Browse Prior Art Database

New FET On SOI Structure

IP.com Disclosure Number: IPCOM000121557D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Wang, LK: AUTHOR

Abstract

Disclosed is a new FET/SOI structure with improved short channel effect by using a dielectric layer to separate the conducting channel and the highly doped back channel.

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New FET On SOI Structure

      Disclosed is a new FET/SOI structure with improved short
channel effect by using a dielectric layer to separate the conducting
channel and the highly doped back channel.

      Conventional FET/SOI has poor short channel effect behavior
because the thick buried oxide can not prevent drain field feedback
into the channel even though there is no conduction current under the
drain region.  Although bulk punchthrough may not be observed, the
threshold roll-off can be much worse than in conventional bulk
silicon devices.  In this disclosure, a new field-effect transistor
has a structure in which the device channel region is separated from
the back channel by an insulator layer.  Although the surface channel
is lightly doped for conduction of the transistor, the back channel
substrate is highly doped in order to terminate the drain electric
field feedback into the channel region of the short channel devices.
Thus, the short channel effect can be reduced by this highly doped
shield region under the dielectric layer.  Also this dielectric layer
can provide a diffusion barrier to prevent the dopant of the highly
doped back channel region from getting into the lightly doped
conduction channel region.

      Furthermore, this structure provides a heterojunction substrate
where the material used for the channel region can be different from
that of the underlying substrate in order to gain high mobility.

      Reference
M. Fukima, "Lim...