中間層對超奈米微晶鑽石膜成長的影響

Effect of buffer layer on the growth behavior of UNCD films

劉畊甫(Keng-Fu Liu)

指導教授 ： 戴念華 ； 林諭男

國立清華大學/工學院/材料科學工程學系/碩士(2009年)

摘要

本實驗發現在製程中加入鉬薄膜中間層，明顯的促進超微晶奈米鑽石(UNCD)薄膜在矽基板上的成核與成長。鑽石膜在矽基板上並不容易成核，但在預鍍一層鉬薄膜當中間層之後，在矽基板上可以成長品質良好的UNCD。雖然鉬薄膜明顯的促進了UNCD的成核，但是它導致了UNCD場發特性變差，因為在成長UNCD時鉬薄膜會形成一層碳化鉬層，此碳化鉬層會阻擋矽基板與UNCD之間電子的傳遞。本實驗利用較厚的鉬薄膜促進了UNCD的成核，並且降低其對場發射特性的影響，其啟始電場為13 V/m，在電場30 V/m下電流密度為55 mA/cm2。
另外，本實驗欲利用超微晶奈米鑽石(UNCD)薄膜搭配氮化鋁壓電薄膜作為表面聲波元件的基板，但由於氮化鋁成長在UNCD上會有裂膜的現象發生，所以本實驗在UNCD沈積氮化鋁前先沈積一層鋁金屬當緩衝層，之後再成長氮化鋁薄膜。而實驗中製作表面聲波元件電極的方法則是利用奈米轉印法來製作。

關鍵字

超奈米微晶鑽石 ； 表面聲波元件

並列摘要

In this study, we found that Mo-coating on Si-substrate can significantly improve the formation of diamond nuclei and the growth behavior of ultra- nanocrystalline diamond (UNCD)films. Contrary to the phenomenon that diamond nuclei are only scarcely formed on bare Si-substrates, this work can growth high quality UNCD films on the Mo-coated Si- substrates. While the Mo-coating markedly enhances the nucleation of diamonds, it degrades the electron field emission (EFE) properties of UNCD films. It is attributed to the conversion of the conducting Mo- metallic film into a resistive Mo2C layer during growth of UNCD films. A sufficiently thick Mo-layer is found to enhance the nucleation of diamonds, while minimizing deleterious effect on their EFE properties with an improved turn-on-field of 13 V/m and a current density of 55 mA/cm2 at the applied field of 30 V/m.
Moreover, we try to fabricate a SAW device using UNCD films incorporated with AlN piezoelectric films. Because AlN films peel off easily on UNCD films, the coated Al films are acted as buffer layer for AlN growth. The electrode of SAW devices was fabricating using the nano-transfer printing process.

參考文獻

[1] A. Lavoisier, “Elements of Chemistry”, Dover Publications (1772).

[2] Willem J.P. Van Enckevort, “Physical, chemical and microstructural characterisation and properties of diamond in Synthetic diamond: emerging CVD science and technology”, edited by Spear, K.P. and Dismukes, J.P., J. Wiley & Sons, Inc., New York (1994).

[3] May, P.W., Molecule of the Month, July 1996.

[4] Yoder, M.N., “The vision of diamond as an engineered material in Synthetic diamond: emerging CVD science and technology”, edited by Spear, K.P. and Dismukes, J.P., J. Wiley & Sons, Inc., New York (1994).

[5] May, P.W., “CVD diamond - a new technology for the future”, Endeavour, 19, 101 (1995).