Electron migration control in interconnect structures
A method for improving reliability of interconnect structures for semiconductor devices is disclosed. The method includes forming a contact structure on a transistor and forming a metallization layer on the contact structure. The forming the metallization layer includes depositing an inter-metal dielectric (IMD) layer on the transistor, forming an opening within the IMD layer to expose a top surface of the contact structure, depositing a metallic layer to fill the opening, forming an electron barrier layer within the IMD layer, and forming a capping layer within the metallic layer. The electron barrier layer has a hole carrier concentration higher than a hole carrier concentration of a portion of the IMD layer underlying the electron barrier layer. The capping layer has a hole carrier concentration higher than a hole carrier concentration of a portion of the metallic layer underlying the capping layer.
1. An interconnect structure, comprising:
a conductive nitride layer disposed on a substrate;
a first barrier layer disposed on the conductive nitride layer;
a dielectric layer disposed on the first barrier layer;
a second barrier layer disposed on the dielectric layer and comprising a nitride of a material of the dielectric layer; and
a conductive structure disposed in the first barrier layer, the dielectric layer, and the second barrier layer, wherein the conductive structure comprises:
a conductive layer;
a conductive capping layer disposed on the conductive layer; and
a conductive liner disposed on sidewalls of the conductive layer and the conductive capping layer.
2. The interconnect structure of claim 1 , wherein the conductive capping layer comprises a nitride of a material of the conductive layer.
3. The interconnect structure of claim 1 , wherein the conductive capping layer comprises copper nitride.
4. The interconnect structure of claim 1 , wherein the first barrier layer comprises a nitride layer and an oxide layer disposed on the nitride layer.
5. The interconnect structure of claim 1 , further comprising an etch stop layer disposed between the first barrier layer and the dielectric layer, wherein an atomic density of a material of the first barrier layer is greater than an atomic density of a material of the etch stop layer.
6. The interconnect structure of claim 1 , further comprising a liner-free conductive structure disposed between the conductive nitride layer and the substrate.
7. The interconnect structure of claim 1 , wherein the second barrier layer comprises an oxynitride layer.
8. The interconnect structure of claim 1 , wherein the conductive structure further comprises a metal line and a metal via;
wherein the metal line is disposed in the dielectric layer and the second barrier layer; and
wherein the metal via is disposed in the dielectric layer and the first barrier layer.
9. The interconnect structure of claim 1 , wherein a thickness of the conductive capping layer is less than a thickness of the second barrier layer.
10. The interconnect structure of claim 1 , wherein top surfaces of the conductive capping layer and the second barrier layer are substantially coplanar with each other.
11. An interconnect structure, comprising:
an oxide layer;
a nitride layer disposed on the oxide layer;
a stack of diffusion barrier layers disposed on the nitride layer;
a stack of etch stop layers disposed on the stack of diffusion barrier layers; and
a liner-free conductive structure disposed in the oxide layer and the nitride layer.
12. The interconnect structure of claim 11 , wherein the stack of diffusion barrier layers comprises a metal nitride layer and a metal oxide layer disposed on the metal nitride layer.
13. The interconnect structure of claim 11 , wherein atomic densities of materials of the stack of diffusion barrier layers are greater than atomic densities of materials of the stack of etch stop layers.
14. The interconnect structure of claim 11 , wherein top surfaces of the nitride layer and the liner-free conductive structure are substantially coplanar with each other.
15. The interconnect structure of claim 11 , wherein the liner-free conductive structure comprises a metal layer and a capping layer disposed on the metal layer.
16. The interconnect structure of claim 15 , wherein the capping layer comprises a nitride of the metal layer.
17. A method, comprising:
depositing a dielectric layer on a substrate;
depositing a conductive layer in the dielectric layer;
converting a portion of the dielectric layer into a first nitride layer;
converting a portion of the conductive layer into a second nitride layer; and
forming a diffusion barrier layer on the first and second nitride layers.
18. The method of claim 17 , wherein converting the portion of the dielectric layer comprises performing a nitridation process on the dielectric layer.
19. The method of claim 17 , wherein converting the portion of the conductive layer comprises performing a nitridation process on the conductive layer.
20. The method of claim 17 , wherein forming the diffusion barrier layer comprises:
depositing a metal nitride layer on the first and second nitride layers; and
performing an oxidation process on the metal nitride layer.