Specific Process Knowledge/Etch/Etching of Titanium

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Etching of Chromium

Etching of chromium can be done either by wet etch, dry etch or by sputtering with ions.

• Etching of Cr by wet etch
• Etching of Cr by dry etch
• Sputtering of Cr

Comparison of Aluminium Etch Metodes

	Cr wet etch 1	Cr wet etch 2	ICP metal	IBE (Ionfab300+)
Generel description	Wet etch of Cr that you need to mix your self	Wet etch of Cr premixed	Dry plasma etch of Cr	Sputtering of Cr - pure physical etch
Etch rate range	~40-100nm/min	~?nm/min	~14 nm/min (depending on features size and etch load)	~30nm/min (not tested yet)
Etch profile	Isotropic	Isotropic	Anisotropic (vertical sidewalls)	Anisotropic (angles sidewalls, typical around 70 dg)
Substrate size	Any size and number that can go inside the beaker in use	Any size and number that can go inside the beaker in use	smaller pieces on a carrier wafer #1 100mm wafers (when set up to 100mm wafers) #1 150mm wafers (when set up to 150mm wafers)	Smaller pieces glued to carrier wafer #1 50mm wafer #1 100mm wafer #1 150mm wafer #1 200mm wafer
Allowed materials	No restrictions cross contamination wise as long as you use the right beaker and make sure that they are safe to enter in the chemicals	No restrictions cross contamination wise as long as you use the right beaker and make sure that they are safe to enter in the chemicals	Silicon Quartz/fused silica Photoresist/e-beam resist PolySilicon, Silicon oxide Silicon (oxy)nitride Aluminium Titanium Chromium	Silicon Silicon oxides Silicon nitrides Metals from the +list Metals from the -list Alloys from the above list Stainless steel Glass III-V materials Resists Polymers Capton tape

Ething of Titanium 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 Titanium

Fume hood: positioned in cleanroom 2.
Wet Etch of Titanium can take place in this pp tank or in a beaker in this fume hood

We have two solutions for wet titanium etching:

1. BHF
2. Cold RCA1

Do it by making your own set up in a beaker in a fume hood - preferably in cleanroom 2 or 4. BHF etching can also take place in the PP-etch bath in the fume hood in cleanroom 2.

Comparing the two solutions

	BHF	Cold RCA1
General description	Etch of titanium with or without photoresist mask.	Etch of titanium (as stripper or with eagle resist).
Chemical solution	HF:NH4F	NH3OH:H2O2:H2O - 1:1:5
Process temperature	Room temperature	Room temperature
Possible masking materials	Photoresist (1.5 µm AZ5214E)	Eagle resist
Etch rate	Not known (it bubbles while etching)	Not known
Batch size	1-5 4" in beaker 1-25 wafers at a time in PP-etch bath	1-5 4" wafer at a time
Etch bath	Beaker or PP-etch bath in the fume hood in cleanroom 2.	Beaker
Allowed materials	No restrictions when used in beaker or PP-etch bath in the fume hood in cleanroom 2. Make a note on the beaker of which materials have been processed.	No restrictions when used in beaker. Make a note on the beaker of which materials have been processed.

Dry etching of titanium

See the ICP Metal Etch page.