Question
A layer of 2µm thick silicon dioxide is deposited on <100> silicon wafer. SiO2 layer is patterned using lithography and dipped in BOE to etch the layer. While etching oxide layer, 10nm of silicon is also etched. What is the selectivity of BOE to etch SiO2, when Si is etch stop layer?
200:1
20:1
50:1
100:1
200:1
20:1
50:1
100:1