Brushing – scrubbing – and general cleaning – Machines – Wiping
Reexamination Certificate
1999-09-08
2002-10-22
Chin, Randall E. (Department: 1744)
Brushing, scrubbing, and general cleaning
Machines
Wiping
C015S097100, C015S088300
Reexamination Certificate
active
06467120
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed generally to chemical mechanical polishing operations performed during integrated circuit manufacturing, and more particularly to polishing brushes used for mechanical or chemical-mechanical planarization of a semiconductor substrate.
BACKGROUND OF THE INVENTION
Chemical mechanical polishing (“CMP”) is a method used in semiconductor processing to planarize step-like features on a semiconductor wafer. Using the CMP process, a wafer is pressed (upside down) against a rotating polishing pad in the presence of a chemical corrosive slurry. The action of the slurry and the rotary motion of the polishing pad combine to remove a desired amount of material from the wafer and achieve a planar surface. Polishing is automatically stopped at a desired level or location so that no more than the desired amount of material is removed.
The main purpose for a typical CMP process is to achieve a high degree of flatness or planarity across the wafer surface. Local planarity (for closely spaced features) and global planarity (for uniformity across the wafer surface) are both important. Both forms of planarity are difficult to achieve because when semiconductor wafers are made they often do not result in uniformly flat surfaces. Also, during the processing steps of manufacturing the integrated circuit many different features of various sizes and densities are created and deposited across the wafer surface. Both inherent non-uniformities in the wafer surface and non-uniformities that result from the plurality of diffusion and etching steps are created, which can be removed through CMP.
Typically, the polishing pad includes brushes that perform the mechanical aspect of the CMP process. Brushes can be in the form of a pad or in the form of a roller. The roller can also be used to clean the wafer, and commonly includes a plurality of brushes around the outer cylindrical surface of the roller. Currently available CMP roller brushes have rectangular protrusions set at a fixed pitch across the entire body of the roller. An example of one such roller brush used throughout the industry is shown in FIG.
1
. The brush
10
is made of polyvinyl alcohol (“PVA”) across its entire body
12
and inserted over a core roller
14
that attaches to a drive mechanism (not shown). The drive mechanism is used to rotate the brush
10
and promote cleaning of wafers for the semiconductor industry. Two common systems that use this style brush configuration are made by Ebara Technologies and OnTrak Systems, Inc.
One problem encountered with the above-described brushes is the inclusion of a square or rectangular protrusion
16
, which collects or proliferates contamination (e.g., slurry build-up) around the outer edge
18
of the protrusion
16
. This contamination is due to the shape of the protrusion
16
, which can also cause scratches to the underlying copper (Cu) metalization and thereby reduce yield. A need therefore exists for an improved shape to the protrusion
16
that eliminates or substantially reduces the scratching of the wafer surface.
SUMMARY OF THE INVENTION
In view of the above, there is provided a wafer cleaning brush profile modification. According to one aspect of the invention, a brush for cleaning a wafer includes a cylindrical sleeve with openings formed therein. The brush also includes a compressible member inserted into the sleeve, and an expandable core member inserted into the sleeve along an axis thereof. Expansion of the core member causes portions of the compressible member to protrude radially through the openings of the sleeve such that these portions have a substantially uniform profile with respect to the sleeve. In one presently preferred embodiment of the invention, the uniform profile is rounded, diamond-shaped, mushroom shaped, or can take on any conceivable shape.
The invention thus builds on the roller brush concept to improve uniformity, deionized (“DI”) water channeling, less foreign matter (“FM”) due to less brush material exposed, selective contouring of protrusions and brush density variation ability. It is an object of the invention therefore to help eliminate brush induced scratching and FM to improve chip yield across the wafer. It is another object of the invention to promote DI water channeling directly to the point of contact of brush protrusion to wafer surface, henceforth decreasing brush absorption of contaminants and prolonging brush life.
These and other features and advantages of the invention will become apparent to those skilled in the art upon a review of the following detailed description of the presently preferred embodiments of the invention, viewed in conjunction with the appended drawings.
REFERENCES:
patent: 5311634 (1994-05-01), Andros
patent: 5441598 (1995-08-01), Yu et al.
patent: 5558563 (1996-09-01), Cote et al.
patent: 5609517 (1997-03-01), Lofaro
patent: 5645469 (1997-07-01), Burke et al.
patent: 5766058 (1998-06-01), Lee et al.
patent: 5785584 (1998-07-01), Marmillion et al.
patent: 5870792 (1999-02-01), Shurtliff
patent: 5870793 (1999-02-01), Choffat et al.
patent: 6070284 (2000-06-01), Garcia
patent: 6247197 (2001-06-01), Vail
patent: 6299698 (2001-10-01), Emami
One sheet of Rippey PVA Products from www.rippey.com Web site, Aug., 1999.
Goodwin David
Khoury Raymond M.
Ocasio Jose M.
Ziemins Uldis Artis
Anderson Jay H.
Chin Randall E.
LandOfFree
Wafer cleaning brush profile modification does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Wafer cleaning brush profile modification, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wafer cleaning brush profile modification will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2975305