| 摘要 |
PROBLEM TO BE SOLVED: To increase the width of a depletion layer under the end of an electrode, and alleviate the concentration of electric fields for enhancement of reverse voltage withstand by forming on a surface layer of silicon carbide crystal a ring-shaped low-concentration region of the same conductivity type, containing the end of a Schottky electrode. SOLUTION: An epitaxial wafer obtained by growing a n-epitaxial layer 2 on a substrate 1 of low-resistance 4H-type SiC single crystal is used, and aluminum ions are selectively implanted in the surface layer of the n-epitaxial layer 2. At this time, a low-concentration region 3 is defined by photoresist or the like. After implantation, annealing is performed in an Ar atmosphere under normal pressure. Then a Ni film is formed on the underside of the substrate 1 by sputtering, and subsequently an ohmic electrode 6 is formed by heat treatment. Thereafter, a Ni film is formed on the surface of the epitaxial layer 2 by sputtering to obtain a Schottky electrode 4. As a result, the depletion layer 5 at the time of backward voltage bypassing is sufficiently spread even in the vicinity of the end of the Schottky electrode 4, and reverse voltage withstand is enhanced. |
