Abrading – Machine – Rotary tool
Reexamination Certificate
1999-07-09
2001-06-05
Banks, Derris H. (Department: 3723)
Abrading
Machine
Rotary tool
C451S398000
Reexamination Certificate
active
06241593
ABSTRACT:
BACKGROUND
The present invention relates generally to chemical mechanical polishing of substrates, and more particularly to a carrier head for chemical mechanical polishing.
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 nonplanar. This nonplanar 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 a 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. Some carrier heads include a flexible membrane that applies pressure to the substrate to load it against the polishing pad. Pressurization or evacuation of a chamber behind the flexible membrane controls the load on the substrate. 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.
SUMMARY
In one aspect, the invention is directed to a carrier head. The carrier head has a base, a flexible membrane extending beneath the base to form a pressurizable chamber, a support structure positioned in the chamber, and a pressurizable bladder formed between the base and the flexible membrane to control a downward pressure on the support structure. A lower surface of the flexible membrane provides a mounting surface on which a substrate can be positioned, and a lower surface of the support structure movable to contact an upper surface of the flexible membrane. At least one of the bladder and support structure is configured to provide a substantially constant contact area between the support structure and the bladder.
Implementations of the invention may include one or more of the following features. The support structure may include an upwardly extending projection having a top surface that contacts a bottom surface of the bladder. The top surface of the projection may be sufficiently smaller than the bottom surface of the bladder that the bladder remains in contact with the entire top surface as the support structure moves vertically. The bladder may extend over the projection to form a convolution. The bladder may includes a thick section that undergoes substantially no deformation as the bladder is inflated to contact the support structure. The bladder may includes two sidewalls connected to the base that have convoluted, e.g., pleated portions. Grooves may be formed in at least one of a bottom surface of the thick section and a top surface the support structure to provide fluid communication through the pressurizable chamber. The thick portion may include an indentation, and the support structure may include a projection that fits into the indentation. The bladder may be joined to the flexible membrane. A bottom surface of the bladder may include a rigid ring to provide a constant contact area with the support structure.
In another aspect, the invention is directed to a carrier head for a chemical mechanical polishing apparatus. The carrier head has a base, a first pressurizable chamber located below the base, support structure located in the first pressurizable chamber, and a second pressurizable chamber to apply a downward pressure to the support structure. The first pressurizable chamber has a first chamber wall formed of a flexible membrane with a lower surface that provides a mounting surface for a substrate, and the support structure contacts an upper surface of the flexible membrane. The second pressurizable chamber has a second chamber wall configured to contact the support structure over a constant contact area.
Implementations of the invention may include one or more of the following features. A top surface of the support structure may be sufficiently smaller than a bottom surface of the second chamber wall that the second chamber wall remains in contact with the entire top surface as the support structure moves vertically. A lower surface of the second chamber wall may includes a thick section to contact the support structure that undergoes substantially no deformation as the second chamber is pressurized. The second chamber may have pleated sidewalls, and the second chamber wall may be formed of a rigid ring. The first chamber wall and the second chamber wall may be portions of a single flexible membrane.
In another aspect, the invention is directed to a carrier head for a chemical mechanical polishing apparatus. The carrier head has a base, a retaining ring coupled to the base, a flexible membrane extending beneath the base to form a pressurizable chamber, a support structure positioned in the chamber, and means for applying a substantially constant downward pressure to an upper surface of the support structure as the retaining ring wears. A lower surface of the flexible membrane provides a mounting surface on which a substrate can be positioned, and a lower surface of the support structure is movable to contact an upper surface of the flexible membrane.
Implementations of the invention may include one or more of the following features. The means for applying a substantially constant downward pressure may includes a convoluted membrane. The means for applying a substantially constant downward pressure may include a bladder with a means for providing a substantially constant contact area with the upper surface of the support structure. The means for providing a substantially constant contact area may include a thick section of the bladder that undergoes substantially no deformation as the bladder is pressurized, or a rigid section of the bladder that undergoes substantially no deformation as the bladder is pressurized.
Advantages of the invention may include one or more of the following features. The pressurizable bladder provides an auxiliary pressure control that can generate a stable load to the wafer. The pressure applied to the support structure is a linear function of the pressure in the chamber. This applied pressure does not change as the retaining ring wears.
Other advantages and features of the invention will be apparent from the following description, including the drawings and claims.
REFERENCES:
patent: 4918869 (1990-04-01), Kitta
patent: 5193316 (1993-03-01), Olmstead
patent: 5205082 (1993-04-01), Shendon et al.
patent: 5423716 (1995-06-01), Strasbaugh
patent: 5449316 (1995-09-01), Strasbaugh
patent: 5584751 (1996-12-01), Kobayashi et al.
patent: 5624299 (1997-04-01), Shendon
patent: 5643053 (1997-07-01), Shendon
patent: 5643061 (1997-07-01), Jackson et al.
patent: 5759918 (1998-06-01), Hoshizaki et al.
patent: 5795215 (1998-08-01), Guthrie et al.
patent: 5803799 (1998-09-01), Volodarsky et al.
patent: 5851140 (1998-12-01), Barns et al.
patent: 5879220 (1999-03-01), Hasegawa et al.
patent: 5957751 (1999-09-01), Govzman et al.
patent: 5964653 (1999-10-01), Perlov et al.
patent: 0 841 12
Bose Frank
Chen Hung Chih
Zuniga Steven M.
Applied Materials Inc.
Banks Derris H.
Fish & Richardson
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