Digital and RF system and method therefor
View Patent ↗A stacked die system ( 10 ) has a first die ( 16 ) having a first surface with active circuitry, a second die ( 18 ) having a first surface with active circuitry, and a conductive shield ( 28 ) interposed between the first surface of the first die and the first surface of the second die. In one embodiment, the distance between the first surfaces of the first and second die is less than one millimeter. The stacked die system may also include a package substrate ( 12 ) where the active circuitry of the first and second die are electrically connected to the package substrate. The electrical connections may be formed using wire bonds ( 56, 58, 60, 62 ). Alternatively, the first die may be connected to the package substrate in a flip chip configuration. In one embodiment, the active circuitry of the first die generates RF signals where the shield helps protect the RF signals from interference caused by the active circuitry of the second die.
1. A method for forming a stacked die system, comprising:
providing a package substrate;
placing a first die over the package substrate, the first die having a first surface with active circuitry;
applying a first epoxy resin over the first die;
placing a conductive shield over the first die and the first epoxy resin after the step of applying the first epoxy resin;
applying a second epoxy resin over the conductive shield after the step of placing the conductive shield;
placing a second die over the conductive shield, the second die having a first surface with active circuitry, wherein the conductive shield is between the first surface of the first die and the first surface of the second die;
forming electrical connections between the active circuitry of the first die and the package substrate;
forming electrical connections between the active circuitry of the second die and the package substrate;
obtaining a wafer having an aluminum coating; and
singulating the wafer to form the conductive shield, wherein the step of obtaining is further characterized by the wafer comprising silicon.
2. The method of claim 1 , wherein the active circuitry in one of the first or second die generates RF signals.
3. The method of claim 1 , wherein forming the conductive shield over the first die comprises forming the conductive shield over the first die to the package substrate, the conductive field substantially surrounding the electrical connections between the active circuitry of the first die and the package substrate.
4. The method of claim 1 , wherein the first die has a second surface opposite the first surface, and wherein placing the first die over the package substrate comprises adhering the second surface to the package substrate.
5. The method of claim 1 , further comprising forming a spacer over the first die, wherein the conductive shield is formed over the spacer.