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Control of the Melt Level in a Czochralski Crystal Growth System by Means of a Solid State Line Scanner Camera

IP.com Disclosure Number: IPCOM000045262D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Riedling, K: AUTHOR

Abstract

A technique is presented for controlling the melt surface position during the Czochralski crystal growth process by using a solid-state line scanner camera.

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Control of the Melt Level in a Czochralski Crystal Growth System by Means of a Solid State Line Scanner Camera

A technique is presented for controlling the melt surface position during the Czochralski crystal growth process by using a solid-state line scanner camera.

Fig. 1 schematically illustrates the technique. A rod or beam of suitable material, e.g., graphite, is mounted within the Czochralski furnace in a fixed position such that it does not touch the melt under any reasonable operating conditions. The rod 1 with a support 2 is heated to a bright glow by the radiation within the furnace. The rod 1 and its reflection 3 on the melt surface 4 are clearly visible and can be observed under a suitable angle by means of a solid-state line scanner camera. Upon a change of the distance (d) 5 between the rod and the melt, the distance between the actual and the reflected images of the rod (2xd) changes accordingly. This causes a shift in the distance between the radiation intensity peaks 6,7 (Fig. 2) as seen by the line scanner camera. This distance can be readily determined by counting the number of picture elements (pixels) in time interval 8 between the two peaks 6,7. A suitable control system can be used either to maintain this distance at a constant value during a growth run, or to vary this distance according to the requirements of the crystal growth process. The range of the permissible melt level position and the spatial resolution depend on the number of pix...