Mock CMOS Processing Update: Metal Etch

MEMS course structures: Full Process (Polymerization)

It seems we have narrowed down the wet etch to a specific temperature range and etch time. Heating the PAN solution to 45-50C and waiting for 45 seconds provides the best results as seen from the pictures below. Scroll down to view all of the pictu res.

Here is what the processing steps were:
Photoresist Patterning
Photoresist used: Shipley S1813
Spin speed: 4000 rpm
Approx. thickness: 1.5 um
Softbake: 90 seconds at 110C on hot plate
Exposure time: 5.3 seconds
Development: 1:1 MIF-312:DI water
Hard Bake: 20 minutes at 120C on oven

Aluminum Etch
Type of etch: Wet Isotropic Etch
Chemical used: Transene Type APre-mixed Aluminum Etch
Machine used: None
Temperature of etch: Room Temperature and 45-50 degrees Celsius
Advertised etch rate: 100 Angstroms/minute
Etch time: See below

Room Temperature, 8 minute etch sample (Click to enlarge)

Room Temperature, 9 minute etch sample (Click to enlarge)

Room Temperature, 9.5 minute etch sample (Click to enlarge)

Room Temperature, 10 minute etch sample (Click to enlarge)

Room Temperature, 10.5 minute etch sample (Click to enlarge)

Room Temperature, 11 minute etch sample (Click to enlarge)

Room Temperature, 11.5 minute etch sample (Click to enlarge)

Room Temperature, 12 minute etch sample (Click to enlarge)

Room Temperature, 12.8 minute etch sample (Click to enlarge)

Room Temperature, 13 minute etch sample (Click to enlarge)

45-50 Celsius, 10 second etch sample (Click to enlarge)

45-50 Celsius, 20 second etch sample (Click to enlarge)

45-50 Celsius, 30 second etch sample (Click to enlarge)

45-50 Celsius, 40 second etch sample (Click to enlarge)

45-50 Celsius, 50 second etch sample (Click to enlarge)