高耐压、低损耗的Si衬底Ga2O3 MOSFET器件制备研究

The rapid development of new energy technologies puts forward higher requirements to the high breakdown voltage, low conduction loss characteristics of the power electronic device. Si, GaN and SiC based high voltage devices are limited by their breakdown electric field strength, so that their unipolar devices cannot be used, only with the complex, high conduction loss bipolar devices. Ga2O3 is a wide gap semiconductor with high breakdown electric field strength (8MV/cm). It is an ideal material for the MOSFET with high breakdown voltage and low conduction loss characteristics. In addition, Si substrate has the advantages of large size, easy heat conduction, low cost and easy integration. To play the advantages of Ga2O3 film and the Si substrate, we propose an innovation project that fabricating Ga2O3 based MOSFET on Si substrate using high temperature oxide MOCVD. GaN multilayer structure and thermal oxidation technology are used to solve the large lattice and thermal mismatch between the Ga2O3 film and Si substrate and grow the high-quality Ga2O3 thin film. We focus on growing the high-quality Ga2O3 thin films on Si substrate under the large mismatch conditions and designing the high breakdown voltage, low conduction loss MOSFET. The project is conducive to open up a new way to fabricate MOSFET with high breakdown voltage, low conduction loss, low cost and easy industrial production.

新能源等技术的飞速发展，对其电力电子装置的高耐压、低损耗特性提出了更高要求。Si、GaN与SiC等高压器件受材料击穿场强限制，其单极器件已不能满足高压装置的应用需求，只能使用工艺复杂、损耗大的双极器件。Ga2O3是一种高击穿场强（8MV/cm）的宽禁带半导体，是制备高耐压低损耗MOSFET单极器件的理想材料。为发挥Ga2O3材料优势，并利用Si衬底大尺寸、易导热、成本低、易集成等优点，本项目创新提出一种Si衬底Ga2O3基MOSFET器件方案。利用创新设计的高温氧化物MOCVD，以GaN系多层结构并结合热氧化技术解决Ga2O3和Si间晶格失配及热失配问题，实现Ga2O3薄膜高质量生长并制备MOSFET。重点研究大失配条件下Si衬底上Ga2O3薄膜的高质量外延生长和高耐压低损耗MOSFET器件结构设计两个科学问题。该项目将开辟一条高耐压、低损耗、低成本、可工业化生产的MOSFET制备新途径。

新能源等技术的飞速发展，对电力电子装置的耐高压、低损耗特性提出了更高的要求。Si、GaN与SiC等高压器件受材料击穿场强限制，其单极器件已不能满足高压装置的应用需求，只能使用工艺复杂、损耗大的双极器件。Ga2O3是一种高击穿场强的宽禁带半导体，是制备高耐压、低损耗MOSFET单极器件的理想材料。为发挥Ga2O3材料优势，并利用Si衬底大尺寸、易导热、成本低、易集成等优点，本项目制备了以Si为衬底的Ga2O3基MOSFET器件。主要研究成果如下：1、研究了Ga2O3薄膜的MOCVD异质与同质外延工艺，掌握了Ga2O3薄膜的制备方法，分别在蓝宝石、Si和单晶Ga2O3衬底上获得了高质量的Ga2O3薄膜，其中异质外延薄膜FWHM小于200arcsec。2、总结出了Ga2O3薄膜的n型掺杂与施主激活工艺，实现电子浓度在1016~1019cm-3范围内的可控掺杂。3、通过对GaN/蓝宝石模板进行热氧化处理，获得了质量较高的Ga2O3薄膜，并在此基础上进行MOCVD生长，获得了高质量的β-Ga2O3外延薄膜。4、按照既定方案，进行了常开型MOSFET的制备工作，获得了性能较高的MOSFET器件。5、此外，我们还进行了Ga2O3薄膜的p型掺杂、纳米结构制备、n-Ga2O3/p-GaN异质结二极管阵列制备等方面的研究。该项目在一定程度上解决了大失配条件下Si衬底上Ga2O3薄膜的高质量外延生长和高耐压、低损耗MOSFET器件结构制备等问题。项目开辟了一条低成本、耐高压、低损耗、易工业生产的MOSFET制备新途径。