臺灣博碩士論文加值系統

本研究主要是探討利用低壓化學氣相沈積法以四異丙烷氧化鈦(TTIP)及矽酸四乙酯(TEOS)鍍製不同比例之TiO2-SiO2複合氧化薄膜退火前後的材料特性以及藉由電性量測(I-V、C-V)探討其作為閘極介電層之特性。
本論文使用拉塞福背向散射能譜進行TiO2-SiO2複合氧化薄膜的成份分析。而複合氧化薄膜的結構與結晶性則使用低掠角X光繞射以及穿透式電子顯微鏡繞射圖進行分析。各種比例之初鍍與不同條件退火後試片的表面型態由掃瞄式電子顯微鏡與穿透式電子顯微鏡進行觀察。另外也利用X光光電子能譜跟傅立葉轉換紅外線光譜對複合氧化薄膜中之化學鍵結進行分析。而對於光學性質的研究，本論文使用橢圓偏光儀量測其折射率大小，並且可同時對其薄膜的厚度進行量測。最後使用PA meter/dc voltage source(HP4140)以及LCR meter(HP4284)進行I-V以及C-V的電性量測。
實驗結果發現，TiO2-SiO2複合氧化薄膜中所含之Si/(Ti+Si)的比例隨著通過TEOS的載氣流量增加而有增加的趨勢，但整體維持(Ti+Si):O ≈ 1:2。而經由低掠角X光繞射的分析，初鍍及退火後之純TiO2皆出現anatase相的結晶。添加不同比例的SiO2後之初鍍複合氧化薄膜皆為非晶質相，而含不同比例SiO2之試片700℃與800℃退火後皆出現結晶現象（anatase相之TiO2），不過添加SiO2之試片的繞射峰強度遠低於純TiO2。加入SiO2後之氧化薄膜不論初鍍或退火後之試片表面型態明顯較為平整。經由X光光電子能譜的分析，TiO2-SiO2複合氧化薄膜之O 1s的殼層電子之束縛能介於純TiO2之O 1s殼層電子束縛能與純SiO2之O 1s殼層電子束縛能之間，並且隨著SiO2含量增加而往純SiO2之O 1s殼層電子束縛能方向偏移。而Ti 2p與Si 2p之殼層電子之束縛能不會隨著所含Si/(Ti+Si)比例改變而有所偏移。而傅立葉轉換紅外線光譜分析可以發現退火後試片之各種原子間的鍵結訊號皆明顯增強，這顯示薄膜中鍵結數量增加，薄膜中之原子排列更為整齊。光學性質方面，折射率隨薄膜中SiO2含量的增加而降低。由C-V曲線可以發現不同成份的氧化薄膜600℃、700℃退火後之試片介電常數差異不大。800℃退火後高SiO2含量的氧化薄膜則有介電常數下降的趨勢。而由各條件之I-V曲線可以發現，試片之漏電流密度明顯隨退火溫度升高而降低，而不同成份之間的漏電流密度因為影響的因素太過複雜而不會有明顯的趨勢。

