鎢錯合物(tBuN)2W(NEt2)2在Si(100)表面的化學反應

Abstract

鎢錯合物(tBuN)2W(NEt2)2在Si(100)表面的化學反應之研究可藉由程溫脫附法、低能量電子繞射及X光光電子能譜等方法來進行。由程溫脫附實驗所得到的結果，我們可以得知，反應過程中除了二乙基胺及第三丁基胺分子的脫附以外，在400 ~ 700 K之間，還有imine及isobutene的脫附，而來自於monohydride的H2脫附發生在810 K左右。由XPS數據顯示，在500 K左右開始有金屬鎢的形成，而在800 K以上，所有的鎢物種皆轉變成金屬鎢。依照上述論點，我們推論鎢錯合物(tBuN)2W(NEt2)2在Si(100)表面上反應大致如下:分子上的配位基逐步轉移到矽表面，接著進行類似胺分子的裂解，產生imine、isobutene及H2的脫附，最後表面形成金屬鎢、碳化矽及氮化矽。此外，我們利用O2+離子鈍化Si(100)表面，在此表面成長鎢錯合物(tBuN)2W(NEt2)2，在高溫可以得到氮化鎢及碳化鎢的薄膜。

The surface reaction of (tBuN)2W(NEt2)2 on Si(100) has been investigated using Temperature Programmed Desorption (TPD), Low-Energy Electron Diffraction (LEED) and X-ray Photoelectron Spectroscopy (XPS). TPD result shows that, besides molecular amine desorption, the (tBuN)2W(NEt2)2 precursor decomposes through hydrogen elimination at b and g sites, producing imine and isobutene, respectively, between 400 to 700 K. Additionally, hydrogen desorption occurs at 810 K, characteristic of monohydride desorption. XPS data show the incipient formation of tungsten metal begins at 500 K and the conversion to tungsten metal is completed at above 800 K. Taken together, the thermal decomposition of (tBuN)2W(NEt2)2 seems to proceed as follows. As the surface is heated, the precursor molecules gradually lose the amine ligands to the Si surface and the adsorbed amines then partially desorb and partially decompose via hydrogen eliminations to produce isobutene and imine.