Browse Prior Art Database

Lift off of Semiconductor Films

IP.com Disclosure Number: IPCOM000103183D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Batstone, JL: AUTHOR [+4]

Abstract

Discrete devices can be lifted off the wafers they are grown on and placed on other substrates. Disclosed is a class of polymers for this process which has advantages over the black wax presently used.

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This is the abbreviated version, containing approximately 100% of the total text.

Lift off of Semiconductor Films

      Discrete devices can be lifted off the wafers they are grown on
and placed on other substrates.  Disclosed is a class of polymers for
this process which has advantages over the black wax presently used.

      At the present time, it is known in the art that a layer of
AlAs, grown on a layer of GaAs, can be used as an interposer so that
layers grown above the AlAs layer can be lifted off the substrate.  A
film of black wax puts the top layers of the material in compression,
so that the etch rate of the AlAs layer is much faster that if the
layer is not in compression.  The film "peels back" and allows the
etch fluid (HF or HCl) to penetrate in from the side very rapidly.

      Black wax has been used to put the top layers in compression
because it is impervious to HF and HCl. However, it must be dissolved
away at a later time using acetone.

      Polymers are disclosed which decompose into a vapor at modest
temperatures can be used for the polymer layer. These polymers can be
spun on in well controlled and uniform films.  Examples of such
polymers with degradation temperatures ranging from 220oC to 350oC in
ascending order are:
.   Copolymer of poly(ethylene carbonate) and poly(propylene
carbonate)
.   Poly(propylene carbonate)
.   Poly(a-methyl styrene)
.   Poly(methyl methacrylate)

      Disclosed anonymously.