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|標題:||The Study of Silicon-Surface Damage by Polishing and Related Epitaxial Growth|
|摘要:||Silicon wafers have been extensively used in the microelectronic and semiconductor industry due to their unique properties and plentiful resources. First part of this work studies the effect of surface damage of test wafer by grinding. The other part concentrates at the structural characteristics and purity of epitaxial silicons on the prime or surface-ground wafers, which were prepared by ultrahigh vacuum chemical vapor deposition (UHV-CVD). The lattice strain in the surface-damaged layers was investigated by X-ray diffraction (XRD) and laser scanning techniques. The undoped epitaxial layers were studied using XRD methods. The process of high temperature (900℃) silicon-homoepitaxy was taken in an UHV-CVD reactor ,which consists of an ex situ cleaning and an in situ pre-baking. However, low temperature (550℃) silicon epitaxial growth was achieved on the hydrogen-passivated silicon-surface without using a high temperature in situ baking. Transmission electron microscopy (TEM) was employed to investigate the crystalline qualities of the epitaxial layer and the epi-layer/substrate interface prepared at different temperatures and substrates. The secondary ion mass spectroscopy (SIMS) was performed to investigate the interfacial concentrations of carbon and oxygen. The results of TEM for the sample prepared at 550℃ show the presence of stacking faults, interface, dislocations and rougher surface in the epi-layer. The stacking fault was not observed in the sample polished for three minutes. Nevertheless, all those defects were not observed for the samples prepared by the high temperature process. Chemical purity of the epi-layer was studied using SIMS and Fourier transform infrared spectrometry (FTIR), which indicated lower oxygen and carbon concentrations than those in substrate for the high temperature deposition. For silicon homoepitaxy, the in situ cleaning played a major role in reducing the amounts of surface contaminants and then the quality of epi-layer. High substrate-temperature is advantageous to the high-quality epitaxial growth.|
|Appears in Collections:||材料科學與工程學系|
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