光輔助金屬鈀薄膜蝕刻製程在少層硫化物成長研究

Abstract

本論文目的在開發一個金屬鈀的奈米級蝕刻製程，應用在其成長硫化物層數控制技術開發。首先在大氣與室溫環境下，控制溫濕度條件，利用波長 1064 nm的遠紅外線雷射進行照射，透過不同照射功率與照射次數的改變，探討雷射對金屬鈀薄膜的改質情形。其次，利用雷射照射後的金屬鈀薄膜進行甲酸蒸氣反應實驗，在0.25M、80℃下將甲酸汽化、導入反應腔體與試片反應，進行薄膜單次與循環蝕刻實驗，透過原子力顯微鏡(AFM)的表面粗糙度變化與厚度變化觀察以及光電子能譜儀(XPS)的化學鍵結分析，得知蝕刻反應前後的狀況，包含蝕刻率與蝕刻終點等。透過最佳化蝕刻參數，每循環最小蝕刻速率可小於1nm/cycle，且蝕刻過後表面粗糙度約為0.2nm。在其硫化物成長的製程開發方面，利用單加熱區管型爐來進行，硫粉跟試片被放在加熱中心的相反方向來調整氣化溫度跟反應濃度。調整試片位置與中央加熱區溫度，透過拉曼光譜分析結果，得知Pd-S在中心溫度750℃、與中心加熱區距離20cm，得到最佳的硫化鈀成長結果。

In this study, a nano-scale palladium thin film etch process for few layer sulfide synthesis was investigated. Firstly, an illumination of laser beam of wavelength 1064nm was applied on Pd film surface at room temperature with a controlled humidity and reaction pressure (1 atm). By changing the illumination powers and energy density, the modification of surface bonding before and after illumination were examined. Secondly, the illuminated Pd films were treated by evaporated formic acid steam at 80℃. Through the AFM and XPS inspection in film thickness and binding conditions, the Pd film was etched and the etches thickness were proportional to the applied laser powers. The minimum and maximum etch depth of 0.5 nm and 6.5 nm per cycle were achieved when the applied power were 12W and 27W, respectively. A reliable and cyclable etch process had also been demonstrated.As to the sulfide synthesis, a single zone tube furnace was used for metal film sulfidation. The sulfur and the etched Pd film were put at opposite direction of heating center for sulfur concentration tuning and process optimization. By changing the shown in the heating temperature, and the sample position, the optimal Pd-S condition Raman spectrum of was obtained. The layered Pd-S structure synthesis would be well controlled in such a two-step sulfurization process.