There seems to be a lot of confusion between the production of black
silicon by RIE and the "Black Silicon Method". The Black Silicon
Method, developed by Henri Jenson, uses black silicon or grass as an
indicator of the etch parameters that result in a highly anisotropic Si
etch using SF6 and O2. HOWEVER, he then adds CHF3 until the grass is
gone, leaving an anisotropic, but smooth etched surface. Some people
refer to this method as "Black Silicon Etch", though the resultant
process does not produce black silicon.
Roger Shile
-----Original Message-----
Hi Jeeva,
I am very curious about this phenomenom because now I am looking for a
method to get rough surface, say, 1um deep and 1um serparation. I know
a
method called black silicon method. It is a dry etch of silicon, and
because of some native oxide or dusts on the silicon wafer, they serve
as
micron masks in the RIE(reactive ion etching), so after the etching, the
surface will be rough, grass like surface. Then the surface will become
balck since the incident light is trapped inside the "grass". That's
why
this method is called black silicon method. I think the result of your
experiment has the same reason.
What I want to know is, was your wafer bare silicon? did you cleaned
your
wafer before the KOH etching? how long had your wafer exposed to air
before
your experiment? what's the exactly roughness of your sample, like the
depth
and spacing of those spurs?
If you could tell me some details about it, it would be highly
appreciated.
Thanks very much.
Duan