LPCVD以SiH4低溫下成長高品質矽磊晶

Abstract

本論文是研究我們已經設計了一簡易的熱壁式低壓化學氣相沉積器的 系統,其能夠在550 至 900度成長高品質的矽磊晶.我們利用二次電子顯微 鏡(Secondary Electron Microscopy,SEM)來看表面的平整度,X-射線的繞 射和穿透式電子顯微鏡(Transmission El-ectron Microscopy,TEM)來看 其晶體性質. 為了要在低溫能夠成長出高品質的矽磊晶,我們必須降低 系統的水氣和氧氣含量. 由於我們沒有能抽超高真空的渦輪真空幫浦,以 及預置載入- 鎖住裝置,所以我們盡量使爐管的漏氣達到最低. 我們還將 爐溫升到1000度利用每分鐘六分鐘的氫氣來熱烤爐管以去除水氣和氧. 至 於確定爐管的漏氣達到最低, 我們利用設計化學束磊晶(Chemical BeamEpitaxy ,CBE)的系統來設計我們的系統,其所有氣體的管路,接合點, 以及爐管皆是利用氮氣測漏儀偵測. 在較低溫預烤所成長出來的晶體品 質可由X-射線的半高寬得知是較差.高品質的磊晶層從550度到900度利用 X-射線繞射以及TEM的晶格影像的觀察得知.由我們的實驗結果說明了一個 簡易的LPCVD系統在低壓同樣能夠得到高品質的矽磊晶. We have designed a simple hot-wall low pressure chemical vapor deposition(LPCVD) system to grow high quality epitaxial Si films from 550 to 900C.The quality of the epitaxial Si film found comparable to that of the substratehas been examined by secondary electron microscopy (SEM) for surface morphol-ogy, and by x-ray diffraction,and high-resolution cross-sectional transmissi-on electron microscopy (TEM) for crystallinity. Reduction of moisture and ox-ygen in the ambient is critical to the success of the growth at low temperat-ures. Because there are no high vacuum pump and load-lock used in the system, a combination of a leak-tight LPCVD reactor, a high flow rate of 6 l/min ofH2 purge and a prebake at high temperature of 1000C has been used to achievethe reduction of moisture and oxygen. The leak-tight system design is similar to our previously designed chemical beam epitaxy (CBE) system, where all the gas lines, joints and reactors are carefully leak checked by a He detectorwhere the leak rate is below the detecti on limit. Degrade films form with increasing full-width-at-half-maximum when a prebake at lower temperatures isused. High quality epitaxial layers with structure quality and surface morph-oragy comparable to the substrates are obtained for growth temperatures rang-ed from 550 to 900C, as examined by x-ray diffraction, electron diffraction, and simple system designed LPCVD system can also achieved high quality Si ep-taxy at low temperatures.