P型栅极高电子迁移率晶体管可靠性研究

发布时间：2018-01-01 19:19

本文关键词：P型栅极高电子迁移率晶体管可靠性研究　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：氮化镓基高电子迁移率晶体管(HEMT)是实现高效节能与小型化、轻量化电力电子变换器的下一代功率器件。一方面这是由氮化镓材料本身的优异特性所决定的,如宽禁带宽度(3.4 eV),高临界击穿电场(3500 kV/cm)。另一方面,铝氮化镓与氮化镓异质结的自发极化和压电极化效应可以在异质结界面处形成高电子浓度(10~(13)cm~(-~2)),高电子迁移率(1~200cm~2/V·s)与高电子饱和漂移速度(3.0×10~7cm/s)的二维电子气导电沟道。然而,铝氮化镓/氮化镓异质结结构的HEMT通常是常通型器件,其阈值电压范围在-6 V到-2V。为了使HEMT能具有电路故障保护功能并与传统硅基功率器件栅极驱动IC兼容,需要实现增强型HEMT。全球科研工作者已提出多种实现增强型HEMT的技术手段,包括采用几个纳米厚的AlGaN势垒层,级联拓扑结构,氟化物等离子体处理,肖特基栅极的栅极凹槽结构,金属绝缘体氧化物栅极凹槽结构(MIS)与P型栅极结构。在这些方法中,MIS-HEMT是实现可同时具备高阈值电压与高栅极电压摆幅HEMT的可行方案。然而MIS-HEMT栅极氮化物/电介质界面态的存在也带来了相应的可靠性问题,例如器件阈值电压的偏移。而P型栅极HEMT不仅可以实现高阈值电压与高栅极电压摆幅,同时还可以利用栅极空穴注入的电导调制效应进一步降低器件沟道导通电阻,这使其成为工业界与学术界研究者的关注热点。近十年,P型栅极器件在高漏压开关条件下出现的电流崩塌或动态导通电阻变化已经得到了全世界研究者的深入研究,然而由P型HEMT栅极电流注入所导致的器件可靠性问题仍有待进一步研究。本文对商用P型栅极HEMT在不同大小栅极电压应力与不同器件温度下无自发热的导通电阻大小变化进行了观测分析。器件在额定栅极电压应力下导通电阻变化,阈值电压的偏移以及耐压能力的退化都指向了由于HEMT栅极区域电荷俘获所引发的可靠性问题。本文提出并详述了 HEMT由于栅极区域空穴电子分别被施主陷阱与受主陷阱俘获而导致器件沟道电导不稳定的潜在机理,并通过器件仿真从能带变化对此做了进一步探究。
[Abstract]:Gallium nitride based high electron mobility transistor (HEMT) is an efficient energy saving and miniaturized transistor. The next generation of power devices for lightweight power electronic converters. On the one hand, this is determined by the excellent properties of gallium nitride materials, such as the wide bandgap width of 3.4 EV). A high critical breakdown electric field of 3500 kV / cm, on the other hand. The spontaneous polarization and piezoelectric polarization effects of Al Gallium nitride and Gallium nitride heterojunction can form high electron concentration (10 ~ (10) C ~ (13) C ~ (-1) cm ~ (-1) ~ (-1)) at the interface of the heterojunction. Two-dimensional electron gas conduction channel with high electron saturation drift velocity of 3.0 脳 10 ~ (7) cm ~ (-1) and 2 / 2 / V 路s of high electron mobility ~ (200) cm ~ (-1). Aluminum gallium nitride / gallium nitride heterojunction HEMT is usually a common type device. The threshold voltage ranges from -6 V to -2 V. in order to enable HEMT to have circuit fault protection function and compatible with traditional silicon based power device gate drive IC. It is necessary to realize enhanced HEMT. Researchers all over the world have put forward a variety of techniques to realize enhanced HEMT, including several nanometer-thick AlGaN barrier layers and cascaded topology. Fluoride plasma treatment, Schottky gate gate groove structure, metal insulator oxide gate groove structure (MISS) and P-type gate structure. In these methods. MIS-HEMT is a feasible scheme to realize both high threshold voltage and high gate voltage swing HEMT. However, the existence of MIS-HEMT gate nitride / dielectric interface state also brings about the corresponding results. The question of reliability. For example, the shift of device threshold voltage, and P-type gate HEMT can not only achieve high threshold voltage and high gate voltage swing. At the same time, the conductivity modulation effect of gate hole injection can be used to further reduce the channel on-resistance of the device, which makes it become the focus of attention of researchers in industry and academia. The current collapse or dynamic on-resistance change of P-type gate devices under the condition of high leakage voltage switch has been deeply studied by researchers all over the world. However, the reliability problems caused by P-type HEMT gate current injection still need to be further studied. In this paper, the commercial P-type gate HEMT is not spontaneous at different gate voltage stress and different device temperature. The change of the thermal on-resistance is observed and analyzed. The on-resistance of the device changes under the rated gate voltage stress. The shift of threshold voltage and the degradation of voltage resistance all point to the reliability problems caused by charge capture in HEMT gate region. The potential mechanism of channel conductance instability in HEMT is due to the capture of hole electrons in the gate region by the donor trap and the acceptor trap respectively. And through the device simulation from the energy band change to further explore this.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN386

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