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Shallow Trench Planarization Process With Chemical-mechanical Polish Endpoint

IP.com Disclosure Number: IPCOM000101161D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Warnock, JD: AUTHOR

Abstract

Disclosed is a method which provides an endpoint for the shallow trench oxide chemical-mechanical (chem-mech) polish planarization step. The method relies on the incorporation of a thin polysilicon layer into the shallow trench fill which, through its higher coefficient of polishing friction, serves as an endpoint marker. This eliminates the frequent inspection and measurements presently required to determine the polishing endpoint for various shallow trench isolation processes.

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Shallow Trench Planarization Process With Chemical-mechanical Polish Endpoint

       Disclosed is a method which provides an endpoint for the
shallow trench oxide chemical-mechanical (chem-mech) polish
planarization step.  The method relies on the incorporation of a thin
polysilicon layer into the shallow trench fill which, through its
higher coefficient of polishing friction, serves as an endpoint
marker.  This eliminates the frequent inspection and measurements
presently required to determine the polishing endpoint for various
shallow trench isolation processes.

      Previous work has shown that there is a significant difference
in polishing friction depending on whether oxide/nitride is being
polished or whether polysilicon is being polished.  This difference
in polishing friction results in a dependence of the pad temperature
on the type of film being polished, and this principle has been used
as the basis for a polishing endpoint determination.  Described here
is a scheme for applying this technique to the shallow trench
chem-mech polish process.

      After the conventional shallow trench etch, fill, and partial
etch-back, a layer of polysilicon can be deposited, followed (if
necessary) by a thinner layer of oxide, or an oxidation step to
oxidize some of the polysilicon (Fig. 1a). Then, chem-mech polish is
used to remove the polysilicon and, at the same time, the excess
oxide.  The endpoint is quite clear, since it is reached when the
polysilicon...