Patent ID: 8907432
Filing Date: 2014-12-09
Classification: H01L

Abstract:
1. An isolated device formed in a P-type substrate having an upper surface, the isolated device comprising: an N-type isolated well formed below the upper surface in the P-type substrate; a gate formed on the upper surface, and in the isolated well from top view; a P-type source and a P-type drain, which are formed in the isolated well below the upper surface, and are located at both sides of the gate respectively and separated by the gate, wherein the drain is separated from and not connected with the gate; a P-type drift-drain region formed in the isolated well, the drift-drain region separating the gate and the drain, and part of the drift-drain region being beneath the gate, wherein the drain is located in the drift-drain region and the drift-drain region has a depth deeper than the drain; and an N-type mitigation region, which is formed in the substrate, and is located at a same region with the drift-drain region from top view, and has a shallowest portion located at least below 90% of a depth of the drift-drain region as measured from the upper surface of the substrate, and has a deepest portion connected to an N-type deep well below the isolated well or the substrate and the mitigation region and the drift-drain region are overlapped at a direction of the depth to form a P-type overlapped region; wherein the overlapped region has a lower P-type impurity density compared with the drift-drain region.