Specific Process Knowledge/Etch/Etching of Polymer

Polymer dry etching

Upgrading the silicon etch capability at Danchip with the DRIE-Pegasus has pushed our old ASE (Advanced Silicon Etcher) out of the line so that it now only serves as backup silicon dry etcher. We have therefore decided that the ASE must be converted to a polymer etcher instead. Hence, it will join the plasma asher and to some extend the RIE's where polymer etching is allowed. In RIE1 it is only for removing photo resist before or after a RIE etch if the plasma asher cannot be used for some reason. On RIE2 you can get allowance for some other polymer etching but you have to ask first.

• Etch of Photo Resist using RIE

Etching of polymers on the ASE

SPTS has provided some recipes for polymer etching on the ASE. They have NOT been tested yet (As of August 2011) and we are therefore very interested in learning whatever experiences you have. Please contact Jonas. The recipes are located in the root folder. Please copy them to your own folder and modify them there for your own purposes as you would with any other recipe.

The polymer recipes

Name	Materials		Process parameters								Comments by Kevin Riddell SPTS prior to any tests at Danchip
	Mask	Etched	O2	CO2	SF6	He/Ar	Pressure	Temp	Coil	Platen
poly1	Oxide hard mask	polyimide/PMMA	0	50	0	0	4	0	600	150	This will etch PMGI, PI, & standard resists. We've never tried it for PMMA, but it should work
poly2		standard resists, PI PMMA	20	0	0	20	3	10	600	150	This will give higher etch rates & better selectivities, but slightly more bowed profiles
poly3		BCB	43	0	7	0	4	20	800	150	A good start point for PDMS / Ormocer-type Si/ inorganic-containing polymers. The SF6/O2 ratio will depend on the composition of the polymer.

CYTOP etching: Results by Fei Wang, DTU Nanotech

Recipe

Folder\name	Materials		Process parameters								Comments
	Mask	Etched	O2	CO2	SF6	He/Ar	Pressure	Temp	Coil	Platen
set\microrea\feicy3	1.5 µm PR	CYTOP	5	0	0	20	3	0	600	150	Estimated etch rate ~1.3um/min, selectivity around 1:8, etch load app. 10%

• The results of the CYTOP etching
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Etchning of Polymers

Stripping of polymers are often done by wet chemistry in a solvent that dissolves the given polymer. If wet chemistry cannot be used or a more controled etch of the polymer is needed a plasma system is used instead. Plasma ashers are design for removing polymers in primarily oxygen plasmas. It you need a more directional etch with a masking material RIE2 or ASE can be used.

• Polymer Etch by ASE

• Process description using method 2

• Process description using method 1

• Process description using method 1

• Process description using method 1

Comparison method 1 and method 2 for the process

	ASE	Plasma asher 1	Plasma asher 2	RIE2	By wet etch
Generel description	Generel description - method 1	Generel description - method 2	Generel description - method 3	Generel description - method 4	Generel description - method 5
Parameter 1	A B	A B	A B	A B	A B
Parameter 2	A B C	A	A	A	A
Substrate size	# small samples # 50 mm wafers # 100 mm wafers # 150 mm wafers	# small samples # 50 mm wafers # 100 mm wafers # 150 mm wafers	# small samples # 50 mm wafers # 100 mm wafers # 150 mm wafers	# small samples # 50 mm wafers # 100 mm wafers # 150 mm wafers	# small samples # 50 mm wafers # 100 mm wafers # 150 mm wafers
Allowed materials	Allowed material 1 Allowed material 2	Allowed material 1 Allowed material 2 Allowed material 3	Allowed material 1 Allowed material 2	Allowed material 1 Allowed material 2	Allowed material 1 Allowed material 2