Browse Prior Art Database

Wafer Serial Number Reader

IP.com Disclosure Number: IPCOM000045090D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Hebert, RC: AUTHOR [+2]

Abstract

This article concerns apparatus for inexpensively reading theta modulated wafer identification numbers. The apparatus features use of a laser symbol reader in combination with a computer-controlled wafer alignment table. The apparatus automatically reads the identification number and displays the number to an operator.

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 91% of the total text.

Page 1 of 2

Wafer Serial Number Reader

This article concerns apparatus for inexpensively reading theta modulated wafer identification numbers. The apparatus features use of a laser symbol reader in combination with a computer-controlled wafer alignment table. The apparatus automatically reads the identification number and displays the number to an operator.

The problem addressed by this apparatus is to machine read theta modulated identification numbers on product wafers by means of a small, inexpensive desktop unit. As shown in the figure, the unit 1 is manually loaded with a wafer 2 containing an eight-digit theta-modulated identification number 3. The number is manually scanned under a helium neon laser beam 4 generating a diffraction pattern which is in turn detected by a diode sensor 5. The laser beam reflects from the wafer surface at an angle of approximately 5 degrees from the normal, allowing a 10 degrees separation between the laser and diode detector. Synchronization of the serial number position relative to the point of maximum diffraction is achieved via an encoder/decoder arrangement affixed to the scanning chuck. The chuck functions of wafer alignment and vacuum hold- down are achieved by a simple, manually-operated stage 6. The speed of the scan is controlled by a piston-damping system 7.

The reader sequencing and data handling are controlled by a microprocessor. This device monitors the tool state and processes for all the fraction data with synchronization...