Semiconductor device

Abstract

Abstract PURPOSE:To improve IB characteristics of a low current region in a bipolar transistor and to improve an E-B withstanding voltage, by providing an insulator layer between an N<+> type emitter layer and a P<+> type layer, and electrically isolating the two regions. CONSTITUTION:After the surface of an epitaxial layer 11 is etched, a silicon dioxide film 15 is formed by using a thermal oxidation method. B is doped in a polycrystalline silicon and a P type is obtained. The polycrystalline silicon 6 other than a base taking-out part is oxidized. Annealing is performed in N2 at 900 deg.C. Then B is diffused into the epitaxial layer 11 from a P type polycrystalline silicon 4. A P<+> type diffused layer 5 (graft base) is formed. Thereafter, the polycrystal silicon 6 is deposited, As is doped and the As is diffused by annealing in N2 at 900 deg.C. Thus, an N<+> type layer 7 (emitter region) is provided. The outside of the N<+> type emitter diffused layer 7 is surrounded by silicon dioxide 15. Since the P<+> type graft base 5 is electrically isolated, the IB characteristics in the low current region become excellent, and the E-B withstanding voltage is improved.

Inventors

• 👤 Kazuhiko Sagara
• 👤 和彦 相良
• 👤 Toru Nakamura
• 👤 徹 中村
• 👤 Kazuo Nakazato
• 👤 和郎 中里
• 👤 Tokuo Kure
• 👤 久礼　得男
• 👤 Seiji Ikeda
• 👤 池田　清治

Bibliographic Details