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Optimized Endpoint Exposure for Photoresist Development

IP.com Disclosure Number: IPCOM000040856D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hume, EC: AUTHOR [+3]

Abstract

This article discloses a method for continuously monitoring the photoresist developing process so that the developing can be stopped to achieve optimal line width control and resolution automatically, without human intervention. It is known to provide on a photoresist covered wafer a pattern of boxes, each of which is exposed to a different radiation level. Following developing and analysis of the developed patterns, the optimal radiation exposure level is then determined.

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Optimized Endpoint Exposure for Photoresist Development

This article discloses a method for continuously monitoring the photoresist developing process so that the developing can be stopped to achieve optimal line width control and resolution automatically, without human intervention. It is known to provide on a photoresist covered wafer a pattern of boxes, each of which is exposed to a different radiation level. Following developing and analysis of the developed patterns, the optimal radiation exposure level is then determined.

A test site can be created on a semiconductor wafer which after photoresist application can be exposed to this optimal radiation level. During developing, this test site can be monitored using laser interferometry so that the developing process can be terminated automatically when complete.

The test site can be exposed to the optimal radiation level by various means, depending upon the type of exposure instrument used. For an E-beam exposure, the test site can be directly written at the optimal exposure level. When a step and repeat exposure tool is used, the test site can also be directly exposed at the optimal exposure level. However, when a tool that exposes an entire wafer is used, it is not as easy to expose the test site to a radiation level which differs from the rest of the wafer. This can be accomplished by including on a reticle a grating pattern which effectively reduces the exposure level from that which the rest of the wafer i...