Specific Process Knowledge/Etch/Etching of Silicon Oxide/SiO2 etch using AOE/Standard recipe with resist mask

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This page is written by Berit Herstrøm @ DTU Nanolab (BGHE) if nothing else is stated

The standard recipe

The standard recipe for oxide etching with photo resist as masking material is called: SiO2_res. The parameters and results so fare are as follows:

Parameter	Recipe name: SiO2_res (SiO2 etch with resist mask)
Coil Power [W]	1300
Platen Power [W]	200
Platen temperature [oC]	0
He flow [sccm]	174
C4F8 flow [sccm]	5
H2 flow [sccm]	4
Pressure [mTorr]	4

Etch rates in different materials using the standard "Silicon oxide etch with resist mask"

Material to be etched	Etch rate using SiO2_res
Thermal oxide	~230nm/min (5% etch load) - etch load dependency see here ~200 nm/min (100% etch load) fall 2016 by Martin Lind Ommen @nanotech see here
TEOS oxide (5% load)	233nm/min ±0.7% - "±" represents the non-uniformity over a 100mm wafer - etched in Marts 2013 by LN/BGHE@nanolab
PECVD1 (standard) oxide (5% load)	242nm/min ±0.6% - "±" represents the non-uniformity over a 100mm wafer - etched in Marts 2013 by LN/BGHE@nanolab
Silicon (10% load)	32-36 nm/min - January 2019 bghe@nanolab
Al2O3 from the ALD	34.2 nm/min (1:6 to SiO2) fall 2016 by Martin Lind Ommen @nanotech 50nm can be etched in 10min - See results here etched in November 2014 by Frederik Stöhr @danchip
Silicon rich nitride from furnace B2	136nm was etched in 1min (whole wafer) - etched in October 2015 by bghe@nanolab
Cr	6 nm/min (1:33 to SiO2) fall 2016 by Martin Lind Ommen @nanotech see here
Al	25nm/min (1:8 to SiO2) fall 2016 by Martin Lind Ommen @nanotech see here

Using different resist masks: results using the standard recipe for "Silicon oxide etch with resist mask"

.	Az5214E	MIR701	nLof	KRF	CSAR
Selectivity to thermal oxide [:1]	2-3 - etch load dependency see here 1.9 - tested November 2015 by BGHE 2 - tested December 2022 by BGHE	1.8 - tested November 2015 by BGHE	2.0 - tested November 2015 by BGHE	~2 - tested May 2013 by Christian Østergaard @nanotech.	.
Profile [o]	~90 - depends on the resist profile before etch, this was obtained with a negative process	.	.	.	.
Roughness of the resist after etch - striation on sidewalls	see here	see here	see here	.	.
Images	See here	.	.	See images here	.
Comments	A negative resist process was done to make the mask. I have not had so good results with a positive resist process.	.	.	.	Using the standard oxide recipe (SiO2_res) for 1 min the CSAR looked burned and could not be removed by CSAR stripper (AR600-71). For a better recipe look here Tried again (2016-08-19 bghe) with 1min with CSAR resist and this time it did not look burned.

Variations over the standard "SiO2 etch with resist mask" recipe

Parameter	Recipe name: SiO2_res (SiO2 etch with resist mask)	Variations over SiO2_res made in 2010 by BGHE
Coil Power [W]	1300	1000-1600
Platen Power [W]	200	150-300
Platen temperature [oC]	0	0
He flow [sccm]	174	174, 300
C4F8 flow [sccm]	5	5
H2 flow [sccm]	4	0, 4
Pressure [mTorr]	4	2.3, 4

Typical results	Variations over SiO2_res made in 2010 by BGHE See results here
Etch rate of thermal oxide	~160-340nm/min
Selectivity to AZ resist [:1]	2.7-4.3
Profile angle	83-90
Images	See here
Comments	.