U.S. patent application number 11/014476 was filed with the patent office on 2005-05-26 for method to use a laser to perform the edge clean operation on a semiconductor wafer.
This patent application is currently assigned to LSI Logic Corporation. Invention is credited to Barber, Rennie, Berman, Michael J., Reder, Steven.
Application Number | 20050109369 11/014476 |
Document ID | / |
Family ID | 32824083 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050109369 |
Kind Code |
A1 |
Reder, Steven ; et
al. |
May 26, 2005 |
Method to use a laser to perform the edge clean operation on a
semiconductor wafer
Abstract
A method for performing the edge clean operation on a
semiconductor wafer. A laser beam is used to accurately clean the
edge of the wafer. The wafer is clamped concentrically to a chuck
and rotated at a selectable speed, preferably in the range of 10
rpm to 1,000 rpm. A laser beam of variable power is directed onto
toward the edge of the wafer at an oblique angle through a nozzle
through which an inert purge gas is simultaneously passed. The
laser beam removes unwanted deposits at the edge of the wafer and
the gas is used to blow away the residue and prevent slag buildup
on other parts of the wafer. The process is preferably carried out
in an exhausted chamber.
Inventors: |
Reder, Steven; (Boring,
OR) ; Berman, Michael J.; (West Linn, OR) ;
Barber, Rennie; (Gresham, OR) |
Correspondence
Address: |
LSI LOGIC CORPORATION
1621 BARBER LANE
MS: D-106
MILPITAS
CA
95035
US
|
Assignee: |
LSI Logic Corporation
|
Family ID: |
32824083 |
Appl. No.: |
11/014476 |
Filed: |
December 16, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11014476 |
Dec 16, 2004 |
|
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10360903 |
Feb 7, 2003 |
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6874510 |
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Current U.S.
Class: |
134/1 ; 134/1.3;
134/113; 134/19; 257/E21.237 |
Current CPC
Class: |
B08B 7/0042 20130101;
H01L 21/02021 20130101; H01L 21/67051 20130101; H01L 21/02087
20130101 |
Class at
Publication: |
134/001 ;
134/001.3; 134/019; 134/113 |
International
Class: |
B08B 003/10 |
Claims
The invention is claimed as follows:
1. A system used for performing an edge clean operation on a wafer,
the system comprising: a rotatable chuck which is configured to
clamp the wafer thereon; and a laser capable of emitting both a
laser beam and a gas therefrom for cleaning an edge of the
wafer.
2. A system as defined in claim 1, further comprising a rotatable
chuck which is configured to concentrically clamp the wafer
thereon.
3. A system as defined in claim 1, further comprising a video
monitoring system which monitors the edge of the wafer and a point
of contact of the laser beam.
4. A system as defined in claim 1, further comprising an exhausted
chamber, said chuck and said wafer being positioned within said
exhausted chamber.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method of performing the
edge clean operation on semiconductor wafers. More specifically,
the present invention relates to a method of using a laser to
perform the edge clean operation on semiconductor wafers.
[0002] One of the major problems gaining attention in wafer
processing today is the edge related defects. Edge related defects
contribute to lower die yield and lost revenue. A typical type of
edge defect is the peeling of edge films due to poor adhesion to
underlying layers.
[0003] Many processing schemes have been devised and implemented to
reduce edge related defects. The majority of processing schemes
involve costly photo masking and etching steps in an attempt to
reduce or eliminate the defects. The wafer is coated with photo
resist and run through an edge bead removal step. The wafer is then
etched in a plasma etcher to remove the films on the edge of the
wafer. The resist is then stripped off in both a dry and then wet
process. The wafer is then sent on for subsequent processing.
[0004] The disadvantage associated with these existing solutions is
that the wafers have to run through additional processing steps
that can add both high cost and long cycle times.
[0005] Therefore, an improved method for performing the edge clean
operation on a semiconductor wafer is needed. The present invention
provides such a method for performing the edge clean operation on a
semiconductor wafer. Features and advantages of the present
invention will become apparent upon a reading of the attached
specification, in combination with a study of the drawings.
OBJECTS AND SUMMARY OF THE INVENTION
[0006] A primary object of an embodiment of the invention is to
provide a method of using a laser to perform the edge clean
operation on a semiconductor wafer.
[0007] An object of an embodiment of the invention is to provide a
significant reduction in process steps necessary to accomplish the
edge cleaning process on a semiconductor wafer.
[0008] An object of an embodiment of the invention is to provide
for the elimination of the need for a very expensive resist coating
track, photolithe stepper, plasma etcher, resist asher and solvent
resist strip such that a significant reduction in capital equipment
costs and a decrease in wafer cycle time are achieved.
[0009] Another object of an embodiment of the invention is to
provide the capability to control the laser power and incidence
angle to enable selective cleaning down to any desired layer by
adjusting laser power.
[0010] Another object of an embodiment of the invention is to
provide semiconductor wafers having their edges cleaned by the
method of using a laser with a clean boundary between the clean and
non-cleaned areas.
[0011] Briefly, and in accordance with at least one of the
foregoing, an embodiment of the present invention provides a method
for performing the edge clean operation on a semiconductor wafer.
Specifically, a laser beam is used to accurately clean the edge of
the wafer. The wafer is clamped concentrically to a chuck and
rotated at a selectable speed, such as in the range of 10 rpm to
1,000 rpm. A laser beam of variable power is directed onto the edge
of the wafer at an oblique angle through a nozzle through which an
inert purge gas is simultaneously passed. The laser beam removes
unwanted deposits at the edge of the wafer and the gas is used to
blow away the residue and prevent slag buildup on other parts of
the wafer. The process is carried out in an exhausted chamber.
