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Field-Effect Transistor Produced Using Selective Epitaxy

IP.com Disclosure Number: IPCOM000037107D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Kuech, TF: AUTHOR [+2]

Abstract

Disclosed is a transistor structure fabricated using selective epitaxy which permits lateral tailoring of the dopant distribution and composition within the device structure. The substrate is prepared for selective epitaxy by opening windows in a dielectric mask where the growth is to occur. In this case selective epitaxy will deposit epitaxial layers on the unmasked regions of the substrate, with no deposition occurring on the dielectrically-masked regions. This structure also takes advantage of the conformal nature of selective growth in trenches.

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Field-Effect Transistor Produced Using Selective Epitaxy

Disclosed is a transistor structure fabricated using selective epitaxy which permits lateral tailoring of the dopant distribution and composition within the device structure. The substrate is prepared for selective epitaxy by opening windows in a dielectric mask where the growth is to occur. In this case selective epitaxy will deposit epitaxial layers on the unmasked regions of the substrate, with no deposition occurring on the dielectrically-masked regions. This structure also takes advantage of the conformal nature of selective growth in trenches.

Fig. 1 illustrates a possible structure. In Fig. 1a, the channel has been previously formed, and trenches have been etched in the source and drain regions. The source/drain contacts are selectively deposited only in these trenches. Because of the conformal nature of the deposition, growth will occur simultaneously on the walls and floors of the trenches (but not on the dielectric mask region). The doping concentration and composition can then be altered as this growth proceeds.

In the example of Fig. 1b, the first portion of the contact is less heavily doped than the subsequent part. This permits tailoring of the dopant profile to achieve minimum resistance between the gate and drain and gate and source, as well as preventing premature breakdown if the contact doping is too high. This can also be used to reduce short channel effects. The region between the ohmic...