| 摘要 |
1,146,943. Semi-conductor devices. SONY CORP. 8 Feb., 1967 [9 Feb., 1966], No. 6606/67. Heading H1K. A semi-conductor device comprises a substrate of one conductivity type and an epitaxial layer comprising single crystal portions of the opposite conductivity type and polycrystalline portions surrounded by diffused regions forming PN junctions with the single crystal portions. As shown, Fig. 3, a layer 12 of N-type silicon is grown on a P-type silicon substrate 10 by decomposition of silicon tetrachloride containing phosphorus trichloride. The N-type layer 12 is monocrystalline except at regions above seeding areas formed on the surface of substrate 10 where wedge-shaped polycrystalline regions 13 are produced. The seeding areas may be grooves 11 formed in the surface or areas of silica deposited on the surface. The wafer is then heated to diffuse acceptor impurities from substrate 10 into epitaxial layer 12. Since the impurities diffuse faster through the polycrystalline regions 13 than through the monocrystalline part of layer 12 a P-type layer 14 is formed which completely surrounds the polycrystalline regions 13. Electrodes may be applied to the upper and lower surfaces to produce a variable capacitance diode. In a modification, Fig. 4 (not shown), the substrate and epitaxial layer are both of N-type conductivity and an acceptor impurity is diffused into the surface of the epitaxial layer instead of diffusing the impurity out of the substrate. This produces a surface P-type layer (16) which extends down the sides of the polycrystalline regions (13). An integrated circuit can be produced by planing down the surface of the device shown in Fig. 3 to expose the polycrystalline regions 13, Fig. 5 (not shown). Alternatively the deposition of the epitaxial layer can be stopped before the polycrystalline regions (13) are completely covered. Devices such as transistors, diodes, capacitors, and resistors can be formed in the monocrystalline regions and are electrically isolated from one another by the PN junctions surrounding the polycrystalline regions (13). In further modifications a P-type epitaxial layer is deposited on a P-type or an intrinsic substrate provided with seeding areas and a donor impurity is diffused through the substrate or epitaxial layer respectively into the polycrystalline regions. |
