Anodic bonding of glasses with interlayers for fully transparent device applications

Thermal processing parameters of vacuum deposited titanium thin films are determined for anodic bonding of glass plates with interlayers for fully transparent device applications. Vacuum thin film deposition and sealing conditions strongly influence the quality of the bonds. 10−4 hPa and 10−5 hPa vacuum of 40 nm and 80 nm thick Ti film deposition and 20 min preheating time, 420–530 °C temperature, 0.5–5 min bonding time and 50–200 V voltage were applied during seal fabrication. Both optical transmittance and electrical resistivity of the interlayers were found to increase with higher bonding temperature and voltage due to higher degree of Ti thin film oxidation. The optimal conditions for transparent and conductive interlayer fabrication were determined and seals of 25 MPa tensile strength were manufactured. Titanium thin films have not been reported to be processed for fully transparent device applications so far.