Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1998-06-03
2001-06-26
Mills, Gregory (Department: 1767)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C451S286000
Reexamination Certificate
active
06251215
ABSTRACT:
BACKGROUND
The present invention relates generally to chemical mechanical polishing of substrates, and more particularly to a carrier head for a chemical mechanical polishing apparatus.
Integrated circuits are typically formed on substrates, particularly silicon wafers, by the sequential deposition of conductive, semiconductive or insulative layers. After each layer is deposited, it is etched to create circuitry features. As a series of layers are sequentially deposited and etched, the outer or uppermost surface of the substrate, i.e., the exposed surface of the substrate, becomes increasingly non-planar. This non-planar surface presents problems in the photolithographic steps of the integrated circuit fabrication process. Therefore, there is a need to periodically planarize the substrate surface.
Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier or polishing head. The exposed surface of the substrate is placed against a rotating polishing pad. The polishing pad may be either a “standard” or a fixed-abrasive pad. A standard polishing pad has durable roughened surface, whereas a fixed-abrasive pad has abrasive particles held in a containment media. The carrier head provides a controllable load, i.e., pressure, on the substrate to push it against the polishing pad. A polishing slurry, including at least one chemically-reactive agent, and abrasive particles, if a standard pad is used, is supplied to the surface of the polishing pad.
The effectiveness of a CMP process may be measured by its polishing rate, and by the resulting finish (absence of small-scale roughness) and flatness (absence of large-scale topography) of the substrate surface. The polishing rate, finish and flatness are determined by the pad and slurry combination, the relative speed between the substrate and pad, and the force pressing the substrate against the pad.
A reoccurring problem in CMP is the so-called “edge-effect”, i.e., the tendency of the edge of the substrate to be polished at a different rate than the center of the substrate. The edge effect typically results in over-polishing (the removal of too much material from the substrate) at the substrate perimeter, e.g., the outermost five to ten millimeters of a 200 mm wafer. Over-polishing reduces the overall flatness of the substrate, causing the edge of the substrate to be unsuitable for integrated circuit fabrication and decreasing the process yield.
SUMMARY
In one aspect, the invention is directed to a carrier head for a chemical mechanical polishing apparatus. The carrier head has a substrate mounting surface and a retaining ring to maintain a substrate beneath the mounting surface during polishing. The retaining ring includes a lower portion having a bottom surface for contacting a polishing pad during polishing and made of a first material, and an upper portion made of a second material which is more rigid than the first material.
Implementations of the invention may include the following. The first material may be a plastic, e.g., polyphenylene sulfide, polyethylene terephthalate, polyetheretherketone, or polybutylene terephthalate, which is substantially inert to a chemical mechanical polishing process. The second material may be a metal, e.g., steel, aluminum, or molybdenum, or a ceramic. The lower portion may be thicker than a substrate to be polished, e.g., between about 100 and 400 mils thick. The first material may provide a durometer measurement between about 80 and 95 on the Shore D scale. The second material may have an elastic modulus about ten to one-hundred, e.g., fifty times the elastic modulus of the first material. The lower portion may be adhesively attached, e.g., with a slow curing epoxy, or press fit to the upper portion.
In another aspect of the carrier head, the lower portion is made of a first material having a first elastic modulus and the upper portion is made of a second material having a second elastic modulus, and the second elastic modulus is selected to be sufficiently larger than the first elastic modulus to substantially prevent deflection of the lower surface of the retaining ring during polishing.
In another aspect of the carrier head, the lower portion is made of a first material having a first elastic modulus and the upper portion is made of a second material having a second elastic modulus, and the second elastic modulus is selected to be sufficiently larger than the first elastic modulus to substantially prevent deformation of the lower surface of the retaining ring where the retaining ring is joined to the carrier head.
In another aspect, the invention is directed to a retaining ring for a carrier head having a mounting surface for a substrate. The retaining ring has a generally annular lower portion having a bottom surface for contacting a polishing pad during polishing and made of a first material which is inert in a chemical mechanical polishing process, and a generally annular upper portion joined to the lower portion and made of a second material which is more rigid than the first material.
In another aspect, the invention is directed to a chemical mechanical polishing system with a rotatable polishing pad, a slurry supply to dispense a slurry onto the polishing pad, and a carrier head having a substrate mounting surface and a retaining ring to maintain a substrate beneath the mounting surface during polishing. The retaining ring includes a lower portion for contacting a polishing pad during polishing and made of a first material, and an upper portion made of a second material which is more rigid than the first material.
Advantages of the invention may include the following. The edge effect is reduced, and the resulting flatness and finish of the substrate are improved.
Other advantages and features of the invention will be apparent from the following description, including the drawings and claims.
REFERENCES:
patent: 5205082 (1993-04-01), Shendon et al.
patent: 5423558 (1995-06-01), Koeth et al.
patent: 5584751 (1996-12-01), Kobayashi et al.
patent: 5605488 (1997-02-01), Ohashi et al.
patent: 5635083 (1997-06-01), Breivogel et al.
patent: 5643061 (1997-07-01), Jackson et al.
patent: 5695392 (1997-12-01), Kim
patent: 5759918 (1998-06-01), Hoshizaki et al.
patent: 5851140 (1998-12-01), Barns et al.
patent: 0 747 167 A2 (1996-12-01), None
patent: 0 790 100 A1 (1997-08-01), None
patent: 0 841 123 A1 (1998-05-01), None
patent: 2 307 342 (1997-05-01), None
Osterheld Thomas H.
Rosenberg Lawrence M.
Zuniga Steven M.
Applied Materials Inc.
Fish & Richardson
Mills Gregory
Powell A. C.
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