Specific Process Knowledge/Etch/DRIE-Pegasus/Pegasus-4/SiO2 Etch/Cr mask

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

Start parameters, variations noted in the gallery headline	Recipe name: no 10 with lower platen power
Coil Power [W]	2500
Platen Power [W]	200
Platen temperature [oC]	20
H2 flow [sccm]	25.6
C4F8 flow [sccm]	25.6
He flow [sccm]	448.7
Pressure	Fully open APC valve (8-9 mTorr)
Electromagnetic coils (EM) 'outer coil' / 'inner coil'	'2 A' / '30 A' (PLEASE DO NOT RUN WITH THESE SETTINGS FOR MORE THAN 6 MIN)

• 100 nm Cr mask etched in ICP metal with 500nm DUV neg resist (NUV 2300-0.5) and 65 nm barc.

Results

Temporary conclusions on how the process parameters affect the results in this study:

What process parameters affect the results?

Going from full wafer to small piece on Si carrier: Seemed to give more sidewall passivation Platen power: lowering the platen power gives more sidewall passivation lower etch rate Less trenching Removing the H2 gave: less sidewall passivation Adding O2 gave: less sidewall passivation Process pressure/total gasflow rate Reducing total gasflow rate which reduced the pressur inside the chamber gave: less sidewall passivation Reduced the CD (Critical Dimensions) Coil power: Reducing coil power less CD loss more sidewall passivation Increasing process time: less sidewall passivation more sidewall bow CD loss due to larger mask faceting

Sidewall passivation↑ Sample size↓ Platen power↓ Coil power↓ H2 flow↑ O2 flow↓ Total gas flow rate/pressure↑

Profile SEM images

• SiO2 etch with Cr mask on full wafer 6 min etch
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, O2:5sccm
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:225sccm, Pressure:3.35mTorr
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:225sccm, Pressure:3.35mTorr; platen power 150W, coil power:1200W
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:215sccm O2:10sccm, Pressure:3.6mTorr; platen power 150W, coil power:1200W
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:205sccm O2:20sccm, Pressure:3.6mTorr; platen power 150W, coil power:1200W
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:215sccm O2:10sccm, Pressure:3.6mTorr; platen power 150W, coil power:1800W
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:205sccm O2:20sccm, Pressure:3.6mTorr; platen power 150W, coil power:1800W
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  pitch 800 nm
  Top 461 nm
  @edge 437 nm
  bottom 402 nm
  height 916 nm
  height from edge 827 nm
  Cr left 83.5 nm
  selectivity 55.5
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  156 nm/min
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• SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:205sccm O2:20sccm, Pressure:3.6mTorr; platen power 100W, coil power:1200W
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  pitch 800 nm
  Top 444 nm
  bottom 374 nm
  height 718 nm
  Cr left 85 nm
  selectivity 48
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• SiO2 etch with Cr mask on wafer piece on Si carrier 14 min etch (PLEASE DO NOT REPEAT THIS LONG TIME), H2:0sccm, C4F8:13sccm He:205sccm O2:20sccm, Pressure:3.6mTorr; platen power 100W, coil power:1200W
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  Etch on none patterned wafer, Uniformity: +- 6.4%

• SiO2 etch with Cr mask on wafer piece on Si carrier 10 min etch, H2:0sccm, C4F8:13sccm He:205sccm O2:20sccm, Pressure:3.6mTorr; platen power 150W, coil power:1800W
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• SiO2 etch with Cr mask on wafer piece on Si carrier 14 min etch, EM:0/0 H2:0sccm, C4F8:13sccm He:205sccm O2:20sccm, Pressure:3.9mTorr; platen power 100W, coil power:1200W
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  Etch on none patterned wafer, Uniformity: +-1.7%