
shadow cast over distance 24 adjacent to the outboard side results
in a relatively longer taper of the deposited material than
adjacent to the inboard side.
[0012] The shadowed substrate region on the outboard side of the
feature 26 also experiences a lower deposition rate because it is
effectively further away from the target 28 when the substrate 21
is oriented at the first azimuthal angle. The inboard substrate
region experiences a higher deposition rate because it is closer to
the target 28 when the substrate 21 is oriented at the second
azimuthal angle. Therefore, the deposited material is thinner on
the outboard side of feature 26, due to the outboard region being
further away from the target 28. The asymmetry and difference in
deposition rate, which originate from the beam divergence of the
target 28, increase with increasing radial distance from the center
of substrate 21.
[0013] Feature 30, which is at the same radial distance from the
substrate center as feature 26, experiences the same asymmetries
and differences in deposition rate as feature 26. On the other
hand, the deposited material is radially symmetrical about feature
32 at the substrate center because feature 32 symmetrically shadows
the substrate 21 adjacent to its sidewalls. Other types of surface
treatments, such as etching, will have similar asymmetrical
treatment profiles about the features 26 and 30.
[0014] It would therefore be desirable to provide a deposition
method capable of eliminating or, at the least, significantly
reducing the inboard and outboard asymmetries of the deposited
material adjacent to a feature projecting from the surface of a
substrate.
SUMMARY
[0015] In accordance with an embodiment of the invention, a system
for processing a substrate includes a vacuum chamber containing a
source configured to emit an energetic particle beam. The source
has a major dimension and the beam has a substantially uniform flux
distribution across at least a portion of the major dimension. The
vacuum chamber includes a treatment zone across which the beam
impinges the substrate. The system further includes a fixture
disposed inside the vacuum chamber at a position spaced from the
source. The fixture includes a first stage configured to hold the
substrate and a second stage adapted to translate the first stage
relative to the source. The first stage is configured to index the
substrate about an azimuthal axis to different angular
orientations. The second stage is capable of translating the
substrate through the treatment zone with each of the different
angular orientations and to a parking area outside of the treatment
zone in which the first stage is used to index the substrate.
[0016] In accordance with another embodiment of the invention, a
method is provided for processing a substrate includes supplying an
energetic particle beam having a substantially uniform flux
distribution over at least a portion of a major dimension thereof.
The method further includes aligning features on the substrate
substantially parallel with the major dimension of the beam, moving
the substrate relative to the beam, and exposing the substrate to
the energetic particles in a treatment zone during at least a
portion of the movement.
[0017] Processing may be performed on one side of the feature if
the substrate is moved relative to the major dimension of the
energetic particle beam without rotation. Alternatively, the
substrate may be processed adjacent to both sides of the feature if
the substrate is rotated 180.degree. after each cycle of the
substrate surface treatment, as described herein.
[0018] Various objects and advantages of the invention shall be
made apparent from the accompanying drawings of the illustrative
embodiment and the description thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and, together with a general description of the
invention given above, and the detailed description of the
embodiments given below, serve to explain the principles of the
invention.
[0020] FIG. 1 is a diagrammatic view of a conventional IBD system
in accordance with the prior art;
[0021] FIGS. 2A and 2B are diagrammatic views illustrating the
asymmetrical deposition profile for features on a substrate of the
conventional IBD system of FIG. 1;
[0022] FIG. 3 is a diagrammatic side view of a substrate processing
apparatus in accordance with the invention;
[0023] FIG. 3A is a detailed view of a portion of FIG. 3;
[0024] FIGS. 3B and 3C are diagrammatic perspective views of the
shield of FIG. 3 showing the ability to adjust the position of the
aperture relative to the source and the ability to adjust the width
of the aperture, respectively;
[0025] FIGS. 4A and 4B are diagrammatic perspective views of the
substrate processing apparatus of FIG. 3 illustrating the
geometrical relationships between the source, the aperture, and the
substrate;
[0026] FIG. 5 is a diagrammatic perspective view of the substrate
processing apparatus of FIG. 3 at an initial stage of a processing
method in accordance with an embodiment of the invention;
[0027] FIG. 5A is a detailed view of a portion of FIG. 5
illustrating the orientation of one of the features projecting from
the substrate during processing;
[0028] FIG. 6 is a diagrammatic perspective view of the substrate
processing apparatus of FIG. 3 at a subsequent stage of the
processing method;
[0029] FIG. 6A is a cross-sectional view of the feature of FIG. 5A
receiving treatment while being translated past the aperture during
processing;
[0030] FIGS. 7-9 are diagrammatic perspective views of the
substrate processing apparatus of FIG. 6 at subsequent stages of
the processing method;
[0031] FIG. 9A is a detailed view illustrating the feature of FIG.
6A during processing after the substrate is rotated by 180.degree.
