The collector (anode) of a non punch through IGBT formed in a float zone silicon monocrystaline wafer is formed with a DMOS top structure and is thereafter ground at its bottom surface to a less than 250 micron thickness. A shallow P type implant is then made in the bottom surface and the wafer is then heated in vacuum to about 400° C. for about 30 to 60 seconds to remove moisture and other contaminants from the bottom surface. An aluminum layer is then sputtered on the bottom surface, followed by other metals to form the bottom electrode. No activation anneal is necessary to activate the weak collector junction.