Fully self-aligned via
Apparatuses and methods to provide a fully self-aligned via are described. A first metallization layer comprises a set of first conductive lines extending along a first direction on a first insulating layer on a substrate, the set of first conductive lines recessed below a top portion of the first insulating layer. A capping layer is on the first insulating layer, and a second insulating layer is on the capping layer. A second metallization layer comprises a set of second conductive lines on the second insulating layer and on a third insulating layer above the first metallization layer. The set of second conductive lines extend along a second direction that crosses the first direction at an angle. At least one via is between the first metallization layer and the second metallization layer. The via is self-aligned along the second direction to one of the first conductive lines. The tapering angle of the via opening may be in a range of from about 60° to about 120°.
1. A method to provide a self-aligned via, the method comprising:
depositing first conductive lines in at least one trench formed in a capping layer and a first insulating layer on a substrate, the first conductive lines extending along a first direction on the first insulating layer;
recessing the first conductive lines to form recessed first conductive lines, a top surface of the recessed first conductive lines recessed below a top surface of the capping layer on the first insulating layer;
selectively growing a seed layer on the recessed first conductive lines;
forming pillars on the seed layer on the recessed first conductive lines;
depositing a second insulating layer between the pillars;
removing the pillars to form trenches in the second insulating layer;
depositing a third insulating layer through the trenches onto the recessed first conductive lines; and
etching the third insulating layer selectively relative to the second insulating layer to form a via opening down to one of the first conductive lines, wherein the via opening has a tapering angle in a range of from about 60° to about 120°.
2. The method of claim 1 , wherein the via opening is self-aligned along the first direction and a second direction to the one of the first conductive lines, the second direction crossing the first direction at an angle.
3. The method of claim 1 , further comprising forming a hard mask layer on at least one of the second insulating layer and the third insulating layer.
4. The method of claim 1 , further comprising depositing a conformal first liner on the capping layer and the first insulating layer.
5. The method of claim 4 , further comprising depositing a conformal second liner on the capping layer and the recessed first conductive lines and depositing a conformal third liner on the conformal second liner.
6. The method of claim 1 , further comprising depositing a conductive layer into the via opening.
7. The method of claim 1 , wherein the via opening has a trench portion and a via portion underneath the trench portion.
8. The method of claim 1 , further comprising: forming second conductive lines on portions of the second insulating layer and the third insulating layer, the second conductive lines extending along a second direction that crosses the first direction at an angle.
9. The method of claim 1 , wherein the pillars are removed by etching with a solution of HF and HNO 3 , a solution of NH 4 OH and H 2 O 2 , WCl 5 , WF 6 , niobium fluoride, chlorine with a hydrocarbon.