Systems and methods for producing flat surfaces in interconnect structures
View Patent ↗Methods and apparatus for forming a semiconductor device are provided which may include any number of features. One feature is a method of forming an interconnect structure that results in the interconnect structure having a co-planar or flat top surface. Another feature is a method of forming an interconnect structure that results in the interconnect structure having a surface that is angled upwards greater than zero with respect to a top surface of the substrate. The interconnect structure can comprise a damascene structure, such as a single or dual damascene structure, or alternatively, can comprise a silicon-through via (TSV) structure.
1. A method for fabricating an apparatus comprising one or more semiconductor devices, the method comprising:
(1) forming a workpiece, wherein forming the workpiece comprises:
obtaining a substrate comprising a plurality of holes in a top surface of the substrate, each hole being a through-hole or a recess, the holes being spaced from each other, the top surface comprising a first surface portion not occupied by any of said holes and being above a bottom of each said hole;
forming a separation layer over the substrate to separate the substrate from a subsequently formed conductive layer, the separation layer overlying the first surface portion and extending into each said hole;
forming the conductive layer over the separation layer, the conductive layer extending into each said hole to provide in each said hole at least a part of an interconnect structure in the apparatus, the conductive layer being a different material than the separation layer, a top surface of the conductive layer having a recess over each said hole;
forming a sacrificial layer covering the conductive layer, the sacrificial layer being a material different than the materials of the conductive layer and the separation layer;
wherein a lowest point of the sacrificial layer is higher than a highest point of the separation layer;
(2) polishing a top surface of the workpiece by a process in which:
the sacrificial layer is removed over the first surface portion of the substrate and the conductive layer becomes exposed over the first surface portion of the substrate while the sacrificial layer remains over each said hole; then
a remaining portion of the sacrificial layer is removed, and during a removal of the remaining portion of the sacrificial layer, at least part of the remaining portion of the sacrificial layer is polished simultaneously with polishing the conductive layer but at a lower polishing rate than the conductive layer, to provide the workpiece with a top surface having a protrusion of the conductive layer over each said hole; then
the separation layer is polished away over the first surface portion of the substrate simultaneously with polishing of the conductive layer over each said hole.
2. The method of claim 1 wherein the substrate comprises a semiconductor substrate.
3. The method of claim 1 wherein the sacrificial layer is conformal.
4. The method of claim 1 wherein the sacrificial layer is conductive, and said polishing is ECMP.
5. The method of claim 1 wherein the material of the separation layer is different from any material in a top surface of the substrate.
6. The method of claim 1 wherein the separation layer is conductive.
7. The method of claim 1 wherein the separation layer is a barrier layer.
8. The method of claim 1 wherein the separation layer is an adhesion layer.
9. The method of claim 1 wherein the separation layer is a coupling layer.
10. The method of claim 1 wherein at least one said hole is a through-hole.
11. The method of claim 10 wherein a part of the conductive layer in said through-hole comprises a through-silicon via.
12. The method of claim 1 wherein at least a part of the interconnect structure in at least one said hole is a damascene structure.
13. A method for fabricating an apparatus comprising one or more semiconductor devices, the method comprising:
(1) forming a workpiece, wherein forming the workpiece comprises:
obtaining a substrate comprising a plurality of holes in a top surface of the substrate, each hole being a through-hole or a recess, the holes being spaced from each other;
forming a conductive layer covering the substrate and extending into each said hole to provide in each said hole at least a part of an interconnect structure in the apparatus, the conductive layer being a pre-selected material whose entire bottom surface is in physical contact with one or more materials other than the pre-selected material, the conductive layer having a recess over each said hole; and
forming a sacrificial layer covering the conductive layer, the sacrificial layer being a first material different than the pre-selected material;
wherein a lowest point of the entire sacrificial layer is higher than a highest point of the bottom surface of the conductive layer;
(2) polishing a top surface of the workpiece by a process in which:
the sacrificial layer is removed over the first surface portion of the substrate and the conductive layer becomes exposed over the first surface portion of the substrate while the sacrificial layer remains over each said hole or recess; then
a remaining portion of the sacrificial layer is removed, and during a removal of the remaining portion of the sacrificial layer, at least part of the remaining portion of the sacrificial layer is polished simultaneously with polishing the conductive layer but at a lower polishing rate than the conductive layer, to provide the workpiece with a top surface having a protrusion of the conductive layer over each said hole; then
the conductive layer is polished away over the first surface portion of the substrate simultaneously with polishing of the conductive layer over each said hole.
14. The method of claim 13 wherein the sacrificial layer is conformal.
15. The method of claim 13 wherein the sacrificial layer is conductive.
16. The method of claim 13 wherein operation (1) further comprises forming a separation layer covering the substrate and separating the conductive layer from the substrate, the separation layer being a material different than the first material.
17. The method of claim 16 wherein the material of the separation layer is different from any material in a top surface of the substrate.
18. The method of claim 16 wherein the separation layer is conductive.
19. The method of claim 16 wherein the separation layer is a barrier layer.
20. The method of claim 16 wherein the separation layer is an adhesion layer.
21. The method of claim 13 wherein a part of the conductive layer in said hole comprises a through-silicon via.
22. The method of claim 13 wherein at least a part of the interconnect structure in at least one said hole is a damascene structure.