Planar semiconductor devices

摘要

1,073,554. Transistors. HUGHES AIRCRAFT CO. July 23, 1965 [Aug. 18, 1964], No. 31499/65. Heading H1K. A planar semi-conductor device comprises a PN junction which terminates under an oxide layer, the surface adjacent P region being of lower resistivity and the surface adjacent. N region being of higher resistivity than their respective sub-surface regions. This avoids temperature-voltage dependent leakage which otherwise tends to occur at PN junctions terminating under oxide layers. A PNP transistor is produced by epitaxially depositing a P-type silicon layer 4 on a P-type 0À001 ohm cm., silicon substrate 2 and an N-type, 0À6 ohm cm. layer 6 is produced by diffusion of arsenic. This layer is covered with oxide with the central portion removed to allow further diffusion of N-type impurity to provide the N-type base zone 9 of the transistor. The exposed portions are then covered with oxide 81 which is partially removed to allow conversion of the remainder of layer 6 to low resistivity P-type region 41 leaving wings 91 of high resistivity N-type at the periphery of base zone 9. P-type emitter region 10 is also provided during this process. Ohmic connections are provided to base and emitter regions respectively by evaporating gold. Alternatively wires may be bonded by thermo-compression to base and emitter areas. The epitaxial deposition and diffusion may be interchanged and N-type layers may be provided by outdiffusion of excess acceptor material into an oxide layer.