HIGH BREAKDOWN VOLTAGE PLANAR TYPE SEMICONDUCTOR DEVICE

摘要

PURPOSE:To attain the breakdown voltage at about several hundred volts with good yield by a mthod whereon guard ring structure and field plate stracture are combined and field plates are also provided for guard ring layers. CONSTITUTION:A field plate 61 consisting of a conductor layer maintained at the same potential as that of a diffusion layer 2 is arranged on an insulating film 3 located at the outside of a diffusion layer 2. Field plates 62, 63 consisting of conductor layers maintained at the same potential as that of guard ring layers 71, 72 are arranged on the insulating film 3 located at the outside of the guard ring layers 71, 72. With reverse bias applied to a substrate 1 and the diffusion layer 2, the potential at the plates 61, 62 becomes lower than the potential at the substrate right below the plates 61, 62. Therefore, the expansion of a depletion layer to the outside from the diffusion layer 2 becomes wide. Accordingly, breakdown voltage at about several hundred volts can be attained with good yield by sharing a predetermined voltage to the guard ring layers 71, 72 in accordance with reverse bias voltage.