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Devin K. Brown, Georgia Tech 1 Anti-Charging Methods when electron beam lithography must be performed on insulating substrates (e.g. Quartz, SiC, soda.

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Presentation on theme: "Devin K. Brown, Georgia Tech 1 Anti-Charging Methods when electron beam lithography must be performed on insulating substrates (e.g. Quartz, SiC, soda."— Presentation transcript:

1 Devin K. Brown, Georgia Tech 1 Anti-Charging Methods when electron beam lithography must be performed on insulating substrates (e.g. Quartz, SiC, soda lime, etc.) negative charge buildup can occur on the substrate surface causing beam deflection, and thus pattern distortion ma-N 2403 glass substrate electron beam negative charge accumulation Initial Condition Future Condition repulsive electric potential lines

2 Devin K. Brown, Georgia Tech 2 Au on top of resist Au can be coated on top of resist to dissipate charge –typically 100A is sufficient Au must be deposited with Filament Evaporation –Electron beam evaporation will expose resist Au must be stripped with Potassium Iodine prior to resist development –has worked well with ZEP520A on glass –has not worked well with ma-N 2403 on glass (see next slide) Au ma-N 2403 glass substrate front side Au e-beam exposure

3 Devin K. Brown, Georgia Tech 3 Au incompatible with ma-N 2403 Au on top of ma-N 2403 on glass substrates has not worked well

4 Devin K. Brown, Georgia Tech 4 Ti/Au/Ti ma-N 2403 glass substrate Ti/Au/Ti under resist layer e-beam exposure Ti/Au/Ti under resist layer Ti/Au/Ti can be coated underneath resist to dissipate charge –typically 20/30/20A is sufficient can use Electron beam evaporation since deposition occurs prior to resist coating Ti/Au/Ti must remain after resist development, may not be compatible with process Ti can help with resist adhesion issues to quartz

5 Devin K. Brown, Georgia Tech 5 ESpacer is spin coatable, no evaporation required ESpacer is water soluble –compatible with ma-N 2403 Ebeam exposure must occur shortly after ESpacer application ESpacer ma-N 2403 glass substrate front side ESpacer e-beam exposure ESpacer

6 Devin K. Brown, Georgia Tech 6 GOOD (no charging) BAD (severe charging) Ti/Au/Ti under resist BAD (moderate charging) no anti-charging layer ESpacer > 24 hours Charging causes pattern distortion ESpacer < 1 hour front side Au

7 Devin K. Brown, Georgia Tech 7 GOOD (no charging) BAD (severe charging) Ti/Au/Ti under resist BAD (moderate charging) no anti-charging layer ESpacer > 24 hours 500um field boundary field stitch error also pattern distortion Charging causes pattern distortion & field stitch error ESpacer < 1 hour front side Au


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