Mock CMOS Processing Update
Refining the TiW wet etch
I needed to refine the titanium/tungsten wet etch since there was significant variability at
the previous temperature and time setting. Now I lowered the bath temperature to 40C and timed
the etch at about 1:20 minutes. I determined the etch completion when I could see the green oxide
layer underneath.
Here is what the processing steps were:
Photoresist Patterning
Photoresist used: AZ 4210
Approx. thickness: 1.5 um
Hard Bake: 5 minutes at 200C on hot plate
Aluminum Etch
Type of etch: Wet Isotropic Etch
Chemical used: Transene Type A Pre-mixed Aluminum Etch
Machine used: None
Temperature of etch: 45-50 degrees Celsius
Advertised etch rate: 100 Angstroms/minute
Etch time: 45 seconds
Titanium/Tungsten Etch
Type of etch: Wet Isotropic Etch
Chemical used: Hydrogen Peroxide
Machine used: None
Temperature of etch: 35-40 degrees Celsius
Advertised etch rate: 1000 Angstroms/minute
Etch time: 1:20 minutes
Titanium/Tungsten etched sample (Click to enlarge)
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