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Monitoring Lateral Dimensions of Semiconductor Crystals During Automated Growth

IP.com Disclosure Number: IPCOM000077801D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Corburn, DS: AUTHOR [+3]

Abstract

U. S. Patent 3,621,213 describes a system for automated growth of semiconductor crystals. In addition to the parameters monitored and controlled by the computer control system during crystal growth, a further advantage may be achieved by also automatically monitoring the crystal diameter, particularly during some of the initial stages of growth. The automated crystal growth process is basically divided into growth sections including seeding, necking, shouldering, roundover and, finally, separation from the melt. The present system provides for monitoring crystal diameter from the seeding stage, until the crystal assumes the uniform cylindrical diameter of its main body.

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Monitoring Lateral Dimensions of Semiconductor Crystals During Automated Growth

U. S. Patent 3,621,213 describes a system for automated growth of semiconductor crystals. In addition to the parameters monitored and controlled by the computer control system during crystal growth, a further advantage may be achieved by also automatically monitoring the crystal diameter, particularly during some of the initial stages of growth. The automated crystal growth process is basically divided into growth sections including seeding, necking, shouldering, roundover and, finally, separation from the melt. The present system provides for monitoring crystal diameter from the seeding stage, until the crystal assumes the uniform cylindrical diameter of its main body.

As shown, an IR-TV monitor is fixed to a given point and monitors the surface of the crystal as the crystal is drawn past this point. It is used primarily to measure the crystal diameter during the seeding. neck-in and shouldering phases of crystal growth. With conventional IR-TV equipment, it is possible to measure crystal with a sensitivity of 1150 counts per inch and a resolution of +
0.015 inch. This information is fed to the computer control system which thereupon provides the proper feedback for controlling the necking-in and shouldering phases of growth, so as to maintain the diameter within the requisite specifications.

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