Fabrication of polysilicon thin-film transistors using nickel/copper double-layer-induced lateral crystallization

Abstract

The material properties and thin-film transistors characteristics of nickel/copper-induced polysilicon are investigated. It was discovered that by combining Cu and Ni, the lateral growth rate of polysilicon is about an order of magnitude higher than that induced by Ni alone, and much better than the Cu-induced case. The grain size of Ni∕Cu-induced polysilicon is 1.5 times larger than that of Ni alone, and also 30 times larger than that of the Cu induced case. The mechanism is attributed to the Cu-enhanced Ni silicide migration. The Ni∕Cu-induced low-temperature polysilicon thin-film transistor shows a field-effect mobility of 10–25cm2∕Vs, a threshold voltage of 8–22V, and an on/off current ratio about 106–107.