Method of forming isolation structure for isolating high voltage devices

摘要

A method of forming an isolation structure for isolating high voltage devices is described. A first p-well is formed in and on a substrate. Two field oxides are formed spaced apart from each other over the first p-well. A second p-well is formed in and on the first p-well, wherein the second p-well substantially surrounds and substantially being adjacent to the field oxides in the first p-well. A trench isolation is formed in and on the first p-well and between the field oxides, wherein the trench isolation is substantially deeper than the second p-well. A third p-well substantially surrounding and being adjacent to the trench isolation is formed in the first p-well.