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Gas Supply Configuration for Dry Etching Tools for Improved Etch Uniformity

IP.com Disclosure Number: IPCOM000121424D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Oehrlein, GS: AUTHOR

Abstract

Supply of reactive gases to dry etching tools is conventionally provided through a showerhead or an equivalent device. For many etching applications, e.g., Si trench etching, redeposition of etch product, which leads to passivation of the sidewalls of etching features, is required for satisfactory performance of the etching process. This mechanism causes problems in achieving good etch uniformity. In the center of the wafer a great deal of etch product is produced and satisfactory redeposition results. At the edge of the wafer the concentration of etch product in the gas phase is lower, the etch profiles are non-ideal and/or the etch rate differs from that in the center.

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Gas Supply Configuration for Dry Etching Tools for Improved Etch
Uniformity

      Supply of reactive gases to dry etching tools is conventionally
provided through a showerhead or an equivalent device.  For many
etching applications, e.g., Si trench etching, redeposition of etch
product, which leads to passivation of the sidewalls of etching
features, is required for satisfactory performance of the etching
process.  This mechanism causes problems in achieving good etch
uniformity.  In the center of the wafer a great deal of etch product
is produced and satisfactory redeposition results.  At the edge of
the wafer the concentration of etch product in the gas phase is
lower, the etch profiles are non-ideal and/or the etch rate differs
from that in the center.

      One possible solution of this problem consists of the following
configuration: the supply of the reactive etching gas to the dry
etching tool is provided through two independent channels: and the
etching gas mixture is supplied through the conventional gas supply
device, e.g., a showerhead.  Additionally the etching wafer is
surrounded (at a suitable distance) by a gas distribution ring which
provides a controlled amount of the primary etch product, e.g., SiF4,
SiCl4, or SiBr4 .  By controlling the amount of etch product near the
edge of the wafer independently from the main gas supply it is
possible to balance any concentration gradients of the etch product
which occur at the edge of the wafer, thus i...