Hi, All,

I need to obtain a uniform layer of random pyramids on the (100)
mirror-polished monocrystalline Si surface. I have been trying the
NaOH (1-3%) + Ethyl Glycol(0.6%) + Isopropanol (5-10%) at 78 C. Here
is my questions:

1. I have already HF the sample just before the etch, so that it is
hydrophobic. But I found out that more often than not, it does not
etch. Or it just etches part of the sample. My samples ranges from
2x2cm to 5x5cm.

2. I have found out that if I RCA clean the sample before the NaOH
etch, it is harder to etch the sample.

3. If I use some diamond paste (for polishing) with grit size ranging
from 3 - 9 um to rub the sample surface, the etch begins right away.

4. After most of the surface is covered in pyramids, the surface
should be primarily comprised of (111) surfaces. And since the (111)
etches a lot slower in this solution than (100), isn't that the etch
will basically self-stopping once most of the surface is covered in
pyramids? I measured my wafer thickness before and after the texture
etch and found out that the material removed does not differ much for
20 minutes, 30 minutes and 40 minutes etch.


Any comments are welcome. I am new to the texture etch by NaOH and I
would like to hear more on this topic. Thanks!

Dave