Large metal pads over TSV
Representative techniques and devices including process steps may be employed to mitigate the potential for delamination of bonded microelectronic substrates due to metal expansion at a bonding interface. For example, a metal pad having a larger diameter or surface area (e.g., oversized for the application) may be used when a contact pad is positioned over a TSV in one or both substrates.
1. A method of forming a microelectronic assembly having a plurality of metal contact pads and at least one through substrate via (TSV), the method comprising:
providing a first TSV in a first substrate having a first upper surface, the first TSV normal to the first upper surface;
forming a first metal contact pad in the first upper surface, the first metal contact pad electrically coupled to or formed with the first TSV, the first metal contact pad extending partially into the first substrate below the first upper surface and aligned with the first TSV in the direction from the first upper surface through the first substrate;
forming a second metal contact pad in the first upper surface, wherein no TSV is disposed under the second metal contact pad in the direction from the first upper surface through the first substrate; and
planarizing the first upper surface to have a predetermined maximum surface variance for direct bonding, the planarizing adjusting a first recess of the first metal contact pad relative to the first upper surface by a first amount and a second recess of the second metal contact pad relative to the first upper surface by a second amount that is less than the first amount to compensate for thermal expansion of the TSV, the first metal contact pad, and the second metal contact pad relative to the first upper surface.
2. The method of forming a microelectronic assembly of claim 1 , wherein the first metal contact pad has a larger surface area at the first upper surface than the second metal contact pad.
3. The method of forming a microelectronic assembly of claim 1 , further comprising exposing the first TSV from a surface opposite the first upper surface.
4. The method of forming a microelectronic assembly of claim 1 , further comprising processing a lower surface opposite the first upper surface for direct bonding.
5. The method of forming a microelectronic assembly of claim 1 , further comprising:
providing a second substrate;
direct bonding the planarized first upper surface of the first substrate to the second substrate without an intervening adhesive.
6. The method of forming a microelectronic assembly of claim 5 , wherein the second substrate further comprises an electrically conductive via extending at least partially therethrough.
7. The method of forming a microelectronic assembly of claim 5 , further comprising heating the bonded first and second substrates to provide an electrical path between the first metal contact pad and an electrical feature on the second substrate.
8. A method of forming a microelectronic assembly having a plurality of metal contact pads and at least one through substrate via (TSV), the method comprising:
forming a first TSV provided within a first substrate having a first upper surface, the first TSV extending into the first substrate in a direction normal to the first upper surface;
forming a first metal contact pad and a second metal contact pad in the first upper surface, the first metal contact pad extending partially into the first substrate below the first upper surface, the first metal contact pad disposed over and aligned with the first TSV in the direction from the first upper surface through the first substrate, the second metal contact pad extending partially into the first substrate below the first upper surface, wherein no TSV is disposed under the second metal contact pad in the direction normal to the first upper surface; and
planarizing the first upper surface to have predetermined maximum surface variance for direct bonding and to adjust a first recess of the first metal contact pad and a second recess of the second metal contact pad relative to the first upper surface so that the first recess of the first metal contact pad compensates for thermal expansion of the TSV and first metal contact pad relative to the first upper surface, wherein an amount of the first recess is greater than an amount of the second recess.
9. The method of forming the microelectronic assembly of claim 8 , wherein the first metal contact pad has a larger surface area than the second metal contact pad.
10. The method of forming the microelectronic assembly of claim 8 , further comprising processing the side of the first substrate opposite the first upper surface for direct bonding.
11. The method of forming the microelectronic assembly of claim 10 , wherein the processing comprises thinning the first substrate and depositing one or more layers to balance a stress in the first substrate caused by the first substrate.
12. The method of forming the microelectronic assembly of claim 11 , wherein thinning the first substrate exposes the first TSV, and the one or more layers are formed over the first TSV, the method further comprising patterning the one or more layers to form an opening over the first TSV.
13. The method of forming the microelectronic assembly of claim 12 , further comprising depositing a barrier layer onto exposed surfaces of the opening; and
depositing a conductive material on the barrier layer and within the opening.
14. The method of forming the microelectronic assembly of claim 10 , further comprising direct bonding the first substrate to a second substrate using a direct dielectric-to-dielectric, non-adhesive bonding technique at the first upper surface of the first substrate.
15. The method of forming the microelectronic assembly of claim 14 , further comprising transferring heat from the first substrate to the second substrate via the first TSV and one or more conductive structures embedded within the second substrate and exposed at a bonding surface of the second substrate.