and immediately before the second half-cycle of the processing
cycle;
[0032] FIG. 10 is a diagrammatic perspective view of the substrate
processing apparatus of FIG. 9 at a subsequent stage of the
processing method;
[0033] FIG. 10A is a cross-sectional view of the feature of FIG. 9A
receiving treatment while being translated past the aperture with
the feature reoriented by 180.degree.;
[0034] FIGS. 11-13 are diagrammatic perspective views of the
substrate processing apparatus of FIG. 10 at subsequent stages of
the processing method;
[0035] FIG. 13A is a detailed view of a portion of FIG. 13
illustrating feature orientation during processing and after a full
cycle;
[0036] FIGS. 14 and 14A are diagrammatic perspective views of a
substrate processing apparatus in accordance with an alternative
embodiment of the invention;
[0037] FIG. 15 is a diagrammatic perspective view of a substrate
processing apparatus in accordance with another alternative
embodiment of the invention;
[0038] FIG. 16 is a diagrammatic side view of a substrate
processing apparatus in accordance with an alternative embodiment
of the invention;
[0039] FIG. 16A is an enlarged view of a portion of FIG. 16;
[0040] FIG. 16B is a diagrammatic perspective view of the substrate
processing apparatus of FIG. 16;
[0041] FIG. 17 is a diagrammatic bottom view of a substrate
processing apparatus in accordance with an alternative embodiment
of the invention;
[0042] FIG. 18 is an enlarged diagrammatic top view of a portion of
FIG. 17;
[0043] FIG. 19 is a diagrammatic top view of a portion of similar
to FIG. 18 in accordance with an alternative embodiment of the
invention;
[0044] FIG. 20 is a diagrammatic perspective view of a substrate
processing apparatus in accordance with an alternative embodiment
of the invention;
[0045] FIGS. 21 and 22 are diagrammatic perspective views similar
to FIG. 20 at subsequent stages of a substrate processing method in
accordance with an alternative embodiment of the invention; and
[0046] FIG. 23 is a diagrammatic perspective view of a substrate
processing apparatus in accordance with an alternative embodiment
of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] With reference to FIGS. 3 and 3A, a processing apparatus 40
includes a source 50, which is preferably rectangular but not so
limited, adapted to emit a beam 42 of energetic particles. The
energetic particles from source 50 may etch a substrate 44, deposit
a thin film or layer of material on substrate 44, or otherwise
treat substrate 44. The source 50 may have a geometrical shape
similar to the geometrical shape of aperture 54, which reduces the
unused portion of the beam 42 from the source 50 that does not
treat the substrate 44. The source 50 is characterized by a major
axis or dimension 49 (FIG. 4A) and a minor axis or dimension 51
(FIG. 4A). Beam 42 has a substantially uniform flux distribution
along the major dimension 49 of the source 50.
[0048] The processing apparatus 40 includes a vacuum chamber 46
that is isolated from the surrounding environment. Vacuum chamber
46 may be evacuated to a suitable vacuum pressure by a vacuum pump
48 as recognized by a person of ordinary skill in the art. A
sealable port (not shown) is provided in the vacuum chamber 46 for
accessing the interior of vacuum chamber 46 to exchange processed
substrates 44 for unprocessed substrates 44.
[0049] The source 50 of beam 42 is any ion beam source capable of
generating energetic particles for performing a thin film
deposition, an etching process, a reactive ion etching process, a
sputtering process, or other ion beam treatment. For example, the
source 50 may be a magnetron of with a sputtering target of any
material that provides thin film deposition. Another example is a
rectangular ion beam source 50 with flat or dished grid ion optics
to emit energetic particles in direction to the aperture 54 that
provides a substrate surface etch. In a preferred embodiment of the
invention, the source 50 is an ion beam deposition (IBD) source
including a target of deposition material sputtered by a beam of
inert gas ions and a magnetron confining a plasma proximate to the
target that provides the source of the gas ions. Such sources 50
and, in particular, rectangular sources 50, require no further
description herein in order to be understood by persons of ordinary
skill.
[0050] The substrate 44 and source 50 are positioned in different
parallel planes. A shield 52 may be located in an intervening
position between the substrate 44 and the source 50 so that the
aperture 54 is located in a plane that is substantially parallel to
the plane of the substrate 44. The optional shield 52 has a
rectangular opening or aperture 54 characterized by a major axis or
dimension 65 (FIG. 4A) substantially aligned with the major
dimension 49 (FIG. 4A) of the source 50 along which beam 42 is
uniform. The aperture 54 in shield 52 collimates beam 42 so that
only a fraction of energetic particles emitted from source 50,
preferably a majority of the energetic particles, are transmitted
through the aperture 54 and strike the substrate 44 in a treatment
area or zone 38 to thereby treat the substrate 44. Typically, the
major dimension 65 (FIG. 4A) of aperture 54 is greater than the
diameter of substrate 44 and the minor dimension 64 (FIG. 4A) of
aperture 54 is less than or equal to the diameter of substrate 44.
The location of the treatment zone 38 remains fixed as the
substrate 44 is moved.
[0051] References herein to terms such as "vertical", "horizontal",
etc. are made by way of example, and not by way of limitation, to
establish a frame of reference. It is understood that various other
frames of reference may be employed without departing from the
spirit and scope of the invention. For example, a person of
ordinary skill will recognize that the arrangement of the source 50
and the fixture 55 may be inverted so that the substrate 44 is
above the source 50.
[0052] With continued reference to FIGS. 3 and 3A, the substrate 44
is held and supported by a two-stage fixture 55 having a rotational
stage 56 adapted to rotate the substrate 44 in at least one
rotational sense about an azimuthal axis 45 of the rotational stage
56. Rotation of the substrate 44 about the azimuthal axis 45
changes the orientation of features 66 (FIG. 5A) on the substrate
44 relative to the direction of the beam 42. A translation stage 58
of fixture 55, which supports the rotational stage 56, is adapted
to move or translate the substrate 44 linearly and bi-directionally
(i.e., reversibly) relative to the aperture 54. The translation
stage 58 is movable over a range of motion adequate to position
substrate 44 in flux-blocked positions on opposite sides of
aperture 54 in which the shield 52 is interposed between the
substrate 44 and source 50. The movements of stages 56 and 58 are
mutually independent so that the substrate 44 may be translated by
stage 58 without rotation and, conversely, the substrate 44 may be
rotated by stage 56 without translation. The translation stage 58
translates the substrate 44 in a direction approximately orthogonal
to the major dimension 65 (FIG. 4A) of aperture 54.
[0053] In an alternative embodiment of the invention, the
translation stage 58 may be replaced by a planetary stage (not
shown) that revolves the substrate 44 and rotational stage 56 about
a relatively large radius of curvature in a plane parallel to the
substrate plane. The radius of the curve traced by the substrate 44
when moved by the planetary stage is large enough to be
approximately linear over the minor dimension 64 of aperture 54.
Preferably, the center of the source 50 and aperture 54, and the
arc traced by the center of fixture 55 are in a cylindrical plane
with a radius of curvature exceeding the distance between the
source 50 and aperture 54.
