Method for improved process latitude by elongated via integration
View Patent ↗Interconnect dual damascene structure are fabricated by depositing on a layer of at least one dielectric, a mask forming layer for providing the via-level mask layer of the dual damascene structures; creating an elongated via pattern in the via-level mask layer; depositing a layer of line-level dielectric and creating a line pattern through the layer of line-level dielectric, and transferring the line pattern through the projected intersection of the elongated via-level pattern and of the line-level pattern thereby generating an aligned dual damascene structure. A conductive liner layer is deposited in the dual damascene structure followed by filling the dual damascene structure with a conductive fill metal to form a set of metal lines. The metal and liner layers are planarized.
1. A method for fabricating an interconnect dual damascene structure which comprises:
a) providing a layer of at least one dielectric on a substrate surface;
b) depositing on the layer of the at least one dielectric, a mask forming layer for providing a via-level mask layer;
c) creating an elongated via pattern in the via-level mask layer; wherein said elongated via pattern is elongated in the orthogonal direction to a subsequently to be formed line level pattern;
d) depositing a layer of line-level dielectric;
e) creating a line pattern through the layer of line-level dielectric;
f) transferring the line pattern through the projected intersection of the elongated via-level pattern and of the line-level pattern to generate an aligned dual damascene structure, which is self aligned in said orthogonal direction;
g) depositing a conductive liner layer and then filling the dual damascene structure with a conductive fill metal to form a set of metal lines; and
h) planarizing the metal and liner layers so that the metal is coplanar with the top of layer of at least one dielectric on the substrate surface.
2. The method of claim 1 , wherein the mask-forming layers are hardmask materials.
3. The method of claim 1 , wherein the elongated via pattern is elongated by at least 10% of the line-to-line spacing.
4. The method of claim 1 , wherein the elongated via pattern is elongated by less than ½ the line-to-line spacing.
5. The method of claim 1 , wherein the elongated via pattern is elongated from about 10% to less than ½ the line-to-line spacing.
6. The method of claim 1 , wherein the conductive fill material comprises Cu or Ag alloy.
7. The method of claim 1 , wherein the planarizing comprises chemical-mechanical polishing.
8. The method of claim 1 , wherein the barrier material comprises tungsten.
9. An interconnect structure obtained by the process of claim 1 .