Method and apparatus for providing structural support for interconnect pad while allowing signal conductance
View Patent ↗A method provides an interconnect structure having enhanced structural support when underlying functional metal layers are insulated with a low modulus dielectric. A first metal layer having a plurality of openings overlies the substrate. A first electrically insulating layer overlies the first metal layer. A second metal layer overlies the first electrically insulating layer, the second metal layer having a plurality of openings. An interconnect pad that defines an interconnect pad area overlies the second metal layer. At least a certain amount of the openings in the two metal layers are aligned to improve structural strength of the interconnect structure. The amount of alignment may differ depending upon the application and materials used. A bond wire connection or conductive bump may be used with the interconnect structure.
1. A method for providing structural support for an interconnect pad, the method comprising:
providing a substrate;
providing a first metal layer overlying the substrate, the first metal layer having a plurality of openings;
providing a first electrically insulating layer overlying the first metal layer;
providing a second metal layer overlying the first electrically insulating layer, the second metal layer having a plurality of openings;
providing an interconnect pad overlying the second metal layer, the interconnect pad defining an interconnect pad area;
creating a physical layout shape from a logic operation on the first metal layer and the second metal layer;
determining a value X which is a metal density of the physical layout shape within a region of the interconnect pad; and
using the value X to determine if sufficient alignment of the plurality of openings of the first metal layer and the plurality of openings of the second metal layer exist for sufficient structural support.
2. The method of claim 1 , further comprising:
requiring the value X to be less than or equal to a predetermined threshold.
3. The method of claim 2 wherein the predetermined threshold comprises 0.85.
4. The method of claim 2 wherein the predetermined threshold comprises a range from 0.80 to 0.85, inclusive.
5. The method of claim 2 wherein the predetermined threshold comprises a range from 0.70 to 0.95, inclusive.
6. The method of claim 1 , further comprising:
providing a second electrically insulating layer overlying the second metal layer; and
providing a third metal layer interposed between the second electrically insulating layer and the interconnect pad, the third metal layer having a plurality of openings.
7. The method of claim 6 wherein the first electrically insulating layer and the second electrically insulating layer comprise a same material.
8. The method of claim 1 wherein the first electrically insulating layer comprises a dielectric.
9. The method of claim 1 wherein the first electrically insulating layer has a permittivity less than 4.
10. The method of claim 1 , wherein the first electrically insulating layer has a modulus value less than 80 gigaPascals.
11. The method of claim 1 , wherein the plurality of openings in the first metal layer and the plurality of openings in the second metal layer are substantially filled with the first electrically insulating layer.
12. The method of claim 1 , wherein the first metal layer and the second metal layer respectively have a physical metal density in a range of 20-80% for respective areas of the first metal layer and the second metal layer.
13. The method of claim 1 , further comprising:
providing one or more vias through the first electrically insulating layer to electrically connect at least a portion of the first metal layer to at least a portion of the second metal layer.
14. The method of claim 1 , further comprising:
providing a passivation layer interposed between the interconnect pad and the second metal layer.
15. The method of claim 1 wherein at least one device is formed in the substrate underlying the interconnect pad.
16. A method for providing structural support for an interconnect pad, the method comprising:
providing a substrate;
providing a first conductive layer overlying the substrate, the first conductive layer having a plurality of openings;
providing a first electrically insulating layer overlying the first conductive layer;
providing a second conductive layer overlying the first electrically insulating layer, the second conductive layer having a plurality of openings;
providing an interconnect pad overlying the second conductive layer, the interconnect pad defining an interconnect pad area;
creating a physical layout shape from a logic operation on the first conductive layer and the second conductive layer;
determining a value X which is a density of the physical layout shape within a region of the interconnect pad; and
using the value X to determine if sufficient alignment of the plurality of openings of the first conductive layer and the plurality of openings of the second conductive layer exist for sufficient structural support.
17. The method of claim 16 further comprising:
providing a second electrically insulating layer overlying the second conductive layer; and
providing a third conductive layer interposed between the second electrically insulating layer and the interconnect pad, the third conductive layer having a plurality of openings.
18. The method of claim 16 further comprising:
providing one or more vias through the first electrically insulating layer to electrically connect at least a portion of the first conductive layer to at least a portion of the second conductive layer.
19. The method of claim 16 further comprising:
providing a passivation layer interposed between the interconnect pad and the second conductive layer.
20. A method for providing structural support for an interconnect pad, the method comprising:
providing a substrate having one or more active or passive devices formed therein;
providing a first conductive layer overlying the substrate, the first conductive layer having a plurality of openings;
providing a first electrically insulating layer overlying the first conductive layer;
providing a second conductive layer overlying the first electrically insulating layer, the second conductive layer having a plurality of openings;
providing an interconnect pad overlying the second conductive layer, the interconnect pad defining an interconnect pad area;
creating a physical layout shape from a Boolean OR operation on the first conductive layer and the second conductive layer;
determining a value X which is a density of the physical layout shape within a region of the interconnect pad; and
using the value X to determine if sufficient alignment of the plurality of openings of the first conductive layer and the plurality of openings of the second conductive layer exist for sufficient structural support.