Aiming at the demand of the backside leads of MEMS devices, a process for the fabrication of 10.16cm (4inch) wafer substrates based on the through-glass-vias (TGV) processing method is presented. Firstly, the conductive silicon wafer was deeply etched, then anodic bonding was performed between the silicon wafer and the glass wafer, and then the bonded glass-silicon wafer was heated at a high temperature to fill the glass into the silicon wafer. Then the front glass and back silicon of the glass-silicon wafer was grinded and polished until the silicon and the embedded glass were on the same plane. Finally, a 4inch substrate with a thickness of 258μm was obtained. The arithmetic mean deviation of the profile, the maximum profile height and the microscopic unevenness are 13, 71 and 49nm respectively. In addition, the measured resistivity of the silicon via in the wafer is 0.023Ω·cm.