Specific Process Knowledge/Etch/AOE (Advanced Oxide Etch)/Silicon Nitride Etch using AOE

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Silicon nitride - fast - with resist mask

Parameter	Recipe name: SiN_res (SiN etch with resist mask)
Coil Power [W]	1300
Platen Power [W]	350
Platen temperature [oC]	0
He flow [sccm]	174
CF4 flow [sccm]	40
Pressure [mTorr]	4

Typical results	Test Results
Etch of Si3N4 with DUV mask	See images here
Etch rate of Si3N4	~435nm/min (50% etch load) Marts 2016 by bghe@nanolab
Etch rate of Silicon	~264nm/min (50% etch load) Marts 2016 by bghe@nanolab
Etch rate of DUV resist]	~600nm/min (50% etch load) Marts 2016 by bghe@nanolab
Profile [o]	close to 90 degrees see the images

Small variation of the Silicon nitride etch SiN_res - with Cr mask

Done by Anders Simonsen @nbi.dk

Parameter	Recipe name: SiN_AS
Coil Power [W]	1300
Platen Power [W]	350
Platen temperature [oC]	5
He flow [sccm]	174
CF4 flow [sccm]	40
O2 flow [sccm]	4
Pressure [mTorr]	4

Typical results	Test Results
Etch of Si3N4 with Cr mask	See results here: Cr etch development and silicon nitride report summery by Anders Simonesen, summer of 2022 Here are the raw test data and SEM images from Anders Simonsen
Etch rate of Si3N4	~420 nm/min Summer 2022 by asimonsen@nbi.ku
Etch rate of Cr	1:17, see discussion in the summery
Profile [o]	close to 90 degrees see the images in the links

Silicon nitride etch with the standard silicon oxide etch

The standard recipe for oxide etching with photo resist as masking material is called: SiO2_res. It can also be used for nitride etching. 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

Typical results	Test Results
Etch rate of Silicon rich nitride from furnace B2	136nm was etched in 1min (whole wafer) - etched in October 2015 by bghe@nanolab
Etch of Si3N4 with DUV mask	See images here
Etch rate of thermal oxide	~230nm/min (5% etch load)
Selectivity SiO2 to AZ resist [:1]	~3
Selectivity SiO2 to DUV resist [:1]	~2.0 - tested May 2013 by Christian Østergaard @nanotech.
Profile [o]	~90

Silicon nitride etch with lower etch rate

Test of etch in silicon nitride (LPCVD). 105nm nitride had to be removed - it was removed after 1min and 40s with a very small over etch in Si.

Parameter	Recipe name: Nitr_res (Silicon Nitride etch using resist mask)
Coil Power [W]	700
Platen Power [W]	100
Platen temperature [oC]	0
C$_{4}$F$_{8}$ flow [sccm]	5
He flow [sccm]	174
H$_{2}$ flow [sccm]	4
Pressure [mTorr]	4

Typical results	Resist mask	Resist mask
Silicon nitride (LPCVD) etch rate	~60 nm/min	99-108 nm/min (LN/BGHE 20130514)
Selectivity to photo resist [:1]	?	~between 2.5 and 4.0 (LN/BGHE 20130512)
Etch rate in Si	?	?
Etch rate in SiO2	?	?
Profile [o]	not tested	not tested
Etch uniforminty over a wafer [o]	not tested	± 1.1% to ±1.8% (Eric Jensen @nanotech, oct. 2013)
Images	.	.
Comments	.	.