Patent ID: 9093494
Filing Date: 2015-07-28
Classification: H01L

Abstract:
1. A guard structure for a semiconductor structure, comprising: a first guard ring having a first conductivity type; a second guard ring having a second conductivity type, and surrounding the first guard ring; a third guard ring having the first conductivity type, and surrounding the second guard ring, wherein the first, the second and the third guard rings are grounded; wherein the first guard ring, the second guard ring, and the third guard ring comprising at least an upper portion, a middle portion and a lower portion, the lower portion further comprising a first portion and a second portion; at least one of the first guard ring, the second guard ring, and the third guard ring having a lower dopant concentration in the middle portion relative to the upper portion and the lower portion; and at least one of the first guard ring, the second guard ring, and the third guard ring having a higher dopant concentration in the first portion relative to the second portion and the middle portion, and wherein the first portion is between the second portion and the middle portion.