SOI wafer manufacturing
Most SOI wafers are fabricated by use of one of two basic
approaches.
- SOI wafers may be fabricated with the SIMOX(TM) (Separation by
IMplanted OXygen) process, which employs high dose ion implantation of
oxygen and high temperature annealing to form the buried oxyde (BOX)
layer in a bulk silicon wafer.
- Alternately, SOI wafers can be fabricated by bonding a device
quality silicon wafer to another silicon wafer (the “handle” wafer)
that has an oxide layer on its surface. The pair is then splitted
apart, using a process that leaves a thin, device-quality layer of
single crystal silicon on top of the oxide layer (which has now become
the BOX) on the handle wafer.
The “layer transfer” approach has lead to the development of at
least three production methods for fabrication of SOI wafers
:SmartCut(TM) SOI wafers, NanoCleave(TM)SOI wafers, and ELTRAN(TM) SOI
wafers. The SmartCut(TM) and NanoCleave(TM) processes both employ high
dose ion implantation (using hydrogen or other light species), either
alone or in combination with other steps, to form a weakened silicon
layer that splits (i.e., “peels off”) the donor wafer. The ELTRAN(TM)
method employs a layer of porous silicon, which is formed by anodic
etching and annealing, to form the splitting layer.
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