Vacuum packaging development and testing for an uncooled IR bolometer device

A vacuum package has been developed for 128×128 array IR bolometer device with Ge window having anti reflection (AR) coating. For a good vacuum package hermeticity and low out gassing are the two critical elements. A good hermetic sealing has been achieved with Ge window attachment using solder bonding. Different metallization structures have been tried and metallization of oxide/Ti/Ni/Au with additional annealing process was found to have good adhesion and solder wetting. Getters have been activated before final vacuum sealing of the package to absorb the outgassing gases from the packaging materials. Residual Gas analysis (RGA) showed that Thermo electric cooler used inside the package outgassed more compared to other materials. Vacuum inside the package was measured by using a single element IR bolometer device and found to have vacuum of 50milli torr. The developed vacuum package has been tested functionally and found to be no degradation in image before and after packaging.