Patent ID: 8652934

Claim:
A method of forming isolation regions having different depths in a semiconductor substrate, the method comprising: forming an etch mask material over a semiconductor substrate; using a single reticle in a photolithographic process to pattern the etch mask material to define first and second openings for forming first and second trench isolation areas, the second openings being wider than the first openings; etching first and second trench isolation areas in the semiconductor substrate using the patterned etch mask material; forming an isolation material within each of the first and second trench isolation areas; removing isolation material at the bottom of the second trench isolation areas to expose the semiconductor substrate, while leaving trench isolation material in the first trench isolation areas; further etching the exposed semiconductor substrate at the second trench isolation areas, such that the depth of the second trench isolation areas exceeds that of the first trench isolation areas; forming a trench isolation material within the deeper second trench isolation areas; forming an electronic device on the substrate which is electrically isolated by first trench isolation areas; and, forming a photonic device over the trench isolation material within the second trench isolation areas such that the photonic device is optically isolated from the substrate.