A new wafer-bonder of ultra-high precision using surface activated bonding (SAB) concept

A robot-controlled wafer bonding machine was developed for the bonding of different sizes of wafers ranging up to 8 inches diameter. The features of this equipment are such that: (1) After the automatic parallel adjustment for 8-inch wafers to a margin of error within $\pm 1\mu {\rm m}$, the X, Y, and Saxis alignments are performed, allowing a margin of error within ±0.5 urn in bonding accuracy; and (2) Room-temperature bonding is enabled using the surface activated (SAB) bonding concept. 8-inch diameter silicon wafers ware successfully bonded by the SAB process at room temperature for the first time. Preliminary investigations across the interface using an Infrared camera show that no bubbles are visibly present in the bonding region.