Hydrogen-induced silicon wafer splitting

The wafer splitting in the "smart-cut" process was analyzed by using the linear elasticity theory and thermodynamics under the assumption that the process is controlled by the nucleation and growth of microcracks. It was found that the nucleation size for the initiation of microcracks in the hydrogen-implanted region decreases with the amount of the implanted atomic hydrogen. By considering the annihilation of the implanted atomic hydrogen to form molecular hydrogen, the growth behavior of a microcrack was calculated, from which the maximum crack size was found to be proportional to the square root of the temperature and the amount of the implanted hydrogen. The growth rate of the microcrack increases with temperature and the amount of implanted hydrogen. A lower bound estimate of the amount of molecular hydrogen needed for the growth of the microcrack was established, which is a function of the crack size and fracture toughness of silicon. (C) 2003 American Institute of Physics.