U.S. patent application number 09/128343 was filed with the patent office on 2001-12-20 for rotating belt wafer edge cleaning apparatus.
Invention is credited to BERMAN, ILAN, MOINPOUR, MANSOUR, PARK, YOUNG C..
Application Number | 20010052159 09/128343 |
Document ID | / |
Family ID | 25110471 |
Filed Date | 2001-12-20 |
United States Patent
Application |
20010052159 |
Kind Code |
A1 |
MOINPOUR, MANSOUR ; et
al. |
December 20, 2001 |
ROTATING BELT WAFER EDGE CLEANING APPARATUS
Abstract
An apparatus for cleaning edges and/or bevel areas of
substrates. In one embodiment, the present invention provides a
cleaning mechanism that cleans particles off the edge of the wafer
based upon friction at the contact point between the wafer and a
rotating belt.
Inventors: |
MOINPOUR, MANSOUR;
(CUPERTINO, CA) ; BERMAN, ILAN; (SUNNYVALE,
CA) ; PARK, YOUNG C.; (MOUNTAIN VIEW, CA) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN
12400 WILSHIRE BOULEVARD
7TH FLOOR
LOS ANGELES
CA
90025
|
Family ID: |
25110471 |
Appl. No.: |
09/128343 |
Filed: |
August 3, 1998 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09128343 |
Aug 3, 1998 |
|
|
|
08777518 |
Dec 30, 1996 |
|
|
|
5868857 |
|
|
|
|
Current U.S.
Class: |
15/102 ; 134/6;
134/902; 15/88.2; 15/97.1; 451/44 |
Current CPC
Class: |
H01L 21/67028 20130101;
B24B 9/065 20130101; B08B 1/008 20130101; Y10S 134/902 20130101;
B24B 21/00 20130101; B24B 37/04 20130101 |
Class at
Publication: |
15/102 ; 15/97.1;
134/6; 451/44; 134/902; 15/88.2 |
International
Class: |
B08B 007/00; A47L
001/02 |
Claims
We claim:
1. An apparatus for cleaning an edge of a wafer comprising: a belt
having an inner surface and an outer surface; a first roller having
an outer surface and a first axis of rotation, said outer surface
of said first roller engaging said inner surface of said belt; a
second roller having an outer surface and a second axis of
rotation, said outer surface of said second roller engaging said
inner surface of said belt, said second axis of rotation being
fixed in relationship to said first axis of rotation; a motor
coupled to said first roller for rotating said belt about said
first and second rollers; and means for positioning said belt
against said edge.
2. The apparatus of claim 1 wherein said positioning means
comprises a pivoting mechanism for pivoting said first roller about
a pivot point located at said second axis to position said belt
against said edge.
3. The apparatus of claim 1 wherein said positioning means
comprises a movable carrier, said first and second rollers being
attached to said carrier.
4. The apparatus of claim 1 wherein said wafer is rotated about a
third axis of rotation.
5. The apparatus of claim 4 wherein said first and second axes of
rotation are perpendicular to said third axis of rotation.
6. The apparatus of claim 4 wherein said first and second axes of
rotation are oblique to said third axis of rotation.
7. The apparatus of claim 1 wherein said motor comprises a variable
speed motor.
8. The apparatus of claim 1 wherein said belt comprises poly vinyl
alcohol.
9. The apparatus of claim 1 wherein said belt comprises nylon.
10. The apparatus of claim 1 wherein said belt comprises a
combination of abrasive materials.
11. The apparatus of claim 1 further comprising a water jet
propelling water at a contact area between said belt and said wafer
edge.
12. The apparatus of claim 1 further comprising a jet propelling at
least one chemical at a contact area between said belt and said
wafer edge.
13. An apparatus for cleaning an edge of a wafer comprising: a belt
having an inner surface and an outer surface; a first roller having
an outer surface and a first axis of rotation, said outer surface
of said first roller engaging said inner surface of said belt, said
first roller being attached to a carrier at a first point; a second
roller having an cuter surface and a second axis of rotation, said
outer surface of said second roller engaging said inner surface of
said belt, said second roller being attached to said carrier at a
second point; said carrier being movable to engage and disengage
said belt with said edge; and a motor coupled to said first roller
for rotating said belt about said first and second rollers.
14. The apparatus of claim 13 wherein said belt comprises a
combination of abrasive materials.
15. The apparatus of claim 13 further comprising a water jet
propelling water at a contact area between said belt and said wafer
edge.
