ELECTRICAL AND STRUCTURAL-PROPERTIES OF POLY-SI FILMS GROWN BY FURNACE AND RAPID THERMAL ANNEALING OF AMORPHOUS SI

In the present work, the effect of rapid thermal annealing (RTA) on th e electrical and structural properties of poly-Si thin films, grown by the crystallization of a-Si films deposited by rapid thermal low-pres sure chemical vapor deposition, has been studied. Structural and elect rical results were obtained using atomic force microscopy, transmissio n electron microscopy, electron spin resonance, electrical resistivity , and Hall mobility techniques. The effects of the grain size, grain b oundaries, and surface roughness on the electrical characteristics of poly-Si films have been investigated. Amorphous Si (a-Si) films crysta llized by RTA at 850 degrees C for 45 s result in the formation of pol y-Si with small grains, an electron spin density N-s=5.2 x 10(16) cm(- 3), and a Hall mobility mu(H) = 30 cm(2) V-1 s(-1). A two-stage anneal ing, involving low-temperature annealing at 600 degrees C for 6 h, fol lowed by RTA at 850 degrees C in five steps of 30 s each, results in t he formation of poly-Si films with large grains free of in-grain defec ts, low surface roughness, and higher Hall mobility mu(H) = 43 cm(2) V -1 s(-1), characteristics rendering such poly-Si films suitable for th e fabrication of good performance thin film transistors. (C) 1998 Amer ican Institute of Physics. [S0021-8979(98)03615-9].