Fabrication of Through-glass Vias (TGV) based 3D microstructures in glass substrate by a lithography-free process for MEMS applications

Fabrication of Through-glass Vias (TGV) based 3D microstructures in glass substrate by a lithography-free process is presented. Through-holes having an opening size ∼ 300–500 µm and spiral-shaped embedded redistribution lines 290 width 50 depth were directly created 400 μm thick the electrochemical discharge machining. A 20 nm conformal seed layer was deposited electroless nickel deposition, which can be cost-effective alternative to vacuum-based physical vapor deposition techniques. The surface morphology characterized using atomic force microscope field emission scanning electron microscopy. Scotch-tape test showed good adhesion with substrate. Copper electrodeposition performed increase thickness, after thermal annealing carried out release residual stress film. electrodeposited copper significantly improved at 240 °C for 30 min. Electrodeposition again thickness desired level. current–voltage characterizations show connectivity, average electrical resistance 3-turn square-shaped 2.41 Ω. Other spirals designs are also fabricated prove flexible capability this ‘lithography-free’ technique.