[0054] With reference to FIG. 4A, the position of aperture 54 with
respect to the source 50 determines the incident angle at which
energetic particles from the beam 42 (i.e., particle flux) impinge
the substrate 44. The source 50 may be considered to be a line
source having a centerline 59 extending across its major dimension
49. The average incident angle, .alpha., of the particle flux is
defined as the inverse sine of the quotient of a dividend given by
the perpendicular distance from the centerline 59 of source 50 to
the plane of the optional shield 52, labeled with the alphanumeric
character "n" in FIG. 4A, divided by a divisor given by the
distance from the centerline 59 of the source 50 to the mid-line of
the aperture 54 defined between edges 60, 62, labeled with the
alphanumeric character "m" in FIG. 4A. As is apparent, the average
incident angle increases (i.e., becomes more oblique) as the
distance from centerline 59 to the center of aperture 54
increases.
[0055] With reference to FIG. 4B, the minor dimension 64 (FIG. 4A)
of the aperture 54 determines the collimation of beam 42. The
collimation angle is determined from the angular arc subtended from
the source 50 to the opposite edges 60, 62 of the aperture 54 and
defines the angular distribution of the flux about the average
incident angle. Edge 60 is most distant from source 50 and edge 62
is closest to source 50. The distance in the plane of the shield 52
between edges 60, 62 specifies the minor dimension 64 of the
aperture 54. The aperture 54 also has a major dimension 65
orthogonal to the minor dimension 64. The collimation angle, .phi.,
is equal to the difference between the inverse cosine of the
quotient of a dividend given by the distance, n, divided by a
divisor given by the distance from the centerline 59 to edge 60
minus the inverse cosine of the quotient of a dividend given by the
distance, n, divided by a divisor given by the distance from the
centerline 59 to edge 62. As is apparent, the collimation angle for
the deposition flux may be reduced by reducing the separation
between edges 60, 62.
[0056] With reference to FIGS. 3B and 3C, the shield 52 may
preferably include two members 52a, 52b that are relatively movable
in a direction perpendicular to the major dimension 49 (FIG. 4A) of
the source 50. The location of the aperture 54 may be adjusted
relative to the source 50 by moving the members 52a, 52b toward or
away from the source 50, as shown in FIG. 3B. This relocation of
the aperture 54 is effective for changing the average incident
angle of the beam 42 relative to the plane of the substrate 44. The
movement of members 52a, 52b is illustrated as increasing the
average incident angle relative to the arrangement shown in FIG.
4A, although not so limited. The minor dimension 64 (FIG. 4A) of
aperture 54 may be adjusted by moving the members 52a, 52b relative
to each other so that the distance between edges 60, 62 changes, as
shown in FIG. 3C. This width adjustment of aperture 54 is effective
for changing the collimation angle of the beam 42 across the
treatment zone 38. The movement of members 52a, 52b is illustrated
as increasing distance to provide a minor dimension 64a greater
than minor dimension 64 (FIG. 4B), which increases the collimation
angle relative to the arrangement shown in FIG. 4B. However, moving
the edges 60, 62 of the members 52a, 52b closer together will
decrease the collimation angle relative to the arrangement shown in
FIG. 4B.
[0057] With reference to FIGS. 5-13 in which like reference
numerals refer to like features in FIGS. 3, 3A, 4A, and 4B, a
method of exposing the substrate 44 to a beam 42 of energetic
particles is described that provides a symmetrical treatment
profile on opposite sides of features 66 projecting upwardly from
the substrate 44. Beam 42 will be described as a beam of deposition
material that incrementally accumulates as a thin film on substrate
44, although the invention is not so limited. Alternatively, the
beam 42 may etch the substrate 44 by sputtering, chemical reaction,
or a combination thereof, remove contaminants from the surface of
substrate 44, or perform another type of ion beam treatment of
substrate 44. The method will be described in terms of a single
processing cycle or sequence including two distinguishable
half-cycles, which may be repeated or iterated to thicken the
deposited thin film or achieve the desired surface treatment.
[0058] With specific reference to FIGS. 5 and 5A, substrate 44 is
loaded onto the fixture 55 in a home position in which the
substrate 44 is shielded from source 50 by the shield 52.
Accordingly, the beam 42 does not treat the substrate 44 in the
home position. While the substrate 44 is stationary in the home
position, the rotational stage 56 of fixture 55 orients substrate
44 about azimuthal axis 45 so that each of the features 66,
exemplified by feature 66 visible in FIG. 5A, has opposite first
and second sidewalls 68, 70 aligned generally parallel with the
major dimension 65 of the aperture 54 and so that sidewall 68 is
closest to edge 60.
[0059] The features 66 may be, for example, portions of a patterned
photoresist layer. To that end, resist is applied by, for example,
a spin-on process to substrate 44, exposed with radiation projected
through a photomask to impart a latent projected image pattern
characteristic of features 66, and developed to transform the
latent image pattern into a final image pattern. The resist is
stripped from the substrate 44 after the substrate 44 is treated by
beam 42. The features 66 of the patterned resist may be used as a
mask in a lift-off process following deposition of the layer 71 of
deposition material in processing apparatus 40.
[0060] The source 50 is energized to generate the beam 42 of
energetic particles, which are directed toward the rectangular
aperture 54 in the shield 52. The projection of the beam 42 through
the aperture 54 defines the treatment zone 38 in the plane of the
substrate 44. The substrate 44, when positioned in the treatment
zone 38 by fixture 55, is exposed to the energetic particles of
beam 42.
[0061] With reference to FIGS. 6 and 6A, the translation stage 58
of fixture 55 translates the substrate 44 in a plane below the
shield 52 and past the rectangular aperture 54. The translation is
in a direction substantially orthogonal to the major dimension 65
of the aperture 54. While the substrate 44 is in the line of sight
between the source 50 and aperture 54, the beam 42 impinges the
exposed surface of the substrate 44 and the energetic particles in
the beam 42 provide the surface treatment. In this exemplary
embodiment, the energetic particles in beam 42 are resident in a
layer 71 of deposition material deposited on the substrate 44.
