Papers by Keyword: Doping Uniformity

Abstract: In this paper, the performance of a new CVD reactor (called PE1O8) designed by LPE and developed in the European project REACTION to process uniform 4H-SiC homoepitaxy on 200 mm substrate is reported. Its tunable multi-zone injection system and new gas delivery configuration ensure the uniform gas distribution throughout the substrate. Excellent thickness and doping uniformity on 200 mm substrates are achieved with run-to-run variation less than 1.4% and 5.6% respectively.

Abstract: We report on the results of a Design of Experiments (DOE) matrix of growth runs used to tune and improve the uniformity of thickness and doping across both 100 mm and 150 mm SiC epiwafers in our epitaxy reactor. Improvement of uniformity beyond the initial process recipe from the tool vendor is shown. Temperature measurement along an entire wafer platter indicate that there is a gas cold region extending into the growth zone that maybe the root cause of the non-uniformity.

Abstract: Doping incorporation and good uniformity along the wafer it is a mandatory for application in high voltage electronic devices. In this work the effect of the Hydrogen (H) flux position inside the reaction chamber on homo-epitaxial 4H-SiC growth process has been studied. Capacitance-Voltage and FT-IR analyses show as the different position of the gas injector affect the doping and thickness uniformity and profile. On the other hand, By Candela and AFM analyses no morphological or surface influence by Hydrogen flux position has been observed.

Abstract: A 100μm silicon carbide epilayer with mean doping concentration 6×10¹⁴ cm^-3 was achieved on 3 inch silicon carbide substrate using a growh rate of 30 μm/h. Hydrogen gas foil rotation was adopted to improve the doping uniformity. The intra-wafer thickness and doping uniformity was 1.83% and 7.51%, respectively. Schottky diodes fabricated on this epilayer presented a breakdown voltage of 10kV. This is the first report of 10kV schottky diodes fabricated on silicon carbide epilayer made in China.

Abstract: We performed deep trench filling by using epitaxial SiC growth. It was found that the trench filling condition depend on trench width. A high growth temperature was needed to fill a narrow trench and a low growth temperature was needed to fill a wide trench structure. We optimized the filling condition and successfully filled 7μ m deep and 2 μm wide trench without void formation. We also investigated the 2D doping distribution of the filled area by SSRM. As a result, it is found that the existence of a sub-trench was related to the generation of a doping distribution in the filled area. The trench filling mechanism and doping distribution are discussed.

Abstract: The in-situ doping of aluminum and nitrogen in migration enhanced embedded epitaxy (ME3) is investigated with the aim to apply it to the realization and fabrication of all-epitaxial, normally-off 4H-SiC JFET devices. This ME3 process consists of the epitaxial growth of an n-doped channel and a highly p-doped top gate in narrow trenches. We found that the nitrogen doping in the n-channel (a-face) is a factor 1.5 higher than layers grown with the same process on Si-face wafers. Due to the low C/Si ratio and the low silane flow rate used in the ME3 process, the growth of the p-doped top gate needs high flow rates of the aluminum precursor trimethylaluminum for several hours, which contaminates the CVD reactor and causes aluminum memory effects. These aluminum memory effects can be reduced by an extra high temperature bake-out run.