Single-mask alternating line deposition
Integrated chips and methods of forming lines in the same include forming first lines on a underlying substrate. Conformal dielectric spacers are formed on sidewalls of the first lines. Second lines are formed on the underlying substrate, in open areas between the dielectric spacers.
1. A method of forming lines in an integrated chip, comprising:
depositing an etch stop layer on an underlying substrate;
depositing a dielectric layer on the etch stop layer;
forming trenches in the dielectric layer with an etch that stops on the etch stop layer;
etching away portions of the etch stop layer exposed by the trenches to expose portions of a top surface of the underlying substrate;
forming first lines on the underlying substrate;
forming conformal dielectric spacers on sidewalls of the first lines; and
forming second lines on the underlying substrate, in open areas between the dielectric spacers.
2. The method of forming lines in an integrated chip according to claim 1 , wherein forming the conformal dielectric spacers comprises conformally depositing a layer of dielectric material on the first lines and removing the dielectric material from horizontal surfaces above and between the first lines.
3. The method of forming lines in an integrated chip according to claim 2 , wherein removing the dielectric material from horizontal surfaces above and between the first lines comprises performing an anisotropic etch that is blocked in part by a top portion of the conformal dielectric spacers, such that the conformal dielectric spacers each include a foot of dielectric material that extends laterally from a bottom portion of the respective conformal dielectric spacer, into a space between the first lines.
4. The method of forming lines in an integrated chip according to claim 1 , wherein forming the first lines comprises:
depositing first line material in the trenches; and
polishing away any first line material above the dielectric layer using a chemical mechanical planarization process that stops on the dielectric layer and that removes any connecting first line material from between the trenches.
5. The method of forming lines in an integrated chip according to claim 4 , further comprising:
isotropically etching away the dielectric layer from between the first lines, before forming the conformal dielectric spacers, to create a space between the first lines; and
anisotropically etching away portions of the etch stop layer that are not protected by the conformal dielectric spacers, leaving etch stop remnants between the conformal dielectric spacers and the underlying substrate, to extend the space between the first lines down to the underlying substrate.
6. The method of forming lines in an integrated chip according to claim 1 , wherein forming the trenches in the dielectric layer is performed with an anisotropic etch that leaves sloped sidewalls, such that the trenches in the dielectric layer taper at the bottom, from a relatively large width at the top to a relatively small width at the bottom.
7. The method of forming lines in an integrated chip according to claim 6 , wherein the first lines taper at the bottom and the second lines taper at the top.
8. The method of forming lines in an integrated chip according to claim 1 , wherein the first lines are formed from a first conductive material, and wherein the second lines are formed from a second conductive material having a conductive composition is distinct from the first conductive material.
9. A method of forming lines in an integrated chip according to forming lines in an integrated chip, comprising:
depositing an etch stop layer on an underlying substrate, the etch stop layer having gaps that expose a top surface of the underlying substrate;
forming first lines on the exposed surface of the underlying substrate in the gaps of the etch stop layer;
conformally depositing a layer of dielectric material on exposed surfaces of the first lines;
anisotropically etching dielectric material, from the layer of dielectric material, that is on horizontal surfaces above and between the first lines, wherein the anisotropic etch is blocked in part by a top portion of the conformal dielectric spacers, such that the conformal dielectric spacers each include a foot of dielectric material that extends laterally from a bottom portion of the respective conformal dielectric spacer, into a space between the first lines; and
forming second lines on the underlying substrate, in openings left between the dielectric spacers.
10. The method of forming lines in an integrated chip according to claim 9 , further comprising anisotropically etching away portions of the etch stop layer that are not protected by the conformal dielectric spacers, leaving etch stop remnants between the conformal dielectric spacers and the underlying substrate, underneath the foot of dielectric material, such that the etch stop remnants extend at least as far laterally as each respective foot of dielectric material.
11. The method of forming lines in an integrated chip according to claim 9 , wherein the first lines taper at the bottom and the second lines taper at the top.
12. The method of forming lines in an integrated chip according to claim 9 , wherein the first lines are formed from a first conductive material, and wherein the second lines are formed from a second conductive material that is distinct from the first conductive material.
13. A method of forming lines in an integrated chip, comprising:
depositing an etch stop layer on an underlying substrate;
depositing a dielectric layer on the etch stop layer, from a material that is selectively etchable with respect to the etch stop layer;
forming trenches in the dielectric layer with a selective anisotropic etch that stops on the etch stop layer;
etching away portions of the etch stop layer exposed by the trenches, using a selective anisotropic etch, to expose portions of a top surface of the underlying substrate;
forming first lines on the underlying substrate, after forming the dielectric layer;
forming conformal dielectric spacers on sidewalls of the first lines; and
forming second lines on the underlying substrate, in open areas between the dielectric spacers.
14. The method of forming lines in an integrated chip according to claim 13 , wherein forming the first lines comprises:
depositing first line material in the trenches; and
polishing away any first line material above the dielectric layer using a chemical mechanical planarization process that stops on the dielectric layer and that removes any connecting first line material from between the trenches.
15. The method of forming lines in an integrated chip according to claim 14 , further comprising:
isotropically etching away the dielectric layer from between the first lines, before forming the conformal dielectric spacers, to create a space between the first lines; and
anisotropically etching away portions of the etch stop layer that are not protected by the conformal dielectric spacers, leaving etch stop remnants between the conformal dielectric spacers and the underlying substrate, to extend the space between the first lines down to the underlying substrate.
16. The method of forming lines in an integrated chip according to claim 13 , wherein forming the trenches in the dielectric layer is performed with an anisotropic etch that leaves sloped sidewalls, such that the trenches in the dielectric layer taper at the bottom, from a relatively large width at the top to a relatively small width at the bottom.
17. The method of forming lines in an integrated chip according to claim 16 , wherein the first lines taper at the bottom and the second lines taper at the top.
18. The method of forming lines in an integrated chip according to claim 13 , wherein forming the conformal dielectric spacers comprises conformally depositing a layer of dielectric material on the first lines and removing the dielectric material from horizontal surfaces above and between the first lines.