The Non-quasi-static Effect Involded In MOSEFET, SOI Moseft And LDMOSTE

In present, with the rapid development of RF CMOS integrated circuits, the operating frequency approaches to Giga hertz (GHz). A new physical effect—non-quasi-static (NQS) effect becomes one of dominating factor to influence the performance of MOSFETs. In this thesis, we study the NQS effect involved in bulk MOSFET, SOI MOSFET and LDMOSFET.1) For BULK MOSFET, we develop a simulation tool based on MATLAB to modeling the QS and NQS's surface potentials, inversion charges and terminal circuits. The analytical results from the model show a fair agreement with the numerical results from silvaco, a semiconductor device simulation tool. We also study the NQS effect as the function of the channel length, channel concentration and gate-voltage. Then a critical gate-voltage ramp time is put forward to quantitatively characterize the NQS effect. At last we give some methods to release the NQS effect, which provide instructions on RF MOSFET's design.2) For SOI MOSFET, the source, drain, gate and body currents including NQS effects are investigated in FDSOI and PDSOI MOSFETs. The surface potential and inversion charge are analyzed to explore the mechanism of the NQS effect in SOI MOSFET. The critical ramp time is employed to quantitative research the NQS effect. The influences of the geometric parameters on NQS effects are studied in detail. The result shows that NQS effect in RF SOI MOSFET can be depressed by shrinking the channel length, decreasing the impurity concentration, reducing the thicknesses of the silicon film and gate oxide layer and increasing the buried oxide layer thickness.3) For LDMOSFET, we propose a model to describe the QS and NQS phenomenon in LDMOSFET and a simulation tool based on MATLAB. Using the tool and the silvaco, we study the impact of the different loading types of the gate voltage on the QS and NQS's terminal circuits. The three-dimension figure of QS and NQS's surface potential and inversion charge are used to investigate the physical insight of the NQS effect in LDMOSFET. At last, we research the inner-drain potential and terminal currents in LDMOSFET for the different structure parameters and voltages biased on the electrodes. The result shows shrinking the drift region length, increasing the impurity concentration, increasing the thicknesses of the drift region and shorten the gate-voltage ramp ratio can depress the NQS effect.