Specific Process Knowledge/Etch/DRIE-Pegasus/SOIetch

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SOI

Recipe Name Temp. Deposition step Etch step Comments
Time Pres. C4F8 SF6 O2 Coil Time Pres. C4F8 SF6 O2 Coil Platen Showerhead Runs Key words
SOI etch SOI 20 2 25 250 0 0 2000 3 30 0 400 40 2800 75 (0.025s, 75%) Old 1
SOI 20 2 25 250 0 0 2000 3 30 0 400 40 2800 75 (0.025s, 75%) New 1 OK


SOI etch acceptance test

The SOI etch uses the Low frequency (LF) platen generator to minimize the notching at buried stop layers such as the BOX layer in a SOI wafer.

SOI etch specifications
Parameter Specification Average result
Etch rate (µm/min) > 10 10.7
Etched depth (µm) 100 107
Scallop size (nm) < 800 685
Profile (degs) 91 +/- 1 90.7
Selectivity to AZ photoresist > 100 183
Undercut (µm) <1.5 0.89
Uniformity (%) < 3.5 2.7
Repeatability (%) <4 0.47



SOI etch recipe
Main etch (D->E) Etch Dep
Gas flow (sccm) SF6 400 O2 40 C4F8 250
Cycle time (secs) 3.0 2.0
Pressure (mtorr) 30 25
Coil power (W) 2800 2000
LF Platen power (W) 75 0
LF Platen Pulsing software set-up 0.025s, 75% -
Cycles 96 (process time 08:00)
Common Temperature 20 degs, HBC 10 torr, Long funnel, with baffle & 100 mm spacers