Specific Process Knowledge/Etch/Etching of Silicon Oxide

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Comparing silicon oxide etch methods at Danchip

There are a broad varity of silicon oxide 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.

• Wet Silicon Oxide Etch
• SiO2 etch using RIE2
• SiO2 etch using AOE
• IBE/IBSD Ionfab 300
• SiO2 etch using Plasma Asher (isotropic)

Compare the methods for Silicon Oxide etching

	Wet Silicon Oxide etch (BHF/HF)	RIE (Reactive Ion Etch)	AOE (Advanced Oxide Etch)	ICP metal	IBE/IBSD Ionfab 300
Generel description	Isotropic etch	Anisotropic etch: vertical sidewalls	Anisotropic etch: vertical sidewalls	Anisotropic etch: almost vertical sidewalls We prefer that SiO2 etch takes place in the AOE, since it is a very polymeric process an the ICP is not heating as much as the AOE.	Primarily for pure physical etch by sputtering with Ar-ions
Possible masking materials	Photoresist PolySilicon Silicon nitride (LPCVD) Blue film Cr/Au for deeper etches (plastic beaker)	Photoresist DUV resist E-beam resist Silicon Oxide Silicon Nitride 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 this)	Photoresist DUV resist E-beam resist Si Silicon Nitride Aluminium Chromium Ti	Any material that is accepted in the machine
Etch rate range	~75 nm/min (Thermal oxide) in BHF ~90 nm/min (Thermal oxide) in SIO Etch ~25 nm/min (Thermal oxide) in 5%HF ~3-4µm/min in 40%HF	Process dependent Tested range: ~20nm/min - ~120nm/min	Process dependent Tested range: ~230nm/min - ~550nm/min	Process dependent Tested range: ~	Process dependent Tested once ~22nm/min
Substrate size	#1-25 100mm wafers in our 100mm bath What can be fitted in a plastic beaker	As many small samples as can be fitted on the 100mm carrier. #1 100mm wafer (or smaller with carrier) #1 150mm wafer (only RIE2 when 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 when the system is set up to 150mm)	As many small samples as can be fitted on a 150mm wafer #1 50 mm wafer fitted on a 150mm wafer #1 100 mm wafer fitted on a 150nm wafer #1 150 mm wafers	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	In the dedicated bath: Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride Photoresist Blue film In a plastic beaker: No limits cross contamination wise	Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride Photoresist DUV resist E-beam resist 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 DUV resist E-beam resist Aluminium Chromium (try to avoid it) Quartz/fused silica	Please take a look in the cross contamination sheet in LabManager for details Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride Photoresist DUV resist E-beam resist Aluminium Chromium Titanium W 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