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Increasing Carbon Content in Czochralski Grown Crystals

IP.com Disclosure Number: IPCOM000049879D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Ahlgren, DC: AUTHOR [+5]

Abstract

This article describes apparatus for introducing small amounts of carbon to Czochralski grown silicon having low oxygen content in order to improve the minority carrier lifetime and associated yield of bipolar devices made from the material. The apparatus features means for introducing carbon to the molten silicon as the crystal is pulled.

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Increasing Carbon Content in Czochralski Grown Crystals

This article describes apparatus for introducing small amounts of carbon to Czochralski grown silicon having low oxygen content in order to improve the minority carrier lifetime and associated yield of bipolar devices made from the material. The apparatus features means for introducing carbon to the molten silicon as the crystal is pulled.

As shown in the figure, the apparatus includes the conventional elements of a Czochralski crystal puller, for example, a silicon dioxide crucible 1 containing molten silicon 2, a rotatable table 3 for mounting crucible 1 and controllably rotating the molten silicon, a puller 4 coupled to the silicon crystal seed and pulled ingot 5, and a heater 6 for maintaining the silicon in the molten state.

In order to introduce carbon in small amounts to the crystal, the apparatus features a heater 6 made of carbon. Additionally, heater 6 has been provided with gas ports 7 to permit passage of ambient gas 8 over the heater face and to molten silicon 2 in crucible 1. In this way carbon at heater 6 may be controllably introduced to the molten silicon 2. In an alternate form of the apparatus, one or more gases such as Co, CO(2). CH(4), CF(4) and oxygen may be used to increase the amount of carbon brought to the molten silicon.

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