Monte Carlo Analysis Of Radio Frequency Noise Mechanism Of Nano-MOSFET

Compared with the sample testing and analysis in the mature stage,in the initial stage of the development of new devices,it is necessary to rely on the simulation of the performance parameters of semiconductor devices to clarify the performance changes of devices.Among them,predicting the noise disturbance law of short channel devices and exploring its noise mechanism are particularly important for the practicality of short channel devices represented by 40 nm MOSFET.Drift diffusion model and hydrodynamic model are mainly used in traditional semiconductor device parameter simulation tools,which can not simulate the RF noise performance of devices with channel length less than 100 nm.Therefore,the high-frequency power density of the intrinsic drain current noise of MOSFET with channel length of 40 nm is calculated by two-dimensional Monte Carlo simulation,and the suppressed shot noise characteristics are analyzed accordingly.Although the simulation accuracy of Monte Carlo simulation analysis is not high,the simulation process of this method is relatively simple,and it is enough to distinguish the noise mechanism of short-channel device from that of long-channel MOSFET.It is of great significance to evaluate the performance of short-channel device and guide device development.The work of this paper includes the following three aspects:Firstly,the two-dimensional Monte Carlo simulation process is defined.Particle initialization is achieved by setting the initial positions and wave vectors of all particles.Then,the charge density of all grid nodes is set reasonably according to the space position of particles in the grid,so as to realize the charge distribution of carriers in the device.Based on this,the finite difference method is used to discretize the Poisson equation to update the internal potential of the device for the next iteration of time step,and the carrier transport model is determined to ensure the accurate simulation of carrier transport.The original data of device noise can be obtained by statistical averaging of simulation results after iteration of multiple time steps.Secondly,using the two-dimensional Monte Carlo simulation process,the original data of40 nm MOSFET high frequency noise are simulated by setting simulation parameters and compiling simulation program,and the high frequency power spectral density of its intrinsic drain current noise is calculated.After the steady-state test,the leakage current of MOSFET is calculated by using the obtained carrier instantaneous velocity.Thus,the static test of the simulation device is realized.By observing its static output,the preliminary verification of the simulation analysis is realized.Based on the original data of simulation analysis,through simulation calculation,it is found that the RF noise mechanism of 40 nm MOSFET in strong reflection region is suppressed shot noise,and the suppression degree of shot noise decreases with the decrease of gate bias.Finally,in order to verify the simulation results of the high frequency noise mechanism in the strong inversion region of 40 nm MOSFET,experiments were carried out to verify theresults.Based on the transistor RF noise measurement system,the scattering parameters and four noise parameters of NMOS are measured,and the parameters of small signal equivalent circuit elements and the power spectral density of leakage current noise are extracted.Noise measurement not only verifies the validity of Monte Carlo simulation for predicting noise disturbance,but also shows that the intrinsic leakage current noise of 40 nm is suppressed shot noise,and the suppressed characteristic decreases with the decrease of gate bias.