Browse Prior Art Database

Particle Collector

IP.com Disclosure Number: IPCOM000082779D
Original Publication Date: 1975-Feb-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Gates, GA: AUTHOR [+2]

Abstract

During laser dicing of silicon wafers hot particles of silicon erupt from the surface being cut. These particles leave the surface at various angles and various velocities. If not controlled these particles deposit on the objective lens of the laser, causing power loss and destruction of the lens.

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Particle Collector

During laser dicing of silicon wafers hot particles of silicon erupt from the surface being cut. These particles leave the surface at various angles and various velocities. If not controlled these particles deposit on the objective lens of the laser, causing power loss and destruction of the lens.

This problem is avoided by using a particle collector around the laser lens. A shroud 10 surrounds a long focal length lens 12 which focuses a laser beam 14 on an objective 16. The shroud is fitted with an inlet 18 and an outlet 19 arranged to cause a positive pressure flow across the face of the lens 12. In the center of the shroud 10 around the optical path of the lens is a long hollow V- tapered shroud 20, which creates a ringed particle trapping chamber 21. Positioned below the V-tapered shroud 20, is a vacuum collector ring 22 having a central aperture through which the beam can pass and an evacuation port 23.

If air is introduced into port 18 and a vacuum applied to port 19, the stream of air deflects any particles traveling back along the optical path away from the lens
12. The vacuum collector ring 22 collects the airborne particles with lesser velocity, so that they do not reach the air flow across the face of the lens 12.

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