Brushing – scrubbing – and general cleaning – Miscellaneous
Reexamination Certificate
2000-07-25
2002-09-24
Chin, Randall E. (Department: 1744)
Brushing, scrubbing, and general cleaning
Miscellaneous
C015S001510
Reexamination Certificate
active
06453496
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for removing undesired particles on a photomask that may cause defects during a semiconductor lithography; and, more particularly, to an apparatus for removing the undesired particles from the photomask by using an electrostatic force.
BACKGROUND OF THE INVENTION
The presence of an undesired particle on a photomask may cause a critical defect in a semiconductor wafer when the contaminated photomask is used for semiconductor lithography. Since patterns of the photomask are highly miniaturized and transcribed on a semiconductor device, even the smallest particles may render a resultant semiconductor device useless.
In the prior art, therefore, there is known a wealth of apparatuses and/or methods used to remove contaminant particles on the photomask. One of such prior art methods is taught in U.S. Pat. No. 4,744,833 to Douglas W. Cooper et al., entitled “ELECTROSTATIC REMOVAL OF CONTAMINANTS”. The method includes the steps of: establishing a first electrically conductive base connected to one terminal of a DC supply, locating a surface on which the contaminant particles are attached on the first conductive base, positioning a second electrically conductive base connected to the other terminal of the DC supply above the surface on which the contaminant particles are attached, placing an insulator between the second base and the surface on which the contaminant particles are attached, and applying an electric field between the first and the second base to electrostatically remove the contaminant particles.
In operation, when the DC supply is driven, the first conductive base charges the contaminant particles at the same potential as the surface and sets up an electrostatic field between the first and the second conductive bases. The thickness of the insulator and the voltage difference between the bases produce an electric field, thereby removing the contaminant particles from the surface.
However, such method requires the conductive bases, insulator, DC supply, etc., which render the entire structure rather complicated and costly.
SUMMARY OF THE INVENTION
It is, therefore, a primary object of the present invention to provide a simple-structured apparatus for removing contaminant particles on a photomask.
It is another object of the present invention to provide an apparatus for removing contaminant particles on the photomask without damaging the photomask.
In accordance with the present invention, there is provided an apparatus for removing undesired particles on a target object, comprising:
an electrostatic charge inductor for attracting the undesired particles on the target object;
an electrostatic charge developer coming into contact with the electrostatic charge inductor; and
a driving source for rotating the electrostatic charge developer to cause a frictional contact with the electrostatic charge inductor,
wherein the static electricity for removing the undesired particles off the target object is generated by the frictional contact between the electrostatic charge inductor and the electrostatic charge developer.
REFERENCES:
patent: 4744833 (1988-05-01), Cooper
patent: 404027190 (1992-01-01), None
Anam Semiconductor Inc.
Chin Randall E.
Katten Muchin Zavis & Rosenman
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