SiO2/4H-SiC界面氮化退火

通过1 300℃高温干氧热氧化法在n型4H-SiC外延片上生长了厚度为60 nm的SiO2栅氧化层.为了开发适合于生长低界面态密度和高沟道载流子迁移率的SiC MOSFET器件产品的栅极氧化层退火条件,研究了不同退火条件下的SiO2/SiC界面电学特性参数.制作了MOS电容和横向MOSFET器件,通过表征SiO2栅氧化层C-V特性和MOSFET器件I-V特性,提取平带电压、C-V磁滞电压、SiO2/SiC界面态密度和载流子沟道迁移率等电学参数.实验结果表明,干氧氧化形成SiO2栅氧化层后,在1 300℃通入N2退火30 min,随后在相同温度下进行NO退火120 min,为最佳栅极氧化层退火条件,此时,SiO2/SiC界面态密度能够降低至2.07×1012 cm-2·eV-1@0.2 eV,SiC MOSFET沟道载流子迁移率达到17 cm2·V-1·s-1.

Nitridation Annealing on SiO2/4H-SiC Interface

A SiO2 gate oxide layer with a thickness of 60 nm was grown by the high temperature (1 300 ℃) dry oxidation method on the n-type 4H-SiC expitaxial wafer.Electrical characteristic parameters of SiO2/SiC interface were investigated under different post oxidation annealing (POA) conditions,in order to develop a suitable annealing condition of gate oxide layer for SiC MOSFET devices with lower interface state density and higher channel carrier mobility.The MOS capacitor and lateral MOSFET device were fabricated.The flatband voltage,C-V hysteresis voltage,interface state density of SiO2/SiC and channel carrier mobility were extracted from C-V characteristics of SiO2 gate oxide layer and I-V characteristics of MOSFET devices.The experiment results indicate that the SiO2 gate oxide layer is grown by dry oxidation and annealed in N2 for 30 min at 1 300 ℃,and annealed in NO for 120 min at 1 300 ℃,which is the most suitable annealing condition for the gate oxide layer.At this time,the interface state density of SiO2/SiC is reduced to 2.07× 1012 cm-2 · eV-1@0.2 eV and the SiC MOSFET channel carrier mobility can reach 17 cm2 · V-1 · s-1.