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Browse Prior Art Database

Method of Producing Lateral Composition Changes in Semiconductors

IP.com Disclosure Number: IPCOM000103879D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 4 page(s) / 84K

Publishing Venue

IBM

Related People

Jackson, TN: AUTHOR [+2]

Abstract

Disclosed is a simple method for producing lateral composition changes in semiconductors. The performance of many devices, both electronic and optical, can be enhanced through the use of lateral changes in the semiconductor composition. However, current techniques for producing these lateral changes are quite involved, requiring multiple etching, patterning and growth steps.

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Method of Producing Lateral Composition Changes in Semiconductors

      Disclosed is a simple method for producing lateral composition
changes in semiconductors.  The performance of many devices, both
electronic and optical, can be enhanced through the use of lateral
changes in the semiconductor composition.  However, current
techniques  for  producing  these  lateral changes are quite
involved, requiring multiple etching, patterning and  growth steps.

      This disclosure  describes  how  to  make  a  laterally
selective  change in a compound semiconductor material which can be
used in a variety of  devices.    The  basic  concept takes
advantage  of the difference in the thermal stability (i.e., vapor
pressure) of the constituent materials.    These materials  are
usually  heated in an ambient containing the high vapor pressure
material to  prevent  the  surface  from decomposing.  For example,
As preferentially evaporates from GaAs,  and  so  is  heated in an As
ambient to stabilize the surface.  If this heating is done in a
different ambient, V sub 2 such that the compound IIIV sub 1 is less
stable than the compound IIIV sub 2 , then the V sub 1 material will
evaporate and the V sub 2 will be incorporated in its place.  As an
example,  heating InP  in  an  As flex will result in a surface layer
of InAs.  This can be used  to  convert  the  entire  surface,  or
by suitable  masking,  only  a portion of the surface.  Typical
masking materials can be dielectric films  such  as  silicon nitride,
refractory  metals  or  previously  deposited  and patterned
epitaxial films which contain the same high  vapor pressure  material
as  the ambient in which the material is heated.   A dopant can also
be  added  to  the  ambient  to selectively dope the converted
region.

      Figure 1 shows an example using a dielectric film to pattern an
InP channel,  resulting  in  a  non-alloyed  InAs source/drain
contact.  In Fig. 1a the channel is grown, the gate and dielectric
mask are  deposited  and  etched.  ...