Hybrid bump capacitor
A device fabricated on a chip is disclosed. The device generally includes (A) a first pattern and a second pattern both created in an intermediate conductive layer of the chip, (B) at least one via created in an insulating layer above the intermediate conductive layer and (C) a first bump created in a top conductive layer above the insulating layer. The first pattern generally establishes a first of a plurality of plates of a first capacitor. The via may be aligned with the second pattern. The first bump may (i) be located directly above the first plate, (ii) establish a second of the plates of the first capacitor, (iii) be suitable for flip-chip bonding, (iv) connect to the second pattern through the via such that both of the plates of the first capacitor are accessible in the intermediate conductive layer. The first pattern and the second pattern may be shaped as interlocking combs.
1. A device comprising:
a first pattern and a second pattern both created in an intermediate conductive layer of a chip, wherein said first pattern establishes a first of a plurality of plates of a first capacitor;
at least one via created in an insulating layer above said intermediate conductive layer, wherein said via is aligned with said second pattern; and
a first bump created in a top conductive layer above said insulating layer, wherein (A) said first bump (i) is located directly above said first plate, (ii) establishes a second of said plates of said first capacitor, (iii) is suitable for flip-chip bonding and (iv) connects to said second pattern through said via such that both of said plates of said first capacitor are accessible in said intermediate conductive layer and (B) said first pattern and said second pattern are shaped as interlocking combs.
2. The device according to claim 1 , wherein said first pattern and said second pattern are isolated from each other by at least one fence structure.
3. The device according to claim 1 , further comprising a circuit located under said first bump and connected to said first plate such that said circuit is AC coupled to said first bump.
4. The device according to claim 1 , further comprising a first circuit proximate a first side of said first bump and connected to said first plate such that said first circuit is AC coupled to said first bump.
5. The device according to claim 4 , wherein said first circuit comprises a high-speed signal receiver circuit.
6. The device according to claim 5 , further comprising a second circuit proximate a second side of said first bump, wherein said second side is opposite said first side.
7. The device according to claim 6 , wherein said second circuit comprises a high-speed signal termination circuit.
8. The device according to claim 6 , wherein said second circuit is connected to said second plate such that said second circuit is DC coupled to said first bump.
9. The device according to claim 6 , further comprising a signal trace created in a lower conductive layer below said intermediate conductive layer, said signal trace (i) passing under said first bump and (ii) connecting said first circuit to said second circuit.
10. The device according to claim 4 , further comprising a second bump proximate said first circuit, wherein said second bump forms a second capacitor coupled to said first circuit.
11. The device according to claim 1 , further comprising a volume between said first plate and a substrate of said chip, wherein no other circuitry is located in said volume to minimize a parasitic capacitance of said first bump.
12. A method of fabricating a device on a chip, comprising the steps of:
(A) creating both a first pattern and a second pattern in an intermediate conductive layer of said chip, wherein said first pattern establishes a first of a plurality of plates of a first capacitor;
(B) creating at least one via in an insulating layer above said intermediate conductive layer, wherein said via is aligned with said second pattern; and
(C) creating a first bump in a top conductive layer above said insulating layer, wherein said (A) first bump (i) is located directly above said first plate, (ii) establishes a second of said plates of said first capacitor, (iii) is suitable for flip-chip bonding and (iv) connects to said second pattern through said via such that both of said plates of said first capacitor are accessible in said intermediate conductive layer and (B) said first pattern and said second pattern are shaped as interlocking combs.
13. The method according to claim 12 , further comprising the step of:
creating both a third pattern and a fourth pattern in a lower conductive layer below said intermediate conductive layer, wherein (i) said third pattern is located under said first bump and establishes part of said first plate and (ii) said fourth pattern is connected to said second plate such that both of said plates of said first capacitor are accessible in said lower conductive layer.
14. The method according to claim 12 , further comprising the step of:
creating a first signal trace in said intermediate conductive layer between said first plate and a first circuit such that said first bump is AC coupled to said first circuit.
15. The method according to claim 14 , further comprising the step of:
creating a second signal trace in said intermediate conductive layer between said second plate and a second circuit such that said first bump is DC couple to said second circuit.
16. The method according to claim 14 , further comprising the step of:
creating a second bump proximate said first circuit, wherein said second bump forms a second capacitor coupled to said first circuit.
17. The method according to claim 12 , further comprising the step of:
creating a signal trace in a lower conductive layer below said intermediate conductive layer such that said signal trace passes under said first bump.