Specific Process Knowledge/Etch/DRIE-Pegasus/Pegasus-4/Nitride Etch

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

Etching of silicon rich nitride (SRN) with recipes developed for SiO2 etching

Unless otherwise stated, all content in this section was done by Berit Herstrøm, DTU Nanolab

Parameter	Recipe name: SiO2_res_10	Recipe name: DOE2/Post_II_21
Coil Power [W]	2500	3840
Platen Power [W]	300	300
Platen temperature [oC]	20	20
H2 flow [sccm]	25.6	0
He flow [sccm]	448.7	0
C4F8 flow [sccm]	25.6	30
Pressure [mTorr]	8.8	0.9

Measured results	SiO2_res_10	DOE2/Post_II_21
Average etch of SRN on 6" wafer	166 nm/min [+- 17% over a 6" wafer]	142 nm/min [+- 9% over a 6" wafer]
Etch rate of Si3N4	?	?
Etch rate of SiO2	250 nm/min [+- 3% over a 6" wafer]	306 nm/min [on small piece]
Etch rate in Si	?nm/min	? nm/min
Etch rate of Mir resist	? nm/min	? nm/min

Etch rate uniformity

• SRN (LPCVD) etch uniformity with recipes optimized for SiO2 etching tested on unpatterned wafers
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Adding electromagnets (EM) to see if that could improve the uniformity

Recipe used: SiO2_res_10

SRN etch with SiO2_res and EM:02/30. The electromagnets did not change much. Average etch rate: 166.5 nm/min +-12%

SRN etch with SiO2_res and EM:10/0. The outer coil just seems to make it worse. Average etch rate: 114 nm/min +-60%