An embodiment of the apparatus of forming a semiconductor device is provided. The semiconductor device may be surrounded in part by a first isolation structure comprising a first pin projecting to pass through the top surface. The semiconductor device also comprises a partly surrounded by a second isolation structure and a second pin protruding by passing through the top surface. The first top surface of the isolation structure increases the top than cotton of the second isolation structure, the second pin has a height greater than the first pin. A second isolation structure has a higher dopant concentration than the first isolation structure.