An embodiment of the present invention is a technique to heat spread at wafer level. A silicon wafer is thinned. A chemical vapor deposition diamond (CVDD) wafer processed. The CVDD wafer is bonded to the thinned silicon wafer to form a bonded wafer. Metallization is plated on back side of the CVDD wafer. The CVDD wafer is reflowed to flatten the back side.