Processing Development for Making High Power Microwave 4H-SiC Devices

点击翻译按钮获取中文摘要

9711128 Rao This project is aimed at developing processing technology for high-power and microwave devices in semi-insulating (SI) and semi-conducting SiC. The N and Al ion implantations in SI 4H-SiC and Al ion implantation in n-type 4H-SiC epitaxial layers will be thoroughly pursued in order to develop planar selective area doping technology in this material. Exploratory work on As-implantation to obtain donor doping in SiC will be performed. Due to the complementary lattice positions occupied by N and P (As) donors in SiC, N/P and N/As coimplantations will be used to obtain highly conductive n( regions in SiC. Results of the coimplantation work will be useful for minimizing contact and bulk series resistances of microwave and high power devices, which is crucial for obtaining optimal device performance. Microwave and pulsed induction rapid thermal heating set-ups will be developed to anneal 2" diameter implanted SiC wafers at temperatures as high as 1700 (C. The implanted/annealed material will be thoroughly characterized by van der Pauw Hall, SIMS, Rutherford Backscattering, TEM, and photoluminescence measurements. These measurements will be used to gain information about dopant electrical activation, dopant thermal stability, doped region lattice perfection, and ionization energy of the dopants, etc. A new ohmic contact metal system (Si/Al/Si/Ti/Pt) with different Si and metal layer thicknesses will be tried to achieve high performance ohmic contacts on p-type SiC. Contacts will be alloyed at different temperatures using a halogen lamp rapid thermal annealing station. The contacts will be characterized by TLM pattern measurements, SEM, Auger electron spectrometry, and x-ray diffraction measurements. The reliability of the contacts for high-temperature and high-power operation will be studied. Schottky and planar p-n junction diodes will be made by selective area implantation in SI and semi-conducting 4H-SiC and thoroughly characterized for I-V and C-V performance at various temperatures up to 500 (C. DLTS measurements will be performed on the diodes to detect deep levels in the implanted region and at the interface of the implanted region and the SI substrate. Using the optimum implantation and ohmic contact conditions developed in this work, MESFETs and JFETs will be made in SI and n-type 4H-SiC respectively, and thoroughly characterized for their DC, microwave, and high-power performance at various operating temperatures and also for extended period operation at high temperatures. The proposed work will be performed in collaboration with the scientists at General Electric Research Center, Shenectady, NY, Naval Research Laboratory, Oak Ridge National Laboratory, and the National Institute of Standards and Technology. ***