[0062] Layer 71 extends up to the base of the sidewall 68 of
feature 66, as feature 66 does not block the line-of-sight of beam
42 to substrate 44 proximate to the base of sidewall 68. However,
feature 66 shadows the substrate 44 adjacent to sidewall 70 over a
width 74. As a result, energetic particles from beam 42 do not
impinge the portion of substrate 44 adjacent to sidewall 70, and
layer 71 does not accumulate or thicken over width 74 during this
segment of the cycle.
[0063] Because each feature 66 is exposed continuously to beam 42
over the entire extent of the apparatus collimation angle (FIG.
4B), beam divergence across the minor dimension 64 (FIG. 4A)
between edges 60, 62 does not cause variations in the profile of
layer 71 adjacent to sidewall 70 among features 66 at different
locations on substrate 44. In addition, the uniformity of the flux
distribution of beam 42 along its major dimension 49 promotes
uniformity in the profile and thickness of layer 71 across the
surface of substrate 44.
[0064] With reference to FIGS. 7 and 8, the motion of the
translation stage 58 is stopped at an end point beneath the shield
52 after passing the rectangular aperture 54. At the end point, the
substrate 44 is stationary and the beam 42 is blocked by shield 52
from reaching substrate 44. The translation direction of stage 58
is then reversed so that the substrate 44 moves back toward the
rectangular aperture 54 in a direction again substantially
orthogonal to the major dimension 65 of the aperture 54. The
exposed surface of substrate 44 is again exposed to beam 42 while
in the treatment zone 38 so that the energetic particles in the
beam 42 provide the surface treatment. Another thickness of layer
71 deposits on the substrate 44. Layer 71 again accumulates or
thickens uniformly up to the base of sidewall 68 because, over the
return path to the home position, feature 66 still does not block
the line-of-sight of beam 42 to substrate 44 proximate to the base
of sidewall 68. However, the feature 66 again shadows the substrate
44 adjacent to sidewall 70 over width 74. As a result, energetic
particles from beam 42 do not impinge the portion of substrate 44
adjacent to the base of sidewall 70 and, therefore, layer 71 does
not accumulate or thicken over width 74 during this segment of the
processing cycle.
[0065] With reference to FIG. 9, the translation stage 58 returns
the substrate 44 to its home position in which beam 42 is blocked
by shield 52 from reaching the substrate 44. While the fixture 55
is stationary in this home position, the rotational stage 56
rotates the substrate 44 by 180.degree. about azimuthal axis 45 so
that sidewall 70 is closest to edge 60 and sidewall 68 is remote
from edge 60. The sidewalls 68, 70 are aligned generally parallel
with the major dimension 65 of the aperture 54 after the
180.degree. rotation.
[0066] With reference to FIGS. 10-12, the procedure shown in FIGS.
6-8 is repeated so that the region of substrate 44 adjacent to the
base of sidewall 70 (i.e., width 74 shown in FIG. 6A) receives a
surface treatment identical to the region of substrate 44 adjacent
to the base of sidewall 68 (i.e., width 72). In other words, the
widths 72 and 74 are equal, neglecting the thickness of layer 71
forming on the substrate 44 across widths 72 and 74. While the
substrate 44 is positioned beneath aperture 54 (FIGS. 10 and 12),
energetic particles from the beam 42 treat the substrate 44.
Accordingly, another thickness of layer 71 deposits on the
substrate 44.
[0067] Layer 71 thickens up to the base of sidewall 70 over each of
the two passes beneath the aperture 54 because feature 66 does not
block the path of beam 42 to substrate 44 adjacent to the base of
sidewall 70. However, feature 66 shadows the substrate 44 adjacent
to sidewall 68 over width 72. As a result, energetic particles from
beam 42 do not impinge the portion of layer 71 adjacent to sidewall
68 and layer 71 does not accumulate or thicken over width 72 during
these segments of the cycle.
[0068] When the substrate 44 is returned by the translation stage
58 to the home position in FIG. 13, the rotational stage 56 rotates
the substrate 44 by 180.degree. about azimuthal axis 45 so that
sidewall 68 of feature 66 is again closest to edge 60. The
procedure embodied in the segments of FIGS. 5-13 is repeated for a
number of cycles sufficient to achieve a targeted processing
result. For example and as described, the procedure may be repeated
for a number of cycles sufficient to provide a targeted thickness
of material deposition. Feature 66 may be removed from substrate 44
after the targeted thickness of deposition material in layer 71 is
achieved.
[0069] In an alternative embodiment of the invention, the
half-cycle depicted in FIGS. 6-8 may be repeated for a number of
passes past aperture 54 with sidewalls 68, 70 aligned generally
parallel with the major dimension 65 of the aperture 54 and
sidewall 68 nearest to edge 60 and the substrate 44 rotated by
180.degree. about azimuthal axis 45. Then, the half-cycle depicted
in FIGS. 10-12 repeated for a substantially equivalent number of
passes with sidewalls 68, 70 aligned generally parallel with the
major dimension 65 of the aperture 54 and sidewall 70 nearest to
edge 60. Preferably, the two half-cycles of the sequence alternate
as described herein. In other words, the substrate 44 is translated
through the treatment zone 38 a plurality of times before being
rotated by 180.degree. about azimuthal axis 45 to re-orient the
features 66.
[0070] The result of the processing procedure is that neither
sidewall 68, 70 constitutes an inboard or outboard side of feature
66 as the features 66 are alternatively aligned relative to the
major dimension 65 (FIG. 4A) of the aperture 54 and translated
relative to beam 42. This results in a symmetrical deposition or
treatment profile on substrate 44 adjacent to the sidewalls 68, 70
of feature 66. In addition, the deposition or processing profile
does not exhibit a radial dependence relative to the center of
substrate 44.
