POLYCRYSTALLINE SILICON CHARACTERISTICS DEPENDENCE ON STARTING AMORPHOUS MATERIAL

Silicon films, typically 1 mu m thick are deposited by low pressure ch emical vapor deposition using pure silane at 550 degrees C and 3 depos ition rates : 13, 23 and 45 Angstrom/mn. Using numerous physical, opti cal and electrical characterization techniques, we show an evident amo rphous character of these as-deposited films. Films deposited at high rate correspond more likely to the relaxed amorphous network. The qual ity of the polysilicon produced by annealing these high deposition rat e films at 600 degrees C is largely enhanced The crystallization time, defined from the in-situ conductivity measurements at 600 degrees C, is about 4 h for the high deposition rate amorphous film. Such time is very attractive in the attempt to obtain simultaneously << acceptable >> crystallization time and high quality polysilicon. This assertion is emphasized if we consider the total time t of the process (depositi on time and crystallization time).