Splashed gold bump dependence of cleavage of InSb chip under cyclic liquid nitrogen shocking tests

Abstract

Local cleavage of indium antimonide (InSb) chip always occurs in the manufacture of the InSb infrared focal plane detectors (IRFPAs), and this specific fracture phenomenon restricts the improvement of the yield of the InSb IRFPAs. After analysis, we think that the cleavage of InSb chip in the edge region of the InSb IRFPAs is related to the splashed gold bump existing in this region, and this failure phenomenon dominates in the low-cyclic liquid nitrogen shocking tests. In order to clarify the influence of the splashed gold bump on the cleavage of the InSb chip, we establish a structural model of the InSb IRFPAs containing the splashed gold bump, and analyze the influence of the splashed gold bump on the thermal stress distribution in the InSb chip. Besides, we preset the initial cracks with different lengths at the stress concentration sites to describe the dislocations in InSb wafers. Using the energy release rate as criterion, we obtain the relationship between the cleavage of the InSb chip and the dislocation line length in the presence of splashed gold bump. The main conclusions are drawn as follows. 1) The influence of the splashed gold bump on the cleavage of the InSb chip is localized, and two stress concentration sites are formed in the outermost part of the contact region between the splashed gold bump and the InSb chip. 2) The energy release rate surrounding the preset crack increases promptly with the preset crack length increasing. 3) Cleavage of the InSb chip caused by the splashed gold bump belongs to the type I fracture failure mode. In the cyclic liquid nitrogen shocking tests, the dislocation line gradually punches through the InSb chip under the driving of the concentrating stress, and forms the macro cleavage of the InSb chip.