(100)矽基材上立方晶碳化矽層對方向性鑽石形成之影響

Abstract

本論文主要探討以微波電漿化學氣相沉積(MPCVD)立方晶碳化矽(β-SiC)及鑽石薄膜的形成過程，並分析其晶向分布。論文第一部分主要探討製程參數對於碳化矽層形成之影響，藉由使用不同的反應氣體、微波功率的大小、偏壓時間的長短，以此控制β-SiC層的形成。第二部分則是藉由所製成之性質佳的β-SiC，以控制反應氣體濃度及製程溫度，成長方向性鑽石薄膜，並探討製成之β-SiC對方向性鑽石膜成長關聯性 在碳化矽製程部分，藉由上電極的使用，以丙烷和氫氣作為氣體源，碳化加熱Si(100)基材，使表面覆蓋一層碳化層，接續對基材施以負偏壓輔助碳化矽形成。經由改變偏壓階段的微波功率及偏壓時間可以控制β-SiC的成份比例、顆粒尺寸及排列密度。分析技術方面，應用掃描式電子顯微鏡(SEM)觀察表面形貌及顆粒尺寸；X光繞射儀(XRD)及X光光電子能譜儀(XPS)分析結構相與化學組成；穿透式電子顯微鏡(TEM)分析β-SiC與矽基材介面的關係。β-SiC形貌呈長條形島狀物，長寬尺寸各為0.2μm及0.1μm。 在鑽石薄膜成長部分，以甲烷和氫氣作為反應氣體，比較基材在電漿球的不同位置及不同的甲烷濃度對於方向性鑽石膜成長的影響。利用SEM、XRD及Raman光譜儀對鑽石膜作表面形貌、晶向及鍵結情形作分析，並對前製程製備之碳化矽層與鑽石膜成長的影響作分析與討論。 藉由具有<100>織構的β-SiC，在適宜的成長溫度，即700℃及甲烷濃度1%的沉積條件下，可以在1小時的成長過程得到磊晶比例高達38%且具有<100>織構的高品質鑽石薄膜。

This dissertation focuses on the study of formation of cubic SiC (β-SiC) and oriented diamond film by microwave plasma chemical vapor deposition (MPCVD). In the first part of the dissertation, the main focus is on formation of β-SiC buffer layer using various deposition parameters including precursors, microwave power, and bias time. In the second part, the fabricated β-SiC was used as the substrate for the study of growth of oriented diamonds. Before SiC growth, carburization MPCVD had been performed using propane and methane as carbon sources. The <100> β-SiC layers on Si(100) substrates were synthesized by MPCVD using a mixture of propane and hydrogen gases as precursors with the application of a negative bias on the specimen. The morphology, crystallinity and chemical bonding after β-SiC formation on Si substrates were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). It is found that the microwave power and the bias time have great influence on the formation of α-SiC and β-SiC phases, their sizes and the density. The β-SiC islands exhibit a stripe morphology with width and length of 0.2μm and 0.1μm, respectively. In the diamond thin film growth process, only methane in hydrogen was used as reacted gases. Temperature and methane concentration are the major factors affecting oriented diamond growth based on the results of SEM, XRD, and Raman spectroscopy. It is demonstrated that <100>textured β-SiC in the first process can be used to fabricate high-quality diamond films with the <100>texture in which the epitaxial ratio approaches 38% for one hour growth under proper deposition conditions of 1% CH4 and growth temperature at 700℃.