An integrated structure of an IGBT and a diode includes a plurality of doped cathode regions, and a method of forming the same is provided. The doped cathode regions are stacked in a semiconductor substrate, overlapping and contacting with each other. As compared with other doped cathode regions, the higher a doped cathode region is disposed, the larger implantation area the doped cathode region has. The doped cathode regions and the semiconductor substrate have different conductive types, and are applied as a cathode of the diode and a collector of the IGBT. The stacked doped cathode regions can increase the thinness of the cathode, and prevent the wafer from being overly thinned and broken.