Halbleiteranordnung

摘要

1,188,688. Semi-conductor devices. ALLMANNA SVENSKA ELEKTRISKA A.B. 27 June, 1967 [28 June, 1966], No. 29552/67. Heading H1K. The PN junction 1 between regions 3 and 8 of a semi-conductor body is formed by diffusion of suitable impurity into a plane surface 2 of the body under such conditions that the angleαbetween the junction 1 and the surface 2 is less than 45 degrees and preferably within the range 1 to 10 degrees. The junction may be the sole junction of a diode or, as shown, the centre junction of a PNPN thyristor. To achieve the required value for the angleα, the surface 2 is covered before diffusion with a layer of a substance in which the diffusion rate is at most of the same order as the rate of diffusion in the semi-conductor, e.g. in the case of silicon as semi-conductor a layer of silicon dioxide or nitride or carbide. This layer is thin or non-existent at the centre of the surface 2 and of progressively increasing thickness towards the edge. When impurity is diffused through this layer into the semi-conductor. the depth of penetration into the latter is of gradually diminishing extent with increasing distance from the centre, thus providing the required tapering shape for the junction edge. In a preferred process (Figs. 3a to 3c, not shown) the retarding layer (4) is of SiO 2 and, before diffusion, both this layer and the surfaces of the semi-conductor body not covered by the layer are covered with polycrystalline silicon (5). The latter acts as a barrier between the SiO 2 and a subsequently deposited layer (6) of dopant, to prevent the SiO 2 from dissolving in the dopant layer.