[0071] In an alternative embodiment, the processing apparatus 40
may be employed to perform a static etch or other wafer surface
treatment under oblique beam incidence. This embodiment eliminates
the 180.degree. rotation of substrate 44 about azimuthal axis 45 in
the home position after the conclusion of each half cycle. With
reference to either the half cycle shown in FIGS. 5-9 or the half
cycle shown in FIGS. 9-13, the substrate 44 is translated past the
aperture 54 without using rotational stage 56 to change the angular
orientation of the substrate 44.
[0072] In another alternative embodiment of the invention, the
substrate 44 may be held stationary and the source 50 and aperture
54 are moved relative to the substrate 44 so that the deposition
flux is scanned across the surface of the substrate 44.
[0073] With reference to FIGS. 14 and 14A in which like reference
numerals refer to like features in FIGS. 3-13 and in accordance
with an alternative embodiment of the present invention, the beam
42 emitted by a source 50a has a flux distribution of energetic
particles that is symmetrical relative to the plane of the motion
of fixture 55. Shield 52 includes a second rectangular aperture 54a
that is identical in major dimension 64 and minor dimension 65 to
rectangular aperture 54. The rectangular apertures 54, 54a are
preferably positioned symmetrically relative to the centerline 59
of the source 50 (i.e., symmetrically to energetic particles plume
distribution), although the invention is not so limited. This
symmetry causes the surface treatment (e.g., deposition or etch) to
be substantially identical adjacent to both sidewalls 68, 70 (FIG.
5A) of feature 66 when the substrate 44 is translated by the
translation stage 58 past the rectangular apertures 54, 54a. This
embodiment of the invention does not require a 180.degree. rotation
about azimuthal axis 45 to produce symmetrical substrate treatment
proximate to the base of the sidewalls 68, 70 of features 66
projecting from substrate 44.
[0074] With reference to FIG. 15 in which like reference numerals
refer to like features in FIGS. 3-13 and in accordance with an
alternative embodiment of the present invention, the vacuum chamber
46 of processing apparatus 40 may include a plurality of at least
two sources 80, 82, each of which is substantially identical to
source 50, in which the emitted energetic particles may have
different or identical characteristics. Associated with each source
80, 82 is a corresponding one of at least two rectangular apertures
84, 86, each of which is substantially identical to aperture 54.
The processing apparatus 40 is configured and the source 80 and
aperture 84 are arranged such that substrate 44 is impinged by
energetic particles from source 80 only when in the line-of-sight
of source 80 as viewed through aperture 84. Similarly, processing
apparatus 40 is configured and source 82 and aperture 86 are
arranged such that substrate 44 is impinged by energetic particles
from source 82 only when in the line-of-sight of source 82 as
viewed through aperture 86. The sources 80, 82 may be used to
deposit individual layers of a multilayer structure. Alternatively,
source 80 may be used to etch substrate 44 and source 82 may be
used to deposit a layer on substrate 44, or source 80 may deposit a
layer on substrate 44 and source 82 may be used to ion beam process
the layer on substrate 44 under an oblique angle of incidence.
Other combinations of surface treatments are contemplated by the
invention, as is the presence of more than two sources and
associated apertures inside vacuum chamber 46 for depositing
additional layers, performing additional dry etches, or otherwise
ion beam processing the substrate 44.
[0075] With reference to FIGS. 16, 16A, and 16B in which like
reference numerals refer to like features in FIGS. 3-13 and in
accordance with an alternative embodiment of the present invention,
the shield 52 (FIGS. 3, 3A-C) may be omitted from the vacuum
chamber 46 of processing apparatus 40 while retaining the
advantages characteristic of the present invention. To that end,
the processing apparatus 40 is provided with a source 90, which is
preferably rectangular but not so limited, that is adapted to emit
the beam 42 of energetic particles with a substantially uniform
flux distribution along at least a portion of a major dimension 89
of the source 90 (FIG. 16B). The beam 42 is confined parallel to
the direction of motion of the substrate 44 and shaped to provide
the substantially uniform flux distribution along at least a
portion of the major dimension 89. The source 90 is also
characterized by a minor dimension 91 (FIG. 16B) orthogonal to the
major dimension 89. The energetic particles from source 90 may etch
substrate 44, deposit a thin film or layer of material on substrate
44, or otherwise treat substrate 44, as understood by a person
having ordinary skill in the art. Eliminating the shield 52 may be
advantageous for reducing the likelihood of substrate contamination
originating from material physically sputtered from such
shields.
[0076] Linear ion sources 90 suitable for surface treatments like
etching include, but are not limited to, the product line of linear
anode layer ion sources commercially available from Veeco
Instruments Inc. (Woodbury, N.Y.), which have beam energies between
100 eV and 1800 eV and beam currents up to 30 mA/linear cm. The
beam 42 in these linear ion sources 90 has a high aspect ratio such
that the cross-sectional profile of the beam 42 is larger in one
dimension than the other. The substrate 44 is translated in a
single dimension through the beam 42. In these instances, the
cross-sectional profile of the beam 42 has one dimension that is
larger than one dimension of the substrate 44. As a result, in one
or more passes through the beam 42, the substrate 44 receives a
uniform dose of ions.
[0077] The substrate 44 is impinged by energetic particles in the
beam 42 from source 90 across a treatment area or zone 94 defined
in the plane of substrate 44 as the substrate 44 is moved
back-and-forth and optionally periodically rotated as described
herein. Treatment zone 94 may be considered to extend over the
entire region across which the moving substrate 44 is exposed to
the beam 42 during each scan. The substantially uniform portion of
the source 90 is positioned over treatment zone 94 such that the
flux distribution of the source 90 over the treatment zone 94 is
substantially uniform along the major dimension 89 of the source
90. The capability of the source 90 to emit the beam 42 of
energetic particles with a substantially uniform flux distribution
along at least a portion of the major dimension 89 eliminates the
need to provide shield 52 for beam confinement, shaping, and
collimation. Alternatively, the translation stage 58 of fixture 55
may be adapted to translate the substrate 44 in an arc relative to
the major dimension 89 of the source 90, as opposed to the
illustrated back-and-forth movement.
