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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	Comments	SEM gallery
On 6" wafer 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		text SiO2 etch with Cr mask on full wafer 6 min etch
Piece on Si carrier 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		More sidewall passivation on chip than on full wafer 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		text 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		text 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		text 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		text 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
Coil Power [W]:1200 Platen Power [W]: 150 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 10 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:215 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		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
Coil Power [W]:1200 Platen Power [W]: 150 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 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		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
Coil Power [W]:1800 Platen Power [W]: 150 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 10 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:215 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		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
Coil Power [W]:1800 Platen Power [W]: 150 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 Pressure:Fully open APC valve (3.6 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'2 A' / '30 A' PLEASE DO NOT RUN WITH THESE SETTINGS FOR MORE THAN 6 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 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 55.5 156 nm/min
Coil Power [W]:1200 Platen Power [W]: 100 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 Pressure:Fully open APC valve (3.6 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'2 A' / '30 A' PLEASE DO NOT RUN WITH THESE SETTINGS FOR MORE THAN 6 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
Coil Power [W]:1200 Platen Power [W]: 100 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 Pressure:Fully open APC valve (3.6 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'2 A' / '30 A' PLEASE DO NOT RUN WITH THESE SETTINGS FOR MORE THAN 6 MIN		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%
Coil Power [W]:1800 Platen Power [W]: 150 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 Pressure:Fully open APC valve (3.6 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'2 A' / '30 A' PLEASE DO NOT RUN WITH THESE SETTINGS FOR MORE THAN 6 MIN		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
Coil Power [W]:1200 Platen Power [W]: 100 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 Pressure:Fully open APC valve (3.9 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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% tilt 30 degrees tilt 30 degrees tilt 20 degrees tilt 20 degrees
Coil Power [W]:2500 Platen Power [W]: 100 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 Pressure:Fully open APC valve (3.9 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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
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 (3.9 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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
14 min Coil Power [W]:2500 Platen Power [W]: 200 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 20 C₄F₈ flow [sccm]: 13.0 He flow [sccm]:205 Pressure:Fully open APC valve (3.9 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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
Back to start setting without EM coils - 14 min Coil Power [W]:2500 Platen Power [W]: 200 Platen temperature [^oC]: 20 H2 flow [sccm]:25.6 O2 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':'0 A' / '0 A'		text SiO2 etch with Cr mask on wafer piece on Si carrier 14 min etch, EM:0/0
Coil Power [W]:600 Platen Power [W]: 50 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 10 C₄F₈ flow [sccm]: 6.5 He flow [sccm]:100 Pressure:Fully open APC valve (<2 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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
Coil Power [W]:300 Platen Power [W]: 25 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 10 C₄F₈ flow [sccm]: 6.5 He flow [sccm]:100 Pressure:Fully open APC valve (<2 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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
45 min Coil Power [W]:300 Platen Power [W]: 25 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 10 C₄F₈ flow [sccm]: 6.5 He flow [sccm]:100 Pressure:Fully open APC valve (<2 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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
Coil Power [W]:300 Platen Power [W]: 20 Platen temperature [^oC]: 20 H2 flow [sccm]:0 O2 flow [sccm]: 10 C₄F₈ flow [sccm]: 6.5 He flow [sccm]:100 Pressure:Fully open APC valve (<2 mTorr) Electromagnetic coils (EM) 'outer coil' / 'inner coil':'0 A' / '0 A'		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