Transparent Protective Coating Technique for Amorphous Si Image Sensor

To obtain the best moisture‐proof and most reliable protective coating for an amorphous silicon image sensor (A4 documents), three methods of coating and patterning processes and 15 types of resin classified into five kinds of materials were evaluated. Through this study, a screen‐printing method using silicone resin material cured under conditions of 150°C for 60 minutes to form a 60 µm thick protective coating film was selected because of the simplicity of its fabrication process compared with the other two methods. The a‐Si photodiodes were tested under conditions of 121°C‐2 atm. for 300 hours, −30°C to 100°C for 350 cycles and 85°C for 500 hours, and their characteristics were not negatively affected.