Polycrystalline Si films fabricated by low temperature selective nucleation and solid phase epitaxy process

With a selective nucleation and solid phase epitaxy (SNSPE) process, grain sizes of 10 mu m have been achieved to date at 620 degrees C in 100 nm thick silicon films on amorphous SiO2, with potential for greater grain sizes. Selective nucleation occurs via a thin film reaction between a patterned array of 20 nm thick indium islands which act as heterogeneous nucleation sites on the amorphous silicon starting material. Crystal growth proceeds by lateral solid phase epitaxy from the nucleation sites, during the incubation time for random nucleation. The largest achievable grain size by SNSPE is thus approximately the product of the incubation time and the solid phase epitaxy rate. Electronic dopants, such as B, P, and Al, are found to enhance the solid phase epitaxy rate and affect the nucleation rate.