Browse Prior Art Database

PREVENTION POLYMER BUILD UP ON A PLASMA ETCH VIEW PORT

IP.com Disclosure Number: IPCOM000007540D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2002-Apr-04
Document File: 3 page(s) / 99K

Publishing Venue

Motorola

Related People

Audrey Lin: AUTHOR [+3]

Abstract

In a batch reactor you have two viewport open- ings, one for endpoint and the other for observation. The viewports are opening in chamber walls (anode) with quartz inserted to allow for viewing of inside the chamber. The chamber wall of plasma reactor is heated some of the heat from the wall is conducted to the quartz viewport but because of heat loss and size of the opening the center ofthe viewport is always 3 to 5 degrees cooler than the edge of viewport or chamber wall. This creates a cool spot in the plasma and a good location for non-volatile by-products to accumulate. Over time this accumulation builds up so thick that it blocks any light from passing through. When the viewport is used for detection of endpoint the build up can reduce signal which will prevent the accurate detection of endpoint.

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Technical Developments

PREVENTION POLYMER BUILD UP ON A PldSMA ETCH VIEW PORT

by Audrey Lin, Jeff Martsching and James Tolei

  In a batch reactor you have two viewport open- ings, one for endpoint and the other for observation. The viewports are opening in chamber walls (anode) with quartz inserted to allow for viewing of inside the chamber. The chamber wall of plasma reactor is heated some of the heat from the wall is conducted to the quartz viewport but because of heat loss and size of the opening the center ofthe viewport is always 3 to 5 degrees cooler than the edge of viewport or chamber wall. This creates a cool spot in the plasma and a good location for non-volatile by-products to accumulate. Over time this accumulation builds up so thick that it blocks any light from passing through. When the viewport is used for detection of endpoint the build up can reduce signal which will prevent the accurate detection of endpoint.

  Non-volatile by-product have a lower vapor pres- sure which will cause them to form on cooler sur- faces. Any cool spot in a plasma reactor will cause these by-products to accumulate. Introducing energy by increasing the temperature of surfaces exposed enhances the vapor pressure and evaporation rate. Therefore non-volatile by-product accumulation is retarded.

  To prevent the non-volatile by-products from accumulating in the center of the viewport a flexible heater pad was designed and placed in direct con- tact with the surface. The circular opening is pro-

vided for the purpose of fiber optic cables, emission detection or laser interferometry The heater pad is 5-10 degrees warmer than the chambe...