Specific Process Knowledge/Etch/Etching of Chromium

Ething of Chromium can be done either wet or dry. For wet etching please see below on this page. Dry etching can be done either with ICP using Chlorine chemistry or with IBE by sputtering with Ar ions.

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. We have two solution for this:

1. HNO$_{3}$:H$_{2}$O:cerisulphate - 90ml:1200ml:15g - standard at Danchip
2. Commercial chromium etch

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

How to mix the Chromium etch 1:

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 HNO$_{3}$
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
Chemical solution	HNO$_{3}$:H$_{2}$O:cerisulphate - 90ml:1200ml:15g	.
Process temperature	Room temperature	.
Possible masking materials	Photoresist (1.5 µm AZ5214E)	.
Etch rate	~40-100 nm/min	.
Batch size	1-25 wafers at a time	.
Size of substrate	4" wafers	.
Allowed materials	No restrictions. Make a note on the bottle of which materials have been processed.	.

Dry etching of chromium

On the ICP Metal Etch tool a recipe for chromium is being developed.