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Detection of Physical or Chemical Vapor Deposited Solid or Liquid Phase Debris by Acoustic Emission

IP.com Disclosure Number: IPCOM000113138D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Bobroff, N: AUTHOR [+4]

Abstract

An instrument is disclosed which detects solid or liquid phase debris contamination during the physical or chemical vapor deposition of thin films. The acoustic signature produced during the collision of the debris with the deposition substrate is detected using a high frequency microphone together with appropriate electronic amplifiers and filters.

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Detection of Physical or Chemical Vapor Deposited Solid or Liquid
Phase Debris by Acoustic Emission

      An instrument is disclosed which detects solid or liquid phase
debris contamination during the physical or chemical vapor deposition
of thin films.  The acoustic signature produced during the collision
of the debris with the deposition substrate is detected using a high
frequency microphone together with appropriate electronic amplifiers
and filters.

      This acoustic detection method has been implemented on an Airco
FC3200 electron beam evaporator.  A high frequency piezo-electric
microphone was mounted to the back of a silicon wafer using vacuum
grease.  The electronic signal from the transducer was amplified with
a pre-amp and oscilloscope for a total amplification of 90 dB.  A
band pass filter in the range of 300-600 KHz was used to eliminate
the acoustic background noise from the signal.  The silicon wafer and
coupled transducer were placed approximately 0.75 m above a silicon
electron beam deposition source.  The source material was induced to
spit by rapid nonuniform heating which causes great instabilities in
the silicon melt.  A clear signal of 0.1Volts to 5Volts is observed
when spit debris impacts the wafer.  The envelope of the oscillating
signal decays with the acoustic damping constant of the detector.  In
this manner, solid Si particles 0.02 to 0.2 mm in size were detected.

      The potential uses of this invention cover many asp...