Ar气退火温度对4H-SiC热氧化层致密性影响研究

Effect of Ar Annealing Temperature on the Densification of SiO_2 Film Grown by Thermal Oxidation on 4H-SiC

在Ar气气氛下对热氧化n型4H-SiC生长的SiO2薄膜进行了1 100℃以下不同温度的退火,采用反射式椭圆偏振光谱、红外透射光谱研究了退火温度对SiO2薄膜致密性的影响。椭偏测试的结果表明,600℃退火后样品具有最大的折射率1.47和最小的厚度84.63 nm。红外研究的结果显示,600℃退火后LO峰强度最强,认为是对应Si-O结构单元浓度最高。Al/SiO2/SiC MOS结构SiO2的漏电特性研究表明,600℃退火后的SiO2薄膜漏电流相比于其他温度退火的氧化层漏电流小了两个数量级。在外加反向偏压5 V时,漏电流密度仅仅只有5×10?8 A/cm2。600℃退火能显著地改善热氧化层SiO2的致密性。

The effect of different temperature （below 1 100 ℃） post-oxidation annealing in Ar atmosphere （Ar POA） on the densification of thermally grown SiO 2 film on n-type 4H-SiC has been studied by reflective spectroscopic ellipsometry （SE） and Fourier transform infrared （FTIR） spectroscopy. The spectroscopic ellipsometry studies show that the 600 ℃ annealed SiO 2 film has the highest refractive index of 1.47 and the lowest thickness of 84.63 nm in all samples. It is obtained from FTIR that 600 ℃ annealed sample has the highest LO phonon intensity, which may be attributed to the highest concentration of Si-O bonds. The leakage current-voltage measurement of Al/SiO 2/SiC MOS capacitor was also performed. The leakage current is decreased by two orders of magnitude of the SiO 2 thin film after annealing at 600 ℃. When a reverse bias voltage of 5 V is applied, the reverse leakage current density is only 5＆#215;10-8 A/cm2. According to all studies, we conclude that annealing at 600 ℃ can greatly improve the compactness of thermally oxidized SiO2.