Methods for forming a metal line in a semiconductor manufacturing process
View Patent ↗In a disclosed method for manufacturing a semiconductor device, a lower insulating layer, a lower metal line and an upper insulating layer are sequentially stacked. A first photosensitive film is patterned on the upper insulating layer and the upper insulating layer is subsequently etched. The photosensitive film is removed. An etched portion of the upper insulating layer is then filled with a nitride film. The upper insulating layer is then removed. A second photosensitive film is then patterned and the lower metal line is subsequently etched. An IMD layer is deposited over the resultant construct, thereby forming an air gap within the IMD layer. The IMD layer is planarized. The nitride film is then etched away to thereby form a hole in the IMD layer. The hole is filled with a conductive material to form a contact plug. An upper metal line is deposited over the resultant construct.
1. A method for forming a metal line, comprising:
stacking a lower insulating layer, a lower metal layer and an upper insulating layer;
patterning a first photosensitive film on the upper insulating layer;
using the patterned first photosensitive film as a mask, etching the upper insulating layer until at least a portion of the lower metal layer is exposed;
filling an etched portion of the upper insulating layer with a nitride film;
patterning a second photosensitive film over the lower metal layer and the nitride film;
using the second photosensitive film as a mask, etching the lower metal layer until the lower insulating layer is exposed to form a lower metal line pattern;
depositing an IMD (Inter Metal Dielectric) layer on the lower metal line pattern, including the sidewalls of the lower metal line pattern, the lower insulating layer, and the nitride film, thereby forming an air gap within the IMD layer between lines in the lower metal line pattern;
planarizing the IMD layer to expose the nitride film;
removing the nitride film, thereby forming a contact hole in the IMD layer exposing an upper surface of the lower metal line pattern;
filling the contact hole with a conductive material;
depositing an upper metal line over the conductive material.
2. A method as defined in claim 1 , wherein depositing the upper metal line comprises an Al/Cu damascene process.
3. A method as defined in claim 1 , further comprising removing the first photosensitive film after etching the upper insulating layer.
4. A method as defined in claim 3 , further comprising removing the upper insulating layer after filling the etched portion of the upper insulating layer with the nitride film and before patterning a second photosensitive film.
5. A method as defined in claim 4 , further comprising removing the second photosensitive film before depositing the IMD.
6. A method as defined in claim 1 , further comprising, after depositing the IMD and before removing the nitride film, planarizing the IMD layer sufficiently to expose the nitride film.
7. A method as defined in claim 1 , wherein the nitride film is removed by wet etching.