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Browse Prior Art Database

Self-Aligned N+-Contacts in MESFETs

IP.com Disclosure Number: IPCOM000119664D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Kuech, TF: AUTHOR [+3]

Abstract

Although, the source/drain regions in the state of the art III-V MESFETs can be formed in a self-aligned manner, there is no known process which can provide self-aligned source/drain contacts in the MESFETs. This article describes a method to fabricate self-aligned contacts in MESFETs using a novel n+-doping process from a Si cap. It has been demonstrated previously that carrier concentrations of 5x1018 - 1x1019 cm-3 are obtained when Si-capped GaAs undergoes a combination of rapid thermal oxidation (RTO) and rapid thermal annealing (RTA) steps. After the doping, the same Si cap is used as a template to achieve self-aligned contact formation in MESFETs in a manner analogous to that used in the Si technology.

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This is the abbreviated version, containing approximately 60% of the total text.

Self-Aligned N+Contacts in MESFETs

      Although, the source/drain regions in the state of the
art III-V MESFETs can be formed in a self-aligned manner, there is no
known process which can provide self-aligned source/drain contacts in
the MESFETs.  This article describes a method to fabricate
self-aligned contacts in MESFETs using a novel n+doping process from
a Si cap.  It has been demonstrated previously that carrier
concentrations of 5x1018 - 1x1019 cm-3 are obtained when Si-capped
GaAs undergoes a combination of rapid thermal oxidation (RTO) and
rapid thermal annealing (RTA) steps.  After the doping, the same Si
cap is used as a template to achieve self-aligned contact formation
in MESFETs in a manner analogous to that used in the Si technology.
For example, in a Si MOSFET with a poly-Si gate containing SiO2
sidewalls, contacts to the gate, source and drain regions can all be
formed in a self-aligned manner by a single blanket metal deposition
step followed by a low-temperature (<900@C) RTA step.  The formation
of self-aligned contacts utilizes either the self-aligned silicide
process (TiSi2 or CoSi2) or the selective chemical vapor deposition
(CVD) of W in Si-based devices.  The contact alignment occurs
because, the refractory or near-refractory metals used to form the
contacts do not react with SiO2 at temperatures (<600@C) where they
strongly react with Si.  The same process can be used to fabricate
self-aligned contacts in III-V MESFETs if pure SiO2 or Si...