Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2000-08-22
2003-08-19
Rachuba, M. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C051S307000
Reexamination Certificate
active
06607424
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to the polishing and planarization of integrated circuit surfaces, particularly those comprising silicon dioxide films (TEOS, thermal oxide or BPSG), low-K ILD films, silicon nitride films, metal films (lines) and the mixtures of these.
2. Discussion of Related Art
CMP is an enabling technology used in the semiconductor industry to remove/planarize various thin films from the surface of semiconductor substrates during the production of IC. Various types of abrasives have been used for CMP. The polishing pad, typically made of polymer materials, is another important part in the CMP process. Particles of silicon dioxide, metal oxide (alummina, ceria, titania and ziconia etc.) or a mixture of the like are typically used as the abrasive in CMP slurries.
Achieving IC wafer planarization with smooth, scratch-free and low defect surfaces is greatly challenged by the presence of abrasive particles and the micro-asperities of the polymer pads. A CMP slurry which is not properly formulated will generate scratches and residues on the polished surfaces. The scratches may result from the trace tracks of the particles (slurry abrasives and residue from removed materials), while the residue coating may come from the gelled slurries and the re-deposition of the removed materials (metal oxide in the case of metal CMP and silanol or silicates in the case of silicon oxide CMP.) The dense scratching texture will heavily contribute to the higher level of roughness on the wafer surfaces. It has been observed that the slurry coating and re-deposition of residue will preferentially occur in the dense pattern areas, especially small features and interconnection lines in areas where the surface energy is high and the residue can be readily accommodated.
U.S. Pat. No. 5,704,987 addresses the problem of removing residual slurry particles adhered to a wafer surface after chemical-mechanical polishing. Proposed is a two step cleaning operation. The first step uses a basic aqueous solution of a nonionic polymeric surfactant; the second step uses purified water.
U.S. Pat. No. 5,783,489 discusses the use of surfactants, stabilizers, or dispersing agents to promote stabilization of a polishing slurry including oxidizing agents against settling, flocculation and decomposition. Surfactants may be anionic, cationic, nonionic, or amphoteric. It was found that the addition of a surfactant may be useful to improve the within-wafer-non-uniformity (WTWNU) of the wafers, thereby improving the surface of the wafer and reducing wafer defects.
The present invention provides compounds that can be used in CMP slurries to prevent scratching, minimize surface roughness, and eliminate coating of gelled slurries or residue on the IC wafer surfaces. The chemical compounds listed in this patent work effectively with abrasive particles including, but not limited to, silicon dioxide, metal oxides and any other inorganic oxides, and mixtures of the like. The slurries of this invention work effectively on CMP processes for sheet wafers, pattern wafers with the films/lines of silicon dioxide (TEOS, BPSG, thermal oxide), low K polymers, silicon nitride and metals, as well as mixtures of the like.
SUMMARY OF THE INVENTION
A composition is provided which is useful for the polishing of a semiconductor wafer substrate comprising an organic polymer having a backbone comprised of at least 16 carbon atoms, the polymer having a plurality of moieties with affinity to surface groups on the semiconductor wafer surface.
Another composition is provided which is useful for the polishing of a semiconductor wafer substrate comprising a surfactant having a carbon chain backbone comprised of at least 16 carbon atoms.
Yet another polishing composition is provided for the chemical mechanical polishing of semiconductor wafers having a metal circuit comprises an aqueous composition having a pH of under 5.0 and comprises polyacrylic acid having a number average molecular weight of about 20,000-150,000, or blends of high and low number average molecular weight polyacrylic acids.
A further aspect of this invention is the method of polishing a semiconductor wafer substrate, wherein the substrate is pressed against a polishing pad, the substrate and the pad are moved relative to each other, and a polishing composition is applied to the pad during the polishing operation, the polishing composition comprising an organic polymer having a backbone comprised of at least 16 carbon atoms, the polymer having a plurality of moieties with affinity to surface groups on the semiconductor wafer surface.
Yet another aspect of this invention is the method of polishing a semiconductor wafer substrate, wherein the substrate is pressed against a polishing pad, the substrate and the pad are moved relative to each other, and a polishing composition is applied to the pad during the polishing operation, the polishing composition comprising a surfactant having a carbon chain backbone comprised of at least 16 carbon atoms.
The compositions of this invention may optionally further comprise one or more of the following: submicron abrasive particles, a dispersing agent, an oxidizing agent, and a complexing agent.
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Barker, II Ross E.
Costas Wesley D.
Lack Craig D.
Mandigo Glenn C.
Shen James
Biederman Blake T.
Fricke Hilmar L.
Rodel Holdings Inc.
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