TGV Through-Glass Via Etching: Laser Modify + Wet Etch
Glass has no natural etch direction like silicon; TGV uses femtosecond laser modification plus wet etch to achieve high aspect-ratio vias.
1The two-step principle
Femtosecond/picosecond pulses selectively modify the glass along the optical axis across full thickness; wet etch then removes modified material tens to hundreds of times faster than unmodified glass, growing the modified track into a via. A single pulse can modify full thickness for high throughput.
2Key geometry
Aspect ratio can exceed 1:10 and microvias can be under 5µm; vias may be blind or through, with controlled taper angle and uniformity. Aperture, taper and wall roughness jointly determine metallization yield.
3Vs. silicon TSV
Glass is insulating with tunable CTE, giving smooth sidewalls and no need for the dielectric liner silicon TSV requires; but glass has low thermal conductivity and is brittle, so the window (laser energy, etch temperature/time) is more sensitive and should be calibrated on coupons.