16. The apparatus of claim 13 further comprising a jet propelling
at least one chemical at a contact area between said belt and said
wafer edge.
17. The apparatus of claim 13 wherein said wafer is rotated about a
third axis of rotation.
18. The apparatus of claim 17 wherein said first and second axes of
rotation are oblique to said third axis of rotation.
19. The apparatus of claim 13 wherein said motor comprises a
variable speed motor.
20. An apparatus for cleaning an edge of a wafer comprising: a
first roller having a first axis of rotation; a second roller
having a second axis of rotation; a third roller having a third
axis of rotation, said third axis of rotation being fixed in
relationship to said first and second axes of rotation; an abrasive
belt rotatably coupled to said first, second and third rollers; a
motor coupled to said third roller to rotate said abrasive belt
about said first, second and third rollers; and a pivoting
mechanism for pivoting said second and third rollers about said a
pivot point located at said third axis to engage and disengage said
abrasive belt with said edge.
21. The apparatus of claim 20 further comprising means for rotating
said wafer about a fourth axis of rotation.
22. The apparatus of claim 21 wherein said first, second and third
axes of rotation are parallel and wherein said first, second and
third axes of rotation are oblique to said fourth axis of
rotation.
23. The apparatus of claim 20 wherein said motor comprises a
variable speed motor.
24. The apparatus of claim 20 wherein said abrasive belt comprises
a combination of abrasive materials.
25. The apparatus of claim 20 further comprising a water jet
propelling water at a contact area between said abrasive belt and
said wafer edge.
26. The apparatus of claim 20 further comprising a jet propelling
at least one chemical at a contact area between said abrasive belt
and said wafer edge.
27. A method for cleaning the edge of a wafer, said method
comprising the steps of: rotating an abrasive belt along a first,
second and third roller having a first second and third axis of
rotation, respectively; and pivoting said second and third rollers
in relationship to said first roller to engage said abrasive belt
with said wafer edge.
28. The method of claim 27 further comprising the step of
delivering a cleaning fluid to a contact area between said belt and
said wafer edge.
29. The method of claim 27 wherein said abrasive belt comprises a
combination of abrasive materials.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of semiconductor
wafer processing; more particularly, the present invention relates
to cleaning the edges and/or bevel areas of semiconductor
wafers.
BACKGROUND OF THE INVENTION
[0002] Semiconductor manufacturers use semiconductor wafers as the
base for manufacturing integrated circuits. In one step of the
manufacturing process, the wafers are put through chemical
mechanical polishing (CMP). CMP is becoming the main planarization
technology for both dielectric and metal layers. For the CMP of
dielectric layers, such as BPSG, BPTEOS, and PECVD Oxides (often
referred to as the ILD0, ILD1, ILD2 . . . layers, respectively), a
fumed silica-based slurry is normally used. Other slurries, such as
dispersed silica, fumed or dispersed allumina, are also being used
for CMP of both oxides and metals (such as tungsten (W), copper
(Cu), aluminum (al), and titanium (Ti)). When the CMP process is
completed, the wafers' surfaces are covered in particles, referred
to as a slurry residue. At later steps in the process flow, some of
this slurry residue is redistributed across the front of the wafer,
thereby resulting in a loss in die yield and/or device performance.
To prevent the slurry redistribution, all surfaces of a wafer must
be free of contamination.
[0003] Different post CMP cleaning methods have been introduced in
the last few years. These include cleaning the wafers in wet
stations using conventional wet cleaning methods, such as SC1, HF
and megasonic cleaning. Other cleaning methods in use are based on
scrubbing wafers with brushes of various kinds and configurations
using DI water or a combination of DI with chemicals such as
Ammonia and Citric acid.
[0004] One system used to remove wafer contaminants is a double
sided scrubber. In a double sided scrubber, a semiconductor wafer
is scrubbed simultaneously on both sides by brushes. Since the
wafer is being scrubbed simultaneously on both sides by the
brushes, there must be a way of holding the wafer in place and
rotating the wafer so the entire surface of the wafer is cleaned. A
mechanism used for this purpose is commonly referred to as a
roller.
[0005] Today, double sided scrubbers are usually automated and
comprise a conveyor type mechanism, rollers, and brushes. In
general, the wafer lies flat on the conveyor mechanism and the
conveyor mechanism moves the wafer into the brushes. While being
scrubbed, the wafer is supported (or held horizontally) by the
conveyor mechanism, brushes, rollers, or a combination thereof.
FIG. 1 illustrates a conventional double sided wafer scrubber.
