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UHV-compatible, Inert Wafer Heater for Use in Gas Source MBE

IP.com Disclosure Number: IPCOM000121511D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Ek, BA: AUTHOR [+3]

Abstract

ABSTRACT Conventional tantalum/graphite heaters are incompatible with the precursor gases typically used in gas-source MBE (such as disilane, germane, diborane, arsine, phosphine).

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UHV-compatible, Inert Wafer Heater for Use in Gas Source MBE

      ABSTRACT
Conventional tantalum/graphite heaters are incompatible with the
precursor gases typically used in gas-source MBE (such as disilane,
germane, diborane, arsine, phosphine).

      We disclose a technique to modify the graphite heaters through
the use of a Si or SiC or SiCx conformal coat over a pyroelectric
boron nitride (pBN) heater with graphite filaments embedded in it.
INTRODUCTION

      Resistivity heated tantalum and graphite filaments are commonly
used in silicon MBE to heat a silicon wafer during epitaxy.  These
filaments react with the precursor gases used in gas source MBE and
turn brittle.  Pyroelectric Boron Nitride (pBN) is a low thermal mass
dielectric material commonly used to make crucibles for effusion
cells in MBE. Pyroelectric Boron Nitride (pBN) heaters with graphite
filaments embedded in them are also commercially available for
epitaxial applications.  However, pBN tends to dissociate at
temperatures greater than 1100oC and release nitrogen.  Beyond
1400oC, rapid nitrogen evolution occurs. For the range of
temperatures typically employed for epitaxy (500oC-800oC), the local
temperatures in the heater filaments are often over 1100oC.
INVENTION

      We disclose a technique that permits the use of pyroelectric
boron nitride heaters embedded with graphite filaments, but renders
them UHV-compatible and inert.  This is achieved through the use of a
conformal sil...