鑽石膜之選擇成長與摻硼研究

Abstract

利用化學氣相沉積之鑽石膜如要在電子元件上應用，選擇成長與電性質良 好的各種摻雜鑽石膜之製作技術是亟待克服的關鍵問題。為了解決這些問 題，本實驗在矽基板上以控制製程參數，如碳源濃度、成長時間、酸液浸 蝕 (dipping) 時間及光罩材料 ( mask materials) 等，來成長選擇性良 的鑽石薄膜。再者討論摻硼鑽石膜經過退火熱處理之後，硼原子在鑽石結 構中所存在的位置變化情形對電流-電壓特性的影響。由實驗結果得知， 經由控制上述的各項實驗參數，可以很輕易地成長出選擇性良好的鑽石膜 。其中，用氫氟酸和硝酸的水溶液在製程中浸蝕試片，不僅可以使在非成 長區域 (undesired region) 中已成核的鑽石顆粒 (crystallites)剝落 ，更可以在該非成長區部分形成一層氧化矽膜，以降低非成長區域鑽石的 成核密度，進而提高鑽石膜的選擇性成長效果。另外，在摻硼鑽石膜的電 流- 電壓特性的量測中，發現摻硼的鑽石膜經退火熱處理後其電流- 電壓 的特性有很明顯的變化。此特性由退火前的整流效果改變為退火後類似歐 姆接面 (Ohmic contacts) 的特性。造成此種變化的原因，可由傅立葉轉 換紅外線光譜 (FTIR) 分析，載子濃度 (carrier concentrations) 的量 測以及陰極螢光光譜 (cathodolumines- cence spectra) 結果，得知對 摻硼鑽石膜施予退火熱處理會使鑽石膜內原本在未活化位置 [如格隙型 (interstitial) 或叢集 (cluster)]的硼原子經活化後轉換成在鑽石結構 中的取代型位置 (substitutional sites)。因為在這種取代型結構的硼 原子數目增加所以導致其電流-電壓特性的改變。 It is important to produce diamond films with patterns of sel ective growth and impurity-doped diamond films for the modern el ectronic applications. In this thesis, we attemped to deposit sel ective diamond films on the silicon substrate by controlling the hydrocarbon concentrations, deposition duration, solution etching time and materials of mask. The variations of the boron atoms in the boron-doped diamond films and the effects on the I-V charact eristics were examined when the diamond films were experienced wi th annealing treatments. From the results, selective growth of diamond films can be ea sily achieved using selective damaged by ultrasonic agitation wit h diamond powders and properly controlling the hydrocarbon concen trations, deposition durations, materials of mask and solution et ching time. Achievement of the solution etching have been confirm ed by the scanning electron microscopy (SEM) and electron spectro scopy for chemical analysis (ESCA) measurements. The HF:HNO3:H2O (1:1.1:10) solution could remove the undesired diamond crystallit es and a thin oxide film was formed by the oxidation reaction o n the substrate. Diamond films with excellent selectivity could b e obtained through the above procedures. This novel procedure is more convenient and efficient than the other techniques of selec tive diamond films growth.