Metal Bonding

Summary

Aluminum, copper, and gold are commonly used metallization materials for microelectronic and micro electro mechanical system applications. Typically metal wafer bonding technologies are diffusion‐based methods. Metal‐based wafer bonding uses relatively low temperatures. Solid liquid interdiffusion bonding (SLID) is a possible way to bond at a low temperature with a resulting interface that is stable at temperatures higher than the bonding temperature. Besides semiconductor wafer substrates, other materials can also be used with SLID bonding, example, ceramics or glasses. At first Cu/Sn SLID bonding was used in the field of 3D integration by using solder balls. Metal thermocompression bonding is a form of solid state bonding, more specifically diffusion bonding. The bonding happens in three phases: interface formation, grain reorientation, and grain growth. A eutectic is a mixture of two materials that solidifies or melts at a temperature that is lower than the melting temperature of each material.