Refrigeration – Cryogenic treatment of gas or gas mixture – Liquefaction
Reexamination Certificate
2003-02-11
2004-05-18
Doerrler, William C. (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Liquefaction
C062S617000, C423S220000, C423S437100, C422S171000
Reexamination Certificate
active
06735978
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the treatment of supercritical fluids utilized in semiconductor manufacturing, e.g., supercritical fluids such as supercritical carbon dioxide (SCCO2) that are used in supercritical fluid compositions for the stripping of photoresists and etching residues, for deposition of thin film materials, etc.
DESCRIPTION OF THE RELATED ART
Semiconductor manufacturing involves the use of photoresists that are applied to wafer substrates and subsequently developed to produce specific patterned regions and structures on the wafer. The exposed photoresist is subsequently etched and optionally ashed to remove undesired material from the substrate. Other semiconductor manufacturing operations involve etching of deposited films to form the desired microelectronic device architecture. Applied films of the semiconductor device structure may be planarized by chemical mechanical polishing (CMP) operations, using a solvent-based slurry composition including fine particles of an abrasive medium, such as finely divided forms of metals or ceramics.
These material removal operations typically leave residues on the substrate that must be removed in order to render the product device structure suitable for its intended purpose. For this purpose, a variety of cleaning agents have been proposed and used in the art. Supercritical fluids have been proposed for such application, as solvating and/or entrainment media to effect or assist removal of the unwanted material from the substrate.
Additionally, supercritical fluids are of interest for the deposition of epitaxial thin films and materials in the manufacture of semiconductor products, as carrier media for chemical vapor deposition, ion implantation, and other deposition operations.
A supercritical fluid has the characteristics of both a liquid and a gas. Like a gas, it diffuses rapidly, has low viscosity, near-zero surface tension, and penetrates easily into deep features on the semiconductor substrate. Like a liquid, it has bulk flow and solvating capabilities and therefore is useful as a wash or carrier medium.
In the foregoing semiconductor manufacturing operations in which supercritical fluids are used as process solvents, the supercritical fluid can be formulated with other components to improve its utility for the intended use and/or the supercritical fluid as used in the semiconductor manufacturing can become contaminated with extraneous material such as the post-ash, post-etch residue when the supercritical fluid is used for resist removal. Thus, although it would be desirable to recycle the supercritical fluid for reuse in the semiconductor manufacturing facility, or to release the supercritical fluid (e.g., carbon dioxide) to the atmosphere after its use, the presence of extraneous material in the supercritical fluid composition precludes such disposition.
The art therefore is in need of approaches that would enable the supercritical fluid compositions containing extraneous material to be processed for removal of the extraneous material so that the supercritical fluid can be reused in the process in which it is initially employed and/or discharged from the process free of such extraneous material.
SUMMARY OF THE INVENTION
The present invention relates to the treatment of supercritical fluids utilized in semiconductor manufacturing, e.g., supercritical fluids such as supercritical carbon dioxide (SCCO2) that are used in supercritical fluid compositions for the stripping of photoresists and etching residues, for deposition of thin film materials, etc., to remove extraneous components from such supercritical fluid compositions so that they can be recirculated for reuse and/or discharged as a treated effluent from the manufacturing facility.
In one aspect, the invention relates to a process for utilization and disposition of a supercritical fluid composition, comprising
(a) utilizing a supercritical fluid (SCF) composition in an SCF-using process system;
(b) removing the supercritical fluid composition from the SCF-using process system, wherein the supercritical fluid composition contains at least one extraneous component in respect of further disposition of said supercritical fluid composition;
(c) converting the supercritical fluid composition to a pressurized liquid; and
(d) treating the pressurized liquid to at least partially remove said at least one extraneous component therefrom, thereby preparing it for said further disposition.
In another aspect, the invention relates to a system for utilization and disposition of a supercritical fluid composition, comprising
(a) a supercritical fluid (SCF) composition source;
(b) a SCF-using process facility coupled in supercritical fluid composition-receiving relationship with said supercritical fluid composition source, whereby said supercritical fluid composition is provided for use in said SCF-using process facility, and wherein the SCF-using process facility is arranged to discharge therefrom the supercritical fluid composition after said use, wherein the supercritical fluid composition contains at least one extraneous component in respect of further disposition of said supercritical fluid composition;
(c) a converter arranged to convert the supercritical fluid composition discharged from the process facility to a pressurized liquid; and
(d) a treatment facility arranged to treat the pressurized liquid to at least partially remove said at least one extraneous component therefrom, thereby preparing it for said further disposition.
Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing disclosure and appended claims.
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Baum Thomas H.
Ghenciu Eliodor G.
Korzenski Michael B.
Tom Glenn M.
Xu Chongying
Advanced Technology & Materials Inc.
Chappuis Margaret
Doerrler William C.
Hultquist Steven J.
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