90°?

Question 2.3 On a (100) silicon wafer (400 μm thick), a 1000-A-thick SigN4 has been deposited and patterned for open

rectangles and open U-shape as shown below (with the drawings to scale). On the figure belowsketch the cross-sectional

views (across A-A) of the resulting etch fronts if the wafer is etched in KOH for 1 hour. Assume that the KOH etches (100)

silicon plane at 1 um/min while (111) silicon plane is etched at 0.02 um/min.

400 pm

20 μm

T

6 μm

Silicon

A

[110]

Vanolied to the cathode, how much force does