選擇性成長矽磊晶層的結構分析

Abstract

選擇性成長矽磊晶層是在低壓化學汽相沉積的反應爐中來長矽磊晶膜所使 用的物質是二氯矽烷和氫氣,我們將討論晶片的準備,沉積的溫度,和二氯 矽烷的流速問題.矽磊晶表面的平整與否及磊晶的品質主要是受到沉積溫 度的影響.在九百度成長的矽磊晶層可達到光滑的表面及平整的邊緣但同 時在兩個(100)方向磊晶面的交叉部分形成(110)的切面另外在八百五十度 的矽磊晶膜也顯示無任何雜質,將沉積的時間拉長,其磊晶膜將長在場氧化 層的上面,並且有好的品質.至於八百度的矽磊晶與在預熱過程後降溫至八 百度的時間長短有關,對於短時間的降溫,我們得到的是光滑的表面和粗糙 的邊緣,否則就是得到具缺陷的表面.另外我們也討論磊晶成長速率和二氯 矽烷流速的相依性.實驗告訴我們隨著二氯矽烷流速的增加,矽磊晶成長速 率也提高了. Low-temperature selective epitaxial growth (SEG ) of silicon sing dichlorosilane - hydrogen mixture in an LPCVD hot-wall reactor has been discussed with respect to the wafer preparation, the deposition temperature, and the flow rate of dichlorosilane. The surface morphology and the quality of Si epilayers are highly affected by the deposition temperature. Epilayers deposited at 900 C can always achieve specular surface morphology and smooth edges. However, significant (110) facets between two (100)rowth fronts are also observed. Epilayers deposited at 850 C shows defect-free quality. Also, high quality overgrown Si epilayers on field oxide are obtained through extending the deposition duration. It is found that the quality of epilayers deposited at 800 C is strongly dependent of ramp down step in the deposition cycle. With a short duration ramp down step, epilayers with specular surface morphology but rough edges arebtained. Otherwise the surface is defective with pits and/or textured structures. In addition, the dependence between therowth rate and the flow rate of DCS indicates that the growth of Si epitaxy increases with increasing DCS flow rate.