研究生: |
鄭易沂 |
---|---|
論文名稱: |
金屬(Al)/氧化鋯(ZrO2)/矽(Si)薄膜電容器與場效電晶體之製作與電性分析 Fabrication and Characterization of Metal (Al)-Oxide-Si Capacitors and Field-effect Transistors Using ZrO2 Gate Oxide |
指導教授: |
李雅明
Joseph Ya-Min Lee |
口試委員: | |
學位類別: |
碩士 Master |
系所名稱: |
電機資訊學院 - 電子工程研究所 Institute of Electronics Engineering |
論文出版年: | 2005 |
畢業學年度: | 93 |
語文別: | 中文 |
論文頁數: | 130 |
中文關鍵詞: | 氧化鋯 、電容器 、電晶體 |
外文關鍵詞: | ZrO2, Capacitor, Field-effect Transistor |
相關次數: | 點閱:3 下載:0 |
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本實驗中,我們成功地製作了金屬(Al)/氧化鋯(ZrO2)/半導體(p-Si)結構的電容器,在1MV/cm的偏壓電場下漏電流為-8.78×10-2 A/cm2,介電常數為14.4,ZrO2薄膜的厚度為14.7 nm。利用自恰法可求得在氧化鉿薄膜中電子有效質量為0.39 m0,Al/ZrO2能障高度為0.987 eV。
接下來,我們也製備N通道的金屬(Al)/氧化鋯(ZrO2)/半導體(p-Si)的場效電晶體。在基本電性上的表現,如:C-V,ID-VG及ID-VD等,皆證明電晶體能夠正常的操作。經由變溫實驗 (300~420K),得到N通道的氧化鋯(ZrO2)-閘極場效電晶體有效通道電子移動率的衰減機制與臨限電壓 (threshold voltage, VTH) 的漂移狀況。對於有效載子移動率 (effective mobility),有效電場(effective field) 隨溫度改變的情況,經過系統化的分析。這種情況可用soft optical phonons來加以解釋。我們以split C-V的方式,量測了三種頻率下的閘極-通道電容(gate-to-channel capacitance)。通道電阻的效應(channel resistance) 也會在文章中介紹。
經由閘控二極體的量測,我們亦得到一些結果,分別如下:界面缺陷電荷密度為1.5x1012 cm-2-eV-1,表面複合速率244 cm/s,少數載子活期為 2.55x10-6 sec。
至於材料物性方面,我們也作了SIMS、XRD、ESCA等分析,亦有了些許的收穫。
經由和傳統SiO2電晶體與學長的Ta2O5電晶體作一比較,發現電晶體特性及相關參數沒有傳統SiO2電晶體好,但由於熱穩定性較Ta2O5好,所以ZrO2非常適合當作下一代電晶體的閘極氧化層材料。
Al/ZrO2/p-Si metal-insulator-silicon (MIS) capacitors fabricated to characterize the electrical properties of the ZrO2 dielectric. The leakage current density is -8.78×10-2 A/cm2 when the applied electric field is 1MV/cm and the ZrO2 thickness is 14.7 nm, and the dielectric constant measured from a separate metal-ZrO2-silicon capacitor is 14.4. The electrical conduction mechanisms of ZrO2 thin film as functions of temperature were studied. Both the intercept of the fitted Schottky emission line and the slope of the fitted Fowler-Nordheim tunneling line are functions of barrier height and electron effective mass in ZrO2. An analysis of self-consistent iteration method was used to show that the extracted Al/ZrO2 barrier-height and electron effective mass in the ZrO2 film (equivalent oxide thickness = 3.88 nm) are about 0.987 eV and 0.39 m0.
N-channel metal-oxide-semiconductor field effect transistors (MOSFETs) using ZrO2 gate oxide were also fabricated successfully. The C-V, ID-VD and ID–VG characteristics are measured. The degradation mechanisms of effective electron channel mobility and the threshold voltage shift in ZrO2-gated n-MOSFETs have been studied by analyzing experimental data at various temperatures from 300 to 420K. The soft optical phonons are proposed to explain the extra source for severe phonon scattering in ZrO2-gated n-MOSFETs.
The interface trapped charge density, the surface recombination velocity, and the minority carrier life time in the field-induced depletion region measured from gated diodes were 1.5x1012 cm-2-eV-1, 244 cm/s, and 2.55x10-6 sec, respectively.
Secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD), and electron spectroscopy for chemical analysic (ESCA) were used to examine the material properties of ZrO2.
A comparison with MOSFETs using SiO2 gate oxides was made. The ZrO2/Si interface is generally inferior compared with that of the SiO2/Si interface. But the ZrO2/Si interface is comparable to that of the Ta2O5/Si interface. The thermodynamic stability of ZrO2 gate oxide is much better than that of Ta2O5 gate oxide. In the future, MOSFETs with ZrO2 gate oxide will be a promising candidate for sub-0.1 □m MOSFETs.
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