Preferably, there is accurate wafer concentricity and laser
alignment to the wafer edge. Preferably, an accurate form of wafer
to chuck alignment system is used. This can be insured by use of a
co-axial closed-loop video monitoring system that monitors both the
edge of the wafer and the point of contact by the laser.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The features of the present invention which are believed to
be novel, are described in detail herein below. The organization
and manner of the structure and operation of the invention,
together with further objects and advantages thereof, may best be
understood by reference to the following description taken in
connection with the accompanying drawings wherein like reference
numerals identify like elements in which:
[0013] FIG. 1 is a flow chart illustrating a method of performing
an edge clean process of a semiconductor wafer in accordance with
an embodiment of the present invention; and
[0014] FIG. 2 is a side-elevational view of the system used for
performing the method illustrated in FIG. 1.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
[0015] While this invention may be susceptible to embodiment in
different forms, there is shown in the drawings and will be
described herein in detail, a specific embodiment with the
understanding that the present disclosure is to be considered an
exemplification of the principles of the invention, and is not
intended to limit the invention to that as illustrated and
described herein.
[0016] The present invention provides a method 100 of performing an
edge clean operation on a semiconductor wafer 20, which is
illustrated in FIG. 1. The system 15 used for performing the method
100 is illustrated in FIG. 2.
[0017] As illustrated in FIG. 2, the system 15 used for performing
the method 100 includes the wafer 20 having an edge 25. Film 30 is
attached to a top surface 35 of the wafer 20. The system 15 further
includes a chuck 40, a laser 45 having a nozzle 50, and a video
monitoring system 55. The laser 45 is capable of emitting a laser
beam 60 through the nozzle 50. An inert purge gas 65 is also
emitted through the nozzle 50 of the laser 45. The video monitoring
system 55 is preferably a co-axial closed-loop video monitoring
system. The laser 45 is configured to emit laser beams 60 of
variable power. The system is provided within an exhausted chamber
70, although the video monitoring system 55 does not necessarily
have to be provided within the exhausted chamber 70.
[0018] The method 100 of the present invention will now be
discussed with reference to FIG. 1. The first step 110 of the
method 100 is to clamp the wafer 20 to the chuck 40 such that the
top surface 35, and thus the film 30 on the top surface 35 of the
wafer 20, are not positioned on the chuck 40. The wafer 20 is
preferably clamped concentrically to the chuck 40.
[0019] The second step 120 of the method 100 is to rotate the chuck
40, with the wafer 20 clamped thereto, at a selectable speed. The
selectable speed of the rotation of the chuck 40, with the wafer 20
clamped thereto, is preferably between ten revolutions per minute
(10 rpm) and one-thousand revolutions per minute (1,000 rpm).
[0020] The third step 130 of the method 100 is to direct the laser
beam 60 at an oblique angle through the nozzle 50 of the laser 45
to the edge 25 of the wafer 20.
[0021] The fourth step 140 of the method 100 is to remove unwanted
deposits, such as the film 30 on the top surface 35 of the wafer
20, at the edge 25 of the wafer 20 with the laser beam 60. Thus, as
illustrated in FIG. 2, the top surface 35 of the wafer 20 proximate
to the edge 25 thereof is clean of unwanted deposits, such as the
film 30.
[0022] The fifth step 150 of the method 100 is to blow away the
removed unwanted deposits 30 from the wafer 20 with an inert purge
gas 65 which is passed through the nozzle 50 of the laser 45. The
inert purge gas 65 is preferably passed through the nozzle 50 of
the laser 45 at the same time the laser beam 60 is removing
unwanted deposits 30 from the top surface 35 of the wafer 20 in the
fourth step 140. Because the inert purge gas 65 blows away the
removed unwanted deposits 30 from the wafer 20, slag build up on
other parts of the wafer 20 is prevented.
[0023] The method 100 is preferably performed in the exhausted
chamber 70. Preferably, there is accurate concentricity of the
wafer 20 and alignment of the laser 45 with the edge 25 of the
wafer 20. Preferably, an accurate form of wafer 20 to chuck 40
alignment system is used. This can be insured by the use of the
co-axial closed loop video monitoring system 55 that monitors both
the edge 25 of the wafer 20 and the point of contact by the laser
beam 60.
[0024] It should be understood that the sequence of steps 110, 120,
130, 140, 150 described in the method 100 is only the preferred
sequence of operation of the steps 110, 120, 130, 140, 150, such
that certain steps 110, 120, 130, 140, 150 could be performed prior
to other steps 110, 120, 130, 140, 150 or could be done
simultaneously with other steps 110, 120, 130, 140, 150. For
instance, the third step 130 could be performed prior to, or
simultaneously with the second step 120. Likewise, the fourth and
fifth steps 140, 150 could be performed simultaneously.
[0025] The system 15 and method 100 provide a number of advantages
in cleaning the edge 25 of a wafer 20 in comparison to those of the
prior art. The system 15 and method 100 provide a significant
reduction in process steps necessary to accomplish the edge
cleaning process. The system 15 and the method 100 eliminate the
need for a very expensive resist coating track, photlithe stepper,
resist asher, and solvent resist strip, such that a significant
reduction in capital equipment costs and a decrease in wafer cycle
time are achieved. An additional advantage of the system 15 and the
method 100 is the capability to control the power of the laser 45
and the incidence angle to enable selective cleaning down to an
desired layer by adjusting the power of the laser 45. Further, the
edge clean accomplished by this method leaves a clean boundary
between clean and non-cleaned area.
[0026] While a preferred embodiment of the present invention is
shown and described, it is envisioned that those skilled in the art
may devise various modifications of the present invention without
departing from the spirit and scope of the appended claims.
* * * * *