Methods for forming arrays of small, closely spaced features
Methods of forming arrays of small, densely spaced holes or pillars for use in integrated circuits are disclosed. Various pattern transfer and etching steps can be used, in combination with pitch-reduction techniques, to create densely-packed features. Conventional photolithography steps can be used in combination with pitch-reduction techniques to form superimposed patterns of crossing elongate features with pillars at the intersections. Spacers are simultaneously applied to sidewalls of both sets of crossing lines to produce a pitch-doubled grid pattern. The pillars facilitate rows of spacers bridging columns of spacers.
1. A multi-level manufacture for forming fine-featured devices, the manufacture comprising:
a waffle-shaped grid having:
crossing lines having sidewalls, the lines on a lower level;
openings defined at the lower level between the lines where the lines do not intersect, the openings defined on four sides by the facing sidewalls of two sets of crossing lines; and
pillars at intersections of the lines, the pillars extending vertically on an upper level above the lower level; and
coatings on the sidewalls surrounding the openings at the lower level of the waffle-shaped grid and on the sidewalls of the pillars at the upper level of the waffle-shaped grid,
wherein the coating on the sidewalls surrounding each opening at the lower level forms a continuous lower band of coating material in each opening, and
wherein the coating on the sidewalls of each pillar at the upper level forms a continuous upper band of coating material around each pillar.
2. The manufacture of claim 1 , wherein the lower bands are linked across crossing lines by the upper bands to form a continuous multi-level coating complex.
3. The manufacture of claim 1 , wherein the crossing sets of lines are substantially perpendicular to one another.
4. The manufacture of claim 1 , wherein the pillars have four sidewalls that are generally aligned in the same vertically-extending planes as the sidewalls of the lines at the lower level.
5. The manufacture of claim 1 , wherein the crossing lines and the pillars are formed of the same material.
6. The manufacture of claim 5 , wherein the crossing lines and the pillars are formed of amorphous carbon.
7. The manufacture of claim 5 , wherein the coatings are formed of a material selectively etchable relative to the crossing lines and the pillars.
8. The manufacture of claim 5 , wherein the coatings are formed of silicon.
9. The manufacture of claim 8 , wherein the coatings are formed of silicon oxide.
10. The manufacture of claim 1 , wherein a temporary layer is disposed between the waffle-shaped grid and an underlying substrate.
11. The manufacture of claim 10 , wherein a temporary layer comprises a dielectric anti-reflective coating.
12. The manufacture of claim 1 , wherein the coatings have a thickness of about 60 nm or less.
13. The manufacture of claim 12 , wherein the thickness is about 20-50 nm or less.
14. The manufacture of claim 1 , wherein a step coverage of the coating is about 80% or greater.
15. The manufacture of claim 14 , wherein the step coverage is about 90% or greater.
16. The manufacture of claim 1 , wherein the fine-featured devices are memory chips.
17. The manufacture of claim 16 , wherein the memory chips are non-volatile memory devices.
18. The manufacture of claim 17 , wherein the non-volatile memory devices are flash memory devices.