以胺基鉭錯化合物經化學氣相沉積碳氮化鉭及氧化鉭薄膜

Abstract

本研究以Ta(NEtMe)5為前驅物，並通入不同的載流氣體(H2、Ar) 及反應氣體 (O2) 經低壓化學氣相沉積 (LPCVD) 成長碳氮化鉭及氧化鉭薄膜。所有條件的沉積溫度皆介於723K~923K之間，沉積壓力則在10-3~1 torr。以Si(100)為基材所沉積的碳氮化坦薄膜有著黃灰色的金屬光澤，由SEM及AFM得知薄膜顆粒均小於70 nm，且以XRD測得薄膜為立方晶形結構。薄膜成分則利用ESCA、Auger和EPMA來鑑定，結果顯示薄膜為TaCxNyOz x = 0.42~0.91、y = 0.88~1.69、z =0.07~0.34，為一碳含量較高的薄膜，且碳量隨著沉積溫度上升有增加的趨勢，氮含量則剛好相反；當以氫氣為載流氣體時，薄膜擁有最高的碳含量。 同樣以Si(100)為基材，通入200 sccm的氧氣為反應氣體，可獲得一彩色薄膜；未經回火的薄膜經EPMA及XRD可知為一b 相的五氧化二鉭，且朝著經面(001)成長。由ESCA以及EPMA得知薄膜中幾乎只有氧與鉭的環境，氮含量低於儀器的偵測極限，碳也僅有C/Ta =0.03~0.1，氧的含量為O/Ta=2.1~3。 最後利用NMR及IR觀察U形管所收集的揮發性產物，可推測沉積時可能發生的反應路徑。進而瞭解碳氮的來源。

In this research, we used pentakis(ethylmethyl-amido) tantalum as precursor with different carrier gas (H2 and Ar) to deposit tantalum carbonitride thin film and with O2 as reactive gas to deposit tantalum oxide thin film by low-pressure chemical vapor deposition. The deposition temperature in our experiment was between 723 K~923 K and the base pressure is between 10-3~1 torr. The tantalum carbonitride films on the Si (100) substrate have yellow-gray color The grain size that was measured by SEM and AFM is small than 70nm. Then we used XRD to measure the microstructure of deposited films. At lower temperature 723 K, we could see diffraction pattern from XRD and know the polycrystalline thin films is cubic phase tantalum carbonitride. AES, ESCA and EPMA analysis revealed the composition of the films, we could show the composition as TaCxNyOz x = 0.42~0.91, y = 0.88~1.69, z = 0.07~0.34 , this is a carbon-rich thin films. When H2 was carrier gas, we can see highest carbon level in the films. Tantalum oxide was deposited on Si (100) by using O2 as a reactive gas. From the EPMA and ESCA analysis, we knew the film is Ta2O5 and contain much lower carbon and nitrogen level. The nitrogen contents is even lower than the limit of instrument. As evidenced by X-ray diffraction, an orthorhombic Ta2O5 was obtain in our experiment, and prefer to (100). Finally, we proposed the possible reaction mechanism based on the byproduct gas