Investigation and Simulation of Thermomechanical Stress Induced by Plated Cu Contacts on Si Heterojunction Solar Cells

ABSTRACT This study investigated the thermomechanical stress induced by annealing plated Cu contacts on pyramidal surfaces of Si heterojunction (SHJ) solar cells. The homogeneity of cell temperature during annealing was assessed by both experiment and simulation. Several influential factors on the Si stress were evaluated, including Cu geometries, contact edge locations, contact width, pyramid size, and annealing temperature. The simulated stress, which was verified by Raman spectroscopy, was applied to predict the probability of fracture in combination with the Weibull diagram obtained from four‐point flexural (4PF) tests. Despite the identification of limiting flaw populations at the Si surface of Cu‐plated SHJ cells, a low fracture probability was estimated for a typical annealing temperature of 200°C.