Specific Process Knowledge/Etch/Etching of Chromium

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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 ICP metal
• Sputtering of Cr

Comparison of Chromium Etch Methods

	Cr wet etch	ICP metal	IBE (Ionfab300+)
Generel description	Wet etch of Cr premixed (Chrome etch 18)	Dry plasma etch of Cr	Sputtering of Cr - pure physical etch
Etch rate range	~150nm/min at room temperature	~14 nm/min (depending on features size and etch load)	~30nm/min (not tested yet)
Etch profile	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	150 mm wafers Smaller wafers or pieces on a 150 mm carrier wafer	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	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

Comparison of Chromium Etch Methods

	Cr wet etch	ICP metal	IBE (Ionfab300+)	DRIE-Pegasus 2
General description	Wet etch of Cr premixed (Chrome etch 18)	Dry plasma etch of Cr	Sputtering of Cr - pure physical etch	Primarily shallow etching of silicon but also thin layers of SiO2, TaO2 and Cr
Etch rate range	~150nm/min at room temperature	~14 nm/min (depending on features size and etch load)	~30nm/min (not tested yet)	very slow
Etch profile	Isotropic	Anisotropic (vertical sidewalls)	Anisotropic (angles sidewalls, typical around 70 dg)	Anisotropic (vertical sidewalls)
Substrate size	Any size and number that can go inside the beaker in use	150 mm wafers Smaller wafers or pieces on a 150 mm carrier wafer	Smaller pieces glued to carrier wafer 50mm wafer 100mm wafer 150mm wafer 200mm wafer	150mm wafer Smaller wafers or pieces on 150mm carrier
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	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	Silicon Silicon oxides Silicon nitrides Thin layers of Cr, TaO2