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A Process for Obtaining Positive Resist Slopes

IP.com Disclosure Number: IPCOM000061879D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Barber, JR: AUTHOR [+3]

Abstract

Resist slopes can be tailored by using an optical stepper in conjunction with an automatic reticle changer. For example, if a positive resist slope is desired, the resist can first be exposed through a mask having dimensions N x N. Next, the automatic reticle changer will align a second mask having dimensions M x M, where M is greater than N, and the photoresist will again be exposed. This masking sequence would be carried out on each wafer.

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A Process for Obtaining Positive Resist Slopes

Resist slopes can be tailored by using an optical stepper in conjunction with an automatic reticle changer. For example, if a positive resist slope is desired, the resist can first be exposed through a mask having dimensions N x N. Next, the automatic reticle changer will align a second mask having dimensions M x M, where M is greater than N, and the photoresist will again be exposed. This masking sequence would be carried out on each wafer.

The result of this two-reticle process is an optical image with two levels of energy. Since photoresist develop rates are proportional to the amount of light energy delivered, a resist slope could be tailored as desired. Theoretically, any number of reticles can be aligned and exposed in sequence. The automatic reticle changes minimizes problems due to misalignment of the reticles.

With this process, optimal profiles for contacts and vias could easily be obtained, and for certain applications, this process could enhance the negative photoresist profile required for metal liftoff.

Disclosed anonymously.

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