Analysis of thermal stresses in InSb IDAs assembly with thinner silicon ROIC

Abstract Thermal mismatch problems can trigger the cracking of the InSb photosensitive layer, the local delamination and the performance degradation of the InSb infrared detector arrays (IDAs). We preferred the balanced composite structure (BCS) proposed by Jeffrey Barton to eliminate these typical failure phenomena. In the BCS, the silicon readout integrated circuit (Si-ROIC) was thinned to make its effective coefficient of thermal expansion (CTE) match the CTE of the InSb photosensitive layer. In order to assess the efficacy of the thinner Si-ROIC in the BCS, with the help of the established InSb IDAs assembly equivalent structure model, we quantitatively analyzed the effectivity of the thinned Si-ROIC in the elimination of the tensile stress (causing the InSb photosensitive layer to crack), the interfacial shear stress (leading to the local delamination of the InSb IDAs), and the peeling stress (giving rise to the edge delamination of the InSb IDAs). We observed that the tensile stress in the InSb photosensitive layer decreases linearly with the thinned Si-ROIC, besides, the interfacial shear stress and the peeling stress also decrease linearly with the thinned Si-ROIC in the range of 300–50 μm. When the Si-ROIC is thinner than 50 μm, the location, in which the local maximal shear stress or the maximal peeling stress appears, moves inward and deviates from its preceding location. All these simulation results clearly confirm that the thinner Si-ROIC in the BCS is an effective approach to concurrently reducing the three main failure stress components in the InSb IDAs assembly, and this major characteristic of concurrently decreasing the three main failure stress components contributes to completely solve the thermal mismatch problems in the InSb IDAs assembly.