Abrading – Machine – Sandblast
Reexamination Certificate
1999-07-09
2001-11-20
Young, Lee (Department: 3729)
Abrading
Machine
Sandblast
C361S234000, C134S072000
Reexamination Certificate
active
06319102
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present relates generally to devices that utilize a cryogenic aerosol spray to remove particulates from substrates and the like, and more particularly to devices and methods for reducing the effect of tribocharges that may occur during such a spray cleaning operation.
2. Description of the Prior Art
The removal of micron-sized contaminating particulates from the surfaces of substrates is a significant problem encountered in the semiconductor fabrication industry, as well as other industries where micron-sized particulates are of concern. One system for the removal of such particulates utilizes a cryogenic aerosol spray, typically carbon dioxide, that is sprayed onto the substrate surface. The cryogenic aerosol is sprayed from a nozzle in a high speed liquid stream and forms solid particulates, termed a snow, following emission from the nozzle. The snow and perhaps some liquid impact the contaminating particulates to mechanically remove them from the substrate surface to clean the surface.
A significant problem of electrostatic charge build-up has been encountered utilizing the cryogenic aerosol cleaning methods. Particularly, because the material that comprises the cryogenic aerosol, typically carbon dioxide, and the material of the substrate surface, such as a metal, or an insulator, differ with regard to their position on the triboelectric scale (also known as the “work function”), a significant triboelectric charge or tribocharge can be created during the cleaning process. The tribocharge can result in significant electric fields and electrostatic discharge which can damage sensitive components of the substrate.
One solution to this problem has been to ground the metal chuck which supports the substrate within a cleaning system. However, the inventors have discovered that the grounded chuck does not adequately resolve the tribocharge build-up. A need therefore exists or an improved device and system for reducing the effects of tribocharges during a cryogenic aerosol, spray cleaning operation.
SUMMARY OF THE INVENTION
The cryogenic aerosol substrate cleaning system of the present invention includes a substrate support system that is disposed within a cleaning enclosure. A wafer, or other article to be cleaned is disposed upon the substrate support system. A cryogenic aerosol spray cleaning device is disposed within the enclosure to direct a cryogenic aerosol spray upon the surface of the wafer. The substrate support system includes an electrically floating chuck which supports the wafer, such that the chuck is separated from a grounded plane by an insulator. The chuck is capacitance-coupled to the grounded plane, and in alternative embodiments the chuck is also electrically coupled to the grounded plane. The substrate support system of the present invention acts to reduce the creation of tribocharges on the wafer, such that damage to wafers caused by such tribocharges is reduced and a cleaner wafer surface is created.
It is an advantage of the present invention that it provides an apparatus and method for protecting static-sensitive devices from damage due to electrostatic discharge when they are cleaned using a carbon dioxide spray cleaning system.
It is another advantage of the present invention that it provides a substrate support system for use in a cryogenic aerosol spray cleaning enclosure which reduces the effects of tribocharges created during aerosol spray cleaning, resulting in a cleaner more defect free substrate.
It is a further advantage of the present invention that it provides a substrate support system for use in a cryogenic aerosol spray cleaning device, having a floating chuck that is capacitance-coupled to a grounded plane member, whereby the effects of tribocharges are reduced.
It is yet another advantage of the present invention that it provides a substrate support system for use in a cryogenic aerosol spray cleaning device that has a floating chuck that is both capacitance-coupled and electrically coupled to a grounded plane member, whereby the effects of tribocharges are reduced.
It is yet a further advantage of the present invention that it provides a means for the reduction of tribocharges, whereby ionizers are more effectively utilized.
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Guillot Robert O.
International Business Machines - Corporation
Oppenheimer Wolff & Donnelly LLP
Smith Sean
Young Lee
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