EP1423679A2 - Procede et dispositif destines a reduire l'absorption lumineuse, la diffusion de la lumiere et la contamination pour des longueurs d'onde inferieures a 200 nm - Google Patents

Procede et dispositif destines a reduire l'absorption lumineuse, la diffusion de la lumiere et la contamination pour des longueurs d'onde inferieures a 200 nm

Info

Publication number
EP1423679A2
EP1423679A2 EP02779421A EP02779421A EP1423679A2 EP 1423679 A2 EP1423679 A2 EP 1423679A2 EP 02779421 A EP02779421 A EP 02779421A EP 02779421 A EP02779421 A EP 02779421A EP 1423679 A2 EP1423679 A2 EP 1423679A2
Authority
EP
European Patent Office
Prior art keywords
gas
vacuum chamber
purge gas
vacuum
beam path
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02779421A
Other languages
German (de)
English (en)
Inventor
Angela Duparre
Stefan Gliech
Gunther Notni
Jörg STEINERT
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV
Original Assignee
Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV filed Critical Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV
Publication of EP1423679A2 publication Critical patent/EP1423679A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/15—Preventing contamination of the components of the optical system or obstruction of the light path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/21—Polarisation-affecting properties
    • G01N21/211—Ellipsometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/02—Mechanical
    • G01N2201/023—Controlling conditions in casing
    • G01N2201/0233—Gas purge

Definitions

  • the invention relates to a method and a device for avoiding the absorption of light of wavelengths less than 200 nm in optical beam paths with simultaneous suppression of light scattering and contamination in the beam path.
  • Areas of application are e.g. the measurement of scattered light, reflection and transmission and ellipsometry at 157 nm and 193 nm, as well as imaging systems, VUV microscopy and lithography systems at 157 nm.
  • a gas e.g. nitrogen or helium
  • nitrogen or helium which does not absorb at the wavelength of use
  • the absorption in air or other gases is reduced according to the pressure range used.
  • the residual pressure in the vacuum chamber can thus be below the boiling pressures of other compounds or molecules that had previously deposited on the surfaces of the vacuum chamber and are then increasingly in the gas phase in the vacuum system.
  • These compounds or molecules are therefore in a much higher concentration than at normal pressure in the vacuum chamber and, because of the low residual pressure, have a much larger free path. They are therefore deposited much more frequently on optical functional surfaces of the beam path and can thus lead to contamination, which can additionally be formed into deposits by irradiation with the wavelength of use.
  • the contamination and in particular the deposits can lead to increased absorption in the beam path and, due to stray light, to a deterioration in the imaging behavior or the beam shape.
  • the present invention is therefore based on the object of improving beam paths for wavelengths below 200 nm with reduced absorption in such a way that stray light is suppressed at the same time and contamination or deposits are avoided.
  • Claim 9 specifies a device according to the invention for solving the problem.
  • At least a partial vacuum is generated in at least one part of an optical beam path and, at the same time or subsequently, a predetermined amount or a predetermined flow of purge gas, such as. B. N 2 or He, the beam path.
  • a purge gas can be used to reduce the scattering of light, so that a lower light absorption at a given purge gas pressure. tion coefficient than would have water vapor and oxygen at the same partial pressure.
  • a flushing gas is to be used for the method according to the invention, which is present at the application wavelength, at the pressure present in the part of the beam path which is at least partially evacuated and brought to subatmospheric pressure with at least one flushing gas and over the path length of the at least partially evacuated and with at least one flushing gas part of the beam path brought under atmospheric pressure has a total absorption of at most 50%, preferably of 20%, preferably of 10% or even 5%.
  • the advantage of the method according to the invention lies in the fact that a lower absorption is brought about by means of vacuum, but the additional use of purging gas does not result in contamination on the surfaces of the vacuum system, the partial suction pressures of which are above the vacuum pressure as it would be without purging gas go into the gas phase.
  • the free path length of contaminating gas molecules is also reduced.
  • the purge gas only needs to be added in small amounts (that is, to such an extent that a subatmospheric pressure remains in the beam path treated in this way), so that the scattering on the purge gas is reduced.
  • the flushing gas inlet and vacuum connection should advantageously be located on the opposite ends or opposite sides of the beam path.
  • a flushing gas pressure is generated by a pumping process and a simultaneous addition of flushing gas, which pressure should be so low that the light scattering on the flushing gas molecules lengang not negatively affected.
  • the gas pressure is so low that the absorption in the gas atmosphere in the beam path does not exceed the above-mentioned limits.
  • the permanent supply of purge gas in connection with the simultaneous pumping advantageously results in a purge gas flow in the beam path, which significantly reduces the concentration of the compounds or molecules in the gas phase, which are the cause of contamination and deposits.
  • This procedure also allows the beam path treated in this way to be evacuated to total pressures below the boiling pressures of contaminants, since these are increasingly removed in the gas phase by the purge gas flow. As a result, the concentration of these compounds or molecules is kept at a low level in spite of the low pressure in the beam path, which results in a reduction in contamination and deposits.
  • the invention can be used in any type of beam paths with wavelengths less than 200 nm (in particular 157 nm and 193 nm).
  • FIG. 1 shows a schematic representation of an exemplary embodiment of an optical beam path for measuring scattered light which lies in two vacuum chambers and through which flushing gas flows.
  • An exemplary system in which this invention is used is a measuring system for determining the total scattered light at 157 nm and 193 nm
  • Fig. 1 shows the structure of the vacuum system of this measuring system schematically.
  • the vacuum system consists of a first vacuum chamber (1) and a second vacuum chamber (2). These vacuum chambers are connected by a gas-tight, lockable connecting element.
  • a light beam with a wavelength of 157 nm is first guided into the first vacuum chamber (1).
  • the first vacuum chamber (1) is used for beam preparation.
  • the light beam is adapted to the respective requirements with regard to energy density and diameter as well as beam shape.
  • the jet then enters the second vacuum chamber (2).
  • the second vacuum chamber (2) is used to measure stray light.
  • the signal detection takes place by means of a Coblentz ball arranged in the chamber (not shown). First of all, the absorption of light at these wavelengths must be avoided.
  • the interior of the two vacuum chambers (1, 2) is at least partially evacuated by means of a pump system (3, 4) of absorbing or scattering gases.
  • the pump system consists of a high vacuum pump (3) and a backing pump (4).
  • the high vacuum pump (3) is connected to the measuring chamber via a gas-tight, lockable connection to the vacuum system and evacuates at least some of the gases in the vacuum system via a gas-tight, lockable discharge line into a fore-vacuum pump (3).
  • the forevacuum pump (3) is connected to the measuring chamber via a further gas-tight, closable discharge line with the vacuum system.
  • the backing pump (3) is also connected to the jet processing chamber via a further gas-tight, closable discharge line.
  • both vacuum chambers are evacuated via the high vacuum pump.
  • the direct feed lines of the forevacuum pump to the vacuum chambers are closed, so that those of the forevacuum pump (3) only pumps gas from the high vacuum pump.
  • a defined small flow of nitrogen via the feed line (5) and / or the feed line (6) into the two chambers (1, 2) can be added simultaneous pumping with the pump system (3, 4) are added.
  • the pump system (3, 4)
  • This goal can be Vacuum pressure less than 10 2 Pa, at which the purge gas contributes more than a fifth to the vacuum pressure.
  • the pressure can be measured by the pressure controls or pressure gauges (8, 9) and the supply of purge gas can be regulated via the valves (10, 11).

