Influences of different structures on the characteristics of H_2O-based and O_3-based La_xAl_yO films deposited by atomic layer deposition

H_2O-based and O_3-based La_xAl_yO nanolaminate films were deposited on Si substrates by atomic layer deposition(ALD). Structures and performances of the films were changed by different barrier layers. The effects of different structures on the electrical characteristics and physical properties of the La_xAl_yO films were studied. Chemical bonds in the La_xAl_yO films grown with different structures and different oxidants were also investigated with x-ray photoelectron spectroscopy(XPS). The preliminary testing results indicate that the La_xAl_yO films with different structures and different oxidants show different characteristics, including dielectric constant, equivalent oxide thickness(EOT), electrical properties, and stability.     

新一代SiC功率MOSFET器件研究进展

自2017年报道SiC(碳化硅)功率金属-氧化物半导体场效应晶体管(MOSFET)技术进展以来,针对器件比导通电阻(RON,SP)高等问题不断优化器件结构设计,本课题组改进关键加工工艺,使1200 V SiC MOSFET的RON,SP从8 mΩ·cm2降低到4.8 mΩ·cm2.与此同时,本课题组采用新一代SiC MOSFET设计和工艺技术研制出6.5 kV、10 kV以及15 kV等高压低导通电阻SiC MOSFET,其中10 kV和15 kV器件的比导通电阻分别为144 mΩ·cm2和204 mΩ·cm2,接近单极型SiC器件的理论极限.     

Evidence of GeO volatilization and its effect on the characteristics of HfO2 grown on a Ge substrate

HfO2 films are deposited by atomic layer deposition(ALD) using tetrakis ethylmethylamino hafnium(TEMAH) as the hafnium precursor,while O3 or H2O is used as the oxygen precursor.After annealing at 500℃ in nitrogen,the thickness of Ge oxide's interfacial layer decreases,and the presence of GeO is observed at the H2 O-based HfO2 interface due to GeO volatilization,while it is not observed for the O3-based HfO2.The difference is attributed to the residue hydroxyl groups or H2 O molecules in H2 O-based HfO2 hydrolyzing GeO2 and forming GeO,whereas GeO is only formed by the typical reaction mechanism between GeO2 and the Ge substrate for O3-based HfO2 after annealing.The volatilization of GeO deteriorates the characteristics of the high-κ films after annealing,which has effects on the variation of valence band offset and the C-V characteristics of HfO2 /Ge after annealing.The results are confirmed by X-ray photoelectron spectroscopy(XPS) and electrical measurements.