Directional patterning methods
Directional patterning methods are disclosed herein. An exemplary method includes performing a lithography process to form a pattered hard mask layer over a wafer, wherein the patterned hard mask layer includes a hard mask feature having an associated horizontally-defined characteristic; tuning an etching process to direct etching species in a substantially horizontal direction relative to a horizontal surface of the wafer, such that the etching process horizontally removes portions of the patterned hard mask layer, thereby modifying the horizontally-defined characteristic of the hard mask feature; and forming an integrated circuit feature that corresponds with the hard mask feature having the modified horizontally-defined characteristic. Horizontally-defined characteristic can include a length, a width, a line edge roughness, a line width roughness, a line end profile, other horizontally-defined characteristics, or combinations thereof. In some implementations, the directional patterning method disclosed herein can achieve oblique interconnects and/or slot (rectangular) via interconnects.
1. A method comprising:
forming a patterned hard mask layer over a wafer, wherein the patterned hard mask layer includes a hard mask feature; and
performing a surface directional etching process to modify a horizontal profile of the hard mask feature, wherein:
the surface directional etching process directs etching species in a substantially horizontal direction relative to a horizontal surface of the wafer, and
the surface directional etching process does not etch in a vertical direction.
2. The method of claim 1 , further comprising forming an integrated circuit feature that corresponds with the hard mask feature.
3. The method of claim 1 , wherein the surface directional etching process directs the etching species towards a horizontal surface of the wafer at an angle θ that is less than about 10° relative to a horizontal plane that is substantially parallel to the horizontal surface.
4. The method of claim 1 , wherein the surface directional etching process further directs the etching species in an in-plane direction.
5. The method of claim 4 , wherein the hard mask feature is an opening, and further wherein the surface directional etching process is implemented with the in-plane direction along sidewalls of the opening to increase a horizontal dimension of the opening.
6. The method of claim 4 , wherein the hard mask feature is an opening and an end-to-end space is defined between the opening and an adjacent opening, wherein the surface directional etching process is implemented with the in-plane direction along sidewalls of the opening and sidewalls of the adjacent opening to decrease the end-to-end space.
7. The method of claim 4 , wherein the hard mask feature is a line having a line width roughness, and further wherein the surface directional etching process is implemented with the in-plane direction along edges of the line to reduce the line width roughness.
8. The method of claim 4 , wherein the hard mask feature is an opening having an end portion, and further wherein the surface directional etching process is implemented with the in-plane direction oblique to the end portion to reshape the end portion.
9. A method comprising:
forming a patterned hard mask layer over a wafer, wherein the patterned hard mask layer includes a hard mask feature; and
performing a surface directional etching process to modify a horizontal profile of the hard mask feature, wherein:
the surface directional etching process directs etching species in an in-plane direction and a substantially horizontal direction relative to a horizontal surface of the wafer,
the hard mask feature is an opening, and
the surface directional etching process is implemented with the in-plane direction oblique to portions of the opening, thereby transforming the opening into an oblique opening.
10. A method comprising:
forming a patterned hard mask layer over a wafer, wherein the patterned hard mask layer includes a hard mask feature; and
performing a surface directional etching process to modify a horizontal profile of the hard mask feature, wherein:
the surface directional etching process directs etching species in in an in-plane direction and a substantially horizontal direction relative to a horizontal surface of the wafer,
the hard mask feature is a circular-shaped via opening used to define a square-shaped via, and
the surface directional etching process is implemented with the in-plane direction along sidewalls of the circular-shaped via opening, thereby transforming the circular-shaped opening into an oval-shaped opening used to define a slot-shaped via.
11. A method comprising:
performing a lithography process to form a patterned hard mask layer over a wafer, wherein the patterned hard mask layer includes a hard mask feature having an associated horizontally-defined characteristic;
tuning an etching process to direct etching species in a substantially horizontal direction relative to a horizontal surface of the wafer, such that the etching process horizontally removes portions of the patterned hard mask layer, thereby modifying the horizontally-defined characteristic of the hard mask feature; and
forming an integrated circuit (IC) feature that corresponds with the hard mask feature having the modified horizontally-defined characteristic, wherein the horizontally-defined characteristic is a minimum characteristic achievable by the lithography process, and the modified horizontally-defined characteristic is smaller than the minimum characteristic achievable by the lithography process.
12. The method of claim 11 , wherein the horizontally-defined characteristic is a line width roughness associated with the hard mask feature, an end-to-end spacing associated with the hard mask feature, or a line end profile associated with the hard mask feature.
13. The method of claim 11 , wherein modifying the horizontally-defined characteristic of the hard mask feature includes forming an oblique opening.
14. The method of claim 11 , wherein modifying the horizontally-defined characteristic of the hard mask feature includes increasing a length or a width of the hard mask feature.
15. A method comprising:
forming a patterned material layer over a substrate, wherein an opening is defined in the patterned material layer;
forming a hard mask layer over the patterned material layer;
performing a surface directional implantation process on the hard mask layer, wherein the hard mask layer includes an implanted portion and a non-implanted portion;
removing the non-implanted portion of the hard mask layer; and
performing an etching process to modify a horizontal profile of the opening, wherein the implanted portion of the hard mask layer protects a portion of the patterned material layer that defines the opening during the etching process.
16. The method of claim 15 , wherein surface directional implantation process implants doping species along sidewalls of the opening extending in a single direction.
17. The method of claim 15 , wherein the performing the surface directional implantation process includes modifying an etching characteristic of the hard mask layer, such that the implanted portion has a different etching resistance than the non-implanted portion.
18. The method of claim 15 , wherein the etching process is a surface directional etching process that directs etching species in a substantially horizontal direction relative to a horizontal surface of the substrate.
19. The method of claim 15 , wherein the implanted portion of the hard mask layer forms a sidewall mask along a sidewall of the opening.
20. The method of claim 1 , wherein the surface directional etching process selectively etches the patterned hard mask layer relative to the wafer.