System for Contactless Cleaning, Lithographic Apparatus and Device Manufacturing Method
First Claim
1. A system for contactless removal of a particle from a surface of an object, comprising:
- a source of plasma constructed to generate He plasma in a vicinity of the surface; and
a control unit constructed to modify plasma parameters to cause an increased generation of He metastables in the He plasma without affecting the source of plasma.
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Accused Products
Abstract
Embodiments of the invention relate to a system for contactless cleaning of an object surface, a lithographic apparatus including the system, and a method of manufacturing a device. The system may include a He plasma source contained in a chamber and a control unit constructed to modify plasma parameters in use, such as the electron energy distribution of the plasma for causing an increase in formation of He metastables without modifying operational parameters of the plasma source. The control unit may include an electrical biasing unit constructed to apply a positive bias voltage to the object, for attracting free electrons from the plasma. The system may include a supplementary gas source, which may be either pre-mixed with He or be supplied from a further gas source. The supplementary gas may be selected based on a pre-knowledge on a type of particles to be expected on the surface of the object.
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Citations
14 Claims
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1. A system for contactless removal of a particle from a surface of an object, comprising:
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a source of plasma constructed to generate He plasma in a vicinity of the surface; and a control unit constructed to modify plasma parameters to cause an increased generation of He metastables in the He plasma without affecting the source of plasma. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A device manufacturing method, comprising:
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providing a beam of EUV radiation using optical elements; projecting the beam onto a target portion of a layer of radiation-sensitive material; and cleaning a surface of at least one optical element using He plasma, wherein a population of He metastables in the He plasma is increased without affecting a source of He plasma. - View Dependent Claims (14)
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Specification