碳化矽金氧半電容元件上新穎氧化矽與氧化鋁高介電常數閘極介電層

Novel SiO2 and Al2O3 High-K Gate Dielectrics on 4H-SiC MOS Capacitors

許家銘(Chia-Ming Hsu)

指導教授 ： 胡振國

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.03196

摘要

本論文提出三種新穎製程，於碳化矽基板上成長介電層。在純水中以陽極氧化，再經快速熱退火製備氧化矽，以電導方法求得界面缺陷密度約為3×1011cm-2eV-1，此介電層崩潰電場大於6.3MV/cm 且電容電壓曲線無遲滯現象。於己二酸銨水溶液中使用陽極氧化法成長氧化鋁，首度應用於閘極介電層，先蒸鍍鋁薄膜再以陽極氧化得到超薄氧化鋁，等效氧化層厚度1.9 奈米，電容電壓曲線無遲滯現象，界面缺陷密度約為8×1011 cm-2eV-1，崩潰電場高達14.5 MV/cm 且在偏壓2 V時有著極小漏電流6×10-3 A/cm2。此外，以電漿濺鍍氧化製備氧化鋁介電層金氧半電容，閘極漏電流小於氧化矽一個數量級，從電容電壓曲線而言，低頻時比高頻時較接近理想值，且電容值與頻率於1k~500 kHz 時呈線性相關，我們提出一個等效電路模型，引入電感來解釋此現象，在電漿氧化過程中，並非所有的金屬都被氧化而部分奈米金屬殘留在介電層中。根據論文數據，這三種製程對於碳化矽高壓金氧半元件，有著重大突破。

關鍵字

金氧半 ； 電容 ； 氧化矽 ； 氧化鋁 ； 高介電 ； 絕緣層 ； 碳化矽 ； 己二酸銨 ； 陽級氧化 ； 濺鍍

並列摘要

This thesis contains three novel dielectric processes about gate dielectric on 4H-SiC substrate. SiO2 was prepared by anodization in DI water followed by rapid thermal nnealing. The oxide breakdown strengths are greater than 6.3 MV/cm and the capacitance–voltage hysteresis is negligible. The interface state density was extracted using the conductance method and the value is of 3×1011cm-2eV-1. The first demonstration of anodized aluminum oxide (Al2O3) was grown in aqueous Ammonium Adipate solution as dielectric on 4H-SiC MOS capacitors. Ultrathin Al2O3 film (1.9nm) was prepared by anodic oxidation of ultrathin Al film followed by furnace annealing. The capacitance-voltage hysteresis is negligible and the interface trap density is low to ~8×1011 cm-2eV-1. The much higher breakdown field of 14.5 MV/cm and lower gate leakage current of 6×10-3 A/cm2 at 2 V are obtained.
Furthermore, we present the SiC MOS capacitor with Al2O3 film fabricated by plasma sputtering oxidation. The leakage current was one order This thesis contains three novel dielectric processes about gate dielectric on 4H-SiC substrate. SiO2 was prepared by anodization in DI water followed by rapid thermal annealing. The oxide breakdown strengths are greater than 6.3 MV/cm and the capacitance–voltage hysteresis is negligible. The interface state density was extracted using the conductance method and the value is of 3×1011cm-2eV-1. The first demonstration of anodized aluminum oxide (Al2O3) was grown in aqueous
Ammonium Adipate solution as dielectric on 4H-SiC MOS capacitors. Ultrathin Al2O3 film (1.9nm) was prepared by anodic oxidation of ultrathin Al film followed by furnace annealing. The capacitance-voltage hysteresis is negligible and the interface trap density is low to ~8×1011 cm-2eV-1. The much higher breakdown field of 14.5 MV/cm and lower gate leakage current of 6×10-3 A/cm2 at 2 V are obtained.Furthermore, we present the SiC MOS capacitor with Al2O3 film fabricated by plasma sputtering oxidation. The leakage current was one order smaller than the typical thermal SiO2 and with good stress reliability. The low-frequency C-V curves are close near to ideal condition than high frequency and exhibit linear dependency on frequency from 1k to 500 kHz. We proposed a two-element equivalent circuit model including inductance to explain this phenomenon. It’s suggested that under the sputtering oxidation process, not all of the metal was oxidized completed and nanocrystal could be left inside the dielectric. Based on the reported results, the three processes could be useful to SiC MOS high-power devices.

並列關鍵字

MOS ； capacitor ； SiO2 ； Al2O3 ； high-k ； dielectric ； Ammonium Adipate ； anodization ； sputter

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