氧化釔4H碳化矽金氧半電容在高溫下的特性分析

Abstract

本論文所製作的金氧半電容元件是將介電層氧化釔（Y2O3）用射頻濺鍍機沉積在C-Face的4H碳化矽基板，接著使用真空退火做四種不同溫度條件的退火五分鐘，分別是退火溫度300度、400度、500度及600度，最後鍍上鋁金屬當閘極完成元件製作。 實驗部分主要是探討在不同退火溫度下氧化釔對於閘極漏電流和崩潰電場所帶來的影響，藉由電容－電壓量測、電流－電壓量測以及高溫下的量測分析，來算出介面捕捉電荷密度、介電係數值以及平帶電壓的偏移量，從中探討介電層的品質、介電層和基板間的缺陷問題以及介電層內部電荷的關係。 根據Ｘ光粉末繞射儀的分析，退火溫度達到400度時，在電流－電壓量測上，能有較低的漏電流。而在高溫量測方面，經過快速熱退火的過程，平帶電壓的偏移有明顯的降低，達到減少氧化層電荷的作用。但在介面缺陷的部分，由於使用真空熱退火，因此在介面缺陷的修復上效果沒有很明顯。介電層強度方面，在無退火的情況下，介電層的強度大概在1.3 MV/cm，隨著退火溫度達到600度時，崩潰電場的強度達到了約3.1 MV/cm，也就是在有退火的情況下，介電層的強度有效的被提升。

In this research, Y2O3 film was deposited on carbon(C)-face 4H-SiC substrates by using a RF sputter. Then Y2O3 films were treated with RTA (rapid thermal annealing) process in vaccum ambient at 300℃, 400℃, 500℃ and 600℃, respectively for five minutes. Finally, we deposited the aluminum as the gate metal In the experiment, we investigate the relationship between the effects of post-deposition annealing on the Y2O3 thin film structure and the gate leakage current. By the C-V, and I-V measurement at the high temperature measurement, we calculate the interface trapped density, dielectric constant and the shift of flat-band voltage. Then, we can discuss the insulator quality, interface defects and oxide charge. The Y2O3 film shows the lower leakage currents at the annealing temperature of 400℃. Comparing with samples with no RTA process, the anneal samples with the anneal treatment display the lower flat-band voltage shift because the oxide charge in the insulator have been improved. However, the interface traps is not reduced due to the vacuum annealing. The dielectric breakdown field with no annealing process is about 1.3 MV/cm. As the annealing temperature reach to 600℃, the dielectric breakdown field increase to 3.1 MV/cm. The result shows dielectric strength have been improved under the annealing process.