Dual damascene dual alignment interconnect scheme

1. A method of forming a metal interconnect structure comprising:

forming a first line trench extending through a first dielectric material layer on a substrate;

forming a stack, from bottom to top, of a first metal line and a dielectric cap material portion within said first line trench, said dielectric cap material portion having a top surface coplanar with a top surface of said first dielectric material layer;

forming a second dielectric material layer over said first dielectric material layer and said stack;

forming a second line trench extending through said second dielectric material layer;

forming a via cavity extending to a top surface of said first metal line underneath said second line trench by removing a portion of said dielectric cap material portion, wherein said via cavity is laterally surrounded by said first dielectric material layer; and

forming a dual damascene line and via structure including a second metal line located within said second line trench and a via structure located within said via cavity.

2. The method of claim 1 , wherein said forming of said dual damascene line and via structure comprises:

depositing at least one conductive material within said second line trench and said via cavity; and

recessing said at least one conductive material below a top surface of said second dielectric material layer to form said dual damascene line and via structure.

3. The method of claim 1 , wherein said dual damascene line and via structure is formed as an integral structure without a physically manifested interface between said second metal line and said via structure.

4. The method of claim 1 , wherein said forming of said first line trench further comprises:

applying and patterning a photoresist layer over said first dielectric material layer; and

transferring a pattern in said patterned photoresist layer to a bottommost surface of said first dielectric material layer.

5. The method of claim 1 , wherein said forming of said stack comprises:

depositing a conductive material within said first line trench;

recessing a top surface of said conductive material to a height lower than said top surface of said first dielectric material layer to form said first metal line; and

depositing and planarizing a dielectric material different from a dielectric material of said first dielectric material layer within said first line trench and above said first metal line to foam said first dielectric cap material portion.

6. The method of claim 1 , wherein said first dielectric material layer comprises an organosilicate glass (OSG), and said first dielectric cap material portion comprises a material selected from silicon oxide, nitrogen-doped organosilicate glass, and silicon nitride.

7. The method of claim 1 , wherein said forming of said via cavity comprises:

applying a photoresist layer over said second dielectric material layer and within said second line trench; and

lithographically patterning said photoresist layer with a via pattern including at least one via hole, wherein said removed portion of said dielectric cap material portion is etched employing said first dielectric material layer and said second dielectric material layer as etch mask layers.

8. The method of claim 7 , wherein said removed portion of said dielectric cap material portion has a horizontal cross-sectional area of a composite pattern that is an intersection of said via pattern, a pattern of said second line trench, and a pattern of said dielectric cap material portion.

9. The method of claim 1 , further comprising:

forming an etch stop layer over said first dielectric material layer and said dielectric cap material portion;

applying, and patterning with a via pattern including at least one via hole, a photoresist layer over said second dielectric material layer and within said second line trench;

transferring a pattern that is an intersection of said via pattern and a pattern of said second line trench into said etch stop layer.

10. A method of forming a semiconductor structure comprising:

forming a first dielectric material layer on a substrate;

forming a stack, from bottom to top, of a first metal line and a dielectric cap material portion within said first dielectric material layer, wherein said stack has a first width in a first direction perpendicular to a lengthwise direction of said stack, and said dielectric cap material portion has a top surface coplanar with a top surface of said first dielectric material layer;

forming a second dielectric material layer over said first dielectric material layer and said stack; and

forming a dual damascene line and via structure including a second metal line and a via structure, wherein said second metal line is embedded within said second dielectric material layer and said via structure is embedded within said first dielectric material layer, wherein said dual damascene line and via structure has a second width in a second direction perpendicular to a lengthwise direction of said dual damascene line and via structure, and said via structure has said first width in said first direction, a bottom surface of said via structure in direct contact with a portion of a top surface of said first metal line.

11. The method of claim 10 , wherein said forming of said dual damascene line and via structure comprises:

depositing at least one conductive material within a second line trench located in said second dielectric material and a via cavity located in said first dielectric material; and

recessing said at least one conductive material below a top surface of said second dielectric material layer to form said dual damascene line and via structure.

12. The method of claim 11 , wherein said forming of said first line trench comprises:

applying and patterning a photoresist layer over said first dielectric material layer; and

transferring a pattern in said patterned photoresist layer to a bottommost surface of said first dielectric material layer.

13. The method of claim 12 , wherein said forming of said stack comprises:

depositing a conductive material within said first line trench located in said first dielectric material layer;

recessing a top surface of said conductive material to a height lower than said top surface of said first dielectric material layer to form said first metal line; and

depositing and planarizing a dielectric material different from a dielectric material of said first dielectric material layer within said first line trench and above said first metal line to form said first dielectric cap material portion.

14. The method of claim 11 , wherein said via cavity is formed by:

applying a photoresist layer over said second dielectric material layer and within said second line trench; and

lithographically patterning said photoresist layer with a via pattern including at least one via hole, wherein said removed portion of said dielectric cap material portion is etched employing said first dielectric material layer and said second dielectric material layer as etch mask layers.

15. The method of claim 10 , wherein said dual damascene line and via structure is formed as an integral structure without a physically manifested interface between said second metal line and said via structure.

16. The method of claim 10 , wherein said first dielectric material layer comprises an organosilicate glass (OSG), and said first dielectric cap material portion comprises a material selected from silicon oxide, nitrogen-doped organosilicate glass, and silicon nitride.