Effects of isolation trough on cleavage of InSb chip in InSb detector

Local cleavage of indium antimonide (InSb) chips restricts the improvement of the yield of InSb infrared focal plane detectors (IRFPAs) under cyclic liquid nitrogen shocking tests. Stress concentration effect may appear in isolation troughs surrounding mesa-junction photosensitive units, drives the dislocation line to nucleate and to propagate, ultimately to punch through InSb chips. In order to analyze quantitatively the influence of isolation troughs on the cleavage of the InSb chip, a structural model of InSb IRFPAs was established, and the in-plane normal stress distribution on the InSb front surface was obtained. Stress concentration phenomena appear on the bottom of V-shaped isolation trough added. Then, the assumed initial cracks with different lengths at the bottom of V-shaped isolation trough were put, here the preset initial cracks were employed to describe dislocation lines in InSb wafers, and were perpendicular to the InSb chips, and obtained the relationship between the energy release rates and the preset crack length. After analyzing these results, the in-plane stress concentration phenomena appears exactly at the bottom of V-shaped isolation trough, and originates from the added V-shaped isolation trough; the enlarged stress at the bottom of V-shaped isolation trough could drive the dislocation lines in the InSb chip to grow and to punch through the InSb chip, thus, the macro cleavage of InSb chip is created; once the preset cracks connect directly with the bottom of V-shaped isolation trough, cleavage of InSb chips is more likely to appear. All these conclusions provide a new perspective to understand the cleavage of InSb chips.