Chemistry Reference
In-Depth Information
Illumination during etching has no effect on the etch rate.
505
The etch rate
decreases sharply at anodic potentials corresponding to the occurrence of passivation
as shown in Fig. 7.29.
516
The etch rates at the OCP are close to the peak values which
is similar to the situation in KOH, indicating very little contribution from electro-
chemical etching at the OCP. At cathodic potentials
n-
and
p
-Si are different; whereas
the etch rate on
p-
Si remains relatively unchanged, that of
n
-Si decreases with increas-
ing cathodic polarization which is also similar to that in KOH. Also, the qualitative
etching characteristics and potential-dependent etch rate are not affected by the addi-
tion of IPA. The dissolution products in 2 and 20% TMAH solutions are mainly
Si
