Low temperature multi layer stack wafer bonding technology development

Abstract

A new wafer bonding approach for 3-D packaging is designed fabricated and tested. We can summarize device market trend in next few words like Low cost, small form factor, integration, high performance, etc. During the last decades, 3-D wafer level packaging (3-D WLP) is highlighted as the next generation packaging method for satisfying market needs. 3-D WLP method has many advantages like low cost (wafer batch process), high performance (shorter electrical length), small form factor (3-D interconnection), low assembly cost and so on. One of the key technologies of 3-D packaging is wafer bonding. In wafer bonding field, low process temperature, high hermeticity, high reliability, multi layer stack and low process cost are main technical stream. Among various fabrication methods polymer bonding, eutectic bonding, silicon fusion bonding and anodic bonding are generally used. In case of polymer bonding, it has difficulty in high hermeticity and high reliability. In case of eutectic bonding, it has very high material cost compared to others. In case of silicon fusion bonding and anodic bonding has very high process temperature. In this paper, new anodic bonding technique is proposed for satisfying low cost, low process temperature, high hermeticity and multi layer stack. Through suggested bonding mechanism, more than 9 glasses to silicones sandwich layer is anodic ally bonded together simultaneously under 200 degree. Obviously, realized sample has very high hermeticity and bonding strength.