Browse Prior Art Database

Wafer Chuck Design for Chemical Vapor Deposition Reactor

IP.com Disclosure Number: IPCOM000109089D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Reynolds, S: AUTHOR

Abstract

Disclosed is an improved wafer chuck design for a chemical vapor deposition (CVD) reactor. An automated CVD reactor often requires a wafer clamp to hold the wafer in place on the chuck, facilitate wafer handling, and prevent backside deposition on the wafer. However, a clamp heatsinks the wafer edges and results in non-uniform wafer heating and non-uniform deposit thickness. This article describes an improved chuck design to minimize or eliminate these non-uniformities.

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Wafer Chuck Design for Chemical Vapor Deposition Reactor

       Disclosed is an improved wafer chuck design for a
chemical vapor deposition (CVD) reactor.  An automated CVD reactor
often requires a wafer clamp to hold the wafer in place on the chuck,
facilitate wafer handling, and prevent backside deposition on the
wafer.  However, a clamp heatsinks the wafer edges and results in
non-uniform wafer heating  and non-uniform deposit thickness.  This
article describes an improved chuck design to minimize or eliminate
these non-uniformities.

      Fig. 1 shows the present wafer chuck and clamp design for our
batch CVD reactor.  The metal chuck is resistively heated to the
deposition temperature (180~C) and the wafer is heated by conduction
from the chuck (radiative heating is insignificant at this
temperature).  Helium is injected behind the wafer to aid heat
conduction and minimize backside deposition of copper.  The clamp
touches the wafer around the edge, unintentionally heatsinking it.
The observed non-uniformity of 7.79% and the known activation energy
of the process imply that the wafer is approximately 4~C hotter at
the center than the edge.

      Fig. 2 shows the improved chuck design, in which a cone-shaped
cut has been made in the chuck (the cone is triangular in the cross
section).  Since heat conduction in this temperature and pressure
regime (180~C and 0.1 to 10 Torr) is inversely related to the
wafer-to-chuck gap, the wafer is heated less in...