Electrostatic chuck
First Claim
1. An electrostatic chuck for holding an electrically conductive workpiece in a low pressure reactor, the chuck, comprising:
- a thermally-conductive base plate;
a plurality of electrostatic structures disposed over the base plate, each electrostatic structure including;
a first dielectric,an electrically conductive electrode forming a first capacitor plate in contact with the first dielectric, anda second dielectric in contact with the electrode, anda dielectric separator between the first and the second dielectrics and surrounding the electrode, wherein the electrically conductive workpiece forms a second capacitor plate and can be held against the first dielectric of at least one of the electrostatic structures under application of an electrical potential across the first and second capacitor plates.
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Accused Products
Abstract
An electrostatic chuck is provided having a plurality of small electrostatic structures for holding an electrically conductive workpiece forming a plate of a capacitor. Each electrostatic structure includes a first thermally conductive single-crystal dielectric sheet, and a first electrode in sheet form sandwiched between the first dielectric sheet and a second dielectric surface. The workpiece, typically a conductive or semiconductive wafer, is juxtaposed to the first dielectric sheet of each electrostatic structure and forms a second electrode. The second dielectric sheet, if thick, is used as a thermally conducting base plate which can be attached to a low pressure reactor. If the second dielectric is a thin sheet, then it is mounted to a thermally conductive metal base plate through which heat can be controllably conducted. The resultant electrostatic structure may optionally be brazed to the metal base plate if the thermal expansion characteristics of the two elements are sufficiently matched. The first thermally conductive dielectric sheet is preferably formed of sapphire (Al2 O3), which is sufficiently thermally conductive to allow for rapid heat transfer between the base plate and the workpiece. The first electrodes of different electrostatic structures are held at different electrical potentials (typically of several thousand volts difference) and a charge is maintained by this potential difference between selected electrostatic structures.
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Citations
15 Claims
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1. An electrostatic chuck for holding an electrically conductive workpiece in a low pressure reactor, the chuck, comprising:
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a thermally-conductive base plate;
a plurality of electrostatic structures disposed over the base plate, each electrostatic structure including;a first dielectric, an electrically conductive electrode forming a first capacitor plate in contact with the first dielectric, and a second dielectric in contact with the electrode, and a dielectric separator between the first and the second dielectrics and surrounding the electrode, wherein the electrically conductive workpiece forms a second capacitor plate and can be held against the first dielectric of at least one of the electrostatic structures under application of an electrical potential across the first and second capacitor plates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15)
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14. An electrostatic chuck for holding an electrically conductive workpiece in a low pressure reactor, comprising:
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a dielectric base; a plurality of electrostatic structures disposed over the dielectric base, each electrostatic structure, including; a first dielectric, an electrically conductive electrode, forming a first capacitor plate, in contact with the first dielectric and bonded to the dielectric base, wherein the contacting surfaces of the first dielectric and the dielectric base are joined by growing additional dielectric material on the contacting surfaces by chemical vapor deposition, and an electrical connector for applying a different electrical potential to the electrode of at least one of the electrostatic structures, wherein the workpiece forms a second capacitor plate and is held against the first dielectric of each electrostatic structure under application of the different electrical potential.
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Specification