Patent ID: 8378480

Claim:
A package structure comprising: a first die; a second die over and bonded to the first die, wherein the second die has a size smaller than a size of the first die; a dummy chip over the first die, wherein the dummy chip comprises a portion encircling the second die, wherein the dummy chip comprises a material selected from the group consisting essentially of silicon and a metal, wherein the dummy chip comprises an opening extending from a bottom surface to an intermediate level of the dummy chip, wherein a portion of the dummy chip covers the opening, and wherein the second die extends into the opening; an adhesive adhering the dummy chip to the first die; metal pillars extending from a top surface to a bottom surface of the dummy chip; a gap in the opening and horizontally between a sidewall of the second die and a sidewall of the dummy chip; and a thermally conductive material horizontally between and contacting the dummy chip and the second die, wherein the thermally conductive material is in physical contact with the sidewall of the second die and the sidewall of the dummy chip.