Masking techniques and contact imprint reticles for dense semiconductor fabrication
A reticle comprising isolated pillars is configured for use in imprint lithography. In some embodiments, on a first substrate a pattern of pillars pitch-multiplied in two dimensions is formed in an imprint reticle. The imprint reticle is brought in contact with a transfer layer overlying a series of mask layers, which in turn overlie a second substrate. The pattern in the reticle is transferred to the transfer layer, forming an imprinted pattern. The imprinted pattern is transferred to the second substrate to form densely-spaced holes in the substrate. In other embodiments, a reticle is patterned by e-beam lithography and spacer formations. The resultant pattern of closely-spaced pillars is used to form containers in an active integrated circuit substrate.
1. A method for forming an imprint reticle including an array of isolated features, comprising:
defining a pattern of features over a substrate;
forming spacers over sidewalls of the features to form an altered pattern of features, wherein forming
spacers comprises performing a first pitch multiplication process to define a first pattern of lines and further comprising performing a second pitch multiplication process to define a second pattern of lines crossing the first pattern of lines; and
transferring at least part of the altered pattern of features to the imprint reticle to define the array of isolated features.
2. The method of claim 1 , wherein the isolated features are pillars.
3. The method of claim 1 , wherein defining comprises using lithography to define an initial pattern of isolated features in a photodefinable layer over the substrate.
4. The method of claim 1 , wherein forming spacers further comprises consolidating the first and second patterns of lines into a single level to form a pattern of holes in the substrate.
5. The method of claim 4 , wherein transferring comprises forming a planar layer over the substrate.
6. The method of claim 5 , further comprising attaching a reticle plate to the planar layer.
7. The method of claim 6 , further comprising etching away the substrate.
8. The method of claim 1 , further comprising consolidating the first and second patterns of lines into a single level to form a pattern of pillars in the substrate.
9. The method of claim 1 , wherein the substrate comprises a quartz reticle plate.
10. The method of claim 9 , wherein the isolated features are quartz pillars.
11. The method of claim 1 , wherein the substrate comprises chrome over quartz.
12. The method of claim 11 , wherein the isolated features are chrome pillars.