Lithographic apparatus and device manufacturing method
A substrate support is provided for a lithographic apparatus. The support comprises a substrate table constructed to hold a substrate and a chuck for the substrate table. In operation, the substrate table is supported by the chuck and clamped thereto. The substrate support comprises a first set of burls on a surface of the support block for abutting against the substrate table during the clamping and a second set of burls on a surface of the substrate table for abutting against the support block during the clamping.
1. A substrate support for a lithographic apparatus comprising:
a substrate table constructed to hold a substrate;
a support block for the substrate table; wherein in operation the substrate table is supported by the support block and clamped thereto;
an array of elongated elements on a surface of the support block for abutting against the substrate table during the clamping; and
a set of burls are provided on a surface of the substrate table for abutting against the support block during the clamping,
wherein the substrate table comprises an electrostatic clamp and the clamping of the substrate table to the support block is performed electrostatically, and
wherein a top surface of the support block comprises a metal conducting layer between elongate elements, such that the electrostatic gap is defined by the sum of the height of the set of burls, measured from the surface from which the burls extend, and the height of a first glass layer between the clamping electrode and the set of burls.
2. The substrate support as claimed in claim 1 wherein an electrode of the electrostatic clamp comprises a single continuous conducting layer.
3. The substrate support of claim 1 wherein the array of elongate elements are 10 or more times taller than the set of burls, when measured from the surface from which they extend.
4. The substrate support of claim 1 wherein the array of elongate elements are 100 or more times taller than the set of burls.
5. The substrate support of claim 1 wherein the array of elongate elements are each over 0.5 mm tall, so as to minimize slip between the substrate table and support block during lateral acceleration of the substrate support.
6. The substrate support claim 1 wherein the set of burls are each under 100 μm tall.
7. The substrate support of claim 1 wherein the support block comprises a mirror block.
8. The substrate support of claim 1 wherein the set of burls are configured to minimize the contact area between substrate table and support block during clamping.
9. The substrate support of claim 1 wherein the array of elongate elements comprises a machined surface of the support block.
10. A lithographic apparatus comprising:
an illumination system configured to condition a radiation beam;
a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; and
a projection system configured to project the patterned radiation beam onto a target portion of the substrate, and a substrate support, wherein the substrate support comprises:
a substrate table constructed to hold a substrate;
a support block for the substrate table; wherein in operation the substrate table is supported by the support block and clamped thereto;
an array of elongated elements on a surface of the support block for abutting against the substrate table during the clamping; and
a set of burls are provided on a surface of the substrate table for abutting against the support block during the clamping,
wherein the substrate table comprises an electrostatic clamp and the clamping of the substrate table to the support block is performed electrostatically, and
wherein a top surface of the support block comprises a metal conducting layer between elongate elements, such that the electrostatic gap is defined by the sum of the height of the set of burls, measured from the surface from which the burls extend, and the height of a first glass layer between the clamping electrode and the set of burls.
11. The lithographic apparatus as claimed in claim 10 , wherein an electrode of the electrostatic clamp comprises a single continuous conducting layer.
12. The lithographic apparatus of claim 10 , wherein the array of elongate elements are 10 or more times taller than the set of burls, when measured from the surface from which they extend.
13. The lithographic apparatus of claim 10 , wherein the array of elongate elements are 100 or more times taller than the set of burls.
14. The lithographic apparatus of claim 10 , wherein the array of elongate elements are each over 0.5 mm tall, so as to minimize slip between the substrate table and support block during lateral acceleration of the substrate support.
15. The lithographic apparatus claim 10 , wherein the set of burls are each under 100 μm tall.
16. The lithographic apparatus of claim 10 , wherein the support block comprises a mirror block.
17. The lithographic apparatus of claim 10 , wherein the set of burls are configured to minimize the contact area between substrate table and support block during clamping.
18. The lithographic apparatus of claim 10 , wherein the array of elongated elements comprises a machined surface of the support block.