Patent ID: 9735265
Date: 2017-08-15
CPC Classifications: H01L

Claim:
1. A process of forming an integrated circuit, comprising the steps of: providing a semiconductor base substrate; ion implanting dopants through exposed areas of an implant mask into the base substrate to form a lower buried layer implanted region; performing a first thermal drive operation so as to diffuse and activate the implanted dopants in the lower buried layer implanted region to form a lower buried layer, the lower buried layer having a conductivity type opposite from a conductivity type of the substrate; ion implanting dopants through exposed areas of an implant mask into the base substrate to form an upper buried layer implanted region; performing a second thermal drive operation so as to diffuse and activate the implanted dopants in the upper buried layer implanted region to form an upper buried layer, the upper buried layer having the same conductivity type as the conductivity type of the substrate; performing an epitaxial process which forms an epitaxial layer of semiconductor on the base substrate, the epitaxial layer having the same conductivity type as the conductivity type of the substrate, the epitaxial layer and the base substrate providing a substrate of the integrated circuit; ion implanting dopants through exposed areas of an implant mask into the substrate in an area defined for a deep well; performing a third thermal drive operation so as to diffuse and activate the implanted dopants in the area defined for the deep well to form the deep well around an isolated device of the integrated circuit, the deep well making electrical contact with the lower buried layer; the deep well having the same conductivity type as the conductivity type of the lower buried layer; and forming a deep trench isolation structure surrounding the isolated device, so that: a lateral separation between the deep trench isolation structure and the upper buried layer along a first side of the isolated device is at least one micron wider than a lateral separation between the deep trench isolation structure and the upper buried layer along a second side of the isolated device; the contact between the deep well and the lower buried layer is increased by at least a micron along the first side of the isolated device compared to the contact between the deep well and the lower buried layer along the second side of the isolated device; and a lateral width of the increased contact is less than one half a perimeter of the isolated device.