Parasitic source resistance at different temperatures for AlGaN/AlN/GaN heterostructure field-effect transistors

The parasitic source resistance（RS） of AlGaN/AlN/GaN heterostructure field-effect transistors（HFETs） is studied in the temperature range 300–500 K. By using the measured RSand both capacitance–voltage（C–V） and current–voltage（I–V） characteristics for the fabricated device at 300, 350, 400, 450, and 500 K, it is found that the polarization Coulomb field（PCF） scattering exhibits a significant impact on RSat the above-mentioned different temperatures. Furthermore, in the AlGaN/AlN/GaN HFETs, the interaction between the additional positive polarization charges underneath the gate contact and the additional negative polarization charges near the source Ohmic contact, which is related to the PCF scattering, is verified during the variable-temperature study of RS.

Trench MOS Controlled Thyristor

A new structure of power MOS-gated thyristor named Trench MOS Controlled Thyristor (TMCT) is presented.The MOSFETs used to turn on and turn off the thrysitor are formed with UMOS technology.No parasitic transistors exist in this structure,so the problems created by the parasitic transistors can be eliminated.So,the TMCT is expected to be of better performance.The experimental results of the multicellular 600V TMCT with the active area of 02mm2 show that the on-state drop is 125V at 300A/cm2,and the maximum controllable current reaches 296A/cm2 at the gate voltage of -20V and with an inductive load.

Experimental and simulation studies of single-event transient in partially depleted SOI MOSFET

In this study, we investigate the single-event transient（SET） characteristics of a partially depleted silicon-on-insulator（PDSOI） metal-oxide-semiconductor（MOS） device induced by a pulsed laser.We measure and analyze the drain transient current at the wafer level. The results indicate that the body-drain junction and its vicinity are more SET sensitive than the other regions in PD-SOI devices.We use ISE 3D simulation tools to analyze the SET response when different regions of the device are hit. Then, we discuss in detail the characteristics of transient currents and the electrostatic potential distribution change in devices after irradiation. Finally, we analyze the parasitic bipolar junction transistor（p-BJT） effect by performing both a laser test and simulations.

Parasitic effects of air-gap through-silicon vias in high-speed three-dimensional integrated circuits

In this paper,ground-signal-ground type through-silicon vias（TSVs） exploiting air gaps as insulation layers are designed,analyzed and simulated for applications in millimeter wave.The compact wideband equivalent-circuit model and passive elements（RLGC） parameters based on the physical parameters are presented with the frequency up to 100 GHz.The parasitic capacitance of TSVs can be approximated as the dielectric capacitance of air gaps when the thickness of air gaps is greater than 0.75 μm.Therefore,the applied voltage of TSVs only needs to achieve the flatband voltage,and there is no need to indicate the threshold voltage.This is due to the small permittivity of air gaps.The proposed model shows good agreement with the simulation results of ADS and Ansoft＇s HFSS over a wide frequency range.

Dynamic avalanche behavior of power MOSFETs and IGBTs under unclamped inductive switching conditions

The ability of high-voltage power MOSFETs and IGBTs to withstand avalanche events under unclamped inductive switching(UIS) conditions is measured.This measurement is to investigate and compare the dynamic avalanche failure behavior of the power MOSFETs and the IGBT,which occur at different current conditions.The UIS measurement results at different current conditions show that the main failure reason of the power MOSFETs is related to the parasitic bipolar transistor,which leads to the deterioration of the avalanche reliability of power MOSFETs.However,the results of the IGBT show two different failure behaviors.At high current mode,the failure behavior is similar to the power MOSFETs situation.But at low current mode,the main failure mechanism is related to the parasitic thyristor activity during the occurrence of the avalanche process and which is in good agreement with the experiment result.

Avalanche behavior of power MOSFETs under different temperature conditions

The ability of high-voltage power MOSFETs to withstand avalanche events under different temperature conditions are studied by experiment and two-dimensional device simulation. The experiment is performed to investigate dynamic avalanche failure behavior of the domestic power MOSFETs which can occur at the rated maximum operation temperature range （-55 to 150 ℃）. An advanced ISE TCAD two-dimensional mixed mode simulator with thermodynamic non-isothermal model is used to analyze the avalanche failure mechanism. The unclamped inductive switching measurement and simulation results show that the parasitic components and thermal effect inside the device will lead to the deterioration of the avalanche reliability of power MOSFETs with increasing temperature. The main failure mechanism is related to the parasitic bipolar transistor activity during the occurrence of the avalanche behavior.

Single-event burnout hardening of planar power MOSFET with partially widened trench source

We present a single-event burnout（SEB） hardened planar power MOSFET with partially widened trench sources by three-dimensional（3 D） numerical simulation. The advantage of the proposed structure is that the work of the parasitic bipolar transistor inherited in the power MOSFET is suppressed effectively due to the elimination of the most sensitive region（P-well region below the N＋ source）. The simulation result shows that the proposed structure can enhance the SEB survivability significantly. The critical value of linear energy transfer（LET）,which indicates the maximum deposited energy on the device without SEB behavior, increases from 0.06 to0.7 p C/μm. The SEB threshold voltage increases to 120 V, which is 80% of the rated breakdown voltage. Meanwhile, the main parameter characteristics of the proposed structure remain similar with those of the conventional planar structure. Therefore, this structure offers a potential optimization path to planar power MOSFET with high SEB survivability for space and atmospheric applications.

Gate length dependence of the shallow trench isolation leakage current in an irradiated deep submicron NMOSFET

The effects of gamma irradiation on the shallow trench isolation（STI）leakage currents in a 0.18μm technology are investigated.NMOSFETs with different gate lengths are irradiated at several dose levels.The threshold voltage shift is negligible in all of the devices due to the very thin oxide thickness.However,an increase in the off-state leakage current is observed for all of the devices.We believe that the leakage is induced by the drain-to-source leakage path along the STI sidewall,which is formed by the positive trapped charge in the STI oxide.Also, we found that the leakage is dependent on the device＇s gate length.The three-transistor model（one main transistor with two parasitic transistors）can provide us with a brief understanding of the dependence on gate length.

Influence of drain and substrate bias on the TID effect for deep submicron technology devices

This paper presents a study of the total ionization effects of a 0.18 #m technology. The electrical para meters of NMOSFETs were monitored before and after irradiation with 6~Co at several dose levels under different drain and substrate biases. Key parameters such as offstate leakage current and threshold voltage shift were studied to reflect the ionizing radiation tolerance, and explained using a parasitic transistors model. 3D device simulation was conducted to provide a better understanding of the dependence of device characteristics on drain and substrate biases.