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

SiO2 trench etching with Cr mask

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.
Cr mask before SiO2 etch 800 nm pitch 50% duty cycle. The The Cr linewidth is clearly less than designed


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

Recipe settings SEM gallery
  • 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
  • SiO2 etch with Cr mask on full wafer 6 min etch
  • 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
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch
  • Coil Power [W]:2500
  • Platen Power [W]: 200
  • Platen temperature [oC]: 20
  • H2 flow [sccm]:0
  • 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
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm
  • Coil Power [W]:2500
  • Platen Power [W]: 200
  • Platen temperature [oC]: 20
  • H2 flow [sccm]:0
  • O2 flow [sccm]: 5
  • 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
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, O2:5sccm
  • Coil Power [W]:2500
  • Platen Power [W]: 200
  • Platen temperature [oC]: 20
  • H2 flow [sccm]:0
  • O2 flow [sccm]: 0
  • C4F8 flow [sccm]: 13.0
  • He flow [sccm]:225
  • Pressure:Fully open APC valve (3.35 mTorr)
  • Electromagnetic coils (EM) 'outer coil' / 'inner coil':'2 A' / '30 A'
  • PLEASE DO NOT RUN WITH THESE SETTINGS FOR MORE THAN 6 MIN
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:225sccm, Pressure:3.35mTorr
  • Coil Power [W]:1200
  • Platen Power [W]: 150
  • Platen temperature [oC]: 20
  • H2 flow [sccm]:0
  • O2 flow [sccm]: 0
  • C4F8 flow [sccm]: 13.0
  • He flow [sccm]:225
  • Pressure:Fully open APC valve (3.35 mTorr)
  • Electromagnetic coils (EM) 'outer coil' / 'inner coil':'2 A' / '30 A'
  • PLEASE DO NOT RUN WITH THESE SETTINGS FOR MORE THAN 6 MIN
  • 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
Text
  • 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
Text
  • 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
Text
  • 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
Text
  • 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
  • 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
    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
  • 156 nm/min
    156 nm/min
Text
  • 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
  • pitch 800 nm Top 444 nm bottom 374 nm height 718 nm Cr left 85 nm selectivity 48
    pitch 800 nm
    Top 444 nm
    bottom 374 nm
    height 718 nm
    Cr left 85 nm
    selectivity 48
Text
  • 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
  • Etch on none patterned wafer, Uniformity: +- 6.4%
    Etch on none patterned wafer, Uniformity: +- 6.4%
Text
  • 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
Text
  • 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
  • Etch on none patterned wafer, Uniformity: +-1.7%
    Etch on none patterned wafer, Uniformity: +-1.7%
Text
  • 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:2500W
Text
  • SiO2 etch with Cr mask on wafer piece on Si carrier 14 min etch, EM:0/0 H2:0sccm, C4F8:13sccm He:225sccm O2:0sccm, Pressure:3.9mTorr; platen power 200W, coil power:2500W
Text
  • 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 200W, coil power:2500W
Text
  • SiO2 etch with Cr mask on wafer piece on Si carrier 14 min etch, EM:0/0
Text
  • C10751: SiO2 etch with Cr mask on wafer piece on Si carrier 20 min etch, EM:0/0 H2:0sccm, C4F8:6.5sccm He:100sccm O2:10sccm, Pressure:?mTorr; platen power 50W, coil power:600W
Text
  • C10752: SiO2 etch with Cr mask on wafer piece on Si carrier 30 min etch, EM:0/0 H2:0sccm, C4F8:6.5sccm He:100sccm O2:10sccm, Pressure:?mTorr; platen power 25W, coil power:300W
Text
  • C10834: SiO2 etch with Cr mask on wafer piece on Si carrier 45 min etch, EM:0/0 H2:0sccm, C4F8:6.5sccm He:100sccm O2:10sccm, Pressure:?mTorr; platen power 25W, coil power:300W
Text
  • C10844: SiO2 etch with Cr mask on wafer piece on Si carrier 50 min etch, EM:0/0 H2:0sccm, C4F8:6.5sccm He:100sccm O2:10sccm, Pressure:?mTorr; platen power 20W, coil power:300W

Profile, top view at tilted SEM images on 800 nm pitch and 50% duty cycle ( look at the Cr mask in top of the page

  • SiO2 etch with Cr mask on full wafer 6 min etch
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, O2:5sccm
  • SiO2 etch with Cr mask on wafer piece on Si carrier 6 min etch, H2:0sccm, C4F8:13sccm He:225sccm, Pressure:3.35mTorr
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
    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
  • 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
  • pitch 800 nm Top 444 nm bottom 374 nm height 718 nm Cr left 85 nm selectivity 48
    pitch 800 nm
    Top 444 nm
    bottom 374 nm
    height 718 nm
    Cr left 85 nm
    selectivity 48
  • 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
  • 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
  • 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, the mask is removed by plasma ashing on top view and tilted view
  • tilt 30 degrees
    tilt 30 degrees
  • tilt 30 degrees
    tilt 30 degrees
  • tilt 20 degrees
    tilt 20 degrees
  • tilt 20 degrees
    tilt 20 degrees
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