Table 1.
Fabrication of process parameters.
| STEP | RECIPE |
|---|---|
| (1) |
Steel foil: stainless steel foil substrate (SS-304 40 μm thick) H2SO4 + H2O2 (cleaning 10 mins) |
| (2) |
AlN sputtering: Ar (8SCCM), N2 (2SCCM), pressure (0.32 Pa), substrate temperature (120 °C), power (170 W) |
| (3) |
Cr / Au evaporating: substrate temperature (100 °C), background pressure (7 × 10−7Torr), Cr thickness (200 Å), Au thickness (2,000 Å) |
| (4) |
Lithography: spin-coated photoresist→ step1:500 rpm, 5s; step2:3,000 rpm, 30 s. soft bake→ 90 °C, 120 s. exposure→ 5 mW/cm2. development→ MF319:DI water = 1:1, hard bake→ 90 °C, 300 s |
| (5) |
Au / Cr etching: Au etching (KI + I2,7 mins), Cr etching (Cr-7, 3 mins) |
| (6) |
PI coating: spin-coated polyimide→ step1:500 rpm, 5s; step2:3,000 rpm, 30s. soft bake→ 90 °C, 120 s. exposure→ 5 mW/cm2. development→ (HTR D-2):(RER 600) = 1:2, hard bake→ 90 °C, 300 s |
| (7) |
PR coating: spin-coated photoresist→ step1:500 rpm, 5 s; step2:3,000 rpm, 30 s. soft bake→ 90 °C, 120 s. |
| (8) |
Define protection layer: exposure→ 5m W/cm2. development→ MF319:DI water = 1:1, hard bake→ 90 °C, 300 s |
| (9) |
Steel foil etching: aqua regia (50 °C) |