| 摘要: | 本研究成功利用聚苯乙烯(Polystyrene, PS)奈米球微影術在矽晶及矽鍺基材上製備出大面積、自組裝(Self-Assembly)排列規則的PS球陣列結構充當模板(Template)，再於此模板上分別鍍製鎳、鈷金屬薄膜以形成尺寸均勻且具二維週期性排列的鎳、鈷金屬奈米點陣列。隨後再將所製備之鎳、鈷金屬點陣列進行不同的熱退火處理以探討其與矽晶及矽鍺基材間之界面反應。 在與矽晶基材反應之實驗方面，當試片分別退火至300 ℃及500 ℃時，由穿透式電子顯微鏡(TEM)及選區電子繞射(SAED)分析，可分別發現磊晶的二矽化鎳(NiSi2)及二矽化鈷(CoSi2)奈米點陣即已生成。此結果顯示越小奈米尺度之鎳、鈷金屬點陣越有利於磊晶結構NiSi2與CoSi2相的成長。而從電子繞射圖形分析得知磊晶的二矽化鎳(NiSi2)與(001)Si基材之磊晶方位關係為[001] NiSi2 // [001] Si，(200) NiSi2 // (400) Si，而磊晶的二矽化鈷(CoSi2)與(001)Si基材之磊晶方位關係為[001] CoSi2 // [001] Si，(200) CoSi2 // (400) Si。進一步利用HRTEM及XTEM觀察分析，可鑑定得磊晶鎳、鈷金屬矽化物奈米點皆為一倒金字塔角錐狀。且實驗發現磊晶金屬矽化物點陣的尺寸隨退火溫度的升高而有逐漸縮小的現象。 製備鈷金屬點陣列結構於矽鍺基材方面，經500 ℃之熱退火處理條件下即生成多晶Co2(Si,Ge)及Co(Si,Ge)的混合相。當退火處理溫度升高至700 ℃時，首次發現在鈷金屬奈米點開始出現鈷矽化物之蝌蚪狀結構，由TEM、SAED及EDS分析，可得知此蝌蚪狀結構由矽、鍺、氧成分所組成，並且為非晶質結構。退火溫度提高至900 ℃後，於單一奈米點上生成大量10-20 nm寛之非晶質SiO2奈米線，推測其生成為固-液-固(Solid-Liquid-Solid, SLS) 之成長機制。 本研究也首度結合自組裝製備微奈米球模板，成功製備出不同維度的有序奈米結構，如奈米環、三維網絡狀之奈米結構，並提出可能的形成機制。同時利用電鍍沉積法可在特定的區域內製備出金屬奈米碗狀及實心鎳金屬球之奈米結構。 The present study has demonstrated that 2D well-ordered arrays of nickel and cobalt metal nanodots were successfully fabricated on (001) Si and SiGe substrates by using the polystyrene nanosphere lithography (NSL) technique. The interfacial reactions of the metal nanodot arrays on Si and SiGe substrates after different heat treatments have been investigated. From the TEM and SAED analysis, epitaxial NiSi2 and CoSi2 nanodots were found to form at a temperature as low as 300 ℃、500 ℃, respectively. The results indicated that the growth of epitaxial NiSi2 and CoSi2 is more favorable for the samples with smaller metal nanodot sizes. The orientation relationships of epitaxial metal disilicide nanodots with respect to (001)Si substrates were identified to be [001] NiSi2 (or CoSi2) // [001] Si and (200) NiSi2 (or CoSi2) // (400) Si. By combining the planview HRTEM and XTEM analysis, the faceted NiSi2 and CoSi2 nanodots were identified to be inverse pyramids in shape. In addition, the average size of the faceted silicide nanodots were measured to decrease with annealing temperature. For the coabalt metal nanodot arrays on Si0.7Ge0.3 substrates after annealing at 500 ℃, Co2(Si,Ge) phase was found to coexist with the dominant polycrystalline Co(Si,Ge) phase. As the annealing temperature was increased to 700 ℃, it is interesting to see that tadpole-like nanowires were found to grow on individual Co silicide nanoparticales. From planview TEM, SAED and EDS analysis, it is indicated that these tadpole-like nanowires were composed of Si, Ge and O, and the nanoscale structure was examined to be amorphous. For the samples annealed at 900 ℃, 10-20-nm-diameter amorphous SiO2 (a-SiO2) nanowires were observed to grow from individual Co silicide nanodot regions. The growth process of a-SiO2 nanowires could be explained by the solid-liquid-solid (SLS) mechanism. By tuning the drop-coasting processes and lift-off conditions, large-area periodic nanoring arrays and 3D well-ordered nanostructures were successfully fabricated on silicon substrates. The possible growth mechanisms were proposed. Furthermore, by utilizing the 3D nanostructures as the templates in conjunction with electrodeposition technique, 2D ordered metal nanobowl and solid Ni metal spheres were obtained in this study. |
