Abrading – Abrading process – Utilizing fluent abradant
Reexamination Certificate
2001-05-31
2004-11-30
Rachuba, M. (Department: 3723)
Abrading
Abrading process
Utilizing fluent abradant
C451S041000, C451S054000, C451S444000
Reexamination Certificate
active
06824448
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present inventions pertain to semiconductor fabrication processing. More particularly, the present inventions relate to a system the quick removal of residue slurry and/or stagnate slurry chemical from the polishing pad during CMP processing of the wafer to control the removal rate of the substrate.
2. Description of the Prior Art
Referring now to
FIGS. 1A-2
, there is shown a partial perspective view of a prior art CMP machine
100
and a side partial perspective view of a wafer
105
(FIG.
2
). The CMP machine
100
is fed wafers to be polished. The CMP machine
100
picks up the wafers with an arm
101
and places them onto a rotating polishing pad
102
. The polishing pad
102
is made of a resilient material and is textured, often with a plurality of predetermined groves, to aid the polishing process. The polishing pad
102
rotates on a platen
104
, or turn table located beneath the polishing pad
102
, at a predetermined speed, usually from 30 up to 60 RPMs. A wafer is held in place on the polishing pad
102
and the arm
101
by a carrier ring and a carrier film not shown. The lower surface of the wafer
105
rests against the polishing pad
102
. The upper surface of the wafer
105
is against the lower surface of the carrier film of the arm
101
. As the polishing pad
102
rotates, the arm
101
rotates the wafer
105
at a predetermined rate. The arm
101
forces the wafer
105
into the polishing pad
102
with a predetermined amount of down force. The CMP machine
100
also includes a slurry dispense tube
107
, extending across the radius of the polishing pad
102
. The slurry dispense tube
107
dispenses a flow of slurry
106
onto the polishing pad
102
.
The slurry
106
is a mixture of deionized water and polishing agents designed to aid chemically the smooth and predictable planarization of the wafer. The rotating action of both the polishing pad
102
and the wafer
105
, in conjunction with the polishing action of the slurry, combine to planarize, or polish, the wafer
105
at some nominal rate. The polishing action of the slurry is comprised of an abrasive frictional component and a chemical component. The abrasive frictional component is due to the friction between the surface of the polishing pad, the surface of the wafer, and abrasive particles suspended in the slurry. The chemical component is due to the presence in the slurry of polishing agents which chemically interact with the material of the dielectric or metal layer of the wafer. The chemical component of the slurry is used to soften the surface of the dielectric layer to be polished, while the frictional component removes material from the surface of the wafer.
Slurry dispense termination is accomplished by turning off a pump, which will stop the flow of slurry onto the pad. After the slurry dispense process is terminated, the wafer substrate is still exposed to the slurry and pad. The residue slurry which was dispensed on the pad will remain on the pad and continue reacting with the wafer substrate. This will result in a non-uniform removal of the wafer substrate due to stagnate slurry on the pad. The standard removal process has a low flow stream of water is dispensed from water dispense tube
108
onto the pad, which does not remove the slurry completely and quickly from the surface of the pad. The wafer substrate is then rid of the slurry.
What is needed is a method and/or apparatus which will quickly remove the slurry from the pad, thus more accurately controlling the removal rate of the substrate.
This object, and others, is satisfied by Applicant's present inventions disclosed herebelow.
SUMMARY OF THE INVENTION
One embodiment of the present inventions relates to a method for clearing slurry from a polishing pad in a CMP process including placing a wafer substrate in contact with a polishing pad while rotating the polishing pad at a first speed. Slurry is dispensed onto the polishing pad while the pad is rotating at the first speed. After slurry dispense has terminated, a high pressure fluid is sprayed around the wafer substrates to remove slurry from between the wafer substrates and the polishing pad. The pad is rotated at a greater speed while the high pressure fluid is sprayed.
In another embodiment of the present inventions, a slurry dispense bar including a high pressure spray portion and a slurry dispense portion located over the polishing pad is provided, wherein the high pressure fluid is sprayed around said wafer substrates to remove slurry from between said wafer substrates and the pad using the high pressure spray portion of said slurry dispense bar.
Related objects and advantages of the present invention will be apparent from the following description.
REFERENCES:
patent: 5551986 (1996-09-01), Jain
patent: 5597443 (1997-01-01), Hempel
patent: 5653622 (1997-08-01), Drill et al.
patent: 5702563 (1997-12-01), Salugsugan et al.
patent: 5711818 (1998-01-01), Jain
patent: 5893753 (1999-04-01), Hempel, Jr.
patent: 5996594 (1999-12-01), Roy et al.
patent: 6220941 (2001-04-01), Bonner et al.
patent: 6283840 (2001-09-01), Huey
patent: 6319098 (2001-11-01), Osterheld et al.
patent: 0967049 (1999-12-01), None
Douglas, Jr. Paul
Guzman Jesse
Vines Landon B.
Wood Parker A.
Rachuba M.
Zawilski Peter
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