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 method of manufacturing a substrate holder, the method comprising:
providing a main body of the substrate holder, the main body having a surface with a roughness and having a plurality of burls projecting from the surface, the burls having end surfaces to support a substrate;
selectively treating a surface of the burls to repel a material used to form a planarization layer;
after the selective treatment, applying the material on at least part of the main body surface to form the planarization layer, the planarization layer at least partially filling in the surface roughness; and
providing a thin film stack on the planarization layer, the thin film stack forming an electric or electronic component.
2. The method according to claim 1 , wherein the treating the surface of the burls comprises treating the surface of the burls to repel a solvent or a precursor of the material used to form the planarization layer.
3. The method according to claim 1 , wherein the treating the surface of the burls comprises applying a repellent substance to the burls.
4. The method according to claim 3 , wherein the applying the repellent substance comprises:
forming a mask on the substrate holder, the mask exposing burls and shielding another part of the substrate holder; and
applying the repellent substance to the part of the substrate holder exposed by the mask.
5. The method according to claim 3 , wherein the repellent substance comprises one or more materials 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.
6. The method according to claim 1 , wherein a part of the surface of the main body underlying the thin film stack is not treated to repel the material.
7. The method according to claim 1 , wherein the applying the material 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.
8. The method according to claim 1 , wherein the material comprises one or more materials selected from the group consisting of: benzocyclobutene; perhydropolysilazene, SiO 2 ; parylene and/or polyimide.
9. The method according to claim 1 , wherein the planarization layer has an outer surface having a peak to valley distance of less than about 10 μm.
10. The method according to claim 1 , wherein the component is a component selected from the group consisting of: an electrode, a heater, a sensor, a transistor and a logic device.
11. The method according to claim 10 , wherein the component is an electrode and the electrode is, in use, that of an electrostatic clamp.
12. The method according to claim 1 , wherein the planarization layer has an edge region surrounding burls and a medial region where the thin film stack is provided, the edge region having a thickness no greater than the medial region.
13. A method of manufacturing a substrate holder; the method comprising:
providing a main body of the substrate holder, the main body having a surface with a roughness and having a plurality of burls projecting from the surface, the burls having end surfaces to support a substrate;
applying a substance onto the main body and a surface of the burls, the substance being repellent to a material used to form a planarization layer;
selectively removing a portion of the substance from between adjacent burls to leave the substance on at least part of the adjacent burls;
after the selective removal, applying the material on at least part of the portion to form the planarization layer, the planarization layer at least partially filling in the surface roughness at the at least part of the portion; and
providing a thin film stack on the planarization layer, the thin film stack forming an electric or electronic component.
14. The method according to claim 13 , wherein the substance is repellent to a solvent or a precursor of the material used to form the planarization layer.
15. The method according to claim 13 , wherein the substance comprises one or more materials 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.
16. A substrate holder system comprising:
a main body of a substrate holder, the main body having a surface with 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, the plurality of burls being repellent to a material used to form the planarization layer; and
a thin film stack provided on the outer surface of the planarization layer and forming an electrical or electronic component.
17. The substrate holder system of claim 16 , wherein an outer surface of the planarization layer has a peak to valley distance of less than about 10 μm.
18. The substrate holder system of claim 16 , wherein the planarization layer has a substantially uniform thickness with an essentially flat outer surface.
19. The substrate holder system of claim 16 , wherein the burls have a coating of repellent substance and the substance comprises one or more materials 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.
20. The substrate holder system of claim 16 , comprising a lithographic apparatus, the lithographic apparatus comprising a projection system arranged to project a beam patterned by a patterning device onto a substrate held by the substrate holder.