Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

Patent · Thu Jan 01 00:00:00 EST 1981

OSTI ID:864003

Ownby, Gary W ^[1]; White, Clark W ^[2]; Zehner, David M ^[3]

---

1. Knoxville, TN
2. Oak Ridge, TN
3. Lenoir City, TN

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.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: W-7405-ENG-26
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 4292093
• OSTI ID: 864003
• Country of Publication: United States
• Language: English

Related Subjects

method
laser
irradiation
production
atomically
clean
crystalline
silicon
germanium
surfaces
relates
removing
surface
impurities
articles
off-the-shelf
p-
n-type
wafers
doped
junction
devices
principal
contaminants
oxygen
carbon
comprises
laser-irradiating
contaminated
non-reactive
atmosphere
q-switched
pulses
parameters
selected
effect
melting
substantial
vaporization
typical
application
plurality
convert
region
wafer
automatically
accomplished
pressure
below
10
-8
torr
ruby-laser
energy
density
range
60
190
mw
cm
laser irradiation
energy density
surface region
laser pulses
method comprises
laser pulse
silicon wafer
crystalline silicon
typical application
method comprise
surface impurities
pressure below
removing surface
moving surface
comprises laser
reactive atmosphere
atomically clean
junction device
junction devices
/134/117/136/148/219/438/