Run Card for cmos150

 

Step 38.0

 

 

 

 

 

Process:  Back side etch

Date

Operator

 

 

 

 

1.

Remove PR in O2 plasma (matrix), piranha clean wafers in sink9 MEMS side (no dip). Dehydrate wafers in oven at 120 C for >30 min.

April 30th, 2002

vorosl

 

 

 

 

2.

Etch backside:

 

 

 

a) Spin PR on front side, hard bake. I-line resist.

 

 

 

b) Dip off oxide (PSG) in 5:1 BHF.

 

 

 

c) Etch poly-Si in lam4.

 

 

 

d) Final dip in BHF until back dewets.

 

 

 

g) Remove PR in O2 plasma, piranha clean wafers in sink9 MEMS side (no dip).

 

 

 

 

 

 

 

Note: only #2, #4, #8, #10 wfrs were back side etched. 10:1 HF was used instead of 5:1 Buffered HF with the corresponding etch time. Always use BHF at this step!

 

 

 

Otherwise this could happen: