奈米孔洞元件與鐵氮薄膜的製備與性質

Fabrication and Characterization of Nanopore Devices and Iron Nitride Thin Films

顏嘉男(Chia-Nan Yen)

指導教授 ： 林敏聰

國立臺灣大學/理學院/物理研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.11163

摘要

磁性穿隧介面以三層結構製造，其結構為//鐵磁層1/穿隧層(絕緣物,有機物….等等)/鐵磁層2//。在磁性穿隧介面製程中，針孔(pinhole)現象會發生在薄膜製程中，由於幾個奈米厚度下的薄膜可能會被打穿當其它層的製程裡，因而造成短路現象。有許多因素會影響針孔機率的發生，像是:介面的面積,長膜的溫度,長膜的壓力和長膜的方法等等。為了降低孔洞發生的機率，我們採用奈米孔洞(nanopore)的製程，這是運用電子束蝕刻(e-beam lithography)與反應性離子蝕刻(reactive-ion etching)去製造一個奈米等級碗形狀的孔洞，在其中並擁有一個火山形狀的閘極。與先前的元件比較，奈米孔洞型元件有許多的傳輸機制可以讓我們去探討。
巨大得飽和磁化量物質被廣泛的運用在現代的磁性記錄工業中，它也扮演越來越重要的角色。鈷鐵合金(Fe65Co35)為大家所知道的非常高飽和磁化量物質它可達到1950 emu/cm3。但在最近研究裡，鐵氮薄膜被研究出高於鈷鐵合金的飽和磁化量。在這份論文裡，高飽和磁化量鐵氮薄膜運用反應式磁性濺鍍被製備在砷化鎵單晶基板上並採用金為種子層，金擁有與鐵氮結構相當小的晶格錯位。經由控制氬氣與氮氣的混合比例,長膜的溫度和後退火的過程，進而得到不同的晶向。經由振動樣品磁化儀(VSM)跟掠角X光繞射去探討出磁性性質與晶格結構，它提供出一個重要的關係在磁學與晶格結構之間在整個鐵氮系統下。

關鍵字

奈米孔洞 ； 鐵氮薄膜 ； 飽和磁化量 ； 掠角繞射 ； 振動樣品磁化儀

並列摘要

The magnetic tunnelling junction (MTJ) is a sandwiched structure, with //ferromagnetic layer 1 (FM1)/tunnelling barrier (insulator, organic material... etc)/ferromagnetic layer 2 (FM2)//. In MTJs, a pinhole phenomenon may take place in the thin film layer, which is only a few nanometers thick and may be penetrated by other layers, and the pinhole may cause a short circuit. There are many factors influencing the probability of the pinhole, for example: the junction area, growth temperature, deposition pressure and material growth methods and so on. To reduce the problem of pinhole, we adopt nanopore fabrication, which uses electron-beam lithography and the reactive-ion etching method to create a nano-scale bowl-shaped pore with a volcano shaped gate electrode on a 30nm-thick silicon nitride (Si$_{3}$N$_{4}$) membrane. As compare to previous MTJ device, the nanopore type devices still have some transport mechanisms to study.

Giant saturation magnetization (M$_{s}$) materials are used widely in the modern magnetic recording industry and are playing more and more important roles. The well known giant saturation magnetization material Fe$_{65}$Co$_{35}$ alloy can reach 1950 emu/cm$^{3}$. But in recent studies, it has been shown that iron nitride thin films can reach higher saturation magnetization than Fe$_{65}$Co$_{35}$. In this thesis, the iron nitride thin films in bct structure, which may possess high saturation magnetization phase Fe$_{16}$N$_{2}$/ Fe$_{8}$N, are fabricated on GaAs (001) single crystal substrates, buffered by Au (001), which was chosen due to its small lattice mismatch, by reactive DC magnetron sputtering. Different phases of iron nitride were observed by controlling the mixture ratio of Ar and N$_{2}$ in different growth temperature and in-situ post-annealing process. Vibrating sample magnetometer (VSM) and grazing incidence x-ray diffraction (GIXRD) carry out measurements of the magnetic properties and the crystalline structure, and in turn provide a important correlation between magnetism and crystalline structure of FeN system.

並列關鍵字

nanopore ； FeN thin film ； saturation magnetization ； GIXRD ； Vibrating sample magnetometer (VSM)

參考文獻

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