Wafer-level die attach metallization
View Patent ↗Embodiments of a semiconductor wafer having wafer-level die attach metallization on a back-side of the semiconductor wafer, resulting semiconductor dies, and methods of manufacturing the same are disclosed. In one embodiment, a semiconductor wafer includes a semiconductor structure and a front-side metallization that includes front-side metallization elements for a number of semiconductor die areas. The semiconductor wafer also includes vias that extend from a back-side of the semiconductor structure to the front-side metallization elements. A back-side metallization is on the back-side of the semiconductor structure and within the vias. For each via, one or more barrier layers are on a portion of the back-side metallization that is within the via and around a periphery of the via. The semiconductor wafer further includes wafer-level die attach metallization on the back-side metallization other than the portions of the back-side metallization that are within the vias and around the peripheries of the vias.
1. A method of manufacturing a semiconductor wafer comprising a plurality of semiconductor die areas, comprising:
forming a plurality of vias through a semiconductor structure of the semiconductor wafer from a back-side of the semiconductor structure to corresponding front-side metallization elements of the plurality of semiconductor die areas on a front-side of the semiconductor structure;
forming a back-side metallization on the back-side of the semiconductor structure and within the plurality of vias such that, for each via of the plurality of vias, a portion of the back-side metallization is within the via and around a periphery of the via;
for each via of the plurality of vias, providing one or more barrier layers on the portion of the back-side metallization that is within the via and around the periphery of the via;
forming a wafer-level die attach metallization on the back-side metallization other than the portions of the back-side metallization that are within the plurality of vias and around the peripheries of the plurality of vias; and
forming streets through the wafer-level die attach metallization around peripheries of the plurality of semiconductor die areas.
2. The method of claim 1 wherein providing the one or more barrier layers for each via of the plurality of vias comprises:
forming one or more barrier materials on the back-side metallization including the portions of the back-side metallization that are within the plurality of vias and around the peripheries of the plurality of vias;
forming a mask on portions of the one or more barrier materials that are on the portions of the back-side metallization that are within the plurality of vias and around the peripheries of the plurality of vias; and
etching the one or more barrier materials using the mask to thereby provide the one or more barrier layers for each of the plurality of vias.
3. The method of claim 2 wherein forming the wafer-level die attach metallization comprises forming the wafer-level die attach metallization on a portion of the back-side metallization exposed by the mask after etching the one or more barrier materials.
4. The method of claim 1 further comprising cutting the semiconductor wafer along the streets to thereby dice the semiconductor wafer to provide a plurality of semiconductor dies.
5. The method of claim 1 wherein forming the wafer-level die attach metallization comprises plating the wafer-level die attach metallization on the back-side metallization other than the portions of the back-side metallization that are within the plurality of vias and around the peripheries of the plurality of vias.
6. The method of claim 5 wherein plating the wafer-level die attach metallization comprising plating a low melting point eutectic mixture of a desired metal alloy on the back-side metallization other than the portions of the back-side metallization that are within the plurality of vias and around the peripheries of the plurality of vias.
7. The method of claim 6 wherein the low melting point eutectic mixture of the desired metal alloy is an approximately 80%, 20% mixture of Gold-Tin (AuSn).
8. The method of claim 1 wherein forming the wafer-level die attach metallization comprises forming an alternating series of one or more layers of a first metal in a desired metal alloy and one or more layers of a second metal in the desired metal alloy such that, when heated, the one or more layers of the first metal and the one or more layers of the second metal mix to provide a low melting point eutectic mixture of the desired metal alloy.