超薄氧化鉭Ta2O5介電薄膜研究

Abstract

本實驗利用磁控射頻濺鍍法製備氧化銥IrOx底電極與非晶質超薄氧化鉭Ta2O5介電薄膜，得到Al/Ta2O5/IrOx/SiO2/Si結構，作物性與電性之分析。超薄薄膜初始厚度為48Å~125Å，探討其在不同成長溫度以及不同條件熱處理下，針對表面形態、漏電流密度及介電性質等參數加以研究。 利用n&k及TEM量測薄膜厚度，可知薄膜厚度大於78Å，膜厚與鍍膜時間成正比。由I-V及C-V量測顯示，在固定電場1.4MV/cm下，初始厚度65Å薄膜有最小漏電流；退火溫度越高，薄膜介電常數隨之高；鍍膜氣氛OMR50%可以得到最大的介電常數值。XPS縱深分析顯示成長之介電薄膜計量比(O/Ta)接近五氧化二鉭之2.5/1。由原子力顯微鏡觀察表面形態顯示退火後表面粗糙度變大，局部電場增加，氧氣氛中退火使漏電流特性劣化。

In this study, we use magnetron frequency sputter technique to make Iridium Oxide (IrOx) bottom electrode and amorphous ultra thin (as-deposited thickness 48Å~125Å)tantalum pentaoxide (Ta2O5). After the Al/Ta2O5/IrOx/SiO2/Si structure is obtained, we study the physical and electrical properties of the film and discussed the relationship between surface roughness, leakage current density and dielectric constant. The film grows proportionally to deposition time after the thickness is larger than 78Å.I-V and C-V measurement revealed that at constant electric field(1.4MV/cm), the film with thickness 65Å has the lowest leakage current density ; the higher the annealing temperature, the higher the dielectric constant. XPS depth profile showed that the O/Ta ratio is close to exact stoichiometery 2.5/1. The Atomic Force Microscope observed that after annealing, the surface becomes rough so that the local electric field deteriorates the leakage current characterization.