Electric heating – Metal heating – By arc
Reexamination Certificate
2002-05-02
2004-05-11
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
By arc
C219S121670
Reexamination Certificate
active
06734388
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a dry surface cleaning apparatus; and, more particularly, to a dry surface cleaning apparatus for generating a laser induced plasma shock wave in a sealed chamber to efficiently remove a plurality of surface contaminants on a workpiece.
BACKGROUND OF THE INVENTION
Surface contaminants such as micron and submicron sized particles on semiconductor surfaces can pose serious problems such as circuit failure and yield loss in a semiconductor device. For example, particles smaller than 0.06 micrometer can cause fatal device defects for a next generation dynamic random access memory and a microprocessor. The contamination control on a silicon wafer is therefore a crucial issue in the manufacturing thereof. More effective techniques to remove smaller and smaller particles from the surface are required as the density of a chip device keeps increasing. However, those small particles are more difficult to remove due to their strong adhesion force on the surface. Conventional cleaning techniques such as high pressure gas jet, scrubbing, ultrasonic and chemical flux are known to be ineffective in removing the small particles of micron or submicron dimensions and further, there is possibility for them to inflict a mechanical action-based damage in the surface profile as well as an environmental pollution problem due to the considerable water consumption and the use of chemicals.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a dry surface cleaning apparatus for converging a laser beam on a laser focus located in a sealed chamber to generate a plasma shock wave around the laser focus in the sealed chamber so that the plasma shock wave may be used to remove a plurality of surface contaminants on a workpiece in the sealed chamber.
In accordance with a preferred embodiment of the present invention, there is provided a dry surface cleaning apparatus for removing surface contaminants on a surface of a workpiece comprising:
a laser for generating a laser beam;
a sealed chamber for holding the workpiece therein, wherein the sealed chamber has a transparent window through which the laser beam is transmitted;
a reflection mirror for introducing the laser beam to the transparent window; and
a laser focusing lens for converging the laser beam on a laser focus around the surface of the workpiece to generate a plasma shock wave around the laser focus, wherein the plasma shock wave is used to detach the surface contaminants on the surface.
REFERENCES:
patent: 5531857 (1996-07-01), Engelsberg et al.
patent: 5614339 (1997-03-01), Tankovich
patent: 6178973 (2001-01-01), Franca et al.
patent: 6407385 (2002-06-01), Okada
patent: 2003/0032297 (2003-02-01), Lindstrom et al.
Cho Sung Ho
Lee Jong-Myong
Elve M. Alexandra
IMT Co., Ltd.
Jacobson & Holman PLLC
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