The material characterizations of various TiO2-SiO2 composite oxide thin films prepared with low pressure chemical vapor deposition, using titanium tetra-iso-propoxide(TTIP) and tetraethoxysilane(TEOS) as precursors, before and after annealing were investigated. The characterizations of TiO2-SiO2 composite thin films as gate dielectrics were investigated by I-V and C-V measurement.
In this study, Rutherford backscattering spectrometry (RBS) analysis was used to determine the composition of TiO2-SiO2 thin films. The structure and crystallography of the composite oxide thin films were characterized by glancing incident angle X-ray diffraction (GIAXRD) and transmission electron microscope (TEM) diffraction patterns. The morphology of TiO2-SiO2 thin films before and after annealing were observed with scanning electron microscope (SEM) and transmission electron microscope (TEM). The chemical bonding of TiO2-SiO2 thin films were investigated with X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Spectroscopic ellipsometry was carried out to measure the refraction index and thickness of TiO2-SiO2 thin films. Finally the electrical properties (I-V, C-V) were measured by PA meter /dc voltage source(HP4140) and LCR meter(HP4284).
From RBS results, the composition ratios of Si/(Ti+Si) in the oxide thin films increased with the increasing carrier flow rates through TEOS. However, the stoichiometry of (Ti+Si):O maintained 1:2 for all films. Pure TiO2 thin film revealed the anatase phase before and after annealing. The as-deposited composite oxide thin films with altering SiO2 ratios were amorphous. The composite oxide thin films with altering SiO2 ratios crystallized after annealing at 600, 700, and 800℃, but the diffraction intensities were much smaller compared with pure TiO2. The morphology of TiO2-SiO2 composite thin films were much smoother than pure TiO2 thin films before and after annealing. The binding energy of O 1s core level electron of TiO2-SiO2 composite thin films were shifted to lower energy as the SiO2 ratio in the composite thin films increased. The binding energy of Ti 2p and Si 2p of TiO2-SiO2 composite thin films remains constant with different SiO2 ratio. The intensity of FTIR signal were much stronger after annealing, indicating that the atoms in the annealed thin films were arranged much uniformly than those as-deposited. The refractive indexes decreased by increasing SiO2 ratio in the thin films. The relative dielectric constants were almost the same with various SiO2 ratios after 600 and 700 ℃ annealing. The relative dielectric constants of high SiO2 composition were smaller than the pure TiO2 films after 800℃ annealing. The leakage current densities decreased as annealing temperature increased. The leakage current densities of various TiO2-SiO2 composite thin films did not exhibit an obvious tendency with the ratio of SiO2 in the thin films.

中文摘要........................................................................I
Abstract......................................................................III
總目錄..........................................................................V
圖目錄........................................................................VII
表目錄.........................................................................XI
第一章 前言.....................................................................1
1-1閘極氧化層...................................................................1
1-2研究目的.....................................................................2
第二章 理論基礎.................................................................4
2-1 TiO2性質介紹................................................................4
2-2混合氧化物之特性.............................................................7
2-3 TiO2-SiO2文獻回顧..........................................................12
2-4氧化薄膜中之缺陷對電性之影響................................................22
2-4-1 氧化薄膜中之缺陷簡介.....................................................22
2-4-2 氧化薄膜中之缺陷之量測方法...............................................23
第三章 實驗方法與步驟..........................................................30
3-1 實驗材料...................................................................30
3-2 實驗設備...................................................................31
3-2-1 化學氣相沉積系統.........................................................31
3-2-2 退火系統.................................................................31
3-3 實驗流程...................................................................34
3-4 鍍層性質分析...............................................................37
3-4-1 拉塞福背向散射(Rutherford backscattering spectrometry， RBS)成分分析.....37
3-4-2 低掠角X光繞射(Glancing incident angle XRD，GIAXRD)結構分析...............39
3-4-3 X光光電子能譜(X-ray photoelectron spectroscopy，XPS)化學鍵結分析.........40
3-4-4傅立葉轉換紅外線光譜分子(Fourier transform infrared spectroscopy，FTIR)鍵結分析...........................................................................41
3-4-5橢圓偏光儀(Ellipsometry)折射率量測........................................42
3-4-6穿透式電子顯微鏡(Transmission electron microscope，TEM)微結構分析.........43
3-4-7電性量測..................................................................46
第四章 結果與討論..............................................................48
4-1 氧化薄膜成分及密度分析.....................................................48
4-1-1 成分分析定量.............................................................48
4-1-2 質量密度與原子密度計算分析...............................................49
4-2氧化薄膜微結構分析..........................................................57
4-2-1 氧化薄膜表面型態.........................................................57
4-2-2 氧化薄膜結晶性與結晶結構.................................................60
4-2-3 氧化薄膜之化學鍵結分析...................................................70
4-3光性分析....................................................................86
4-4電性分析....................................................................90
4-4-1 C-V量測..................................................................90
4-4-2 I-V量測..................................................................92
第五章 結論...................................................................103
第六章 參考文獻...............................................................104

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