Dear All,

I am using 1 micron thick thermal oxide, grown using dry-wet-dry sequence, as
the mask during bulk etching of silicon using KOH solution. After oxidation I
notice pin holes in oxide surface. Because of these pin holes, silicon is
getting etched in KOH at places where I don't want to etch.

Please suggest a remedy.

Note: I am using (100) p-type 1-10 ohm-cm Si wafer.
Cleaning sequence: TCE, acetone, nitric acid, dilute HF
Dry-wet-dry durations: 20 min - 4 hrs - 20 min, followed by 30 min annealing
in N2 ambient.

Thank you

--
H V Balachandra Achar