[0078] The energetic particles in beam 42 emitted by source 90 have
a substantially uniform incident angle, measured relative to a
surface normal of the substrate 44 or relative to the plane of the
substrate 44, at the substrate 44 over the entire treatment zone 94
and across the major dimension 89. This is possible because source
90 emits energetic particles with parallel or substantially
parallel trajectories and a small beam divergence. The distance
between the substrate 22 and source 90 is optimized in view of the
source strength and beam divergence. Source 90 may include a flat
optical grid or dished grid optics to enhance collimation for
providing the parallel or substantially parallel trajectories and
small beam divergence, as understood by a person having ordinary
skill in the art. The shaped beam 42 from source 90 defines the
treatment zone 94.
[0079] The substrate 44 is scanned through the treatment zone 94,
in the various manners described herein, to expose the features 66
and the substrate 44 surrounding features 66 to the energetic
particles in beam 42. When the substrate 44 is outside of the
treatment zone 94, the substrate 44 is either not exposed to beam
42 or exposed to only a negligible energetic particle dose. The
portion of the energetic particle flux distribution outside of the
treatment zone 94 is typically less than about 10 percent of the
total ion flux distribution.
[0080] The substrate 44 may be rotated or indexed in its plane
about its azimuthal axis 45 between consecutive scans through the
treatment zone 94. More specifically, the substrate 44 may be
rotated or indexed about its azimuthal axis 45 at or near the end
of the range of motion (i.e., linear stroke) of the substrate 44
because the features 66 are asymmetrical (e.g., elongated heads).
If fixture 55 is operating in this manner, the rotational stage 56
rotates or indexes the substrate 44 about its azimuthal axis 45 by
180.degree. at a location outside of the treatment zone 94 and
between consecutive scans through treatment zone 94, as described
herein. This aligns the features 66 on substrate 44 relative to the
major dimension 89 of source 90 and, consequently, beam 42 as the
substrate 44 is scanned either linearly or in an arc through the
treatment zone 94. After processing is completed, the surface
treatment of width 72 on substrate 44 adjacent to the base of
sidewall 68 and the similar width 74 (FIGS. 6A, 10A) is
substantially uniform because of the changes in the feature
alignment by rotation outside of treatment zone 94. A processor 95
is provided that controls the operation of the rotational stage 56
and the translation stage 58 such that the substrate 44 is
translated through the treatment zone 94 with a fixed angular
orientation of the translation stage 58 about the azimuthal axis
45.
[0081] The surface treatment of substrate 44 is also substantially
uniform because of the substantially uniform flux distribution of
beam 42 along the major dimension 89 of the source 90. Any
non-uniformity in the flux distribution of the beam 42 in the minor
dimension 91 is averaged by the movement of the substrate 44
through the treatment zone 94.
[0082] The source 90 may be moved among various positions defined
generally along an arc 92, which is effective for adjusting the
average incident angle of the energetic particles in beam 42 in
treatment zone 94 in a direction parallel to the direction of
motion of substrate 44 and the minor dimension 91 of source 90. To
that end, opposite ends of the source 90 are each supported on a
corresponding one of a pair of arms, of which arm 96 is visible in
FIG. 16, that may be pivoted relative to the linear path of the
substrate 44. The source 90 is stationary during substrate
processing. A plasma bridge neutralizer (not shown) may be
associated with the source 90 and may be pivoted along with the
source 90.
[0083] The substrate 44 may need to be moved large distances to
completely pass the substrate 44 out of the beam 42 at each end of
the range of movement. The distance that the substrate 44 must move
to be completely removed from the beam 42 may be affected by the
angle between the beam direction and the plane of substrate
motion.
[0084] With reference to FIG. 17 in which like reference numerals
refer to like features in FIGS. 16, 16A, and 16B and in accordance
with an alternative embodiment of the present invention, a fixture
100 is adapted to hold and support the substrate 44 for movement
relative to the source 90, which includes a plasma bridge
neutralizer 121. The fixture 100 is supported at one end of an arm
98 extending from a linear actuator 102 that moves the fixture 100
in a linearly and bi-directionally (i.e., reversibly) or back and
forth (i.e., reciprocating) manner along an axis 101 relative to
the source 90. The linear actuator 102 may include a drive
mechanism 104 having a driven output 110 coupled with the arm 98
and a pair of stationary rails 105, 106 to which the drive
mechanism 104 and arm 98 are coupled for movement by bearings 107,
108, respectively. A bellows 112 supplies a vacuum-tight connection
with the vacuum chamber 46 and is compliant with the bi-directional
movement of the linear actuator 102.
[0085] The bi-directional motion of fixture 100 may be used to
repetitively scan the substrate 44 through the treatment zone 94,
as described above with regard to fixture 55 (FIGS. 3, 3A). In this
operational mode, the linear actuator 102 translates the substrate
44 in a direction approximately orthogonal to the major dimension
89 (FIG. 16B) of source 90. After processing is concluded, the
surface treatment of width 72 on substrate 44 adjacent to the base
of sidewall 68 and the similar width 74 (FIGS. 6A, 10A) is
substantially uniform because of the changes in the feature
alignment by rotation outside of treatment zone 94.
[0086] With reference to FIGS. 17 and 18, the fixture 100 includes
a rotational stage 120 adapted to rotate the substrate 44 in at
least one rotational sense about an azimuthal axis 122 of the
rotational stage 120. Rotational stage 120 operates in a manner
similar to rotational stage 56 (FIGS. 3, 3A) of fixture 55.
Rotation of the substrate 44 about the azimuthal axis 122, when the
substrate 44 is outside of the treatment zone 94, changes the
orientation of features 66 (FIG. 5A) on the substrate 44 relative
to the direction of the beam 42. The azimuthal axis of the
rotational stage 120 coincides with the azimuthal axis 45 of
substrate 44. The movements of rotational stage 120 and the arm 98
as driven by the linear actuator 102 are mutually independent so
that the substrate 44 may be translated without rotation and,
conversely, the substrate 44 may be rotated without
translation.
