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

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Silicon nitride etch with STS recommended silicon nitride recipe

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 of the STS recommended silicon nitride recipe - with Cr mask

Done by Anders Simonsen @nbi.dk

Parameter Recipe name: SiN_res (SiN etch with resist mask)
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:
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
CF flow [sccm] 5
He flow [sccm] 174
H 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)
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