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, the first structure comprising first dielectric surrounding each contact pad;
providing a substrate comprising a first side comprising one or more silicon regions each of which is surrounded by second dielectric;
attaching the first structure to the substrate so that the first dielectric physically contacts the second dielectric and 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.
2. The method of claim 1 , comprising bonding the first dielectric with the second dielectric.
3. The method of claim 2 wherein each of the first dielectric and the second dielectric is silicon dioxide.
4. The method of claim 2 , 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.
5. The method of claim 1 wherein in said attaching, a first surface of each contact pad meets a first surface of at least one corresponding silicon region of the substrate to form said metal silicide; and
immediately prior to said attaching, the first surface of each contact pad is level with at least one surface of the first dielectric.
6. The method of claim 1 wherein in said attaching, a first surface of each contact pad meets a first surface at least one corresponding silicon region of the substrate; and
immediately prior to said attaching, the first surface of each silicon region is level with at least one surface of the second dielectric.
7. The method of claim 1 wherein immediately prior to said attaching, at least one said contact pad protrudes out of the first dielectric.
8. The method of claim 1 wherein immediately prior to said attaching, the substrate comprises a circuit element and a conductive path connected to the circuit element; and
in said attaching, the conductive path becomes connected to said metal silicide, connecting the metal silicide to the circuit element.
9. The method of claim 8 wherein the circuit element is a transistor.
10. The method of claim 1 further comprising, after said attaching:
forming one or more holes in a second side of the substrate, the second side being opposite to the first side, 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.
11. A microelectronic component comprising:
a substrate comprising one or more silicon regions at a top side of the substrate; and
a first structure comprising circuitry comprising one or more contact pads at a bottom side of the first structure, wherein each said contact pad comprises metal and overlies at least one corresponding silicon region at the top side of the substrate;
wherein for each said contact pad, the microelectronic component comprises:
a metal silicide region underlying and physically contacting the contact pad and overlying and physically contacting the corresponding silicon region, wherein the metal silicide is a compound of silicon and the same metal as present in the contact pad; and
a dielectric region surrounding and physically contacting the contact pad, the metal silicide region, and the silicon region.
12. The microelectronic component of claim 11 wherein:
for each contact pad, the first structure comprises a first dielectric region surrounding and physically contacting the contact pad;
for each silicon region, the substrate comprises a second dielectric region surrounding and physically contacting the silicon region; and
each said dielectric region comprises at least one said first dielectric region and at least one said second dielectric region.
13. The microelectronic component of claim 12 wherein for at least one said contact pad, the dielectric region is silicon dioxide.
14. The microelectronic component of claim 11 wherein the substrate comprises a circuit element and a conductive path interconnecting the circuit element and the metal silicide.
15. The microelectronic component of claim 14 wherein the circuit element is a transistor.
16. The microelectronic component of claim 11 wherein the one or more silicon regions are a plurality of silicon regions which are electrically insulated from each other.
17. The microelectronic component of claim 11 further comprising, for at least one said contact pad, a metal via electrically coupled to at least one said contact pad and extending down through the corresponding silicon region.
18. The microelectronic component of claim 17 wherein the metal via is connected to a contact pad on a bottom of the substrate.
19. The microelectronic component of claim 17 wherein the metal via is located in a hole extending down through the corresponding silicon region.