雙層Mo/Si及CuSi系可寫一次光碟記錄薄膜之研究

Abstract

近年來，提高光碟片容量的方法包含：藍光儲存技術、超解析近場光學光碟、多記錄層技術、多階技術及全像資料儲存……等等，其中以藍光儲存技術發展最快速。 本論文以金屬誘發結晶理論，鍍製半導體-金屬二元合金以及半導體/(金屬元素、半導體-金屬二元合金) bilayer做為無機可寫一次光碟片之記錄層材料。我們使用濺鍍製備Mo(7 nm)/Si(7 nm) bilayer、CuSi(16 nm)、Si(1.5~8 nm)/CuSi(16 nm) bilayer及Ge(1.5~8 nm)/CuSi(16 nm) bilayer記錄薄膜。由熱分析實驗結果得知，Mo(7 nm)/Si(7 nm) bilayer記錄薄膜在250℃~450℃之間會有一階段的反射率變化。CuSi(16 nm) 記錄薄膜在180℃~310℃之間會有一階段的反射率變化。Si(1.5~8 nm)/CuSi(16 nm) bilayer反射率的變化溫度有兩個階段，第一個階段約為150℃到250℃，第二階段約為300℃到350℃。Ge(1.5~8 nm)/CuSi(16 nm) bilayer反射率的變化溫度有兩個階段，第一個階段約為150℃到280℃，第二階段約為300℃到440℃。Mo(7 nm)/Si(7 nm) bilayer初鍍薄膜之TEM 電子繞射分析顯示具有Mo的結晶相，經過300℃、20 分鐘熱處理後會形成hexagonal MoSi2相，，經過500℃、20 分鐘熱處理後會形成hexagonal MoSi2和cubic Mo3Si相二相共存。CuSi(16 nm)初鍍薄膜具有Cu3Si的結晶相，經過300℃、20 分鐘熱處理後會形成Cu3Si和cubic Si二相共存。Si(1.5~8 nm)/CuSi(16 nm) bilayer初鍍薄膜具有Cu3Si的結晶相，經過300℃、20 分鐘熱處理後會形成Cu3Si和cubic Si二相共存，經過500℃、20 分鐘熱處理後，會有cubic Si成長的現象，且會有hexagonal Si相形成。Ge(1.5~8 nm)/CuSi(16 nm) bilayer初鍍薄膜具有Cu3Si的結晶相，經過300℃、20 分鐘熱處理後會形成Cu3Si、Cu3Ge和cubic Si三相共存，經過500℃、20 分鐘熱處理後會形成Cu3Si、Cu3Ge 、cubic Si和cubic Ge四相共存，且cubic Si隨著Ge厚度的增加而減少。BD碟片動態測試結果顯示：Mo(7 nm)/Si(7 nm) 以1X速度寫入時，最佳的jitter值為6.5%，以4X速度寫入時最佳的jitter值為6.8%。CuSi(16 nm) 以1X寫入速度寫入時，最佳的jitter值為8.9%。Si/CuSi在1X的寫入速度下，當Si層的厚度為1.5 nm、3 nm及6 nm時，相對應的最佳jitter值分別為7.5%、5.2%及7.9%。Ge/CuSi在1X的寫入速度下，Ge層的厚度為1.5 nm、3 nm及6 nm時，相對應的最佳jitter值分別為7.5%、7.6%及11.4%。

Recently, the methods to increase data storage of optical disc inclouding of blue laser optical recording, super resolution near field structure, multilayer, multi-level, holographic data storage, etc, and the blue laser optical recording was developed more rapidily than the others. In this study, metal induced crystallization (MIC) mechanism for alloy and bilayer structure of inorganic recording thin films was investigated. The Mo(7 nm)/Si(7 nm) bilayer, CuSi(16 nm), Si(1.5~8 nm)/CuSi(16 nm) bilayer and Ge(1.5~8 nm)/CuSi(16 nm) bilayer recording films were prepared by magnetron sputtering. Thermal analysis shows that the Mo(7 nm)/Si(7 nm) bilayer films have one phase transition step, which temperature is occurred at 250 oC ~450 oC. The CuSi(16 nm) film has one phase transition step, which temperature is occurred 180 oC ~310 oC. The Si(1.5~8 nm)/CuSi(16 nm) bilayer films have two phase transition steps, which temperatures are occurred at 170 oC ~250 oC and 300 oC ~350 oC. The Ge(1.5~8 nm)/CuSi(16 nm) bilayer films have two phase transition steps, which are occurred at 150 oC ~280 oC and 300 oC ~440 oC. The TEM analysis shows that the as-deposited Mo(7 nm)/Si(7 nm) bilayer film is amorphous, and it would transform to the hexagonal MoSi2 phase after annealing at 300 oC for 20 mins. After annealing at 500 oC for 20 mins, it would transform to the hexagonal MoSi2 and cubic Mo3Si coexisting phases. The as-deposited CuSi(16 nm) film has Cu3Si phase, and it would transform to the Cu3Si and cubic Si coexisting phases after annealing at 300 oC for 20 mins. The as-deposited Si(1.5~8 nm)/CuSi(16 nm) bilayer films have Cu3Si phase, and it would transform to the Cu3Si and cubic Si coexisting phases after annealing at 300 oC for 20 mins. The grain size of cubic Si phase increases after annealing at 500 oC for 20 mins, and the hexagonal Si phase would be formed. The as-deposited Ge(1.5~8 nm)/CuSi(16 nm) bilayer films have Cu3Si phase, and it would transform to the Cu3Si, Cu3Ge and cubic Si coexisting phases after annealing at 300 oC for 20 mins. After annealing at 500 oC for 20 mins, it would transform to the Cu3Si, Cu3Ge, cubic Si and cubic Ge coexisting phases, and the amount of cubic Si phase decreases with the increasing of the Ge layer thickness. The dynamic tests show that the jitter value of Mo(7 nm)/Si(7 nm) bilayer film is 6.5% under 1X BD recording situation and 6.8% under 4X BD recording situation. The jitter value of CuSi(16 nm) film is 8.9% under 1X BD recording situation. On the other hand, the jitter values of Si/CuSi bilayer films are 7.5%, 5.2%, and 7.9% under 1X BD recording situation as the Si layer thickness are 1.5 nm, 3 nm, and 6nm, respectively. The jitter values of Ge/CuSi bilayer films are 7.5%, 7.6%, and 11.4% under 1X BD recording situation as the Ge layer thickness are 1.5 nm, 3 nm, and 6nm, respectively.