Figure 3

FESEM images of 20-Îĵm (left), 30-Îĵm (centre), and 50-Îĵm (right) SU-8 patterns photopatterned on plasma-treated FEP (@ 20Â W, 1Â min) (a) and on an Au layer (b) with respect to UV exposure time. (c) The AS between SU-8 and FEP (closed circle in blue), the pattern depth of SU-8 on Au layer (open rectangle), and that of SU-8 on FEP (open circle) with respect to UV exposure time. Pattern depth data were obtained from 50-Îĵm line patterns via step profilometer (Alpha-step 500, KLA-Tencor). Multiplying the UV exposure time by the power density (22.7 mW/cm2 @ 365Â nm) yields the exposure dose in units of mJ/cm2.