Browse Prior Art Database

Real Time Photoresist Development Control

IP.com Disclosure Number: IPCOM000088068D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Moritz, H: AUTHOR

Abstract

During the manufacture of integrated circuits (Fig. 1), semiconductor substrates S coated with photoresist P are exposed L by means of a mask M. In the case of a positive photoresist, the exposed areas are chemically dissolved in a development process.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 64% of the total text.

Page 1 of 1

Real Time Photoresist Development Control

During the manufacture of integrated circuits (Fig. 1), semiconductor substrates S coated with photoresist P are exposed L by means of a mask M. In the case of a positive photoresist, the exposed areas are chemically dissolved in a development process.

The dissolution rate of the exposed photoresist is a sensitive function of exposure light intensity I. Because of diffraction, the light intensity changes only gradually from zero to its maximum value IO at the edges of the mask images in the photoresist plane. Consequently, the resist dissolution rate increases equally gradually. This makes the image size eventually opened very sensitive to many process variables, especially he developer temperature, the concentration, and the resist film t thickness.

An effective means for controlling this process is to measure time TO from the beginning of development to the first breakthrough of the photoresist film on an area size XB exposed to the maximum light intensity IO. The breakthrough can be observed with an endpoint detector. This time TO is used to calculate on- line the total development time TD = (1 + Alpha) TO to obtain an image size XM. The parameter Alpha depends only on exposure parameters, type of exposure tool, light intensity, exposure time, etc., rather than on developer parameters. Thus, it can be set before photoresist development. The image size eventually opened in the photoresist film is approximately a log log...