Hot Carrier Reliability Model and its Applicable Range of High Voltage MOSFET for Different Lightly Doped Drain Doping Concentration

Abstract

In this thesis we study the N-type high voltage metal-oxide–semiconductor field-effect transistor (HV-MOSFET) with different Lightly Doped Drain (LDD) doping concentrations to investigate the reliability and establish the lifetime prediction model First the motivation of the thesis is described The application and the advantages of HV-MOSFET are also illustrated Because the HV device is designed to endure high voltage from the power supply the hot-carrier reliability and devices’ lifetime are important issues to be considered In addition technology computer-aided design (TCAD) simulation plays an essential role in our experiment We will introduce these topics in detail After the introduction the structure of the devices and the definition of the internal region are presented We also describe the measurement setup and methodology including device current (ID-VG ID-VD) substrate current (ISUB-VG) and the calibration of TCAD tool Furthermore the previous work has been shown that long-termed degradation can be obtained from short-time stress For the degradation characteristics all degradation curves are at a similar slope Therefore the degradation trend can form a general degradation curve by shifting along the time axis which means that multiplying a factor named “Scaling factor” to the time coordinate Moreover there is some relationship between scaling factor and device lifetime and it had been proved under the usual N-type MOSFET As a result we apply the concept to the N-HVMOS with different LDD doping concentrations to derive the lifetime equation and present a model based on the terminal characteristic (IS VG and VD) During the period of establishing the model our model is not available for all operation region Therefore we use TCAD to simulation the internal variation and assume how the degradation mechanism would be changed Finally we analyze the devices’ electrical characteristics with different LDD doping concentrations and explain why the device with lower NDD dosage would suffer more influence from the drain to gate voltage which would aggravate the degradation and shorten the lifetime with TCAD simulation

Date of Award	2020
Original language	English
Supervisor	Jone-Fang Chen (Supervisor)