Self-Heating Investigation in SOI MOSFET Structures with High Thermal Conductivity Buried Insulator Layers

The self-heating of thin and short silicon on insulator (SOI) devices is a serious problem limiting operation and reducing device lifetime. The main source of this phenomenon is low thermal conductivity of SiO2 buried oxide (lambda(SiO2)=1.4 W/m.K 100 time lower than that of silicon lambda(Si)=140 W/m.K). In this work three novel buried oxide (BOX) configurations in SOI MOSFET structure which suppress the self-heating effect are analyzed: 1) ultra-thin SiO2 BOX; 2) buried layers with high thermal conductivity material AlN, Al2O3, Si3N4; 3) stack of traditional SiO2 BOX with AlN plug. TCAD was used to study the 2D temperature distribution in device structures. The simulation results show that the thermal dissipation and self-heating were dramatically improved in all the devices. The UTB and UTBB ultra-thin SiO2 BOXes reduce the maximum internal device temperature 25 K and 39 K lower than that of normal SiO2 BOX; AlN, Al2O3, Si3N4 BOXes reduce T-max by 31-24 K lower than that of SiO2 BOX. The advantages and difficulties in practical use of the SOI MOSFETs with novel buried insulator layers are discussed.