Method for fabricating a Schottky diode including a guard ring overlapping an insolation layer

摘要

A Schottky diode includes a deep well formed in a substrate, an isolation layer formed in the substrate, a first conductive type guard ring formed in the deep well along an outer sidewall of the isolation layer and located at a left side of the isolation layer, a second conductive type well formed in the deep well along the outer sidewall of the isolation layer and located at a right side of the isolation layer, an anode electrode formed over the substrate and coupled to the deep well and the guard ring, and a cathode electrode formed over the substrate and coupled to the well. A part of the guard ring overlaps the isolation layer.

主权项

1. A method for fabricating a Schottky diode, comprising:
forming an isolation layer in a substrate in which a deep well of a second conductive type is formed; forming a well region of a second conductive type in the deep well along an outer sidewall of the isolation layer to be located at one side of the isolation layer; forming a guard ring of a first conductive type in the deep well along the outer sidewall of the isolation layer to be located at an opposite side of the isolation layer in such a manner that a part of the guard ring overlaps the isolation layer; and forming an anode electrode over the substrate to be coupled to the deep well and the guard ring and simultaneously forming a cathode electrode coupled to the well region over the substrate, wherein an impurity doping concentration of the well region is reduced in a depth direction from a surface of the substrate, wherein the forming of the well region comprises: forming an ion implantation mask over the substrate to expose the deep well of an outer side of the isolation layer; forming a first impurity region in the deep well by ion implanting a second conductive type impurity by using the ion implantation mask as an ion implantation barrier; forming a second impurity region on an upper portion of the first impurity region by ion-implanting the second conductive type impurity by using the ion implantation mask as an ion implantation barrier, the second impurity region having an impurity doping concentration higher than an impurity doping concentration of the first impurity region; and forming a third impurity region on an upper portion of the second impurity region by ion-implanting the second conductive type impurity by using the ion implantation mask as an ion implantation barrier, the third impurity region having an impurity doping concentration higher than an impurity doping concentration of the second impurity region.