Specific Process Knowledge/Etch/Etching of Silicon

Etch of silicon can be done by either wet etch or dry etch. The standard setups for this here at DANCHIP are:

Wet etches:

• KOH etch
• Wet PolySilicon etch

Dry etches:

• Dry etch using RIE1 or RIE2
• Dry etch using ASE

Comparison of KOH etch, wet PolySilicon etch, RIE etch and ASE etch for etching of Silicon

	KOH	PolySilicon etch	RIE	ASE
What is it good for:	Anisotropic etch in the <100>-plan High selectivity to the other plans	Isotropic etch in Silicon and Polysilicon	Can etch isotropic and anisotropic depending on the process parameters Anisotropic etch: vertical sidewalls independent on the crystal plans	As RIE but better for high aspect ratio etching and deep etches (higher etch rate) Good selectivity to photoresist
Possible masking materials:	Silicon Nitride	?	Photoresist Silicon Oxide Silicon Nitride Aluminium Chromium (ONLY RIE2!)	Photoresist Silicon Oxide Silicon Nitride Aluminium