Browse Prior Art Database

Modified Crystal Pulling System

IP.com Disclosure Number: IPCOM000075933D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Schuenzel, EC: AUTHOR

Abstract

This system is directed to minimization of the problems encountered in silicon crystal pulling by conventional Czochralski systems, which involve varying impurity distributions and subsequent nonuniformity in resistivity along the pulled crystal, and to achieve a more economical method of producing single crystals. Such variation in the silicon crystal is shown in Fig. 1. Such nonuniform resistivity prevents complete utilization of the full length of the silicon crystal, since portions of the crystal must be discarded when they fall outside the tight tolerance limits required by integrated device circuits.

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 100% of the total text.

Page 1 of 2

Modified Crystal Pulling System

This system is directed to minimization of the problems encountered in silicon crystal pulling by conventional Czochralski systems, which involve varying impurity distributions and subsequent nonuniformity in resistivity along the pulled crystal, and to achieve a more economical method of producing single crystals. Such variation in the silicon crystal is shown in Fig. 1. Such nonuniform resistivity prevents complete utilization of the full length of the silicon crystal, since portions of the crystal must be discarded when they fall outside the tight tolerance limits required by integrated device circuits.

This crystal growth system, shown in Fig. 2, (with conventional heating elements omitted) continuously controls the composition of the basic molten silicon and impurity charge 1 by variable addition of molten silicon obtained by heating solid silicon rod 2 with a suitable energy source, such as induction coil 3 with a suitable susceptor. In this manner, the segregation coefficient of the impurities in the molten silicon charge can be taken into account, to permit more uniform and longer crystals 4 to be grown with more tightly controlled resistivity, as shown in Fig. 3. This enables higher yields in the use of the grown silicon crystal due to its more tightly controlled radial and axial resistivity gradients.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]