Browse Prior Art Database

Selectively Reworkable Self-Aligned Adhesive for Semiconductor Chip Stack

IP.com Disclosure Number: IPCOM000104666D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Coteus, PW: AUTHOR

Abstract

A method for obtaining a self-aligned adhesive structure for stacking chips has been previously described [*]. In the preferred embodiment, a liquid adhesive is spun onto the back of the semiconductor wafer before the wafer is diced. By spinning, the thickness may be controlled up to about 10 microns. The adhesive is then partially cured to a solid tack-free state. The wafer is then diced, individual chips are selected and aligned for the chip stack. The stack assembly is completed through the application of elevated temperature or pressure or a combination of the two. Since the dicing operation had cut the chips and adhesive layer to the same dimensions, there will be 100% coverage without void or excess material. Alternatively, the adhesive may be procured as a partially cured dry film, preferably with a release layer.

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This is the abbreviated version, containing approximately 63% of the total text.

Selectively Reworkable Self-Aligned Adhesive for Semiconductor Chip Stack

      A method for obtaining a self-aligned adhesive structure for
stacking chips has been previously described [*].  In the preferred
embodiment, a liquid adhesive is spun onto the back of the
semiconductor wafer before the wafer is diced.  By spinning, the
thickness may be controlled up to about 10 microns.  The adhesive is
then partially cured to a solid tack-free state.  The wafer is then
diced, individual chips are selected and aligned for the chip stack.
The stack assembly is completed through the application of elevated
temperature or pressure or a combination of the two.  Since the
dicing operation had cut the chips and adhesive layer to the same
dimensions, there will be 100% coverage without void or excess
material.  Alternatively, the adhesive may be procured as a partially
cured dry film, preferably with a release layer.  The film is
laminated to the wafer with appropriate conditions of temperature and
pressure to cause it to adhere, but not completely cure.  The chips
are then diced and assembled as described above.

      If the adhesive is a thermo-plastic such as poyimide-siloxane,
adhesion of one chip to another is achieved through application of
heat above the glass transition (Tg) of the polymer, and sufficient
pressure to insure wetting of the surface to be adhered to.  It is
possible to use a hierarchy of materials with different Tg's, with
for example the bottom...