Browse Prior Art Database

Methods to Fabricate Image Size Standard and Pitch Standard

IP.com Disclosure Number: IPCOM000045257D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 4 page(s) / 23K

Publishing Venue

IBM

Related People

Jarry, A: AUTHOR

Abstract

Fabrication of an image size standard may find interesting applications in various domains such as for the calibration of measurement equipment; more particularly, it may generate image size standards on masks (or substrates) which are widely used in the semiconductor industry.

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 46% of the total text.

Page 1 of 4

Methods to Fabricate Image Size Standard and Pitch Standard

Fabrication of an image size standard may find interesting applications in various domains such as for the calibration of measurement equipment; more particularly, it may generate image size standards on masks (or substrates) which are widely used in the semiconductor industry.

Today's very accurate image size standards are limited to a size of 1 to 10 Mum. The proposed method permits the fabrication of image size standards of a range of tens to hundreds of microns, close to true size. It implies the use of a very accurate image repeater and the accurate measurement of a basic image. The basic principles of the method for manufacturing a Mask Standard will be described thereafter with regard to Fig. 1.

The fabrication is comprised of two steps.

The first step (01) consists of the generation of a special clear pattern on a chrome plate using a Pattern Generator or an E-beam.

The second step (02) consists of a photoreduction 1/10X of the special pattern, which is repeated on a resist-coated chrome plate step by step, to form negative and positive images. In front of each negative and positive image a single photoreduction at the same time exposure is printed. The photorepeater must have well-known performances in terms of repeatability and accuracy compared to the absolute.

A positive image consists of two series of consecutive and adjoining image reductions of the special clear pattern separate from of the required image size.

A negative image consists of a succession of consecutive and adjoining image reductions of the special clear pattern.

For the second step the best developing and etching processes are used to minimize the process effect. From a general point of view, a very stable process line is recommended.

The accuracy of the image size standard depends on several parameters which are: Variations of these parameters can be systematic or random

Image placement accuracy (Pa) and precision (Pp) (repeatability)

of the Image Repeater table

Reduction accuracy (Ra) and precision of the Image Repeater

Image size accuracy (Ia) and precision (Ip) over the image

process variation

Temperature variation during fabrication (T)

Clamping of chrome mask (c).

The accuracy can be calculated by the following formula:

Accuracy equals Pa + Ia + T + square root of 2 (Pp)/2/ + 2 (Rp)/2/ + Ip/2/ with all variables in micrometers. (Errors Pp, Ia and Ip are the most important).

1

Page 2 of 4

On the other hand, the pattern size depends on the number of basic patterns stepped and of the size of the first and the last basic patterns stepped.

The left side of the first basic pattern and the right side of the last basic pattern have an effect on generated pattern, equal to one basic pattern effect. d : Basic pattern size

S : Stepping size d Approximately equal to S

D : Pattern size

n : Number of adjoining basic patterns for negative image

m : Number of adjoining basic pattern skips for positive...