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Use of Polysilicon Films to Detect the Presence of Metallic Impurites Resulting from RIE Processing

IP.com Disclosure Number: IPCOM000103022D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Related People

Barbee, SG: AUTHOR [+6]

Abstract

A method has been proposed to detect metal impurities on semiconductor wafers after their undergoing reactive ion etch (RIE) processing. The technique involves the deposition of a polysilicon film on the wafer which highlights abnormalities which otherwise might go undetected.

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This is the abbreviated version, containing approximately 92% of the total text.

Use of Polysilicon Films to Detect the Presence of Metallic Impurites Resulting from RIE Processing

      A method has been proposed to detect metal impurities on
semiconductor wafers after their undergoing reactive ion etch (RIE)
processing.  The technique involves the deposition of a polysilicon
film on the wafer which highlights abnormalities which otherwise
might go undetected.

      Wafers are subject to the deposition of metallic impurities
(e.g., Ni) due to sputtering of metal walls, electrodes and internal
parts of the RIE reactors.  These impurities result in poor device
yield due to leakage, they are difficult to detect, and conventional
methods of de- tection are time-consuming.

      The present method includes the low pressure chemical vapor
deposition (LPCVD) of polysilicon at elevated temperatures on
single-crystal silicon wafers that have been exposed to an extended
RIE process.  If metallic impurities have been sputtered onto the
wafer surface they will heterogeneously catalyze the growth rate of
the polysilicon and result in a very hazy polysilicon film as viewed
by oblique light or SP2OT, as compared to smooth polysilicon
deposited on unetched silicon wafers.  The very hazy polysilicon film
is characterized by large sili- con surface protuberances (bumps)
and, at times, "whiskers", which can be easily verified by a scanning
electron microscope.

      The proposed technique is useful in determining the amount and
source of sputtering...