Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1998-01-08
2001-01-09
Powell, William (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C134S001300, C216S089000, C451S054000
Reexamination Certificate
active
06171436
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates generally to semiconductor wafers and more particularly the invention pertains to the field of Chemical Mechanical Polish (CMP) used during the fabrication of semiconductor chips to planarize the wafers.
2. Background Art
Rapid progress in semiconductor device integration demands smaller and smaller wiring patterns or interconnections which connect active areas. As a result, the tolerances regarding the planeness or flatness of the semiconductor wafers used in these processes are becoming smaller and smaller. One customary way of flattening the surfaces of semiconductor wafers is to polish them with a polishing apparatus.
Such a polishing apparatus has a rotating wafer carrier assembly in contact with a polishing pad. The polishing pad is mounted on a rotating turntable which is driven by an external driving force. The polishing apparatus causes a polishing or rubbing movement between the surface of each thin semiconductor wafer and the polishing pad while dispersing a polishing slurry to obtain a chemical mechanical polish (CMP). CMP in planarization requires the wafer surface to be brought into contact with a rotating pad saturated with either a slurry of abrasive particles or a reactive solution, or both, that attacks the wafer surface. This is done while exerting force between the wafer and polishing pad. The abrasive particles can scratch the surface during the polish operation especially if they agglomerate. Also, after polishing is completed and the wafer is rinsed to remove the abrasive particles, some of the abrasive particles will remain on the wafer surface by simply being imbedded into the surface or strongly attracted to the surface.
The scratches can cause problems in subsequent processing steps as for example in a Damascene process, intra-level where shorting could result. Leaving the particles on the wafer can likewise lead to process problems, most notably photolithographic and etching defects in subsequently processed levels.
Prior art for particle removal involves either a mechanical clean, such as a brush clean, after the wafers have been removed from the polishing apparatus and dried, or a washing step with a surfactant (soap) performed prior to the wafer being dried as disclosed in U.S. Pat. No. 5,320,706, issued to Blackwell on Jun. 14, 1994 and assigned to Texas Instruments Incorporated. These processes are not usually 100% effective and do not address the scratching problem. Therefore, it appears that no prior art per se exists that addresses the scratching problem directly.
SUMMARY OF THE INVENTION
The present invention discloses a method and apparatus for removing slurry abrasive particles in a polishing process for planarization of a semiconductor wafer.
The present invention discloses a method and apparatus for reducing the size of the slurry abrasive particles or agglomerations of slurry abrasive particles in a polishing process for planarization of a semiconductor wafer.
The present invention discloses a method for in situ reduction in size of abrasive particles in a slurry during a polishing process for planarization of a wafer comprising: exposing the slurry to a reagent to reduce the size of the slurry abrasive particles.
The present invention disclose a method for in situ reduction in size of agglomerations of abrasive particles in a slurry during a polishing process for planarization of a wafer, comprising: exposing the slurry to a reagent to reduce the size of the agglomerations of abrasive particles.
The present invention is a method for in situ removal of abrasive particles in a slurry during a polishing process for planarization of a wafer, comprising: exposing the slurry to a reagent to dissolve the abrasive particles.
The present invention discloses a method for in situ reduction in size of abrasive particles in a slurry during a polishing process for planarization of a wafer, comprising: placing the wafer against a rotating polishing pad; applying the slurry to the polishing pad; and applying a reagent to the pad to reduce the abrasive particle size.
The present invention discloses a method for in situ reduction in size of abrasive particles in a slurry during a polishing process for planarization of a wafer, comprising: dispensing a CMP slurry; planarizing a semiconductor thin film using the slurry; reducing the slurry dispense; dispensing a reagent for a predetermined time necessary to reduce the abrasive particle size and agglomerations; and rinsing with DI (de-ionized) water.
The present invention discloses an apparatus comprising: a wafer; a polishing pad which planarizes the wafer; a slurry dispenser which provides slurry containing abrasive particles to the polishing pad; and a reagent dispenser which controllably provides reagent to the polishing pad.
In accordance with the above, it is an advantage of the present invention to solve the problem of slurry abrasive particle removal post-CMP and the problem of scratches on the post-CMP surface.
It is an advantage of the present invention to remove the abrasive particles in situ.
It is an advantage of the present invention to gradually reduce the abrasive particle size in situ.
It is an advantage of the present invention to gradually reduce the size of agglomerations of abrasive particles in situ.
It is an advantage of the present invention to eliminate residual slurry and slurry abrasives on the wafer. It is an advantage of the present invention to break up or reduce the size of abrasive particle agglomerations.
It is an advantage of the present advantage to dissolve the slurry abrasive particles at the CMP tool rather than removal at a subsequent tool.
It is an advantage of the present invention to eliminate slurry abrasive particle residues and reduce if not eliminate scratches.
It is an advantage of the present invention to obviate the need to remove slurry abrasive particles, since the slurry abrasive particles have been destroyed.
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Huynh Cuc K.
Linde Harold G.
Marmillion Patricia E.
Palagonia Anthony M.
Pierson Bernadette A.
Goudreau George
International Business Machines - Corporation
Powell William
Schmeiser Olsen & Watts
Walter, Jr. Howard J.
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