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Process End Point Detect Performance Improvement

IP.com Disclosure Number: IPCOM000048152D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Saraf, LH: AUTHOR [+2]

Abstract

Process End Point Detect (PEPD) is the real time lithography wet and dry process monitoring system. A very narrow beam of light projected on the transparent thin film, either photoresist or oxide, is reflected back. This signal is integrated to give the ability to detect the end point when the thin film is etched completely. This signal is thus very important for its accuracy and precision. If the surface under the thin film is not very smooth and uniform, then the reflected signal is very erratic and noisy, which results in large uncertainty for the end point detection.

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Process End Point Detect Performance Improvement

Process End Point Detect (PEPD) is the real time lithography wet and dry process monitoring system. A very narrow beam of light projected on the transparent thin film, either photoresist or oxide, is reflected back. This signal is integrated to give the ability to detect the end point when the thin film is etched completely. This signal is thus very important for its accuracy and precision. If the surface under the thin film is not very smooth and uniform, then the reflected signal is very erratic and noisy, which results in large uncertainty for the end point detection.

If a blanket silicon wafer is used and processed along with the product job for the thin film deposition, then it can be used as the test wafer for the PEPD control. The silicon smooth uniform surface results in a very clean smooth PEPD signal, and the end point detection is very accurate. Also, it saves the area on the product wafer, increasing the usable wafer area for product chips, thus increasing productivity. Since the etch end point detection is repeatable and accurate, the product dimension control is tighter. Product yields and reliability are enhanced.

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