Question

During ic fabrication why dry oxidation first then wet oxidation

Answer 1

The good quality dry oxide is used for making structures such as gate oxide. The wet oxidationwhich is formed due to the reaction between silicon and water is relatively porous but still better than the product one will get using electrochemicaloxidation.

Answer 2

During wet oxidation, the silicon wafer is settled to a water vapour atmosphere (HO). Wet oxides really fast compared to dry oxidation, which is the biggest advantage, because of its water content, wet oxides films exhibit a lower dielectric strength and more porosity to impurity penetration than dry oxides.