- 學位論文
氧化鋁/砷化銦金氧半電容製備與特性分析
Fabrication and Characterization of Al2O3/InAs Metal-Oxide-Semiconductor Capacitor
摘要
本論文以原子層沉積系統 (ALD) 成長高介電係數材料-氧化鋁 (Al2O3) 於砷化銦 (InAs) 基板，製作成金氧半電容元件 (Metal-oxide-semiconductor capacitor, MOSCAP)。我們於 ALD 成長前使用三甲基鋁 (TMA) 進行前置處理，並透過 X光射線電子能譜 (XPS) 之量測，確認氧化層-半導體界面之原生氧化物被有效抑制。經由穿隧式電子顯微鏡 (TEM) 影像，確認我們所成長的氧化層則為非晶體 (amorphous)，具有良好的閘極漏電流抑制能力，其在 -1 V 時的閘極漏電流密度約為 1×10-8 A/cm2。我們導入了金屬後退火製程，改善費米能階釘扎現象，其電容調變率在室溫 300 K 下可達 32.3 %。 本論文亦在室溫與低溫中進行變頻之電容-電壓量測，觀察到經過金屬後退火處理之元件，於 120 K 的低溫時並未在反轉區有反轉的現象，顯示我們成功改善其界面缺陷。透過電導法，我們求得其在 150 K 下靠進能隙中央處 (mid-gap) 之界面缺陷密度為 1.14×1013 cm-2eV-1 。
並列摘要
In this study, we deposited high dielectric constant material Al2O3 on InAs substrate by ALD and fabricated the Metal-oxide-semiconductor capacitor (MOSCAP). We applied the Try-methyl-aluminum (TMA) pretreatment before oxide growth by ALD, and native oxides was effectively suppressed, which is confirmed by XPS. By TEM image, we found that the oxide layer is amorphous and considered to be good at suppressing gate leakage current, which is about 1×10-8 A/cm2 at -1 V. We also applied post metal annealing to improve the Fermi-level pinning due to interface traps and the capacitance modulation was improved to 32.3 % at room temperature. We measured frequency-variant capacitance-voltage curve under room temperature and low temperature environment. We found that the post-metal-annealed device didn’t inverse in inversion region in low temperature environment (120 K), indicating that we succeeded in improving the interface trap. The interface trap density near mid-gap was 1.14×1013 cm-2eV-1, which is extracted by conductance method.