Microlithographic fabrication of structures
Micro- and nano-patterns in imprint layers formed on a substrate and lithographic methods for forming such layers. The layers include a plurality of structures, and a residual layer having a residual layer thickness (RLT) that extends from the surface of the substrate to a base of the structures, where the RLT varies across the surface of the substrate according to a predefined pattern.
1. A method of fabricating a variable depth pattern, the method comprising:
dispensing, on a surface of a substrate, an imprint fluid according to a predetermined pattern;
contacting the imprint fluid with a surface of an imprint lithography template such that the imprint fluid fills features in the surface of the imprint lithography template; and
solidifying the imprint fluid into a patterned layer, thereby forming, in the patterned layer:
structures that correspond to the features of the imprint lithography template, and
a residual layer having a residual layer thickness (RLT) that extends from the surface of the substrate to a base of one of the structures, wherein a first RLT of a first portion of the patterned layer is different from a second RLT of a second portion of the patterned layer, wherein an RLT in a region between the first portion and the second portion varies gradually from the first RLT to the second RLT; and
etching the patterned layer and the substrate, wherein a depth of features etched into the substrate varies according to variation in the RLT, wherein the imprint lithography template is a master template and, after etching, the substrate is a sub-master lithography template.
2. The method of claim 1 , wherein dispensing the imprint fluid comprises dispensing the imprint fluid in a pattern of drops, wherein a volume of the drops varies according to the predetermined pattern.
3. The method of claim 2 , wherein the pattern of drops corresponds to a fixed drop density in a predetermined region.
4. The method of claim 2 , wherein the pattern of drops corresponds to a varying drop density in a predefined region.
5. The method of claim 1 , wherein dispensing the imprint fluid comprises dispensing the imprint fluid with a jetting dispense system.
6. The method of claim 1 , wherein the features in the imprint lithography template have a uniform feature depth.
7. The method of claim 1 , further comprising:
dispensing, on a surface of a second substrate, a second imprint fluid, a volume of which is substantially uniform across the surface of the substrate; and
contacting the second imprint fluid with a surface of the sub-master lithography template such that the imprint fluid fills features in the surface of the sub-master lithography template, thereby forming, in the second imprint fluid, structures and a residual layer having a RLT that varies in accordance with variations in a dimension of features etched into the sub-master lithography template.
8. The method of claim 1 , wherein the features in the imprint lithography template have a varying feature depth.
9. The method of claim 1 , wherein the predetermined pattern corresponds to a diffraction efficiency output map.
10. The method of claim 1 , wherein the structures are nano-structures.
11. The method of claim 1 , wherein the structures are micro-structures.
12. The method of claim 1 , wherein a difference between the first RLT and the second RLT is between 5 nm and 500 nm.
13. A method of patterning an imprint fluid, the method comprising:
dispensing, on a surface of a substrate, the imprint fluid, a volume of which varies across the surface of the substrate according to a predetermined pattern;
contacting the imprint fluid with a surface of an imprint lithography template such that the imprint fluid fills features in the surface of the imprint lithography template, thereby forming, in the imprint fluid, structures and a residual layer having a residual layer thickness (RLT) that extends from the surface of the substrate to a base of one of the structures, wherein the RLT varies across the surface of the substrate according to the volume per unit area of the imprint fluid, wherein a first RLT of a first portion of the patterned layer is different from a second RLT of a second portion of the patterned layer, wherein an RLT in a region between the first portion and the second portion varies gradually from the first RLT to the second RLT;
solidifying the imprint fluid into a patterned layer; and
etching the patterned layer and the substrate, wherein a depth of features etched into the substrate varies according to variation in the RLT, wherein the imprint lithography template is a master template and, after etching, the substrate is a sub-master lithography template.
14. The method of claim 13 , wherein dispensing the imprint fluid comprises dispensing the imprint fluid in a predefined pattern that corresponds to a volume needed to fill the features in the imprint lithography template.
15. An optical device comprising:
a substrate; and
a polymer imprint resist on a surface of the substrate, the polymer imprint resist comprising:
a plurality of structures forming a diffraction pattern; and
a residual layer having a residual layer thickness (RLT) that extends from the surface of the substrate to a base of one of the plurality of structures, wherein the RLT varies across the surface of the substrate according to a predefined pattern, wherein a depth of each structure of the plurality of structures varies according to
variation in the RLT, wherein variations in the RLT correspond to a diffraction efficiency mapping of a different diffraction grating having a uniform RLT.
16. The device of claim 15 , wherein the polymer imprint resist is an Ultra Violet light curable Nano-Imprint Lithography (UV-NIL) resist.