PELLET FOR GLASS-SEALED CONSTANT-VOLTAGE DIODE USE

PURPOSE:To obtain a high Zener voltage which withstands a contamination at a sealing operation and to fine adjust a comparatively low Zener voltage by a method wherein P-N junctions of a constant-voltage diode are formed respectively on both main-face sides of a semiconductor substrate and the polari ty of the two junctions is the same polarity as one direction in the perpendicular direction of the semiconductor substrate. CONSTITUTION:A P-type epitaxial layer 2 whose resistivity is at about 5OMEGA.cm is formed on one main face of an N type substrate 1 whose resistivity is at about 0.01OMEGA.cm. An N-type epitaxial layer 3 whose resistivity is at about 10OMEGA.cm is formed on the other main face. Then, a P-type diffusion layer 8 is formed inside the N-type epitaxial Iayer 3; a P type diffusion layer 9b is formed. In addition, an Ntype diffusion layer 4 is formed inside the P-type epitaxial layer 2; an N type diffusion layer 5a is formed. In order to prevent the surfaces from being reversed to an N-type and a P-type, a P type diffusion layer 9a and an N type diffusion layer 5b are formed. Lastly, plated electrodes 13 are formed on both main faces.