4. For a square mask opening of length L the maximum etch depth achievable with anisotropic wet etching on a slicon wafer is a. L b. 0.707L c. Unpredictable d. None of these Reason: 5. Which of the following cross-sectional structures could possiblv be the resultant of DRIE on a Silicon wafer with patterned oxide layer on top? DRIE = Deep Reactive lon Etching Reason