Forming cross-coupled line segments
A method is provided for fabricating cross-coupled line segments for use, for instance, as a hard mask in fabricating cross-coupled gates of two or more transistors. Fabricating the structure includes: providing a sacrificial mandrel on the substrate, the sacrificial mandrel including a transverse gap through the mandrel separating the sacrificial mandrel into a first mandrel portion and a second mandrel portion; providing a sidewall spacer along sidewalls of the sacrificial mandrel, where sidewall spacers along sidewalls of the first mandrel portion and the second mandrel portion merge within the transverse gap and form a crossbar; and removing the sacrificial mandrel and selectively cutting the sidewall spacers to define the cross-coupled line segments from the sidewall spacers and crossbar. The transverse gap may be provided by directly printing the first and second mandrel portions spaced apart, or by cutting the sacrificial mandrel to provide the gap.
1. A method comprising:
fabricating a structure comprising cross-coupled line segments on a substrate, the fabricating comprising:
providing a sacrificial mandrel on the substrate, the sacrificial mandrel comprising a transverse gap therethrough separating the sacrificial mandrel into a first mandrel portion and a second mandrel portion;
providing a sidewall spacer along sidewalls of the sacrificial mandrel, wherein sidewall spacers along sidewalls of the first mandrel portion and the second mandrel portion merge within the transverse gap and form a crossbar;
removing the sacrificial mandrel and selectively cutting the sidewall spacers to define the cross-coupled line segments from the sidewall spacers and the crossbar;
wherein providing the sacrificial mandrel comprises lithographically forming a plurality of parallel-extending, elongate sacrificial mandrels on the substrate, the sacrificial mandrel being one elongate sacrificial mandrel of the plurality of parallel-extending, elongate sacrificial mandrels; and
wherein providing the one elongate sacrificial mandrel comprises directly lithographically printing the first mandrel portion and the second mandrel portion on with the substrate, with adjacent ends thereof spaced apart to define the transverse gap through the sacrificial mandrel.
2. The method of claim 1 , wherein providing the sacrificial mandrel comprises directly forming the first mandrel portion and the second mandrel portion on the substrate with adjacent ends thereof spaced apart to define the transverse gap through the sacrificial mandrel.
3. The method of claim 2 , wherein the transverse gap comprises a width which is approximately twice a thickness of the sidewall spacer, or less.
4. The method of claim 1 , wherein providing the sacrificial mandrel comprises forming the sacrificial mandrel on the substrate and cutting the sacrificial mandrel to provide the transverse gap therethrough.
5. The method of claim 4 , wherein the transverse gap comprises a width which is approximately twice a thickness of the sidewall spacer, or less.
6. The method of claim 1 , wherein the transverse gap comprises a width which is approximately twice a thickness of the sidewall spacer.
7. The method of claim 1 , wherein providing the sacrificial mandrel comprises lithographically forming the sacrificial mandrel on the substrate, the substrate comprising a semiconductor wafer.
8. The method of claim 7 , wherein the sidewall spacer is a hard mask and the fabricating further comprises patterning at least a portion of the substrate using the cross-coupled line segments.
9. The method of claim 8 , wherein the sidewall spacer comprises a nitride or an oxide.
10. The method of claim 8 , wherein the substrate comprises polysilicon and the fabricating comprises patterning the polysilicon using, at least in part, the cross-coupled line segments.
11. The method of claim 1 , wherein the transverse gap comprises a width which is approximately twice a thickness of the sidewall spacer, or less.
12. A method comprising:
fabricating a structure comprising cross-coupled line segments on a substrate, the fabricating comprising:
providing a sacrificial mandrel on the substrate, the sacrificial mandrel comprising a transverse gap therethrough separating the sacrificial mandrel into a first mandrel portion and a second mandrel portion;
providing a sidewall spacer along sidewalls of the sacrificial mandrel, wherein sidewall spacers along sidewalls of the first mandrel portion and the second mandrel portion merge within the transverse gap and form a crossbar;
removing the sacrificial mandrel and selectively cutting the sidewall spacers to define the cross-coupled line segments from the sidewall spacers and the crossbar;
wherein providing the sacrificial mandrel comprises lithographically forming a plurality of parallel-extending, elongate sacrificial mandrels on the substrate, the sacrificial mandrel being one elongate sacrificial mandrel of the plurality of parallel-extending, elongate sacrificial mandrels; and
wherein providing the one elongate sacrificial mandrel comprises lithographically forming the one elongate sacrificial mandrel on the substrate, and subsequently cutting the one elongate sacrificial mandrel to provide the transverse gap therethrough.
13. The method of claim 12 , wherein the transverse gap comprises a width which is approximately twice a thickness of the sidewall spacer, or less.
14. A method comprising:
fabricating a structure comprising cross-coupled line segments on a substrate, the fabricating comprising:
providing a sacrificial mandrel on the substrate, the sacrificial mandrel comprising a transverse gap therethrough separating the sacrificial mandrel into a first mandrel portion and a second mandrel portion;
providing a sidewall spacer along sidewalls of the sacrificial mandrel, wherein sidewall spacers along sidewalls of the first mandrel portion and the second mandrel portion merge within the transverse gap and form a crossbar;
removing the sacrificial mandrel and selectively cutting the sidewall spacers to define the cross-coupled line segments from the sidewall spacers and the crossbar;
wherein the selectively cutting comprises forming a first cut through the sidewall spacer provided along the first mandrel portion and a second cut through the sidewall spacer provided along the second mandrel portion, the first cut and the second cut being on opposite sides of the sacrificial mandrel.
15. The method of claim 14 , further comprising using the cross-coupled line segments as a mask in forming cross-coupled gates of a plurality of transistors.
16. The method of claim 15 , wherein the fabricating further comprises forming an electrical contact to the cross-coupled gates at a location offset from a location of the crossbar.
17. The method of claim 15 , wherein the fabricating further comprises forming a single electrical contact to the cross-coupled gates at a location, the location being offset from a location of the crossbar.
18. The method of claim 15 , wherein the fabricating further comprises forming a plurality of transistors, and wherein the cross-coupled line segments facilitate forming cross-coupled gates of the plurality of transistors.