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, wherein the predetermined pattern corresponds with a diffraction efficiency output map;
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 a structure, 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.
2. The method of claim 1 , wherein an RLT in a region between the first portion and the second portion varies gradually from the first RLT to the second RLT.
3. The method of claim 1 , wherein a change in RLT from the first RLT to the second RLT is a step change in a region between the first portion and the second portion.
4. The method of claim 1 , wherein dispensing the imprint fluid comprises dispensing the imprint fluid in a pattern of drops, wherein a volume of drops dispensed across the surface of the substrate varies according to the predetermined pattern.
5. The method of claim 4 , wherein the pattern of drops corresponds to a fixed drop density in a predetermined region.
6. The method of claim 4 , wherein the pattern of drops corresponds to a varying drop density in a predefined region.
7. The method of claim 1 , wherein dispensing the imprint fluid comprises dispensing the imprint fluid with a jetting dispense system.
8. The method of claim 1 , further comprising etching the patterned layer and the substrate, wherein a depth of features etched into the substrate varies according to variation in the RLT.
9. The method of claim 1 , wherein the features in the imprint lithography template have a uniform feature depth.
10. The method of claim 9 , wherein the imprint lithography template is a master template, the substrate is a first substrate, the imprint fluid is a first imprint fluid, the residual layer is a first residual layer, and further comprising:
etching the first substrate to yield a sub-master lithography template;
dispensing, on a surface of a second substrate, a second imprint fluid a volume of which is substantially uniform across the surface of the second substrate; and
contacting the second imprint fluid with a surface of the sub-master lithography template such that the second imprint fluid fills features in the surface of the sub-master lithography template; and
solidifying the second imprint fluid into a second patterned layer, thereby forming, in the second imprint fluid, structures and a second residual layer having a RLT that varies in accordance with variations in a dimension of features etched into the sub-master lithography template.
11. The method of claim 1 , wherein the features in the imprint lithography template have a varying feature depth.
12. The method of claim 1 , wherein the structures are nano-structures.
13. The method of claim 1 , wherein the structures are micro-structures.
14. The method of claim 1 , wherein a difference between the first RLT and the second RLT is between 5 nm and 500 nm.
15. 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, wherein the predetermined pattern corresponds with a diffraction efficiency output map;
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 a structure, wherein the RLT varies across the surface of the substrate according to the volume per unit area of the imprint fluid.
16. The method of claim 15 , 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.
17. 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 a structure, wherein the RLT varies across the surface of the substrate according to a predefined pattern, and variations in the RLT correspond with a diffraction efficiency mapping of a different diffraction grating having a uniform RLT.
18. The device of claim 17 , wherein the polymer imprint resist is a Ultra Violet light curable Nano-Imprint Lithography (UV-NIL) resist.
19. A method of fabricating a variable depth pattern, the method comprising:
dispensing, on a surface of a first substrate, a first imprint fluid according to a predetermined pattern;
contacting the first imprint fluid with a surface of an imprint lithography template such that the first imprint fluid fills features in the surface of the imprint lithography template, wherein the imprint lithography template is a master template and features in the surface of the imprint lithography template have a uniform feature depth;
solidifying the first imprint fluid into a first patterned layer, thereby forming, in the first patterned layer:
structures that correspond to the features of the imprint lithography template, and
a first residual layer having a residual layer thickness (RLT) that extends from the surface of the first substrate to a base of a structure, wherein a first RLT of a first portion of the first patterned layer is different from a second RLT of a second portion of the first patterned layer,
etching the first substrate to yield a sub-master lithography template;
dispensing, on a surface of a second substrate, a second imprint fluid a volume of which is substantially uniform across the surface of the second substrate;
contacting the second imprint fluid with a surface of the sub-master lithography template such that the second imprint fluid fills features in the surface of the sub-master lithography template;
solidifying the second imprint fluid into a second patterned layer, thereby forming, in the second imprint fluid, structures and a second residual layer having a RLT that varies in accordance with variations in a dimension of features etched into the sub-master lithography template.