高密度一次寫入光記錄媒體之顯微結構及記錄機制之研究

Abstract

光碟具有高儲存容量、可交換性和攜帶便利性，對個人資料管理、多媒體等是重要的外部儲存的元件。一次寫入（Write-once）光碟是所有光碟產品中生產比例最高的一種，其記錄層材料可為有機或無機材料，有機染料在藍光系統中有較低的光吸收率、環境污染等困難，本論文研究新穎無機記錄材料、微觀結構與記錄機制等，以供次世代一次寫入光碟之應用。 傳統的的光碟為4至8層的複雜結構，本研究分別以貼靶濺鍍技術及銀銦銻碲（AgInSbTe，AIST）複合靶材製備AIST-SiO2奈米複合薄膜以開發單層HD DVD藍光光碟，此奈米複合薄膜可藉由晶粒粗化而達成記錄目的，研究驗證奈米複合材料應用於光記錄媒體之可行性，也建立一種新穎性的次世代藍光記錄媒體。 以不互溶之鉍-鐵（Bi-Fe）合金系統為記錄層為另一研究重點，先以Bi-Fe靶在氮氣環境中製成Bi-Fe-(N)記錄薄膜，研究發現雷射寫入造成富鉍相與富鐵相之分離，也同時形成晶粒粗化，而提供足夠的訊號區與非訊號區的反射率差異達到記錄的目的，此記錄機制不同於傳統相變化材料系統之結晶與非晶的轉變，亦成功製成超過HD DVD規格書規範的藍光光碟。 本論文亦研究矽/鋁-鈦（Si/Al-Ti）雙層記錄薄膜於HD DVD光碟之應用，經由調整最佳化的膜層結構及燒寫策略，最佳測值測值均已超過HD DVD規格書的規範，記錄機制研究顯示Si/Al-Ti雙層記錄薄膜係藉由界面擴散形成Al3.21Si0.47結晶相而達成記錄。

Optical disks are important external data storage devices for multimedia and personal data management due to their large recording capacity, interchangeability and portability. Among various optical disk types, write-once disks share the largest market. Both organic and inorganic materials have been proposed for write-once recording purposes. However, organic dyes encounter some difficulties in blue-light recording such as low optical absorption, environmental pollution, etc. This inspires the study of inorganic materials for next-generation optical data recording. This thesis studies the microstructure and recording mechanisms of several inorganic material systems for write-once optical disks. AgInSbTe (AIST)-SiO2 nanocomposite thin films were prepared by the target-attachment method and the composite target sputtering method. The sole-layer HD DVD disk sample containing such a nanocomposite film to replace conventional disks containing 4 to 8 multilayer structures was also fabricated. The nanocomposite films were found to achieve signal recording via grain coarsening induced by laser heating, illustrating a new type of recording medium for advanced optical storage. Bi-Fe-(N) thin film deposited by the reactive sputtering of Bi-Fe alloy target was implanted in HD DVD disk. Satisfactory signal properties due to element separation and grain coarsening were observed, rather than the amorphous-to-crystalline structure change observed in conventional optical disks. The Bi-Fe-(N) disk with signal properties exceeding the requirements of HD DVD Specifications was also demonstrated in this study. Si/Al-Ti bi-layer recording layer was also investigated and, with the optimized disk structure and writing strategy, the disk sample with signal properties exceeding the requirements of HD DVD Specifications was achieved. The element mixing/alloy reactions occurs in between Si and Al-Ti layers and the formation of Al3.21Si0.47 crystalline phase is responsible to the signal recording in such a disk sample.