$NVDA IS PUSHING GLASS SUBSTRATES TO EXTREME THICKNESSES According to Korean semiconductor publication KIPOST, NVIDIA is requesting glass substrates with a thickness of 2,000 µm (2 mm), potentially driving the adoption of new metallization technologies, including atomic layer deposition (ALD). As AI packages grow larger to accommodate more GPUs and HBM, substrate rigidity becomes increasingly important. Thicker glass improves mechanical stability and reduces warpage, but makes through-glass vias (TGVs) harder to manufacture. For perspective, a 2 mm substrate with 50 µm vias would have an aspect ratio of 40:1. Conventional sputtering struggles to deposit uniform conductive seed layers inside such deep, narrow holes. ALD's superior conformality could provide a solution. However, ALD isn't the only competing technology. In September, TRUMPF announced its HiPIMS technology for coating deep TGV structures, using highly ionized plasma to improve coverage. Meanwhile, MKS Atotech introduced a wet metallization process combining electroless copper seeding with advanced electroplating. Progress is also being made in drilling. Korean equipment manufacturer Philoptics demonstrated TGV processing on 2 mm-thick, 510 × 515 mm glass panels, claiming zero defective holes in its demonstration.