[0087] The rotational stage 120 of the fixture 100 is pivotally
mounted by a gimbal or pivoting coupling 124 with the arm 98 of the
linear actuator 102. The pivoting coupling 124 provides the fixture
100 with the ability to angularly orient the azimuthal axis 122 of
the rotational stage 120 and, hence, the substrate 44 about an axis
117 that is substantially orthogonal to axis 101. Tilting the
azimuthal axis 122 of the rotational stage 120 changes the incident
angle of the beam 42 relative to the azimuthal axis 122 of the
rotational stage 120. The ability to tilt the substrate 44
effectively shortens the stroke of the linear actuator 102 because
the substrate 44 may be translated linearly over a shorter distance
to place the substrate 44 outside of the treatment zone 94. The
tilting of the rotational stage 120 about the axis 117 is
substantially parallel to the major dimension 89 of source 90,
which operates to maintain the effective substantial uniformity of
the beam 42 at the substrate 44.
[0088] With reference to FIG. 19 in which like reference numerals
refer to like features in FIG. 18 and in an alternative embodiment
of the present invention, a fixture 100a is depicted that is
similar to fixture 100. The rotational stage 120 of fixture 100a is
supported on a base 130 that permits motion of the rotational stage
120 in a plane that is perpendicular to the azimuthal axis 122. To
that end, fixture 100 is provided with a mechanism that permits
bi-directional translation of the rotational stage 120 relative to
base 130 in a direction toward and away from the source 90 when the
azimuthal axis 122 is inclined relative to the direction of beam
42. This additional degree of freedom is indicated diagrammatically
in FIG. 19 by the double-headed arrow 132.
[0089] Embodiments of the present invention provide improvements in
treatment uniformity, feature dimension control, and symmetry of
the treatment properties for symmetrical features on a substrate as
found in various data storage and semiconductor structures.
Embodiments of the present invention are particularly advantageous
for processing large surface-area substrates, such as 300 mm or
larger wafers. In particular, embodiments of the present invention
facilitate ion beam etching of (or deposition on) such substrates
with treatment uniformity, feature dimension control, and symmetry
in treatment properties for symmetrical surface features.
[0090] With reference to FIG. 20 in which like reference numerals
refer to like features in FIGS. 1-19 and in an alternative
embodiment of the present invention, a multiple-stage platform or
fixture 134 is used in conjunction with processing apparatus 40
(FIG. 3) to hold the substrate 44 with three-dimensional features
66 in place and to control its position with three controlled axes
of motion. The fixture 134 includes a rotational stage 136, a tilt
stage 138, and a translation stage 140 adapted to translate the
rotational and tilt stages 136, 138 relative to the ion source 90
and, in particular, to translate the substrate 44 substantially
perpendicular to the major dimension 89 (FIG. 16B) of ion source
90. The movements of the substrate 44 by the stages 136, 138, 140
are mutually independent.
[0091] The rotational stage 136 is adapted to rotate the substrate
44 in at least one rotational sense about an azimuthal axis 142 of
stage 136, which coincides generally with the azimuthal axis 45 of
substrate 44. A rotary actuator built into the rotational stage 136
is controlled to provide indexed rotation of the substrate 44 and a
portion of the rotational stage 136 physically holding the
substrate 44 about the azimuthal axis 142. The tilt stage 138 is
adapted to tilt the rotational stage 136 about a tilt axis 144.
Another rotary actuator built into the tilt stage 138 is controlled
to tilt the tilt stage 138 and substrate 44 about the tilt axis
144, as indicated diagrammatically by double headed arrow 146.
[0092] The movement of the translation stage 140 is linear and
bi-directional (i.e., reversible) relative to the major dimension
89 (FIG. 16B) of ion source 90, as indicated diagrammatically by
double headed arrow 145. In particular, the translation stage 140
translates the substrate 44 in a direction approximately orthogonal
to the major dimension 89 (FIG. 16B) of ion source 90. In the
representative embodiment, the translation stage 140 includes a
pair of adjacent, parallel rail guides 147, 148 and a carriage 149
coupled with the rail guides 147, 148 for guided linear translation
relative to the rail guides 147, 148. A bi-directional linear
actuator (not shown) is coupled with the carriage 149 and is
operated to cause the carriage 149 to translate relative to the
rail guides 147, 148. The range of travel for the translation stage
140, when the fixture 134 is operated to adjust the position of the
substrate 44, is selected such that substrate 44 is positioned in
parking areas 150, 152 on opposite sides of the treatment zone 94
that are out of the beam 42.
[0093] Indexing the substrate 44 by rotation about the azimuthal
axis 142 changes the orientation of features, such as features 66
(FIG. 5A), on the substrate 44 relative to the direction of the
beam 42 (FIGS. 3, 3A). The change in angular orientation may differ
from 180.degree. if asymmetry perpendicular to the scan direction
is important, as described herein below.
[0094] In an alternative embodiment, the translation stage 140 may
be replaced by a planetary stage (not shown) that revolves the
substrate 44 and stages 136, 138 about a relatively large radius of
curvature in a plane parallel to the substrate plane. The radius of
the curve traced by the substrate 44, when moved by the planetary
stage, is large enough to be approximately linear over the minor
dimension 64 of aperture 54. Preferably, the center of the source
50 and aperture 54, and the arc traced by the center of fixture 134
are in a cylindrical plane with a radius of curvature exceeding the
distance between the source 50 and aperture 54.
[0095] In use and with reference to FIGS. 20-22, the translation
stage 140 is operated to move the substrate 44 to a position within
the parking area 150 and the tilt stage 138 is operated to pivot
the rotational stage 136 about the tilt axis 144 to set a tilt
angle for the substrate 44 relative to the direction of the beam 42
from linear ion source 90. The tilt angle sets an angle of
incidence for the beam 42. The tilt axis 144 is substantially
parallel to the major dimension 89 of the energetic particle beam
42.
