A method for manufacturing a semiconductor die may have the steps of:—Providing a semiconductor substrate;—Processing the substrate to a point where shallow trench isolation (STI) can be formed;—Depositing at least one underlayer having a predefined thickness on the wafer;—Depositing a masking layer on top of the underlayer;—Shaping the masking layer to have areas of predefined depths;—Applying a photolithograthy process to expose all the areas where the trenches are to be formed; and—Etching the wafer to form silicon trenches wherein the depth of a trench depends on the location with respect to the masking layer area.