Question

A c100-oriented silicon erystal is etched in a KOH solution through a 1.5 um x 15 Hm window defined in silicon dioxide. The etch rate normal to (100) planes is 0.6 pm/min. The etch rate ratios are 100:16:1 for the (100):(110):(111) planes. Show the etched profile after 20 seconds, 40 seconds, and 60 seconds.

Answer 1

Answer a) 20 Sec O.6X 20 I00) plane = 0.2m -- 60 0.6 X 20 (HD) Plane 0.0125HM 60 0.6 (D Plane O.002m y 20 60 Q X t 22 Hm by 0.6X 40 ---- (100) plane 0.4Mm 1 60 -_{u0) pane 0-0825HM X a - 1 T6 60 0.6 ) plane 0004HM (o0 60 G κοφ = l.5- X 0.93 Mm

c) 60 sec 2 06x1- 0.6Hm -.(100)Pane (10) Plane 16 I0.0375MM 0.6 (n) plane 0.006MM loo X1 11 0.65m shown ing Ha data , the ctched pattem profles on toD> -st ant in betas l 0.012 Hm, Wo= W 5Hm a) 20 Sec l 0.085HM, Wo= W = 0.0375Hm, Wo Wb.Sm c) 60 Sec