[0096] While within the one of the parking areas 150, 152, the
initial angular orientation of the rotational stage 136 about the
azimuthal axis 142 is captured and stored. The initial angular
orientation of the rotational stage 136 and substrate 44 is
indicated by arrow 154. The translation stage 140 is operated to
move the substrate 44 into and through the beam 42 (i.e., through
the treatment zone 94), which exposes the substrate 44 and features
66 to the beam 42, to parking area 152 and back to parking area 150
to execute a single scan. While the substrate 44 is sitting in the
parking area 150 and as shown in FIG. 21, the rotational stage 136
is operated to index the substrate 44 about azimuthal axis 142 with
a fixed, incremental angular arc relative to the initial angular
orientation. The indexing of substrate 44 is reflected by the
counterclockwise reorientation of arrow 154 in comparison with the
angular orientation of arrow 154 in FIG. 20. The tilt angle is
typically not changed, which means that the incident angle of the
beam 42 is unchanged during the upcoming scan through the beam
42.
[0097] The translation stage 140 is again operated to move the
substrate 44 through the beam 42 and back to the parking area 150
in another scan. Successive index and scan cycles are executed to
process the substrate 44 with the beam 42. For example, another
scan cycle is shown in FIG. 22 in which the substrate 44 has been
rotated by another angular increment relative to the angular
orientation in FIG. 22. The sequence shown in FIGS. 20-22 reflects
an angular increment of 90.degree. for indexing the substrate 44
about the azimuthal axis 142 between consecutive scans through the
beam 42.
[0098] This method may be used to etch round or rectangular
photoresist or hard mask features 66 on a substrate 44 to provide
critical dimensions (i.e., shape) control of defined features 66
over the substrate 44. During each sliding pass, the substrate 44
is oriented in the beam 42. The resulting etch profile of the
sidewalls of the features 66 can be controlled based on the
orientation of the beam 42 with respect to the substrate
44--incidence angle and azimuthal angle. The substrate 44
repeatedly can be parked in parking area 150, indexed to a
different angular orientation about the azimuthal axis 142, and
then slid under the beam 42 for further etching at a different
orientation condition. Using this method, the shape of the
sidewall(s) of the features 66 and redepostion of the etched
material on the features 66 can be controlled by multi-step
processing.
[0099] Multiple index/scan cycles are envisioned by the various
embodiments of the invention. The number of selected indexes of
substrate 44 about the azimuthal axis 142 may be two different
angular orientations (e.g., 0.degree. and 180.degree.), four
different angular orientations (0.degree., 90.degree., 180.degree.,
270.degree.), or even more different angular orientations within a
full substrate rotation of 360.degree.. For example, a 30.degree.
to 60.degree. angular increment may be selected for the indexing of
substrate 44. The angular increment for each change in angular
orientation is typically an integer fraction of 360.degree. and, in
one embodiment, is less than an integer fraction of one-half. When
the substrate 44 is indexed about the azimuthal axis 142, such as
from 0.degree. to 180.degree. as shown between pass number 1 in
FIG. 21 and pass number 3 in FIG. 23, exposures of the features 66
to the beam 42 can be equalized.
[0100] For features 66 having two critical perpendicular dimensions
(i.e., "square" features), four scans with orientations about the
azimuthal axis 142 that differ by 90.degree. may be sufficient for
processing the features 66 on the substrate 44. For features 66
having critical dimensions in every direction (i.e., "round"
features), scans may be used that include with many different
angular orientations about the azimuthal axis 142.
[0101] The use of a linear ion source 90 allows for full beam
exposure of relatively large substrates (i.e., 300 mm substrates)
while keeping the grids of the ion source 90 in proper position for
consistent beam optics and without the use of spacers. A lack of
spacers in turn promotes improved spatial uniformity of the beam
42.
[0102] The multiple-stage fixture 134 and its method of use provide
enhanced feature geometry control, diminished inboard/outboard
effects, and are compatible with 200 mm (8 inch) and 300 mm (12
inch) wafer processing, as well as the processing of wafers or
substrates with other dimensions.
[0103] The beam from ion source 90 is used to create a highly
collimated, uniform beam 42 for etching of material off substrate
44. However, a person having ordinary skill in the art will
understand that the ion source 90 may be used to deposit material
on the substrate 22. For example, deposition can be performed in
analogy to an etch process using a linear magnetron as a source of
particles, or a linear ion beam source as a source of an ion
beam.
[0104] With reference to FIG. 23 in which like reference numerals
refer to like features in FIGS. 20-22 and in accordance with an
alternative embodiment of the invention, ion source 90 may be
replaced with the ion source 50 and the shield 52 that includes
aperture 54. In this embodiment, the movement of the translation
stage 140 is linear and bi-directional (i.e., reversible) relative
to the aperture 54 in shield 52. In particular, the translation
stage 140 translates the substrate 44 in a direction approximately
orthogonal to the major dimension 65 (FIG. 4A) of aperture 54 in
shield 52. The range of travel for the translation stage 140 is
selected such that substrate 44 is positioned in flux-blocked
positions on opposite sides of aperture 54 in which a portion of
the shield 52 is interposed between the substrate 44 and source 50.
A person having ordinary skill in the art will also understand that
the method of exposing the substrate 44 to the beam 42 illustrated
in FIGS. 20-22 may be practiced using the embodiment of the
invention depicted in FIG. 23, which also presents a rectangular
source of collimated particles in the beam 42 to the substrate
44.
[0105] While the invention has been illustrated by a description of
various embodiments and while these embodiments have been described
in considerable detail, it is not the intention of the applicant to
restrict or in any way limit the scope of the appended claims to
such detail. Additional advantages and modifications will readily
appear to those skilled in the art. The invention in its broader
aspects is therefore not limited to the specific details,
representative methods, and illustrative examples shown and
described. Accordingly, departures may be made from such details
without departing from the spirit or scope of applicants' general
inventive concept.
* * * * *