Method for forming a three-dimensional structure of metal-insulator-metal type
A method for forming a capacitive structure in a metal level of an interconnection stack including a succession of metal levels and of via levels, including the steps of: forming, in the metal level, at least one conductive track in which a trench is defined; conformally forming an insulating layer on the structure; forming, in the trench, a conductive material; and planarizing the structure.
1. A method for forming a capacitive structure in a metal level of an interconnection stack comprising a succession of metal levels and of via levels, comprising the steps of:
(a) forming, in said metal level, at least one conductive track in which a trench is defined;
(b) conformally forming an insulating layer on the metal level;
(c) depositing, in the trench, a conductive material; and
(d) planarizing the structure;
wherein step (a) comprises forming a conductive track in the metal level and then performing a reactive ion etching of the conductive track to form a through trench.
2. The method of claim 1 , wherein step (b) is preceded by a step of forming a conformal conductive layer.
3. The method of claim 1 , wherein the forming of the conductive track comprises an intermediary step of forming of a conductive layer forming a barrier in the conductive track, the etching of the conductive track being selective over said conductive barrier-forming layer.
4. The method of claim 1 , wherein step (a) comprises forming portions of conductive tracks surrounding an insulating region and then selectively etching the insulating region.
5. The method of claim 1 , further comprising, after step (d), a step of forming of a layer forming a barrier against the diffusion of the material of the conductive track.
6. The method of claim 1 , wherein the trench has, in top view, a comb shape.
7. The method of claim 1 , further comprising, after step (b), a step of forming of a conformal conductive layer.
8. The method of claim 1 , further comprising, after step (d), a step of forming of a via level on the metal level in which a conductive via is provided in front of the conductive material.