Research On The High Temperature Propertites And Design Of Process Parameters To Operate In High Temperature Of Silicon-Based MOS Devices

Electronic equipments applied in petroleum exploration filed are usually required to work in a high temperature environment(over 150?),however,silicon-based devices manufactured using conventional process parameters can't meet the high temperature requirements.Although devices based on wide bandgap semiconductor materials can withstand higher temperature,they are more expensive and inconvenient to integrate.The researches on the process parameters of silicon-based devices to operate in high-temperature and its design method are of great theoretical significance and engineering application value.Based on the analysis of various physical parameters of' silicon material,the temperature characteristics of each performance index parameter of silicon-based MOS devices are studied.As the temperature increases,the leakage current of the MOS device increases rapidly,the threshold voltage decreases,and the transconductance decreases.The relationship between the main process parameters and performance parameters of MOS devices is studied.It is pointed out that the substrate doping concentration has the most significant effect on the leakage current and the threshold voltage,and the gate oxide thickness is the key parameter to determine the temperature coefficient of the threshold voltage.Based on this,a method for designing key process parameters of high-temperature silicon-based MOS devices is proposed,and the expressions of substrate doping concentration,gate oxide thickness,channel length,and source-drain junction depth design interval satisfying the specifications are deduced.The value range of each process parameter that meets the requirements of the technical specification are calculated.Based on the relationship between leakage current,temperature coefficient of threshold voltage and process parameters at high temperature,a process parameter optimization method is proposed.It is concluded that the doping concentration of the substrate is increased as much as possible within the range of the process parameters so that the increase in leakage current of the MOS device with increasing temperature is as small as possible,however,the temperature coefficient of the threshold voltage increases and the transconductance decreases.By reducing the thickness of the gate oxide layer,both the leakage current and the temperature coefficient of the threshold voltage meet the minimum requirements,while the influence on the transconductance is small.A set of high-temperature process parameters that meet the optimization requirements with a smaller range of values and better performance are calculated and obtained.Combining the high-temperature process parameter design and optimization method of silicon-based MOS devices,Silvaco TCAD process simulation software was used to simulate the process parameter design and optimization results of the determined process parameters.The accuracy and the feasibility of theoretical analysis and proposed design optimization methods are verified by the simulation results.