Substrate holder and a method of manufacturing a device
A substrate holder, a method of manufacturing of the substrate holder and a lithographic apparatus having the substrate holder. In one arrangement, a substrate holder is for use in a lithographic apparatus. The substrate holder is configured to support a lower surface of a substrate. The substrate holder has a main body, a plurality of burls and a coating. The main body has a substrate-facing face. The plurality of burls protrudes from the substrate-facing face. Each burl has a distal end configured to engage with the substrate. The distal ends are configured for supporting the substrate. The coating is on the substrate-facing face between the burls. Between the burls the substrate-facing face has an arrangement of areas. Adjacent areas are separated by a step-change in distance below the support plane. Each step-change is greater than a thickness of the coating.
1. A substrate holder for a lithographic apparatus, the substrate holder configured to support a lower surface of a substrate, the substrate holder comprising:
a main body having a substrate-facing face when the main body supports the substrate;
a plurality of burls protruding from the substrate-facing face, each burl having a distal end configured to engage with the substrate, the distal ends substantially conforming to a support plane and configured to support the substrate; and
a coating on the substrate-facing face between the burls,
wherein between the burls the substrate-facing face comprises an arrangement of areas,
wherein adjacent areas are separated by a step-change in distance below the support plane,
wherein each step-change is greater than a thickness of the coating, and wherein a first area of the adjacent areas nearer to the support plane does not overlap a layer of the coating on a second area of the adjacent areas further from the support plane than the first area.
2. The substrate holder of claim 1 , wherein adjacent areas are connected by one or more side walls, and any coating on the one or more side walls is insufficient to transfer stress between adjacent areas.
3. The substrate holder of claim 1 , wherein each area has a lateral dimension greater than the step-changes that separate that area from adjacent areas.
4. The substrate holder of claim 1 , wherein adjacent areas are connected by one or more side walls that extend substantially perpendicularly to the support plane.
5. The substrate holder of claim 1 , wherein each area is arranged to be at one of only two different distances below the support plane.
6. The substrate holder of claim 1 , wherein the arrangement of areas is a grid.
7. A lithographic apparatus comprising:
a support structure configured to support a patterning device;
a projection system arranged to project a beam patterned by the patterning device onto a substrate; and
the substrate holder according to claim 1 arranged to hold the substrate.
8. The substrate holder of claim 1 , wherein the coating has a residual stress.
9. The substrate holder of claim 1 , wherein the coating is discontinuous between adjacent areas.
10. The substrate holder of claim 1 , wherein each step-change is at least 1 μm.
11. The substrate holder of claim 1 , wherein the areas have a lateral dimension less than that of the burls.
12. The substrate holder of claim 1 , wherein each step-change is less than a minimum distance between the substrate-facing face of the main body and the support plane.
13. A substrate holder for a lithographic apparatus, the substrate holder configured to support a lower surface of a substrate, the substrate holder comprising:
a main body having a substrate-facing face when the main body supports the substrate;
a plurality of burls protruding from the substrate-facing face, each burl having a distal end configured to engage with the substrate, the distal ends substantially conforming to a support plane and configured to support the substrate; and a coating on the substrate-facing face between the burls, wherein between the burls the substrate-facing face comprises an arrangement of areas,
wherein adjacent areas are separated by a step-change in distance below the support plane,
wherein adjacent areas are connected by one or more side walls,
wherein a first area of the adjacent areas nearer to the support plane does not overlap a layer of the coating on a second area of the adjacent areas further from the support plane than the first area, and
wherein any coating on the one or more side walls is insufficient to transfer stress between adjacent areas.
14. The substrate holder of claim 13 , wherein the coating has a residual stress.
15. The substrate holder of claim 13 , wherein the coating is discontinuous between adjacent areas.
16. The substrate holder of claim 13 , wherein each step-change is at least 1 μm.
17. The substrate holder of claim 13 , wherein the areas have a lateral dimension less than that of the burls.
18. The substrate holder of claim 13 , wherein each step-change is less than a minimum distance between the substrate-facing face of the main body and the support plane.
19. 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 on a substrate holder, wherein the substrate holder comprises: a main body having a substrate-facing face;
a plurality of burls protruding from the substrate-facing face of the main body, each burl having a distal end engaging with the substrate, the distal ends substantially conforming to a support plane and supporting the substrate; and a coating on the substrate-facing face between the burls, wherein between the burls the substrate-facing face of the main body comprises an arrangement of areas,
wherein adjacent areas are separated by a step-change in distance below the support plane,
wherein each step-change is greater than a thickness of the coating, and
wherein a first area of the adjacent areas nearer to the support plane does not overlap a layer of the coating on a second area of the adjacent areas further from the support plane than the first area.
20. 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 on a substrate holder, wherein the substrate holder comprises: a main body having a substrate-facing face;
a plurality of burls protruding from the substrate-facing face of the main body, each burl having a distal end engaging with the substrate, the distal ends substantially conforming to a support plane and supporting the substrate; and a coating on the substrate-facing face between the burls, wherein between the burls the substrate-facing face of the main body comprises an arrangement of areas,
wherein adjacent areas are separated by a step-change in distance below the support plane,
wherein adjacent areas are connected by one or more side walls, wherein a first area of the adjacent areas nearer to the support plane does not overlap a layer of the coating on a second area of the adjacent areas further from the support plane than the first area, and wherein any coating on the one or more side walls is insufficient to transfer stress between adjacent areas.