Bridging the Gap Between UV and E-beam Lithography with a DUV Stepper

Leif S. Johansen, Matthias Keil, Elena Khomtchenko, Anders M. Jørgensen, Jörg Hübner

DTU Danchip/ CEN, Technical University of Denmark, Bldg 347, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark

31 May 20162

DTU Danchip/Cen• Danish National Center for Micro- and Nanofabrication• Center for Electron Nanoscopy• Part of the Technical University of Denmark (DTU)• 70 staff (scientific and technical)• Cleanroom ISO 9001 certified since 2009• Environmental and Analytical TEMs, FIB, EBSD• DUV Stepper • 1350 m2 (14 500 ft2) cleanroom space (ISO 4, 5 & 6) • 500 registered users • 20 companies• From basic research to small-scale production

31 May 2016

UV and e-beam lithography at DTU Danchip• UV litho

– 2 Süss MA-6 mask aligners – Resolution: 1-2 µm– T-put: ≈10 wafers per hour

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• E-beam litho– JEOL JBX-9500FS– Writing field: 1x1 mm2

– Resolution: 10 nm– T-put: Few wafers per day

GAP

31 May 2016

Bridging the gap• Spin-outs and academia needs:

– Sub-micron resolution– Good reproducibility– Reasonable throughput

• Stepper obvious choice• Difficult to obtain 1 million USD research grant (no scientific novelty)• No small company can afford a stepper on its own• To move on, DTU Danchip took a chance in 2010:

– Bought warehoused Canon stepper: 150 000 USD – condition unknown – Spent > 300 000 USD for installation and on-site refurbishment by Canon– It worked! The stepper became operational in 2011.

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31 May 2016

Stepper technology from scratch

• No previous experience with DUV• Limited resources: Need for team work• Danish National High Technology Fund

grant:– Three companies + Danchip– 3 years, 2.5 million USD

• New Danchip process engineer• Technology and theory from scratch• Many mask design iterations necessary• Stepper far more precise than aligners• All three companies obtained new

products to market– Better yield, higher profit margin– New markets opened up

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31 May 2016

DTU Danchip’s Canon FPA 3000-EX4 • Built in 1998 • 248 nm excimer laser• Placed on vibration damped platform• 5 x reduction optics• Shot size: 22x22 mm2

• NA: 0.4-0.6 (aperture dependent)• Nominal resolution: 250 nm• Achieved resolution: 160 nm • Step-and-repeat stitching <50 nm• Overlay stitching: 50 nm• 6” and 8” wafers• 4” wafers in trays• No dies or wafer pieces• ≈ 1000 six inch wafers/day

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31 May 2016

Peripheral equipment• Süss Gamma coater and development systems• Manual transfer between peripherals and stepper• Peripherals are p.t. the bottleneck

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31 May 2016

Lines and Spaces of 390 nm thick JSR M230Y and 60 nm BARC

Resolution – 390 nm resist

Dose: 220 mJ/m2

Nominal limit

Obtainedlimit

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220 nm250 nm

Super illumination mode SIA2:

160 nm 140 nm

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Resolution – 1.6 µm resist

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Gap aspect ratio: 4

Dose: 360 mJ/m2

Lines and Spaces of 1.6 µm thick JSR M35G and 60 nm BARC

• 640/360 nm lines/spaces for direct deep plasma etching• Gap aspect ratio: 4• Sidewall angle: ~99⁰

1000 nm

640 nm

360 nm

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New product: nano 12 point probe

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Picture courtesy of Capres A/S

750 nm probepitch

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Present load and economics

• Daytime slots nearly fully booked• Six company customers – four with own operators• A couple of research projects• 150-300 wafers per week

• OpEx: 100 000 USD per year• 1.5 full time staff• Industrial income last 12 months: 100 000 USD• ”Leverage effect”:

– 10 000 USD income on stepper– 120 000 USD income on other tools– If no stepper, the customer wouldn’t be at

Danchip

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31 May 2016

Conclusion• Gap between UV and e-beam litho bridged with a DUV stepper• 160 nm resolution obtained• High reproducibility and throughput• Local industry enabled to enter new, more profitable markets• No “cash cow”- expensive to run• However, the stepper has a leverage effect to obtain new customers• Some old customers came back

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31 May 2016

Thank you for your attention…