Research On Modeling And Application Of Electron Devices At Cryogenic Temperatures

Quantum computer is regarded as one of the most promising technical routes among the various technical branches of "Beyond CMOS" in the Post-Moore Era.It has been applied in the fields of finance and biopharmaceuticals and has received exten-sive attention from scientific researchers and commercial companies.Semiconductors and superconducting quantum chips work in the low-temperature environment of tens of milliKelvin,while the measurement and control system is placed at room temper-ature,and the two are interconnected by cables.With the increase in the number of qubits,the above method is no longer applicable due to the number of cables,cooling power,noise,and other reasons.Faced with the above problems,we can design the measurement and control circuits that work at extremely low temperatures,and place the quantum chip and the measurement and control circuits in the same temperature or adjacent temperatures to achieve more qubit chip measurement and control.The working characteristics of the device under cryogenic temperatures will be different from the normal temperature due to the harsh temperature environment.The valid temperature of common device models provided by the manufacturer is from-40?-125?.Due to the large temperature gap and different characteristics of MOS-FET devices at cryogenic temperatures,the model in process design kit is inapplicable to cryogenic circuit simulation.The cryogenic circuit design puts forward an urgent need for the working characteristics of the device at cryogenic temperatures and the accurate cryogenic device model.In response to the above situation,in this thesis,we describe the process of build-ing a cryogenic measurement platform,and select some commercial devices such as Trench MOSFET,SOI MOS,and photodiode for measurement and analysis.Then,the NMOS and PMOS of SMIC's 0.18?m Bulk process were measured and characterized at cryogenic temperatures,and the operating characteristics of the device at cryogenic temperatures were analyzed.On the basis of the measurement data,the cryogenic tem-perature models of resistance device and MOS device are established,the kink effect is corrected,and these are adapted to the Cadence Spectre simulator.In addition,this thesis proposes an evolutionary strategy for the repetitive opera-tions in the process of modeling and circuit performance optimization to allow comput-ers to replace manual parameter adjustment,and the optimization procedure of device model and circuit performance is realized through programming.Through the optimiza-tion procedure,we can obtain a more accurate cryogenic device model and better cir-cuit performance.At the same time,we optimized the BSIM3v3,BSIM4,and EKV2.6 models to verify the scalability of this method,and used the optimization program to optimize the cryogenic models we extracted earlier.The main innovations of this thesis are as follows:1.Cryogenic measurement platform is built to characterize a variety of devices.Moreover,N-MOS and PMOS of SMIC's 0.18?m Bulk process are characterized at the sub-Kelvin,the changes in device performance are analyzed,and the transfer curve was modeled with EKV2.6.2.Propose a method of kink effect correction based on physical principles and use BSIM3v3 and EKV model to simulate the same device.This is the first time that dual models have been used for device simulation.3.We use the evolution strategy to optimize cryogenic device models and circuit performance.This method can replace manual operation and shorten the research and design cycle.