Specific Process Knowledge/Etch/Wet Chromium Etch

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Wet etching of Chromium

Fume hood: positioned in cleanroom 2.
Wet Etch of Chromium can take place in a beaker in this fume hood

Wet etching of chromium at Danchip is done making your own set up in a beaker in a fume hood - preferably in cleanroom 2 or 4. You can see the APV here. We have two solutions for this:

1. Commercial chromium etch (Chrome Etch 18). You can see the KBA here
2. HNO₃:H₂O:cerisulphate - 90ml:1200ml:15g

Etch rate are depending on the level of oxidation of the metal.

How to mix the Chromium etch 2:

1. Take a beaker and add 15g of cerisulphate.
2. Add a little water while stirring - make sure all lumps are gone.
3. Add water until 600 ml - keep stirring (use magnetic stirring)
4. Add 90 ml HNO₃
5. When the cerisulphate is completely dissolved (clear liquid) you can add the other 600 ml of wafer.

Overview of the data for the chromium etches

Chromium etch 1	Chromium etch 2
General description	Etch of chromium	Etch of chromium
Link to safety APV and KBA	see APV here. see KBA here	see APV here
Chemical solution	Chrome Etch 18	HNO3:H2O:cerisulphate - 90ml:1200ml:15g
Process temperature	Room temperature	Room Temperature
Possible masking materials	Photoresist (1.5 µm AZ5214E)	Photoresist (1.5 µm AZ5214E)
Etch rate	~ ? nm/min	~40-100 nm/min
Batch size	1-7 wafers at a time	1-7 wafers at a time
Size of substrate	4" wafers	4" wafers
Allowed materials	No restrictions. Make a note on the beaker of which materials have been processed.	No restrictions. Make a note on the beaker of which materials have been processed.