Study and estimation of the residual stress in porous silicon layer formed on the surface of a crystalline silicon substrate

Recently, it has been suggested that the structural evolution of pores in porous silicon during high temperature annealing depends strongly on the value of the initial residual stress in the film. In this work, the residual stress in porous silicon is calculated from the surface stress acting on the lateral surface of the cylindrical pores. Such a stress is directly related to the strain caused by desorption of hydrogen and rearrangement of Si–Si bonds during annealing. One dimensional distributions as well as 2-D contours of the residual stress are calculated according to the model described here and used in 2-D COMSOL FEMLAB simulations to predict the final pore distribution and shape after annealing. Simulation results are in excellent agreement with the post annealed pore shape and distribution of experimental macro-porous silicon samples annealed at 1150 °C in argon.