在具有氮化鈦緩衝層之(001)矽晶片上成長鑽石之研究

Abstract

本論文主要探討以微波電漿化學氣相沉積(MPCVD)鑽石薄膜於具有氮化鈦緩衝層的矽晶片上的成長情形，並分析其晶向分布。論文第一部分主要探討脈衝雷射沉積(PLD)的製程參數對氮化鈦層生長之影響，藉由不同的氮氣製程和不同的雷射頻率，以得到品質較佳的TiN薄膜層。第二部分則藉由不同品質的TiN薄膜，以較佳的成長參數成長方向性鑽石薄膜，並探討鑽石磊晶成長之可行性。 在TiN製程部分，藉由準分子雷射的高能量熔融TiN靶材表面，使之形成電漿沉積在基板表面上長成連續膜。藉由不同的氮氣製程和不同的雷射頻率控制薄膜的化學組成、表面粗糙度及晶體方向性。分析技術方面，應用掃描式電子顯微鏡(SEM)和原子力顯微鏡(AFM)觀察表面形貌和表面粗糙度；X光繞射儀(XRD)和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TiN與矽基板界面的關係。TiN磊晶品質與氮氣壓力有關，通入氮氣之PLD製程易於形成TiO2；而真空製程，則可得到較佳TiN薄膜。 在鑽石薄膜成長部分，以相同的甲烷和氫氣混合比例、壓力、微波能量、偏壓時間等製程參數，比較不同TiN薄膜品質對方向性鑽石膜成長的影響。利用SEM、Raman光譜儀對鑽石膜作表面形貌、鍵結情形作分析，以TEM分析鑽石、TiN、矽基板三者之間的界面情形，並對磊晶鑽石膜成長的可能性作分析和討論。結果發現氫電漿對TiN薄膜無明顯的蝕刻效應，可以達到保護矽基板之效果，且較佳品質之TiN薄膜有助於<100>織構鑽石膜之形成。 在不通入氮氣和雷射頻率10 Hz的製程條件下，能得到X-ray rocking curve最佳2.43˚的TiN薄膜。並以此TiN/Si(100)結構作為基材，於其上以0.5%甲烷濃度和800 W微波功率成長1小時的沉積條件，可得到具有<100>織構的鑽石薄膜。

This thesis focuses on the study of growth of oriented diamond film on Si (001) substrate using TiN buffer layer by microwave plasma chemical vapor deposition (MPCVD). The effect of various deposition conditions on the growth of TiN buffer layer by pulsed laser deposition (PLD) was firstly explored to obtain high-quality TiN films on Si substrate by varying N2 flow and laser frequency. In the second part, the fabricated TiN/Si (100) was used as the substrate for further growth of oriented diamonds by MPCVD with bias-enhanced nucleation pretreatment. Finally, the possibility of the growth of epitaxial diamond film is discussed. In the TiN film growth process, the TiN target surface was ablated by an excimer laser to produce plasma plume, and then a continuous TiN film was deposited on the substrate. Using various N2 flow process and laser frequency controls the stoichiometry, roughness, and orientation of the thin film. The morphology, roughness, crystallinity and chemical bonding after TiN deposited on Si substrates were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results show that deposition with N2 easily forms TiO2, whereas epitaxial TiN formation is preferred in vacuum. In the diamond growth process, oriented diamond films were produced by the same process parameters including mixed ratio of CH4 and H2, pressure, power, bias time, etc. It is shown that high-quality TiN fiilms increase the percentage of <001> oriented diamond grains in the diamond films based on the results of SEM, Raman spectroscopy, and TEM analysis. Hydrogen plasma and BEN process have no significant etching effect on TiN films which can effectively to protect Si from etching. The TiN/Si interface remains sharp after diamond deposition, and the diamond/TiN interface is also observed to be smooth. It is demonstrated that the TiN thin film with 2.43˚ full width at half maximum of (002) x-ray rocking curve deposited without N2 flow and with 10Hz laser frequency can be used to fabricate <100> textured diamond film by MPCVD with 0.5% CH4 concentration at 800 W microwave power for one hour.