Fabrication of active devices using semiconducting SiC for use in heavy environment

利用半导体3C-碳化硅在重环境中制作有源器件进行了基础性研究。明确了晶体生长条件，获得了器件制作所需的平坦表面。在此基础上，建立了3C-碳化硅的精密加工工艺。利用上述结果，制备了简单的MOS结、肖特基结和pn结。设计了MES FET作为有源器件，并对其电学特性进行了模拟。制作了部分样品。研究结果如下：(1)外延层的平坦度：考察了不同取向((100)、(110)、(111))的外延生长。获得了直径为2英寸的大面积碳化硅单晶。通过观察引起表面粗糙的反相区，提出了一种去除表面粗糙度的新方法。(2)精密加工：利用&lt；CF4&gt；和&lt；O2&gt；气体建立了3C-SiCe的等离子体刻蚀工艺。刻蚀速率可以通过控制气体中氧的含量来控制。(3)二极管的制备：采用3C-碳化硅制备了MOS、肖特基和Ph型三种类型的二极管，并对其电学特性进行了测试。MES场效应管的设计与制作：利用3CSiC单晶设计了MES场效应管的器件结构，并对器件的电学特性进行了模拟。MES场效应管是在掺杂&lt；B2&gt；&lt；H6&gt；获得的高阻p型3C-SiC层上外延生长的3C-SiC层上用肖特基栅作衬底制作的。尽管器件的肖特基特性足够好，但由于源极和漏极的欧姆特性不足，FET无法实现工作。

Fundamental studies on fabrication of active devices have been carried out using semiconducting 3C-SiC for use in heavy environment. The crystal growth conditions were made clear to obtain the flat surface which is strongly required for device fabrication. And, a precise processing of 3C-SiC was developed. Using the above results, simple devices such as MOS, Schottky and pn junctions were prepared. As an active device, MES FET was designed and the electrical characteristics were simulated. Some samples were fabricated. The following results were obtained.(1) Flatness of grown layers: Different orientations ((100),(110),(111)) were examined for the epitaxial growth. Single crystals of 3C-SiC with a large area of 2 inch diameter was obtained. By observing anti-phase domains which cause rough surfaces, a new method to get rid of surface roughness was developed.(2) Precise processing: Plasma etching technology for 3C-SiC was established using <CF_4> and <O_2> gases. The etch rate can be controlled by the content of <O_2> gas. Chromium metal was found to be usable as an etching mask.(3) Preparation of Diodes: Diodes of MOS, Schottky and ph-junction types using 3C-SiC were prepared and the electrical characteristics were measured. Inversion in 3C-SiC MOS diodes under illumination was obtained for the first time.(4) Design and Fabrication of MES FET: Device structures of MES FET using 3CSiC single crystals were designed and the electrical characteristics were simulated. MES FETs were fabricated using Schottky gates on the 3C-SiC layers which were epitaxially grown on high resistive p-type 3C-SiC obtained by doping <B_2> <H_6> . Although Schottky characteristics of the device were enough good, operation of a FET was not obtained due to insufficient ohmic characteristics at source and drain electrodes.