Table 1.

Process details in process A1-RIE, for 100% SU-8.

Step	Equipment	Details	Comments
Photolithography to define via on 100% SU-8
Spin-coat SU-8 6000.5	Spin-coater	1.500 RPM, 5 s, 500 RPM/s 2.6000 RPM, 36 s, 1000 RPM/s 3.0 RPM, 6 s, 1000 RPM/s	SU-8 thickness 433 nm
Soft bake	Hot plate	100°C, 60 s	Hotplate surface temperature
Photolithography	Contact aligner/ stepper, photomask	76 mJ/cm2, 365 nm (i-line) UV (Varies with SU-8 thickness)	Use index matching fluid to improve contact between SU-8 and mask and create hard-contact in the case of contact aligner.
Post-exposure bake	Hot plate	100°C, 120 s	Hotplate surface temperature
Develop in SU-8 developer	Wet bench	30 s	Vigorous swish. Wash developer in IPA, blow dry IPA in N2
Hard bake	Hot plate	100°C, 30 mins	Hotplate surface temperature
Etch-back of the SU-8 to Desired Thickness
SU-8 thickness control etch	RIE-ICP tool	RF power 50 W, ICP power 300 W, 50 sccm O2, 10 mT, He backed substrate cooling at 10 torr	Refer Fig. 4a for SU-8 etch thickness as a function of time