Abstract

Three different types of carrier techniques have been investigated and developed: thermal release tapes, solvable thermoplastic glue layer and mobile electrostatic carrier. These carriers were applied for manufacture of ultra-thin RFID chips, 12 µm thin CMOS image sensors and to a new process sequence that enables the formation of solder balls at the front side of an already thinned device wafer. Technical capabilities of different carrier techniques are compared with respect to allowed temperature range, type of bonding and de-bonding mechanism and their compatibility with typical wafer fab processes. Mobile electrostatic carriers were used to perform solder ball bumping at 55 µm thin silicon wafers. The process sequence demonstrates the capability of electrostatic carrier technology to enable thin wafer processing at elevated temperatures.