A Super Thin Film Transistor in Advanced Poly Si Films

Abstract

A super thin film transistor (SFT), the active layer poly Si of which is 150–200 Å thick, is advanced by Si⁺ implantation and solid phase growth. Poly Si films were amorphized by Si⁺ implantation, and then regrown by annealing at 600°C in N₂ atmosphere for 15 hrs. The maximum grain size increases to 1 µm and electrical properties are advanced. SFT's were fabricated using this technique, and the Si^- dose and acceleration energy dependence of field effect mobility µ_FE were evaluated. µ_FE of more than 100 cm²/V·s is obtained at 40 keV and above 2×10¹⁵/cm² Si⁺ dose in 800 Å thick films before oxidation.