Protective layer for protecting TSV tips during thermo-compressive bonding
A method of protecting through substrate via (TSV) die from bonding damage includes providing a substrate including a plurality of TSV die having a topside including active circuitry, a bottomside, and a plurality of TSVs that include an inner metal core that reaches from the topside to protruding TSV tips that extend out from the bottomside. A protective layer is formed on or applied to the bottomside of the TSV die including between and over the protruding TSV tips. The TSV die is bonded with its topside down onto a workpiece having a workpiece surface and its bottomside up and in contact with a bond head. The protective layer reduces damage from the bonding process including warpage of the TSV die by preventing the bond head from making direct contact to the protruding TSV tips.
1. A protected stacked die precursor, comprising:
a workpiece including a workpiece surface having a plurality of contact pads thereon;
a through substrate via (TSV) die including a substrate having a topside including active circuitry and bonding features on said topside, a bottomside, and a plurality of TSVs comprising a metal inner core that reaches from said topside to protruding TSV tips that extend out from said bottomside, and
a protective layer on said bottomside of said TSV die that extends over said protruding TSV tips, wherein said bonding features of said TSV die are bonded to said plurality of contact pads on said workpiece surface and wherein said TSV tips include a metal cap thereon comprising at least one metal layer that includes a metal that is not in said inner metal core.
2. The protected stacked die precursor of claim 1 , wherein said workpiece comprises an organic substrate.
3. The protected stacked die precursor of claim 1 , wherein said protective layer is a blanket layer that substantially planarizes said bottomside of said TSV die.
4. The protected stacked die precursor of claim 1 , wherein said inner metal core comprises copper and TSV tips include a metal cap thereon that includes at least one of titanium, nickel, palladium, and gold.