Substrate holder, lithographic apparatus, device manufacturing method, and method of manufacturing a substrate holder
A substrate holder for a lithographic apparatus has a planarization layer provided on a surface thereof. The planarization layer provides a smooth surface for the formation of a thin film stack forming an electronic component. The planarization layer is of substantially uniform thickness and/or its outer surface has a peak to valley distance of less than 10 μm. The planarization layer may be formed by applying two solutions of different concentration. A surface treatment may be applied to the burls to repel a solution of the planarization layer material.
1. A substrate holder for use in a lithographic apparatus, the substrate holder comprising:
a main body having a surface, the surface having a surface roughness;
a plurality of burls projecting from the surface and having end surfaces to support a substrate;
a planarization layer provided on at least part of the surface of the main body, the planarization layer at least partially filling in the surface roughness and having an outer surface having a peak to valley distance of less than about 10 μm; and
a thin film stack provided on the outer surface of the planarization layer and forming an electrical or electronic component.
2. The substrate holder according to claim 1 , wherein the burls have an outer surface that has been treated to repel a solvent or precursor of the planarization layer.
3. The substrate holder according to claim 2 , wherein the outer surface of the burls is treated by application of a repellent substance.
4. The substrate holder according to claim 3 , wherein the repellent substance is one or more selected from the group consisting of: polysilazane solution; octadecyltrichlorosilane; a methyl-terminated polymer; a siloxane; a silazane; a fluorinated material; a hydrophobic monolayer material; a silane, a flourinated silane and/or fluoro-octyl-trichloro-silane.
5. The substrate holder according to claim 1 , wherein the planarization layer comprises a first sub-layer formed on the main body and a second sub-layer formed on the first sub-layer that have been applied by applying first and second solutions of a solvate in a solvent respectively, the first solution having a first concentration of the solvate and the second solution having a second concentration of the solvate, the first and second concentrations being different.
6. The substrate holder according to claim 1 , wherein the planarization layer is formed of one or more materials selected from the group consisting of: benzocyclobutene; perhydropolysilazene, SiO 2 , parylene and/or polyimide.
7. The substrate holder according to claim 1 , wherein the electronic component is a component selected from the group consisting of: an electrode, a heater, a sensor a transistor and a logic device.
8. The substrate holder according to claim 7 , wherein electronic component is an electrode and the electrode is, in use, that of an electrostatic clamp.
9. A lithographic apparatus, comprising:
a projection system arranged to project a beam patterned by a patterning device onto a substrate; and
a substrate holder arranged to hold the substrate, the substrate holder comprising:
a main body having a surface, the surface having a surface roughness;
a plurality of burls projecting from the surface and having end surfaces to support a substrate;
a planarization layer provided on at least part of the surface of the main body, the planarization layer at least partially filling in the surface roughness and having an outer surface having a peak to valley distance of less than about 10 μm; and
a thin film stack provided on the outer surface of the planarization layer and forming an electrical or electronic component.
10. A device manufacturing method using a lithographic apparatus, the method comprising:
projecting a beam patterned by a patterning device onto a substrate while holding the substrate in a substrate holder,
wherein the substrate holder comprises;
a main body having a surface, the surface having a surface roughness;
a plurality of burls projecting from the surface and having end surfaces to support a substrate;
a planarization layer provided on at least part of the surface of the main body, the planarization layer at least partially filling in the surface roughness and having an outer surface having a peak to valley distance of less than about 10 μm; and
a thin film stack provided on the outer surface of the planarization layer and forming an electrical or electronic component.
11. A substrate holder for use in a lithographic apparatus, the substrate holder comprising:
a main body having a surface, the surface having a surface roughness;
a plurality of burls projecting from the surface and having end surfaces to support a substrate;
a planarization layer provided on at least part of the surface of the main body, the planarization layer at least partially filling in the surface roughness and having a substantially uniform thickness with an essentially flat outer surface; and
a thin film stack provided on the outer surface of the planarization layer and forming an electrical or electronic component.
12. The substrate holder according to claim 11 , wherein the planarization layer has an edge region surrounding burls and a medial region where the thin film stack is formed, the edge region having a thickness no greater than the medial region.
13. A method of manufacturing a substrate holder for use in a lithographic apparatus, the method comprising:
providing a main body having a surface and a plurality of burls projecting from the surface and having end surfaces to support a substrate, the surface of the main body having a surface roughness;
forming a planarization layer on at least part of the surface of the main body, the planarization layer at least partially filling in the surface roughness and the planarization layer having an outer surface having a peak to valley distance of less than about 10 μm; and
forming a thin film stack on the outer surface of the planarization layer, the thin film stack forming an electrical or electronic component.
14. The method according to claim 13 , further comprising selectively treating the surface of the burls to repel a solvent or a precursor of a material used to form the planarization layer before forming the planarization layer.
15. The method according to claim 14 , wherein treating the surface of the burls comprises applying a repellent substance to the burls.
16. The method according to claim 15 , wherein applying the repellent substance comprises:
forming a mask on the substrate holder, the mask exposing burls and shielding an other part of the substrate holder; and
applying the repellent material to the part of the substrate holder exposed by the mask.
17. The method according to claim 15 , wherein the repellent substance is one or more selected from the group consisting of: polysilazane solution; octadecyltrichlorosilane; a methyl-terminated polymer; a siloxane; a silazane; a fluorinated material; a hydrophobic monolayer material; a silane, a flourinated silane and/or fluoro-octyl-trichloro-silane.
18. The method according to claim 14 , wherein a part of the surface of the main body underlying the thin film stack is not treated to repel a solvent or precursor.
19. The method according to claim 13 , wherein forming the planarization layer comprises:
spraying a first solution of a solvate in a solvent onto the substrate holder;
curing the first solution to form a first sub-layer;
spraying a second solution of solvate in a solvent onto the first sub-layer; and
curing the second solution to form a second sub-layer,
wherein the first and second solutions have different concentrations of the solvate.
20. The method according to claim 13 , wherein the planarization layer is formed of one or more materials selected from the group consisting of: benzocyclobutene; perhydropolysilazene, SiO 2 , parylene and/or polyimide.