Hi all,
i need to realize a Silicon On Nothing (SON) structure of lateral size
about 0.5x0.5mm. Silicon layer should be 20nm, and nothing layer in the
range 40-60nm.

Some questions:
1) which is the best agent to etch SiGe and preserve Si ? (I've found that
PA:HF:H2O, 1:1:1 where PA=paracetic acid) should have a good selectivity,
but did not found a numerical estimate.
2) is it possible to realize a so large SON structure or the thin silicon
layer will surely destroy ?
3) which will be dislocation density in the thin silicon layer ?

Best regards,
Andrea