以低溫水熱–電化學法於TiN/Si上製備鈣鈦礦氧化膜之研究

Synthesis of Perovskite Oxide Films on TiN/Si by a Low Temperature Hydrothermalelectrochemical Method

鈣鈦礦膜因具有介電、鐵電及壓電等特性，已廣泛應用於電子工業中。傳統上以陽極氧化法製備鈣鈦礦膜，皆是以金屬做為底材，本研究室則首創以導電氮化物膜做為陽極氧化之底材。本研究主要是以陽極氧化法在低於100℃下，在鍍氮化鈦之矽基材上製備鈦酸鋇膜做為探究之模式系統，並以鈦金屬膜做為底材之對照組。結果顯示，在定電壓模式1 V時，於70℃反應5分鐘後，即可生成球狀顆粒鈦酸鋇，在定電壓2 V時，反應只要3分鐘後，就可觀察到球狀顆粒鈦酸鋇，鈦酸鋇的生成量隨電壓及溫度的增加而增加。對照在鈦膜上成長鈦酸鋇而言，發現鈦酸鋇膜於氮化鈦膜上成長之速率快了許多，此結果應與反應機制不同有關。

Perovskite oxide films exhibiting dielectric, ferroelectric and piezoelectric characteristics have potentials for various electronic applications. Traditionally, syntheses of perovskite oxide films by anodic oxidation often require metals as seeding layers. In our past work, conductive nitride films have been employed as the seeding layer. The objective of this study is to prepare BaTiO3 films on TiN-coated silicon substrates by a hydrothermal- electrochemical treatment (i.e. anodic oxidation) at temperatures below 100 ℃. Preparation of BaTiO3 on Ti/Si substrates was also conducted for comparison. X-ray diffraction results showed that cubic BaTiO3 films were successfully formed on the TiN/Si substrates by anodic oxidation using a potentiostatic mode with an applied potential of 1 V at 70 ℃ for 5 min. Field-emission scanning electron microscopy revealed that BaTiO3 films exhibited a sphere-like morphology, and spherical BaTiO3 was observed after the anodic oxidation reaction at an applied potential of 2 V for 3 min. The thickness of BaTiO3 increased with the potential as well as the reaction temperature. The growth of BaTiO3 on TiN was much faster, in comparison with that over the Ti film, and the thickness of BaTiO3 could reach 1 μm. The differences were associated with growth mechanisms that are discussed in this work.