Specific Process Knowledge/Etch/Etching of Silicon Oxide

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Comparing silicon oxide etch methods at DTU Nanolab

There are a broad varity of silicon oxide etch methods at DTU Nanolab. 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 ASE
• SiO2 etch using III-V RIE
• SiO2 etch using AOE
• SiO2 etch using ICP metal
• IBE/IBSD Ionfab 300
• SiO2 etch using Plasma Asher (isotropic)

Compare the methods for Silicon Oxide etching

	Wet Silicon Oxide etch (BHF/HF)	ASE	III-V RIE	AOE (Advanced Oxide Etch)	ICP metal	IBE/IBSD Ionfab 300	HF Vapour Phase Etch
Generel description	Isotropic etch	Anisotropic etch: vertical sidewalls	Anisotropic etch: vertical sidewalls Premarily for III-V samples	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	This is a fact about HF VPE
Possible masking materials	Photoresist PolySilicon Silicon nitride (LPCVD) Blue film Cr/Au for deeper etches (plastic beaker)	Photoresist DUV resist E-beam resist Silicon Silicon Nitride Metals if they cover less than 5% of the wafer area	Photoresist DUV resist E-beam resist Aluminum Silicon Silicon Nitride	Photoresist DUV resist E-beam resist Silicon 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	HF VPE mask material 1 HF VPE mask material 2 HF VPE mask material 3
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 - ~250nm/min	Process dependent Tested range: ~1nm/min - ~30nm/min	Process dependent Tested range: ~60nm/min - ~550nm/min	Process dependent Tested range: ~40nm/min - ~200nm/min	Process dependent Tested once ~22nm/min	Sample and load dependent Expected range: 12 - 175 nm/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 (bad/no cooling!). #1 100mm wafer (or smaller with carrier) #1 150mm wafer (only when set up for 150mm)	Up to 20cm in diameter	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	Pieces #1 50 mm wafer #1 100 mm wafer #1 150 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	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 Other metals if they cover less than 5% of the wafer area Quartz/fused silica	Please take a look in the cross contamination sheet in LabManager for details GaAs, GaN, InP, with epitaxial layers Aluminum Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride Photoresist DUV resist E-beam resist	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 (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	Please take a look in the cross contamination sheet in LabManager for details Silicon Silicon oxides Silicon (oxy)nitrides Metals Alloys Stainless steel Glass III-V materials Resists Polymers Capton tape	Please take a look in the cross contamination sheet in LabManager for details Silicon Silicon oxides Aluminium