Referring to FIG. 1, a wafer 102 is being scrubbed by brushes, one
of which is shown as brush 110 and the other being beneath wafer
102 and directly below brush 110. Rollers 108 rotate wafer 102 so
the entire wafer surface may be cleaned. Each of brushes 110 is
rotated about its central axis by a motor 106. The rotary motion of
rollers 108 is then transferred to wafer 102 when the edge of each
of rollers 109 comes into contact with the outer edge of wafer
102.
[0006] Although conventional brush cleaning systems can effectively
clean the front and backs of semiconductor substrates, such systems
fail to provide a sufficient amount of mechanical energy at the
edge/bevel to remove contamination.
[0007] The present invention provides an apparatus that cleans the
edge of substrates, including the bevel area when present.
SUMMARY OF THE INVENTION
[0008] An apparatus for cleaning edges and/or bevel areas of
substrates is described. In one embodiment, the present invention
provides a cleaning mechanism that cleans particles off the edge of
the wafer based upon friction at the contact point between the
wafer and a rotating belt.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will be understood more fully from the
detailed description given below and from the accompanying drawings
of various embodiments of the invention, which, however, should not
be taken to limit the invention to the specific embodiments, but
are for explanation and understanding only.
[0010] FIG. 1 illustrates a prior art double sided wafer
scrubber.
[0011] FIG. 2A illustrates a side view of a rotating belt edge
cleaning apparatus in one embodiment of the present invention with
the rotating belt rotated away from the edge of a wafer.
[0012] FIG. 2B illustrates a side view of the rotating belt edge
cleaning apparatus of FIG. 2A with the rotating belt engaged
against the edge of the wafer.
[0013] FIG. 3A illustrates a rotating belt edge cleaning apparatus
attached to a carrier that moves to engage or disengage the
rotating belt from the edge of a wafer.
[0014] FIG. 3B illustrates another embodiment of the present
invention.
[0015] FIG. 4A illustrates a side view of a rotating belt edge
cleaning apparatus in another embodiment of the present invention
with the rotating belt rotated away from the edge of a wafer.
[0016] FIG. 4B illustrates a side view of the rotating belt edge
cleaning mechanism of FIG. 4A showing the rotational movement of
the mechanism as it engages the edge of the wafer.
[0017] FIG. 5A illustrates a perspective view of a double-sided
edge scrubber system that includes a rotating belt edge cleaning
apparatus.
[0018] FIG. 5B illustrates a perspective view of the double-sided
scrubber of FIG. 5A having a jet spray nozzle for delivering a
cleaning fluid to the surface of the wafer.
[0019] FIG. 6 illustrates a perspective view of a double-sided edge
scrubber system having a plurality of rotating belt edge cleaning
apparatus.
DETAILED DESCRIPTION
[0020] An apparatus for cleaning edges of contaminated substrates
is described. The cleaning process may be used in double sided
scrubber systems or other systems, such as, for instance, chemical
mechanical polishing systems or flat panel display manufacturing
systems. In the following description, numerous specific details
are set forth such as rotation speeds, chemicals, pressures, etc.,
in order to provide a thorough understanding of the present
invention. It will be apparent, however, to one skilled in the art
that the present invention may be practiced without these specific
details. In other instances, well-known components, structures and
techniques have not been shown in detail in order to avoid
obscuring the present invention.
[0021] The present invention provides a method and apparatus that
cleans the edge of substrates, including the bevel area when
present. In the present invention, particles are removed from the
edge and/or bevel area (or any other surface sloping from the edge
to the top or bottom of the substrate) using an edge scrubbing
mechanism that may be incorporated into a scrubber tool.
[0022] Although the present invention is described in conjunction
with the scrubbing of a wafer, it will be appreciated that any
similarly shaped, i.e. generally flat, substrate, may be processed
by the methods and apparatuses of the present invention. Further,
it will be appreciated that reference to a wafer or substrate may
include a bare or pure semiconductor substrate, with or without
doping, a semiconductor substrate with epitaxial layers, a
semiconductor substrate incorporating one or more device layers at
any stage of processing, other types of substrates incorporating
one or more semiconductor layers such as substrates having
semiconductor on insulator (SOI) devices, two or multiple
substrates bonded to each other, or substrates for processing other
apparatuses and devices such as flat panel displays, multichip
modules, etc.
