| 摘要 |
PURPOSE:To fix breakdown voltage of a protection diode between a base and collector of a semiconductor device by a method wherein a semiconductor being introduced with impurities by neutron irradiation or a high resistance layer formed epitaxially is used for a substrate. CONSTITUTION:The n<-> type Si substrate 1 unified by neutron irradiation is prepared, an n<+> type layer 2 is provided on the side face thereof, and P ion implantation and heat treatment are performed on the main face using an SiO2 mask 3 to form an n<+> type layer 4'. The SiO2 mask 3 is removed selectively, and p type layers 5 and an n type layer 4'' are formed by B ion implantation and heat treatment. Openings are formed selectively in the SiO2 mask 3 again, B ion implantation and diffusion in an oxidizing atmosphere are performed to form p<+> type layers 6, and the Zener diode is constituted by the layers 4'', 6. P ions are made to be diffused selectively in the p<+> type layers 6, n<+> type emitters 7 are adhered thereto, the upper face thereof is covered with PSG20, and openings for electrodes are formed selectively. Thereafter electrodes are attached according to the prescribed way. By this constitution, junction of diode is placed at the prescribed depth by the ion implantation method, and concentration at the neighborhood of junction is uniform. Because no unevenness of concentration exists in the n<-> type substrate, extention of the depletion layer of diode junction is fixed always. |
