Optics: measuring and testing – By particle light scattering
Reexamination Certificate
2001-08-02
2004-08-03
Font, Frank G. (Department: 2877)
Optics: measuring and testing
By particle light scattering
C356S038000, C015S421000, C015S246200, C073S864350
Reexamination Certificate
active
06771371
ABSTRACT:
FIELD OF THE INVENTION
The invention is generally related to the field of semiconductor wafer fabrication equipment and more specifically to particle detection and removal in wafer fabrication equipment.
BACKGROUND OF THE INVENTION
During maintenance of wafer fabrication equipment, particles are left in and on the equipment chamber surfaces. These particles cause yield loss and higher baseline defects. The current tools used to remove particles are very ineffective and require a large amount to over cleaning to obtain less than ideal performance. Most wafer fabrication facilities use only a house vacuum or portable hepa filter vacuum with reducers to vacuum wafer chamber areas.
House vacuums are typically used to remove particle contamination. They are good at removing heavy contamination and do not use make up air that can spread contamination. Unfortunately, they cannot be calibrated and are very slow at removing particles from recesses like vented screws.
SUMMARY OF THE INVENTION
The invention is a portable particle detection and removal system that connects to a vacuum source. A particle sensor is connected between the vacuum source and a sample port. The sample port has a smaller diameter and may be used for vacuuming the wafer equipment chamber. The particle sensor detects incoming particles and a particle count is displayed for the operator.
In one embodiment, a modulated cleaning system modulates the vacuum pressure between two vacuum pressure states. For example, a Venturi Boost may be used to provide a greater vacuum state than the vacuum source. The static vacuum pressure of the vacuum source is 5″ of water. When the venturi boost is turned on the vacuum pressure increases to 10″ of water. Modulating between two vacuum pressure states increases the ability to remove particles and the speed at which the particles are removed.
An advantage of the invention is providing a particle detection and removal system that provides feedback to the user and allows faster and more complete removal of contamination especially from small areas.
This and other advantages will be apparent to those of ordinary skill in the art having reference to the specification in conjunction with the drawings.
REFERENCES:
patent: 5367139 (1994-11-01), Bennett et al.
patent: 5542146 (1996-08-01), Hoekstra et al.
patent: 5837094 (1998-11-01), Tsukazaki et al.
Brady III W. James
Brown Khaled
Font Frank G.
Garner Jacqueline J.
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