Methods of fabricating substrates including at least one conductive via
A method of fabricating a substrate is disclosed. Apertures are formed in a substrate blank. A conductive layer is formed on opposing surfaces of the substrate, as well as inside the apertures. Conductive elements are defined on one or both opposing surfaces by masking and etching. Additional layers of conductive materials may be used to provide a barrier layer and a noble metal cap for the conductive elements. The methods of the present invention may be used to fabricate an interposer for use in packaging semiconductor devices or a test substrate. Substrate precursor structures are also disclosed.
1. A method of fabricating a substrate, comprising: providing at least one substrate blank having a surface and another, opposing surface;
forming at least one aperture through the at least one substrate blank between the surface and the another, opposing surface;
forming at least one conductive layer concurrently over the surface, the another, opposing surface and within the at least one aperture of the at least one substrate blank;
forming a mask pattern over the at least one conductive layer including within the at least one aperture;
removing the at least one conductive layer where unprotected by the mask pattern using an etchant to define at least one conductive element extending over a portion of at least one of the surface and the another, opposing surface and over a surface of the at least one aperture;
plating a second conductive layer over at least a portion of the at least one conductive element; and
providing a dielectric layer over at least a portion of the second conductive layer and the at least one conductive element.
2. The method of claim 1 , wherein forming a mask pattern over the at least one conductive layer comprises forming a baffler layer over the at least one conductive layer.
3. The method of claim 1 , wherein forming the at least one conductive layer comprises depositing polysilicon.
4. The method of claim 1 , wherein forming the at least one conductive layer comprises forming a metal layer by electroless or electrolytic plating of the at least one substrate blank.
5. The method of claim 1 , further comprising plating a third conductive layer over at least a portion of the second conductive layer.
6. The method of claim 5 , wherein plating the third conductive layer comprises plating a gold layer.
7. The method of claim 1 , further comprising defining the at least one conductive element to include at least one conductive trace in communication with a conductive lining on the surface of the at least one aperture and extending over at least one of the surface and the another, opposing surface of the at least one substrate blank.
8. The method of claim 7 , further comprising terminating the at least one conductive trace in a conductive pad.
9. The method of claim 8 , further comprising covering the at least one conductive trace with a dielectric layer and leaving at least a portion of the conductive pad exposed.
10. The method of claim 9 , further comprising forming a discrete conductive element on the exposed at least a portion of the conductive pad.
11. The method of claim 10 , further comprising forming the discrete conductive element as a solder ball.
12. The method of claim 1 , wherein providing the at least one substrate blank comprises providing a plurality of unsingulated substrate blanks and further comprising singulating the substrate blanks of the plurality after depositing the another conductive layer of a metal on the at least one conductive element.
13. The method of claim 1 , further comprising forming a dielectric layer over the surface and the another, opposing surface of the at least one substrate blank and over the surface of the at least one aperture before forming the at least one conductive layer.
14. The method of claim 1 , further comprising removing the mask pattern prior to plating the second conductive layer.
15. The method of claim 1 , wherein forming the at least one conductive layer comprises forming a copper layer.
16. The method of claim 1 , wherein plating the second conductive layer comprises plating a nickel layer.