Hi-

I have been attempting to perform a successful Bosch process on an STS
Mulitplex System for about 1 year and continually having problems. I will
attempt to provide all the information of the process.

1. Start with new wafers: 4", P/Boron, Resistivity: >5000 ohm-cm, Both
sides polished
2. Dry out wafer 110C 1-2min
3. Spin on HMDS, followed by AZ P4620
4. Ramp heat on hotplate ending with 115C for about 20min
5. Expose on an MA6; develop with AZ400K at about a 1:3 ratio
6. Rinse DI water for 1-2 min
7. Post bake at 65C for 4-5 hours (high temp causes the resist to flow)
8. Mount the post baked wafer to a new wafer using Cool Grease at 65-70C,
let cool
9. Put in ICP

I am using plastic containers for the developing and metal tweezers (Teflon
came off)

My helium leakup rates have been anywhere from in the 3's to the 8's

The normal ICP parameters are as follows:
Etch = 10s    Passive = 7s  RF Power = 12W (these are the only parameters I
have tried to vary at this point)

Other parameters that might be useful:
Apc mode 68.4%
Base pressure 0.1 mTorr
Pressure Trip 94.0 mTorr

Gases         Etch                   Pass
                Flow   Tol           Flow    Tol
C4f8             0   50             100        5
SF6          130   50              0           5
O2           13.0   50             0          5

13.56 MHz coil
Power 600 W Tol 50%
Platen Power 12W
Electrode 13.56 MHz Match 50%
Range 0-30 W


I have attempted four variations at this point. You can see pictures of the
results along with the varying parameters:
http://www.mirctech.gatech.edu/ICP_problems2.pdf

Generally when I have looked at the wafers prior to the ICP run, I do not
see the particles or if I do there are very few of them.

Has anyone seen something like this before and could provide me with some
insight or suggestions?

Much thanks!
Pete