[0023] FIGS. 2A and 2B illustrate a wafer edge cleaning device in
one embodiment of the present invention. As shown, the edge 203 of
a rotating wafer 202 is cleaned by positioning a rotating belt 206
adjacent to the wafer edge 203 such that an abrasive outer surface
208 of the belt slides across the edge surface. The frictional
forces generated between the outer surface 208 of belt 206 and edge
203 result in the removal of contaminates residing at the contact
points at the belt/edge interface. The relative velocity difference
between belt 206 and wafer 202 also contributes to the removal of
particles from the edge surface. The inner surface 209 of belt 206
is acted upon by the outer surfaces 214 and 216 of rollers 210 and
212, respectively. Each of rollers 210 and 212 have an axis of
rotation 218 and 220, respectively. The location of axis 218 is
fixed, whereas axis 220 is permitted to move along a path 222 as
roller 220 is pivoted in an upward direction about fixed axis 218.
A motor (not shown) is coupled to roller 210 to provide rotational
movement to the roller. The resistance between the outer surface
214 of roller 210 and inner surface 209 of belt imparts the
rotational movement of roller 210 to belt 206.
[0024] As shown in FIGS. 2A and 2B, the edge 203 of wafer 202 is
cleaned by placing the wafer adjacent edge cleaning apparatus 200
and pivoting roller 220 in an upward direction about axis 218 so
that the outer surface 208 of belt 206 contacts the edge 203 of
wafer 202. In one embodiment, belt 206 comprises an elastomer
material that is stretched to fit over rollers 210 and 212.
Alternatively, roller 220 may be slidably mounted. In such an
embodiment, belt 206 is placed around the outer surfaces of the
rollers and the tension of belt 206 is adjusted by slidably
adjusting the position of roller 220. The outer surface 208 of belt
206 is textured such that sufficient frictional forces are produced
at the belt/wafer edge interface to remove contaminates from the
wafer edge during cleaning. The surface roughness of surface 208 is
selected to facilitate the removal of unwanted particles from the
wafer's edge without damaging the wafer itself. In some instances,
the texture of belt 206 may vary along the circumference of the
belt. In this manner, one portion of the belt may be used for
removing one type of contaminate while another portion of the belt
may be used to remove another type of contaminate.
[0025] FIG. 3A illustrates another method of cleaning the edge of a
wafer. As shown in FIG. 3A, rollers 210 and 212 are attached to
support structure 300 at axis 218 and 220. In lieu of using a
pivoting action to bring the belt 206 into contact with wafer edge
203, the lateral movement of support structure 300 is used to
position the edge cleaning apparatus. In addition, rollers 210 and
212 may be spring mounted to structure 300 by springs 310 and 312.
By spring mounting rollers 210 and 212 to structure 300, the amount
of force exerted upon edge 203 by belt 206 is more accurately
controlled.
[0026] In one embodiment, the width of belt 206 is approximately
0.5 inches. The outer surface 208 of belt 206 may comprise PVA,
nylon, or polyurethane.
[0027] With reference to FIGS. 4A and 4B, a belt-type edge cleaning
apparatus 400 in another embodiment of the present invention is
shown. The belt-type edge cleaning apparatus 400 is similar to the
edge cleaning apparatus 200 of FIGS. 2A and 2B, however, apparatus
400 includes three rollers instead of two. Edge cleaning apparatus
400 includes a belt 406 having an inner surface 409 and an outer
surface 408. Belt 406 is held in position and rotated by three
rollers 410-412. Each of rollers 410-412 has an axis of rotation
416, 417 and 418, respectively. Axis 416 is stationary, whereas
axes 417 and 418 are permitted to move generally in the direction
indicated in FIG. 4B as the belt assembly is pivoted upward about
axis 416. A motor (not shown) is coupled to roller 410 to provide
rotational movement to belt 406. As shown in FIG. 4B, the edge 403
of wafer 402 is cleaned by placing the edge of wafer 402 in
proximity to rotating belt edge cleaning apparatus 400 and pivoting
apparatus 400 upward about stationary axis 416 to engage the outer
surface 408 of belt 406 against wafer edge 403.
[0028] Turning now to FIG. 5A, edge cleaning apparatus 500 is shown
incorporated into a double sided scrubber 500. As illustrated in
FIG. 5A, wafer 502 is cleaned by a top-side brush 504 and a
bottom-side brush 506 as it moves through the scrubber (from left
to right). Edge rollers 510 are provided to rotate wafer 502 in a
counter-clockwise direction as indicated. Motors 512 are coupled to
edge rollers 510 to provide rotational movement to the wafer. A
rotating belt edge cleaning apparatus 600 is provided along side
wafer 502. As wafer 502 moves through scrubber 500, edge cleaning
apparatus 600 is rotated upward such that belt 606 is pressed
against wafer edge 503. Hence, as wafer 502 moves through the
double sided scrubber system, top-side and bottom-side brushes 504
and 506 clean the top and bottom surfaces of wafer 502, while
rotating belt 606 removes contaminates along the edge and bevel
areas of the wafer. A motor 602 is coupled to stationary roller 604
to provide rotational movement to the edge cleaning belt 601.
[0029] One benefit of the present invention lies in the combined
use of top-side and bottom-side brushes 504 and 506 and edge
cleaning apparatus 600 to clean all of the exposed areas of the
wafer which may be contaminated with slurry particles. This
includes the top surface, bottom surface and the edge/bevel areas
of the wafer. Another benefit of the present invention is that the
rotating edge cleaning apparatus 600 may be integrated into current
double-side scrubber mechanism with minimal design changes to the
scrubber system. In addition, since the rotation of the edge
cleaning apparatus is independent of the wafer rotation, the
relative velocity of the edge cleaning apparatus may be varied
without affecting the cleaning of the top-side and bottom-side
surfaces of the wafer.
[0030] To further facilitate particle removal, a water jet 535 may
be used to propel water into or near the point of contact between
rotating belt 606 and wafer edge 503, as shown in FIG. 5B. The
water jet may be positioned such that the direction of water flows
from a plane aligned with the rotational axis of the wafer and
contact points between the wafer and the edge cleaning apparatus.
In such a case, the water may simply carry the particles away that
are removed from the wafer by the edge cleaning apparatus or may,
if at sufficient pressure, cause removal of particles by itself.
Note that the water jet is held in place by a support structure
which is well-known in the art. In one embodiment, the water jet is
held in place above the wafer. Such a jet may be as simple as a
barbed coupling with reducing barb to increase the velocity of the
created stream. In one embodiment, the barbed coupling is 1/8" to
{fraction (1/16)}" in diameter. In another embodiment, the jet may
include a nozzle that produces a fanned, knife edge pattern. Water
jets are well-known in the art. Note also that jets that spray
other chemicals may be used, instead of water, to facilitate
particle removal.
[0031] Rotating belt 606 may be cleaned occasionally to remove
build-up of particles. In one embodiment, the scrubber may flow DI
water or a combination of DI water and a chemical such as
NH.sub.4OH or NH.sub.4OH/H.sub.2O.sub.2 mixture through itself. In
an alternate embodiment, the edge cleaning apparatus may be cleaned
by spraying DI or a combination of DI and a chemical such as
NH.sub.4OH or NH.sub.4OH/H.sub.2O.sub.2 onto belt 606 during wafer
cleaning to reduce particle build-up.
[0032] In one embodiment, a splash shield (not shown) may be
provided around the rotating belt edge cleaning apparatus 600 to
minimize the dispersion of water, chemicals and contaminates from
the surface of belt 606 to other areas of the scrubber system.
[0033] Another benefit of the present invention lies in the ability
to use different types of materials to facilitate the cleaning of a
variety of contaminates from the edge or bevel area of a wafer.
Materials of different textures may be used within a single belt,
or may be incorporated into a plurality of rotating belt edge
cleaning devices. In this manner, one material may be used for
removing one type of contaminate while another material may be used
to remove another type of contaminate. FIG. 6 illustrates an
embodiment of the present invention wherein a plurality of rotating
belt edge cleaning apparatus are used to sequentially clean the an
edge 703 of wafer 702. As wafer 702 rotates, a first rotating belt
edge cleaning apparatus 710 containing a first belt 712 of a given
texture that cleans particles from edge. The edge of the wafer is
then rotated toward a second rotating belt edge cleaning apparatus
714. Edge cleaning apparatus 714 includes a second belt 716 that
contains an outer surface having a different texture or
abrasiveness than the first belt 712.
[0034] Another important feature of the present invention lies in
the ability to readily interchange belts of varying types into the
edge cleaning apparatus. As a result, a standard rotating edge
cleaning design may be used when cleaning any of a variety of
contaminates from the edge or bevel area of a wafer. Moreover, it
is important to note that materials of different textures may be
attached to the outer surface of the edge cleaning belt to enhance
the belt's particle removal capability.
[0035] Thus, a method and apparatus for cleaning edges of
substrates, such as wafers, is disclosed.
* * * * *