Investigation Of Electrothermal Characteristics Of Vertical Gate-All-Around Nanosheet Field Effect Transistor

As the manufacturing process of integrated circuits shrinks to the nanoscale,issues such as increasing power density,intensified short channel effects,and thermal limitations in three-dimensional structures have become key constraints for improving chip integration.VGAAFET(Vertical Gate-All-Around Nanosheet Field Effect Transistor)has become a powerful alternative to Fin FET due to its excellent ability to suppress short channel effects,flexible channel width regulation,and smaller CGP(contact gate pitch),bringing new solutions for further improving integration.However,higher power density and thermally constrained three-dimensional structures can lead to increased SHE(self-heating effect)on the device,causing device and circuit performance degradation and even serious thermal reliability problems.Therefore,facing the future development of nanoscale integrated circuit technology,studying the electrothermal characteristics of VGAAFET devices has important guiding significance and reference value for device circuit systems below5 nm process node.This paper conducts systematic research on the analysis of DC and transient electrothermal characteristics,compact models,and basic logic unit circuit electrothermal co-simulation of VGAAFET devices.The main research contents and results are as follows:Firstly,a research platform for the electrothermal characteristics of three-dimensional VGAAFET devices and circuits was built based on the TCAD tool.The simulation calculation model and equation sets are analyzed and selected,the thermal conductivities depending on the thickness of the nano-scale silicon film are calculated,the BEOL(back-end of line)interconnect and substrate equivalent thermal resistance are set,and the calibration of the simulation calculation platform for VGAAFET devices is finally realized.The fitting error is less than 1%,which provides theoretical support and research technical means for the study of its DC and transient electrothermal characteristics.Secondly,based on the TCAD electrothermal characteristics research platform established in this article,a systematic study is conducted on the DC and transient electrothermal characteristics of VGAAFET devices.(1)In the analysis of DC electric heating characteristics,the dependence mechanism of VGAAFET electrothermal characteristics on parameters such as channel size,channel spacing,gate size,oxide layer thickness,sidewall material,environmental temperature,and thermal boundary conditions was mainly studied.(2)In the analysis of transient electrothermal characteristics,the focuses are on studying the regulatory effects of pulse width,duty cycle,power supply voltage,and environmental temperature on the electrothermal characteristics of VGAAFET.On this basis,TCAD hybrid simulation was used to study the static and dynamic characteristics of the inverter,and the effects of power supply voltage,environmental temperature,pulse frequency,and load capacitance on the transmission characteristics and delay of the VGAAFET inverter were discussed and analyzed.Various parameters that affect the electrothermal characteristics of VGAAFET devices were summarized,providing important guidance for their electrothermal optimization.Thirdly,the BSIM-CMG compact electrical model of VGAAFET device was established and the first-order RC and sixth-order RC thermal networks were extracted with fitting errors less than 3.2% and 1%,respectively.A joint SPICE electrothermal simulation platform is constructed based on the first-order RC thermal network,and the circuit-level electrothermal characteristics of the invertor,ring oscillator and SRAM are completed.Compared with TCAD device level simulation,the transmission characteristic error of the inverter in SPICE circuit level simulation is less than 9.3%.In summary,this paper conducts a systematic study on the electrothermal characteristics and regulation mechanism of VGAAFET devices,and establishes a SPICE circuit level electrothermal joint simulation method for them,providing important theoretical basis and research method reference for VGAAFET devices and circuit design optimization.