金屬/氧化鉿(HfO2)/氧化釩(VO2)/HfO2/Si MOS 結構之閘極漏電流分析

Abstract

隨著科技進步，半導體元件達到設計的極限，因此需要尋找新的材料。有金屬-絕緣體相變特性的 VO2 就是個很適合研究的材料。本研究使用Al/HfO2/VO2/HfO2/Si 堆疊的 MOS 結構來研究 VO2 特性，並比較不同製程參數所完成試片的差異。HfO2 是熱穩定性高的高介電常數材料。由於這些特性，即便 VO2 表現得像金屬，介電層仍有介電特性進行擬合，並能在相變時看到明顯的介電常數變化。本研究使用 HiPIMS 長成高品質的VO2 薄膜，以減少 VO2 薄膜的缺陷所造成的實驗誤差。本研究使用漏電流機制擬合獲得的參數(介電常數、陷阱能階、能障高度)來判斷其是否適合作為 MOS 結構之潛力材料。 本研究從實驗結果得出以下結論與推測。第一點，MOS 特徵的減弱主要是因為 Al 的滲透。第二點，可能存在低阻值的類電流通路。第三點，介電常數隨量測溫度增加而減少並在高溫時反轉，主要是因為 VO2 的相變。第四點，可能在介面生成 SiO2。最後，最佳製程參數是 500°C 的退火溫度和40 nm 的 VO2厚度。

關鍵字：二氧化釩、HiPIMS、漏電流機制、介電常數

As technology advances, semiconductor components reach the limits of their design, so we need new materials. VO2, with the metal-insulator phase transition feature, is a very suitable material for research. In this study, the Al/HfO2/VO2/HfO2/Si stacked MOS structure is used to study the VO2characteristics, and wecompare the differences of the samples completed with different process parameters.HfO2 is a high dielectric constant material with high thermal stability.Because of these features, even though the VO2 behaves like metal, thedielectric layer still has a dielectric feature to fit, and obvious dielectricconstant change can be seen during the phase transition. In this study, HiPIMSis used to grow a highquality VO2 film to reduce experimental errors caused bythe defect of the VO2film. In this study, parameters (dielectric constant, trapenergy level, barrier height) obtained bythe fitting of leakage mechanisms are used to judge its suitability as a potential material for a MOS structure.This study draws the following conclusions and speculations from theexperimental results. The weakening of MOS characteristics is mainly due to Alpenetration. There may be low-resistance paths. The dielectric constant decreases as the measurement temperature increases and reverses at high temperature, mainlydue to the phase transition of VO2. There may be SiO2 generated in the interface.The best process parameter is annealing temperature of 500°C and VO2 thickness of 40 nm.

Keyword：VO2, HiPIMS, leakage mechanism, dielectric constant