本研究首度探討規則排列之鎳金屬奈米點陣列與氮氣離子佈植非晶矽基材間不同熱處理條件下之界面反應。從掃描式電子顯微鏡影像觀察分析顯示，直到退火溫度至500℃時，其鎳金屬奈米點陣列尺寸隨著退火溫度升高而有逐漸增加的趨勢。此外，再升高熱處理溫度時，其鎳金屬奈米點形貌將從原本的三角形轉變成環狀結構。從穿透式電子顯微鏡及選區電子繞射圖譜分析顯示，在氮氣離子佈植非晶矽基材上製備之鎳金屬奈米點陣列退火至300-450℃時，其奈米尺寸鎳矽化物點陣生成低電阻相NiSi，當退火溫度升高至500℃甚至更高時，其生成相將完全轉換為高電阻相poly-NiSi2之奈米環。由平面式高解析穿透式電子顯微鏡影像及橫截面影像圖顯示，NiSi2奈米環內部已生成再結晶而外部區域仍為非晶矽型態。退火溫度至550℃時，氮氣離子佈植非晶矽層則完全形成再結晶，相對於一般未鍍製鎳金屬奈米點之氮氣離子佈植非晶矽基材須高於700℃下完全形成再結晶而言，顯示NiSi2奈米環有顯著地提升氮氣離子佈植非晶矽再結晶的溫度約提前200℃。此觀察結果可用鎳矽化物誘發非晶質矽再結晶的製程機制解釋。;We report here the first study on the interfacial reactions of two-dimensional (2D) periodic arrays of Ni nanodots on nitrogen ion-implanted amorphous silicon (N2+-a-Si) substrates at different heat treatments. It was found from SEM observations that the size of the nanodots increased gradually by increasing annealing temperature up to 500 ℃ . Furthermore, for the higher temperature annealed samples, many of the nanodots were found to transit from the original triangular shape to become ring-like in shape. From TEM and SAED analyses, low resistivity NiSi was identified to be the only silicide phase form in N2+-a-Si samples annealed at 300-450 ℃ . As the annealing temperature was increased to 500 ℃ or above, the phase of silicide nanorings was converted into NiSi2 and the structure of the NiSi2 nanorings was polycrystalline. The results of planview HRTEM and cross-section TEM analyses further reveal that the inner region of the NiSi2 nanoring on N2+-a-Si substrate has become crystallized while the outer region of the NiSi2 nanoring is still amorphous. Complete recrystallization of the a-Si layer of the Ni metal nanodots N2+-a-Si sample can be achieved at a temperature as low as 550 ℃, which is about 200 ℃ lower than the annealing temperature required for complete solid-phase recrystallization of the blank N2+-a-Si sample. In addition, the presence of NiSi2 nanodots was found to significantly enhance the recrystallization of N2+-a-Si layer. The observed result can be explained by the Ni-silicide induced crystallization process.
