Radiation source, metrology apparatus, lithographic system and device manufacturing method

Patent metadata

Field	Value
Publication number	US-10420197-B2
Application number	US-201815888362-A
Country	US
Kind code	B2
Filing date	Feb 5, 2018
Priority date	Dec 13, 2013
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

A radiation source apparatus comprising: a container for being pressurized with a gaseous medium in which plasma which emits plasma emitted radiation is generated following excitation of the gaseous medium by a driving radiation, wherein said container is operable substantially to remove radiation with a wavelength of 10-400 nm from said plasma emitted radiation before said plasma emitted radiation exits said container as output radiation. In an embodiment the container comprises: an inlet radiation transmitting element operable to transmit said driving radiation from outside said container to inside said container, and an outlet radiation transmitting element operable to transmit at least some of said plasma emitted radiation from inside said container to outside said container as output radiation; wherein at least one of said inlet and outlet radiation transmitting elements comprises a plane parallel plate.

First claim

The invention claimed is:

1. A radiation source comprising:
a container arranged to be pressurized with a gaseous medium in which plasma which emits plasma emitted radiation is generated following excitation of the gaseous medium by a driving radiation, said container comprising:
an inlet radiation transmitting element operable to transmit said driving radiation from outside said container to inside said container, and
an outlet radiation transmitting element operable to transmit at least some of said plasma emitted radiation from inside said container to outside said container as output radiation;

wherein the center of the plasma is between three to six times as far from said outlet radiation transmitting element and/or said inlet radiation transmitting element as from the nearest wall of the container, and
wherein said container has a non-spherical, elongated shape and an axis of symmetry along which the output radiation is transmitted, and the inlet radiation transmitting element and the outlet radiation transmitting element are perpendicular to the axis of symmetry.

2. The radiation source of claim 1 , wherein the container defines:
an inlet volume through which said driving radiation passes,
an outlet volume through which plasma emitted radiation passes, and
a plasma surrounding volume surrounding said plasma,
wherein an average cross sectional area of the inlet volume and/or outlet volume in a plane perpendicular to an optical axis of the radiation source is greater than an average cross-sectional area of the plasma surrounding volume in a plane perpendicular to the optical axis of the radiation source.

3. The radiation source of claim 1 , wherein said container is operable substantially to remove radiation with a wavelength of 10-400 nm from said plasma emitted radiation before said plasma emitted radiation exits said container as output radiation.

4. The radiation source of claim 1 , wherein both said inlet and outlet radiation transmitting elements comprise a plain parallel plate.

5. The radiation source of claim 1 , wherein said container has side walls that comprise a material more able to withstand plasma emitted radiation than the input and output radiation transmitting elements.

6. The radiation source of claim 1 , wherein said container has side walls that comprise a material more able to withstand plasma emitted radiation than the input and output radiation transmitting elements.

Assignees

• Asml Netherlands Bv

Inventors

• Van Heumen Martijn Petrus Christianus

Classifications

• H01J61/35

  provided with coatings on the walls thereof; Selection of materials for the coatings (using coloured coatings H01J61/40; using luminescent coatings H01J61/42) · CPC title

• G01N21/956

  Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} · CPC title

• H01J65/04 Primary

  Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating {plasma display panels} · CPC title

• H01J61/545

  using an auxiliary electrode inside the vessel (H01J61/542 takes precedence) · CPC title

• G03F7/70191

  Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like · CPC title