Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Patterned Mask Inspection Technique

IP.com Disclosure Number: IPCOM000076947D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Ionta, AM: AUTHOR [+2]

Abstract

Masks used to expose integrated circuit patterns in semiconductor manufacturing processes are difficult to inspect visually, because of the relative size difference between undesirable defects and the mask pattern. This technique allows inspection and identification of random defects in photolithographic masks which have repetitive patterns.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Patterned Mask Inspection Technique

Masks used to expose integrated circuit patterns in semiconductor manufacturing processes are difficult to inspect visually, because of the relative size difference between undesirable defects and the mask pattern. This technique allows inspection and identification of random defects in photolithographic masks which have repetitive patterns.

An original mask 1 containing various types of defects 2 through 7 is shown as A. In order to enable visual inspection, a negative film transparency 8 and a positive film transparency 9 are prepared from mask 1. All defects, as well as original patterns, are now represented as both positive and negative images. Next, transparency 8 and 9 are superimposed and shifted with respect to each other by one pattern length, as shown as D. Defects in original mask 1, both additive and subtractive, are clearly visible as clear areas on the superimposed transparency. Light-sensitive detection equipment may be used to provide identification and/or location of defects. Pattern misalignment may also be detected by this technique.

The same results can be obtained by substituting shifted positive and negative superimposed photoresist exposures on a glass plate for the positive and negative transparencies.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]