Microelectronic assemblies formed using metal silicide, and methods of fabrication
Two microelectronic components ( 110, 120 ), e.g. a die and an interposer, are bonded to each other. One of the components' contact pads ( 110 C) include metal, and the other component has silicon ( 410 ) which reacts with the metal to form metal silicide ( 504 ). Then a hole ( 510 ) is made through one of the components to reach the metal silicide and possibly even the unreacted metal ( 110 C) of the other component. The hole is filled with a conductor ( 130 ), possibly metal, to provide a conductive via that can be electrically coupled to contact pads ( 120 C.B) attachable to other circuit elements or microelectronic components, e.g. to a printed circuit board.
1. A fabrication method comprising:
providing a first structure comprising circuitry comprising one or more contact pads each of which comprises metal;
providing a substrate comprising a first side comprising one or more silicon regions, the substrate also comprising a second side opposite to the first side;
attaching the first structure to the substrate so that at least a portion of the metal of each contact pad reacts with at least a portion of the silicon of a corresponding silicon region to form metal silicide;
forming one or more holes in the second side of the substrate, each hole reaching the metal silicide formed by reacting at least a portion of the metal of the corresponding contact pad; and
forming a conductive via in each hole, the conductive via reaching at least one of the metal of the corresponding contact pad and the corresponding metal silicide, the conductive via extending to the substrate's surface at the second side of the substrate.
2. The method of claim 1 wherein each hole, and the corresponding conductive via, pass at least part way through the metal silicide.
3. The method of claim 1 wherein each hole passes through the metal silicide, and the corresponding conductive via reaches an unreacted metal of the corresponding contact pad.
4. The method of claim 1 wherein:
providing the first structure comprises providing dielectric surrounding each contact pad;
providing the substrate comprises providing dielectric surrounding each silicon region; and
the method further comprises bonding the dielectric surrounding each contact pad with the dielectric surrounding each silicon region.
5. The method of claim 4 wherein the bonding overlaps in time with a silicidation operation in which at least said portion of the metal of each contact pad reacts with at least said portion of the silicon of the corresponding silicon region to form said metal silicide.
6. The method of claim 1 wherein the substrate comprises a non-dielectric region and a dielectric region separating the one or more silicon regions from the non-dielectric region.
7. The method of claim 1 wherein providing the substrate comprises:
providing a second structure comprising a dielectric surface; and
forming the one or more silicon regions on the dielectric surface.
8. The method of claim 1 wherein providing the substrate comprises:
providing a silicon substrate; and
removing part of the silicon substrate to form one or more protrusions at the first side of the silicon substrate, each protrusion comprising one of the one or more silicon regions.
9. The method of claim 8 wherein the one or more silicon regions are a plurality of the silicon regions, and the method further comprises implanting a species into the silicon substrate to electrically insulate the silicon regions from each other.
10. The method of claim 1 wherein providing the substrate comprises:
providing a silicon substrate; and
forming dielectric at a top of the silicon substrate, the substrate comprising one or more silicon regions each of which has a top surface bordering on the dielectric.
11. The method of claim 10 wherein the one or more silicon regions are a plurality of silicon regions whose top surfaces are separated from each other by the dielectric.
12. The method of claim 1 further comprising, after attaching the first structure to the substrate, thinning the substrate from the second side to expose each silicon region at the second side.
13. The fabrication method of claim 1 wherein the one or more silicon regions are a plurality of the silicon regions electrically insulated from each other.
14. A microelectronic component comprising:
a first structure comprising circuitry comprising one or more metal regions at a bottom of the first structure;
for each metal region,
at least one corresponding silicon region;
at least one metal silicide region physically contacting the metal region and the corresponding silicon region;
at least one conductive via reaching at least one of the corresponding metal region and the corresponding metal silicide region from below the silicon region;
the microelectronic component further comprising, at its bottom side, one or more contact pads for attachment to circuitry, each of the one or more contact pads being electrically coupled to at least one of the one or more conductive vias.
15. The microelectronic component of claim 14 wherein each conductive via passes through the corresponding metal silicide region and reaches the corresponding metal region.
16. The microelectronic component of claim 14 wherein each conductive via passes through the corresponding silicon region.
17. The microelectronic component of claim 14 wherein each conductive via is made essentially of metal.
18. The microelectronic component of claim 14 wherein the one or more silicon regions are formed on a dielectric layer, and each conductive via passes through the dielectric layer.
19. The microelectronic component of claim 14 wherein the one or more silicon regions are a plurality of silicon regions electrically insulated from each other.
20. The microelectronic component of claim 14 wherein the one or more silicon regions are electrically insulated from each conductive via.
21. The microelectronic component of claim 14 wherein each conductive via comprises a vertical portion extending along the entire conductive via.