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**Through-Glass Via (TGV) Process for 3D Interconnect** is **the formation of conductive pathways through glass substrates enabling vertical electrical connections in three-dimensional integrated circuits — enabling dense 3D stacking and heterogeneous integration**. Through-Glass Vias (TGV) provide electrical interconnection through glass substrates, enabling 3D integration and heterogeneous integration (bonding different materials and technologies vertically). TGV enables carrier-less wafers and glass substrates for backside power delivery and through-substrate connections. Process steps include: drilling or etching holes through glass, filling with conductive material (copper, tungsten), and establishing connections to device layers. Laser drilling enables precise hole placement in glass. Femtosecond lasers minimize thermal damage and taper. Hole diameter typically 50-100μm. Hole spacing determined by required interconnect density. Wet or dry etching techniques provide alternatives to drilling. Etching offers better dimensional control but slower throughput. Hole sidewall quality affects electrical performance. Rough walls increase leakage and reduce current capacity. Electroplating or CVD fills holes with conductive metal. Electroplated copper offers good conductivity and lower resistivity. CVD-deposited tungsten provides excellent step coverage and higher melting point but higher resistivity. Barrier materials (TiN, Ta, WN) improve adhesion and prevent diffusion. Interface quality between conductive fill and glass affects reliability. Epoxy or other underfill materials may be applied around TGV to reduce stress. Stress at glass/metal interface during thermal cycling can cause delamination or leakage. Thermal expansion mismatch between glass (coefficient 3-5ppm/K) and copper (17ppm/K) creates substantial stress. Mechanical reinforcement and stress management are important. Electrical performance of TGV includes resistivity and parasitic capacitance. Thin-film resistivity of copper TGV is approximately bulk resistivity. Via resistance scales inversely with fill metal cross-section. Parasitic capacitance between via and nearby conductors affects signal integrity and noise. Isolation and shielding reduce parasitic effects. Reliability testing (thermal cycling, moisture absorption, electromigration) validates TGV robustness. **Through-Glass Via technology enables vertical interconnect of 3D-stacked chips and heterogeneous integration, supporting advanced packaging architectures and backside power delivery.**