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Sigma etch improve SiGe strained Si
perofrmance for 45nm
A new selective etch productintroduce sigma etchant etches an exposed
silicon area, creating a well-defined "sigma" shape for epitaxy,
removes
post-etch residue and acts as a preclean
The etchant under etches the “sigma” shape of the gate layer to
improve electrical performance on advanced nodes by selectively etching
doped silicon crystallographic planes <111> and
<110>, without affecting the surrounding materials
Sigma tech was developed as a
“self-cleaning” chemistry; no additional rinse is
required for cleaning after the etch process. By creating well-defined
crystallographic planes, it improves the lattice matching between the
deposited SiGe and the existing silicon for better device performance
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