Semiconductor substrates including I/O redistribution using wire bonds and anisotropically conductive film, methods of fabrication and assemblies including same
Methods and apparatus for eliminating wire sweep and shorting while avoiding the use of under-bump metallization and high cost attendant to the use of conventional redistribution layers. An anisotropically conductive (z-axis) conductive layer in the form of a film or tape is applied to the active surface of a die and used as a base for conductive redistribution bumps formed on the anisotropically conductive layer, bonded to the ends of conductive columns thereof and wire bonded to the bond pads of the die. Packages so formed may be connected to substrates either with additional wire bonds extending from the conductive redistribution bumps to terminal pads or by flip-chip bonding using conductive bumps formed on the conductive redistribution bumps to connect to the terminal pads. The acts of the methods may be performed at the wafer level. Semiconductor die assemblies using the present invention are also disclosed.
1. A semiconductor substrate assembly, comprising:
at least one semiconductor die having a plurality of bond pads formed on an active surface thereof;
at least one anisotropically conductive layer comprising a plurality of laterally isolated conductive elements disposed in a dielectric material and having upper ends exposed therethrough attached to the active surface;
a plurality of conductive bumps on the at least one anisotropically conductive layer with each conductive bump in contact with at least one conductive element of the plurality; and
a plurality of wire bonds extending between the bond pads and the conductive bumps, each wire bond of the plurality having a first end directly attached to a bond pad of the plurality of bond pads and a second end directly attached to a conductive bump of the plurality of conductive bumps.
2. The assembly of claim 1 , wherein the at least one anisotropically conductive layer comprises conductive elements in the form of discrete metal columns embedded in a polymeric material.
3. The assembly of claim 2 , wherein the discrete metal columns have a diameter of about 1 μm to about 15 μm.
4. The assembly of claim 2 , wherein the discrete metal columns have a diameter of about 2 μm to about 8 μm.
5. The assembly of claim 2 , wherein the polymeric material comprises a tape or film.
6. The assembly of claim 1 , wherein the conductive elements comprise at least one of tungsten, aluminum, copper, silver, gold, and alloys thereof.
7. The assembly of claim 1 , wherein the at least one anisotropically conductive layer is attached to the active surface by an adhesive.
8. The assembly of claim 1 , further comprising:
a substrate having a plurality of terminal pads on a surface thereof; and
wire bonds between the plurality of conductive bumps and the plurality of terminal pads.
9. The assembly of claim 8 , wherein the substrate comprises one of a circuit board, an interposer, a semiconductor die, a wafer and a partial wafer.
10. The assembly of claim 7 , further comprising a dielectric layer over the at least one semiconductor die, the bond pads, the conductive bumps and the wire bonds.
11. The assembly of claim 1 , wherein the conductive bumps are attached to the conductive elements by metallurgical bonds.
12. The assembly of claim 1 , wherein the conductive bumps and the wire bonds are formed of gold.
13. A semiconductor substrate assembly, comprising:
at least one semiconductor die having a plurality of bond pads formed on an active surface thereof;
at least one anisotropically conductive layer comprising a plurality of laterally isolated conductive elements disposed in a dielectric material and having upper ends exposed therethrough attached to the active surface; and
a plurality of conductive bumps on the at least one anisotropically conductive layer with each conductive bump in contact with at least one conductive element of the plurality;
wire bonds between the bond pads and the conductive bumps;
wherein the at least one semiconductor die has the plurality of bond pads centrally located along an axis thereof and the at least one anisotropically conductive layer comprises a plurality of anisotropically conductive layers adjacent the plurality of bond pads on opposing sides thereof; and
wherein the at least one semiconductor die comprises a wafer including a plurality of semiconductor dice, and the plurality of anisotropically conductive layers are disposed between pluralities of bond pads of adjacent semiconductor dice and extending over boundaries therebetween.
14. The assembly of claim 1 , wherein the at least one semiconductor die is in the form of a singulated die, a partial wafer comprising a plurality of semiconductor dice or a wafer comprising a plurality of semiconductor dice.
15. A semiconductor substrate assembly, comprising:
at least one semiconductor die having a plurality of bond pads formed on an active surface thereof;
at least one anisotropically conductive layer comprising a plurality of laterally isolated conductive elements disposed in a dielectric material and having upper ends exposed therethrough attached to the active surface;
a plurality of conductive bumps on the at least one anisotropically conductive layer with each conductive bump in contact with at least one conductive element of the plurality;
wire bonds between the bond pads and the conductive bumps; and
another plurality of conductive bumps, each conductive bump of the another plurality disposed on one of the plurality of conductive bumps.
16. The assembly of claim 15 , further comprising:
a substrate having a plurality of terminal pads on a surface thereof with the conductive bumps of the another plurality in alignment with and bonded to the terminal pads.
17. The assembly of claim 16 , wherein the substrate comprises one of a circuit board, an interposer, a semiconductor die, a wafer and a partial wafer.
18. The assembly of claim 17 , wherein the at least one semiconductor die comprises a wafer including a plurality of semiconductor dice and the substrate comprises a wafer-scale substrate.
19. The assembly of claim 16 , further comprising a dielectric underfill material between the at least one semiconductor die and the substrate.
20. The assembly of claim 15 , further comprising a dielectric material covering the plurality of conductive bumps, the bond pads and the wire bonds therebetween and leaving at least a portion of each of the conductive bumps of the another plurality exposed therethrough.