Research On Radiation Effects Of Low-voltage Trench MOSFETs

Trench MOSFET as a discrete power MOSFET device structure,compared with the planar gate VDMOS structure,the vertical trench gate and conductive channel eliminate the effect of JFET region,which can achieve smaller cell size and higher current density,and Trench MOSFET has smaller resistance and Miller capacitance under the same withstand voltage and chip area,which improves the current capability and switching performance of the device,especially in the application field of low-voltage power MOSFET it becomes unique.However,there are still few researches and related products on the radiation effect of power Trench MOSFETs in China,and the excellent characteristics of low-voltage Trench MOSFETs on the ground for commercial use have not yet been demonstrated in the aerospace field where high anti-radiation performance and reliability are required.Based on this,this paper studies the radiation effects and radiation hardening measures of low-voltage Trench MOSFETs,and aims at designing Trench MOSFETs with excellent electrical and anti-radiation performance.It will be applied in the aerospace field in China as soon as possible.First,this paper analyzes the radiation effects of Trench MOSFETs,including cumulative total dose ionizing radiation effects,transient SEB effect,SEGR effect,and micro-dosage effect.Respectively analyses the generation mechanism and the performance of devices of these types of radiation effects,and puts forward the corresponding anti-radiation reinforcement method.Because the influence of SEB and SEGR on the performance of Trench MOSFET is more serious,the influence factors are analyzed,and the single-particle performance is simulated by the simulation software Medici.The SEB performance about the source region doping concentration,P-body body junction depth and the carrier lifetime of the Trench MOSFET are simulated and analyzed.In addition,the electrical and SEB performances of the equivalent withstand voltage Trench MOSFET and VDMOS is compared.In order to further improve the anti-radiation performance of Trench MOSFETs,reinforcement measures have been proposed separately from the manufacturing process and the device structure.In order to improve the device's ability to resist SEGR effect and total dose effect,the manufacturing process needs to be optimized to improve the quality of the gate dielectric,the gate dielectric process and the subsequent hightemperature process are improved,and the body well process and the source region doping process are optimized to improve anti-SEB performance.In terms of structural reinforcement,the performance of the anti-single-event is improved by increasing the buffer layer,deep P+ region extension,trench contact,and shielded gate structure,and the SEB performance of these reinforced structures is analyzed separately by simulation.Compared to conventional Trench MOSFET structure,the SEB threshold voltages of devices with these reinforced structures have increased by 41%,38%,83%,and 45%,respectively,which shows that the anti-single-event effect has been significantly improved,and the manufacturing process and the influence of the electrical parameters performance about reinforced Trench MOSFETs are also considered.In general,the composite reinforced structure with trench contact and deep P+ region expansion can meet the SEB performance of the device,and the manufacturing process is relatively simple to implement,and has little impact on the basic electrical parameters of the device,which provides reference for the actual design of anti-radiation Trench MOSFET products.