Interconnect structure having an etch stop layer over conductive lines
A multilayer interconnect structure for integrated circuits includes a first dielectric layer over a substrate and a conductive line partially exposed over the first dielectric layer. The structure further includes an etch stop layer over both the first dielectric layer and the exposed conductive line, and a second dielectric layer over the etch stop layer. The second dielectric layer and the etch stop layer provide a via hole that partially exposes the conductive line. The structure further includes a via disposed in the via hole, and another conductive line disposed over the via and coupled to the conductive line through the via. Methods of forming the multilayer interconnect structure are also disclosed. The etch stop layer reduces the lateral and vertical etching of the first and second dielectric layers when the via hole is misaligned due to overlay errors.
1. A device comprising:
a conductive feature disposed at least partially in a first oxide dielectric layer;
an etch stop layer disposed on and physically contacting the first oxide dielectric layer and disposed on and physically contacting the conductive feature, wherein a top surface of a first portion of the etch stop layer adjacent the conductive feature is at a greater height than a top surface of a second portion of the etch stop layer disposed away from the conductive feature, wherein the etch stop layer includes a vertical portion extending from the first portion to the second portion of the etch stop layer;
a second dielectric layer disposed on and physically contacting the etch stop layer; and
a via extending through the second dielectric layer and the etch stop layer and coupled to the conductive feature, wherein:
the etch stop layer includes a portion disposed along a sidewall of the conductive feature;
the via includes a bottom surface that extends from the sidewall of the conductive feature to a side surface of the via; and
an entirety of the bottom surface physically contacts the vertical portion of the etch stop layer.
2. The device of claim 1 , wherein the conductive feature includes an upper portion that is disposed above the first oxide dielectric layer and a lower portion that is disposed within the first oxide dielectric layer, wherein the first oxide layer has a top surface and an opposing bottom surface and wherein the conductive feature extends from the top surface of the first oxide layer towards the bottom surface of the first oxide layer without the conductive feature extending to the bottom surface of the first oxide layer.
3. The device of claim 1 , wherein the conductive feature has a top surface facing away from the first oxide dielectric layer, and
wherein the via and the etch stop layer both physically contact the top surface of the conductive feature.
4. The device of claim 1 , further comprising another conductive feature disposed at least partially in the first oxide dielectric layer, the another conductive feature having a top surface facing away from the first oxide dielectric layer, and
wherein the etch stop layer covers the entire top surface of the another conductive feature.
5. The device of claim 1 , wherein the first oxide dielectric layer is formed of a different material than the second dielectric layer.
6. The device of claim 1 , wherein the etch stop layer physically contacts the conductive feature, the first oxide dielectric layer and the second dielectric layer.
7. The device of claim 1 , wherein the conductive feature is a conductive line that is part of an interconnect structure.
8. A method comprising:
forming a conductive feature over a substrate;
forming an etch stop layer on the conductive feature;
forming a first dielectric layer over the etch stop layer;
forming a track trench within the first dielectric layer over the conductive feature;
forming a material within the track trench;
forming a via hole that extends through the material within the track trench to expose the conductive feature; and
forming a via in the via hole.
9. The method of claim 8 , wherein forming the material within the track trench includes forming a multi-layer material layer on the first dielectric layer and within the track trench, the multi-layer material layer includes a resist layer.
10. The method of claim 9 , wherein forming the via hole that extends through the material within the track trench further includes forming the via hole through the resist layer.
11. The method of claim 8 , further comprising removing the material from the track trench after forming the via hole.
12. The method of claim 8 , wherein the forming of the via hole that extends through the material within the track trench to expose the conductive feature includes the via hole exposing a side surface of the conductive feature.
13. The method of claim 8 , further comprising forming a second dielectric layer over the substrate, wherein the conductive feature is at least partially disposed within the second dielectric layer.
14. The method of claim 8 , further comprising removing the material from the track trench after forming the via hole, and
wherein forming the via ( 112 A) in the via hole includes forming a conductive material in the via hole and the track trench during the same forming process.
15. A method comprising:
forming a conductive line over a substrate;
forming an etch stop layer on the conductive line;
forming a first dielectric layer over the etch stop layer;
forming a first trench within the first dielectric layer, the first trench being directly over the conductive line without the first trench exposing the conductive line;
forming a material layer within the first trench;
removing a first portion of the material layer and a portion of the first dielectric layer to form a second trench that extends through a second portion of the material layer, wherein the second trench exposes the conductive line;
removing the second portion of the material layer; and
forming a conductive material in the first and second trenches.
16. The method of claim 15 , wherein the first trench is wider than the second trench.
17. The method of claim 15 , wherein after removing the second portion of the material layer there is no material layer remaining within the first trench.
18. The method of claim 15 , wherein the removing of the first portion of the material layer and the portion of the first dielectric layer to form the second trench that extends through the second portion of the material layer includes removing the first dielectric from a side edge of the first conductive line such that the side edge of the conductive line is exposed within the second trench.
19. The method of claim 15 , wherein forming the material layer within the first trench includes forming the material layer directly on a top surface of the first dielectric layer that faces away from the substrate.
20. The method of claim 19 , wherein the removing of the second portion of the material layer includes removing the material layer from the top surface of the first dielectric layer such that the top surface of the first dielectric layer is exposed.