Specific Process Knowledge/Etch/Etching of Silicon Nitride

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Comparing silicon nitride etch methods at Danchip

There are a broad varity of silicon nitride etch methods at Danchip. The methodes are compared here to make it easier for you to compare and choose the one that suits your needs.

Compare the methods for Silicon Nitride etching

	Wet Silicon Nitride Etch	BHF	RIE (Reactive Ion Etch)	AOE (Advanced Oxide Etch)	IBE/IBSD Ionfab 300
Generel description	Isotropic etch Well suited for removing all nitride on a wafer surface (nitride strip) without a mask. High selectivity Si₃N₄/Si (>100) and Si₃N₄/SiO₂ (>20) @ 180 C.	Isotropic etch Well suited for removing all PECVD nitride on a wafer surface (nitride strip) without a mask. Etches LPCVD nitride very slowly	Anisotropic etch: vertical sidewalls	Anisotropic etch: vertical sidewalls Deep etch	Primarily for pure physical etch by sputtering with Ar-ions
Possible masking materials	Silicon Oxide PolySilicon	Photoresist PolySilicon Blue film	Photoresist DUV resist E-beam resist Silicon Oxide Silicon Nitride Aluminium Metals if they cover less than 5% of the wafer area (ONLY RIE2!)	Photoresist DUV resist E-beam resist Silicon Oxide Silicon Nitride Aluminium Chromium (please try to avoid it)	Any material that is accepted in the machine
Etch rate range	Si₃N₄ @ 180 ^oC: ~84 Å/min Si₃N₄ @ 160 ^oC: ~60 Å/min	PECVD nitride: ~400-1000 Å/min	Typically 40-50 nm/min can be increased or decreased by using other recipe parameters.	Process dependent. Tested once to ~60nm/min	Process dependent. Has not been tested yet.
Substrate size	#1-25 100 mm wafers	#1-25 100mm wafers in our 100mm bath	As many small samples as can be fitted on the 100mm carrier. #1 100mm wafer (or smaller with carrier) #1 150mm wafer (only when the system is set up for 150mm)	As many small samples as can be fitted on a 100mm wafer #1 50 mm wafer fitted on a 100mm wafer #1 100 mm wafer #1 150 mm wafers (only RIE2 when set up to 150mm)	As many samples as can be securely fitted on a up to 200mm wafer #1 50 mm wafer with special carrier #1 100 mm wafer with special carrier #1 150 mm wafers with special carrier #1 200 mm wafer
Allowed materials	Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride	Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride Photoresist Blue film	Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride Photoresist E-beam resists DUV resists Other metals if they cover less than 5% of the wafer area (ONLY RIE2!) Quartz/fused silica	Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride Photoresist E-beam resists DUV resists Aluminium Chromium (try to avoid it) Quartz/fused silica	Silicon Silicon oxides Silicon (oxy)nitrides Metals from the +list Metals from the -list Alloys from the above list Stainless steel Glass III-V materials Resists Polymers Capton tape