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Particle Accelerators (AREA)

Abstract

La présente invention concerne un procédé destiné à réduire l'absorption lumineuse et/ou la diffusion de la lumière et/ou la contamination dues aux gaz pour de la lumière ayant une longueur d'onde d'utilisation inférieure à 200 nm sur des trajectoires de faisceau optiques. A cet effet, les gaz se trouvant sur la trajectoire du faisceau sont évacués au moins partiellement pour donner une pression inférieure à la pression atmosphérique, et un gaz de lavage est introduit simultanément ou ultérieurement dans la trajectoire du faisceau, la pression restant inférieure à la pression atmosphérique malgré cette introduction de gaz de lavage, et l'absorption totale sur la trajectoire de faisceau ainsi traitée valant au maximum 50 %.
EP02779421A 2001-09-25 2002-09-25 Procede et dispositif destines a reduire l'absorption lumineuse, la diffusion de la lumiere et la contamination pour des longueurs d'onde inferieures a 200 nm Withdrawn EP1423679A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10147089 2001-09-25
DE10147089 2001-09-25
PCT/EP2002/010763 WO2003029789A2 (fr) 2001-09-25 2002-09-25 Procede et dispositif destines a reduire l'absorption lumineuse, la diffusion de la lumiere et la contamination pour des longueurs d'onde inferieures a 200 nm

Publications (1)

Publication Number Publication Date
EP1423679A2 true EP1423679A2 (fr) 2004-06-02

Family

ID=7700132

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02779421A Withdrawn EP1423679A2 (fr) 2001-09-25 2002-09-25 Procede et dispositif destines a reduire l'absorption lumineuse, la diffusion de la lumiere et la contamination pour des longueurs d'onde inferieures a 200 nm

Country Status (2)

Country Link
EP (1) EP1423679A2 (fr)
WO (1) WO2003029789A2 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2886015B1 (fr) 2005-05-18 2007-07-13 Commissariat Energie Atomique Procede de mesure de la porosite par ellipsometrie et dispositif mettant en oeuvre un tel procede
DE102022102292A1 (de) 2022-02-01 2023-05-04 Asml Netherlands B.V. Verfahren zum betrieb einer vakuumkammer und vakuumkammer hierfür

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4114276C2 (de) * 1991-05-02 1996-09-19 Spectro Analytical Instr Gasgefülltes UV-Spektrometer
DE4237268A1 (en) * 1991-12-09 1993-06-17 Nanometrics Inc Improving optical measurement stability in UV appts. for determining material characteristics - flushing optically disturbing gas, e.g. ozone produced by oxidation, from optical path using inert gas

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO03029789A3 *

Also Published As

Publication number Publication date
WO2003029789A3 (fr) 2003-12-11
WO2003029789A2 (fr) 2003-04-10

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