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Pulling of Silicon Monocrystals

IP.com Disclosure Number: IPCOM000090319D
Original Publication Date: 1969-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Dreckmann, M: AUTHOR

Abstract

For the computer-controlled pulling of Si monocrystals by the Czochralski method, the diameter of monocrystal 2 may be readjusted by optical electrical diameter measuring apparatus evaluating half the crystallization heat radiation ring. The apparatus comprises a television camera, a television set and a circuit arrangement for measuring the distances of the two intensity maxima on the image line coinciding with the ring diameter.

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Pulling of Silicon Monocrystals

For the computer-controlled pulling of Si monocrystals by the Czochralski method, the diameter of monocrystal 2 may be readjusted by optical electrical diameter measuring apparatus evaluating half the crystallization heat radiation ring. The apparatus comprises a television camera, a television set and a circuit arrangement for measuring the distances of the two intensity maxima on the image line coinciding with the ring diameter.

During this process, the distribution of the radiation intensity on the surface of melt 5 and crystal 2 near the phase boundary is recorded through a filter arrangement by the television camera. Simultaneously, a light double ring is discernible on the crystal peripheries 3 and 4. Image line 6 extending through peripheries 3 and 4 supplies as a video signal a representation of the intensity distribution as shown under 7. The distance of the intensity maxima is either converted into a proportional DC voltage or is clock-frequency counted in a digital system. A logic circuit permits using any image line for distance measurements. The intensity distribution can be simultaneously measured on two lines, the ring diameter DR at the known line distance being computed independently of the location of the image on screen 1. Computation is made by extrapolating the electronic measuring values at several points of the ring.

The radius r of crystal 2 and the derivative partial derivative r/partial derivative t are us...