以微波電漿噴射化學氣相沉積系統合成超奈米晶鑽石膜之研究

Sdudies of synthesizing UNCD films with MPJCVD system

廖文祥(Wen-Hsiang Liao)

指導教授 ： 林啟瑞 ； 蔡哲雄

國立臺北科技大學/機電學院/製造科技研究所/碩士(2009年)

https://doi.org/10.6841/NTUT.2009.00325

摘要

鑽石擁有極其優異的材料特性，被認為具有極高的應用潛力，但是一般CVD所合成的微米鑽石膜(MCD films)，因其表面形貌具有明顯的刻面(facet)菱線與菱角，造成鑽石膜表面粗糙不平，無法將之導入半導體相關製程，所以限制了MCD之應用。為了提升鑽石於光電元件或微機電系統(Microelectro-mechanical systems, MEMS)之應用，合成晶粒尺寸為奈米等級之鑽石膜(Nano Crystalline Diamond)，被視為最佳解決方法之一，其中超奈米晶鑽石膜(Ultra Nano Crystalline Diamond)因其晶粒更小(<10 nm)，可大幅降低薄膜表面因鑽石刻面所造成之高低落差，進而提升鑽石膜表面平整度，且因其晶粒更小，造成晶界比例提高，使其具有更佳的光電應用潛力。
本研究主要是探討鑽石薄膜的孕核與成長，藉由適當的製程控制，成長UNCD薄膜。研究結果顯示在孕核階段以電漿預碳化法前處裡及在成長階段使用Ar-rich製程，成功地提高成核率與促進二次成核，獲得均勻且平坦(Ra=10.5 nm)的鑽石膜，並以TEM證實其晶粒尺寸確實小於10nm，即為所謂的超奈米晶鑽石膜(UNCD)。研究另使用電漿診斷技術 (OES)量測電漿物種與性質，結合鑽石薄膜的特性分析，可清楚分辨CH4+H2電漿、CH4+Ar+H2電漿、CH4+Ar 及CH4+Ar+H2+N2(摻氮)電漿之光放射光譜與成長環境之異同，並成功以氮摻雜製程合成N-type 鑽石半導體(霍爾量測証實)。為了提高鑽石膜應用價值，研究後段利用Ar-rich製程，藉由改變電漿環境，降低鑽石膜成長溫度，進而降低沈積鑽石膜的基材與膜層設計的限制，研究結果成功將鑽石膜成長在Al/AlN多層膜表面，並由SEM觀察其剖面，證實Al中間層相當完好，並未因熔化而造成破壞。

關鍵字

UNCD ； OES ； 低溫製程

並列摘要

Diamond possesses excellent physical and chemical material properties that makes it be a potential candidate for applications in electronic devices and microelectro-mechanical systems (MENS). However, the surface roughness of typical CVD micro-crystalline diamond (MCD) films is too rough to introduce the industrial processes of semiconductor and electronic devices due to its apparent facet. One way of synthesizing nanogranular diamond films can effectively reduce the surface roughness. The grain size of ultra nanocrystalline diamond (UNCD) films is less than 10 nm, therefore it can make the effect of diamond facet greatly decreased. The reduced grain size could increase the grain boundaries containing non-diamond carbon (sp2) in the diamond films that resulted in significant improvement in related electrical properties.
In this study, the pre-carbonization seeding nucleation (P.P) and Ar-rich process were used to obtain uniform and smooth (Ra= 10.5 nm) diamond films that caused the substrate surface have high nucleation density and second nucleation rate. The grain size of diamond films can be clearly observed below 10 nm from the TEM image, which is belong to UNCD. In this work, we also used the in-situ plasma optical emission system (OES) to diagnosis the plasma reaction species and combined the analyzed results of diamond films that can establish the relationships between various concentrations with reacting species in different plasma environments such as CH4+H2 , CH4 +Ar +H2 , CH4 +Ar +H2 +N2 , and CH4+Ar. The research also finished the nitrogen doped in UNCD films synthesis, and the UNCD films be proved to be N-type semiconductor of diamond from Hall measurement.
In this study, we also investigated the low temperature growth process of diamond films via controlling the concentration of argon. The research results showed that diamond films could be grown at low temperature via directly synthesized UNCD films on Al interlayer with low melting point. The Al interlayer is quite completed as clearly observed from the SEM cross-sectional images.

並列關鍵字

UNCD ； OES ； Low temperature process

參考文獻

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