Heat spreading device and method

A method comprising:

• placing a die stack on a front side of a device wafer;
• bonding a front side of a dummy wafer to the front side of the device wafer, the die stack disposed in a recess in the front side of the dummy wafer;
• thinning a back side of the dummy wafer until the recess is exposed, thereby forming an opening extending through the dummy wafer;
• forming a first adhesive in the opening, top surfaces of the first adhesive, the dummy wafer, and the die stack being level;
• forming conductive connectors on a back side of the device wafer;
• and
• singulating the device wafer and the dummy wafer simultaneously, the device wafer singulated to form an integrated circuit die, the die stack disposed on the integrated circuit die, the dummy wafer singulated to form a dummy semiconductor feature, the dummy semiconductor feature laterally surrounding the die stack, the dummy semiconductor feature electrically isolated from the die stack and the integrated circuit die.

A method comprising:

• placing a die stack on a front side of an integrated circuit die;
• forming a plurality of conductive connectors on a back side of the integrated circuit die;
• bonding a dummy wafer to the front side of the integrated circuit die, the dummy wafer having a first portion covering the die stack after the bonding;
• thinning the dummy wafer to remove the first portion of the dummy wafer, the die stack being exposed after the thinning;
• forming a first adhesive between the die stack and the dummy wafer;
• and
• singulating the dummy wafer to form a dummy semiconductor feature on the front side of the integrated circuit die, the dummy semiconductor feature laterally surrounding the die stack, the dummy semiconductor feature being electrically isolated from the die stack and the integrated circuit die.