Metal treatment – Compositions – Heat treating
Patent
1979-12-28
1981-09-29
Roy, Upendra
Metal treatment
Compositions
Heat treating
148 15, 148187, 357 91, 427 531, H01L 21265, H01L 2122
Patent
active
042920930
ABSTRACT:
This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an automatically clean region. This can be accomplished in a system at a pressure below 10.sup.-8 Torr, using Q-switched ruby-laser pulses having an energy density in the range of from about 60 to 190 MW/cm.sup.2.
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Ownby Gary W.
White Clark W.
Zehner David M.
Besha Richard G.
Hamel Stephen D.
Lewis Fred O.
Roy Upendra
The United States of America as represented by the United States
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