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

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

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%