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標題: 銻薄膜應用於穿透式超解析近場光碟之特性研究
A Study of the Characteristics of Sb Thin Films for use in Transmitting-type Super-resolution Near-Field Structure Disc
作者: 張崇銘
Jhang, Chong-Ming
關鍵字: Super-RENS;超解析近場光碟
出版社: 材料工程學研究所
以銻(Sb)薄膜為遮罩層的穿透式超解析近場結構光碟,在讀取時,銻遮罩層經雷射加熱,在雷射光點中央溫度高於銻熔點的區域受到介電層內應力的作用,會形成一小於繞射極限的熔融透明孔徑,因此可讀取到小於繞射極限下的紀錄點。本研究將探討在不同升溫速率下,不同厚度的Sb薄膜在有無ZnS-SiO2介電層保護下的相變化行為,並觀察經熱退火與高功率雷射脈衝退火下單層Sb薄膜與多層ZnS-SiO2 /Sb/ZnS-SiO2多層薄膜的晶體結構與顯微組織的變化,以便了解以Sb薄膜為遮罩層的穿透式超解析近場結構光碟的寫入與讀取機制。
由實驗結果得知,Sb單層薄膜在低於10~15 nm的臨界厚度時,其初濺鍍狀態是呈非結晶態,升溫過程中,Sb薄膜在~100oC附近會由非結晶相轉變成結晶相;當Sb單層薄膜的厚度大於此一臨界厚度時,其初濺鍍狀態是呈結晶態,升溫過程中,Sb薄膜的晶體結構並不會有任何改變。在ZnS-SiO2介電層保護下,Sb薄膜呈結晶態所需的臨界厚度會提高至15~20 nm 之間,高於此一臨界厚度的Sb才能應用於穿透式超解析近場結構光碟。在寫入與讀取過程中,若以較小的雷射功率寫入資料,Sb遮罩層之結構不會發生變化,讀取時,雷射點中央溫度大於Sb熔點的區域,會形成一微小的開口,用以讀取小於繞射極限的訊號,在這種條件下,超解析近場結構光碟的寫入與讀取將可以重複。當寫入的雷射功率增加時,在Sb遮罩層會形成非晶質態的暫時開口,不過讀取時,一樣可形成一微小的開口,讀取小於繞射極限的訊號,而且光碟的寫入與讀取一樣是可以重複的。當施予更高的雷射功率時,因雷射點中央溫度大於Sb熔點的熔融區變大,加上ZnS-SiO2介電層的拉伸應力作用,在Sb遮罩層會形成一永久性的開口,讀取時,此一永久性的開口可以有效縮小雷射點的大小,讀取低於繞射極限的訊號,在這種條件下,超解析近場結構光碟將只能一次寫入。

Sb thin film has been adopted as a mask layer for the transmitting-type super-resolution near-field structure (super-RENS) disk .During readout,a transparent aperture smaller than the diffraction limit will be formed in the center region of the laser center spot,where the temperature in the Sb mask layer is higher than the melting point of Sb,under the influence of internal stress induced by the dielectric layer。As a result,the recorded marks beyond the resolution limit can be successfully retrieved。In this study,we investigated the phase change behavior of Sb thin film of different thickness with and without ZnS-SiO2 protection。The structural changes of single-layered Sb and multi-layered ZnS-SiO2/Sb/ZnS-SiO2 films under thermal annealing and pulsed laser irradiation will be examined to understand the recording and readout mechanisms of transmitting-type super-RENS disk with a Sb mask layer。
Based on the experimental observations,it was found that the single-layered Sb film with thickness lower than the critical thickness (10-15nm) was amorphous in the as-deposited state,and will transform to crystalline Sb phase at ~100℃ during nonisothermal annealing。When the thickness of Sb film is greater than the critical thickness,the as-deposited Sb film became crystalline,and remained unchanged during annealing。 With ZnS-SiO2 protction,the critical thickness for Sb film to become crystalline phase increased to 15~20 nm which is also the minimum thickness for Sb film to be used in the transmitting-type super-RENS disk。During the recording and readout processes,when a low recording power is applied,no structure change will occur in the Sb mask layer,and a small aperture will be created at the center region of laser spot,where the temperature is higher than the melting point of Sb,to retrieve the recording marks beyond the diffraction limit。Under this condition,the super-RENS disk is rewritable。When recording power is increased,although an amorphous aperture will be formed in the Sb mask layer during recording,a small aperture still can be created to retrieve the recording marks,and super-RENS disk is also rewritable。However,when higher laser power is applied,a permanent aperture will be created in the center region of laser spot during recording due to the melting of Sb mask layer and the tensile stress induced by ZnS-SiO2 protection layers。During readout,this permanent aperture can effectively reduce the size of laser spot to read the recording marks beyond the diffraction limit so the super-RENS can only be write-once。
Appears in Collections:材料科學與工程學系

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