Structure Analysis Of Silicon Films Deposited By Plasma Enhanced Chemical Vapor Deposition

The essay dissertates the theory and the process of the manufacture of a-Si:H andμc-Si:H by the usage of PECVD and illustrates the working principles of PECVD. Silicon thin films are deposited on glass substrates at low temperature using SiH4 and H2 as hydrogen and Si sources.The technical condition is as follows, deposition temperature:250-350℃,SiH4 flux:1-40sccm,discharge power: 40-130W, vacuum level: 6.6×10-4Pa, deposition pressure:100Pa, deposition time: 30-540min. Using the method such as raman scattering spectra, scanning electron microscope (SEM),transmission electron microscope(TEM),x-ray diffraction (XRD) to study different preparation techniques such as silane concentration, substrate temperature,discharge power's influence to the silicon thin film's structure,crystalline state and deposition rate.It indicated that the deposition rate of silicon thin films decreased gradually when silane concentration declined from 10% to 1%.When SC (silane concentration) moved to 2%,the new absorption peak of crystal silicon which neared 520cm-1 was detected and the initial absorption peak of amorphous which neared 480cm-1 was gradually weakened.The structure of the silicon thin films changed gradually from amorphous to microcrystalline. When SC turned to 1%, crystallization ratio increased to 18% .The deposition rate of silicon thin films increased gradually with the ascending temperature.It changed from 205nm/h at 163℃to 197nm/h at 350℃.When RF power turned 40W to 70W,the deposition rate increased from 177nm/h to 203nm/h.The deposition rate of silicon thin films would increase slowly and turn to be stable while RF power after 100W.The thickness of thin films would increase linearly when increaseing the temperature.