SiC半导体不同晶面氧化机理及动力学的研究进展

Research progress on the oxidation mechanism and kinetics of a SiC semiconductor with different crystal surfaces

  • 摘要: SiC作为一种综合性能优异宽禁带半导体,在金属氧化物半导体场效应晶体管中具有广泛的应用。然而SiC热氧化生成SiO2的过程具有各向异性,导致不同晶面上的氧化速率差异较大,这会对半导体器件的性能产生不利影响,因而研究SiC各个晶面上SiO2的生长规律尤其重要。建立有效合理的动力学模型是认识上述规律的有效手段。本文从反应机理和拟合准确度两方面对目前具有代表性的改进的Deal-Grove模型(Song模型和Massoud经验关系式)以及硅碳排放模型(Si−C emission model)进行系统研究和比较。在此基础上,分析已有模型的优缺点,提出本课题组建立的真实物理动力学模型应用的可能性,为SiC不同晶面氧化动力学的准确描述提供进一步优化和修正思路。

     

    Abstract: In recent years, efficient electrical equipment for reducing energy consumption has drawn increasing worldwide attention. Although silicon (Si) has been used as a power semiconductor device, its improving effect on the performance of power semiconductor devices is greatly limited by its physical characteristics. Compared with Si, silicon carbide (SiC) as a type of wideband gap semiconductor has more excellent comprehensive physical properties in power device applications, including a triple wideband gap, a triple high thermal conductivity, and a tenfold breakdown electric field. Moreover, SiC can form silicon dioxide (SiO2) on the surface through thermal oxidation, which plays an important role in device manufacturing technology as an insulating layer. Based on these properties, SiC has gradually replaced Si as the preferred material of power devices used in metal oxide field-effect transistors (MOSFETs). The structure of a MOSFET contains a polysilicon-oxide layer (mostly SiO2)-SiC or diamond as the core. This structure is exactly equivalent to that of a capacitor, with SiO2 as the dielectric medium in the middle, and the capacitance value is determined by the thickness and dielectric coefficient of SiO2. However, the anisotropic process during the thermal oxidation from SiC to SiO2 results in a large difference in oxidation rate on different crystal faces, which adversely affects the performance of semiconductor devices. Therefore, studying the growth law of SiO2 on each crystal surface of SiC is of vital importance. Effective and reasonable dynamic models are expected to clarify the behavior. In this paper, the representative modified Deal-Grove model (Song model and Massoud empirical relation) and Si−C emission model were researched and compared systematically in terms of the reaction mechanism and fitting accuracy. On this basis, the advantages and disadvantages of the models were analyzed, and the possibility of the application of the real physical picture model established by our research group was proposed, which can further contribute to optimization and modification for the precise description of the oxidation kinetics of SiC on different crystal faces.

     

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