PATENT COOPERATION TREATY
`
`PCT
`
`INTERNATIONAL SEARCH REPORT
`
`(PCT Article 18 and Rules 43 and 44)
`
`Applicant's or agent's file reference
`2020P00230WO
`
`FOR FURTHER
`ACTION
`
`see Form PCT/ISA/220
`as well as, where applicable, item 5 below.
`
`International application No.
`
`Internationalfiling date (day/month/year)
`
`(Earliest) Priority Date (day/month/year)
`
`PCT/EP2021/078531
`
`14 October 2021 (14-10-2021)
`
`10 November 2020 (10-11-2020)
`
`Applicant
`
`ASML NETHERLANDS B.V.
`
`This international search report has been prepared by this International Searching Authority and is transmitted to the applicant
`according to Article 18. A copy is being transmitted to the International Bureau.
`
`sheets.
`3
`This international search report consists of a total of
`It is also accompanied by a copy of each prior art documentcited in this report.
`
`1. Basis of the report
`a. With regard to the language,the international search was carried out on the basis of:
`the international application in the languagein which it wasfiled
`, which is the language
`a translation of the international application into
`of a translation furnished for the purposesof international search (Rules 12.3(a) and 23.1(b))
`
`noneof the figures is to be published with the abstract
`
`LC]
`
`This international search report has been established taking into account the rectification of an obvious mistake
`authorized by or notified to this Authority under Rule 91 (Rule 43.66/s(a)).
`
`With regard to any nucleotide and/or amino acid sequence disclosed in the international application, see Box No. I.
`
`Certain claims were found unsearchable (See Box No. Il)
`
`[]
`
`Unity of invention is lacking (see Box NoIll)
`
`4. With regard to the title,
`
`the text is approved as submitted by the applicant
`] the text has been established by this Authority to read as follows:
`
`5. With regard to the abstract,
`the text is approved as submitted by the applicant
`the text has been established, according to Rule 38.2, by this Authority as it appears in Box No.IV. The applicant
`may, within one month from the date of mailing of this international search report, submit comments to this Authority
`
`L_}
`
`6. With regard to the drawings,
`a.
`the figure of the drawings to be published with the abstract is Figure No.
`[] as suggested by the applicant
`as selected by this Authority, because the applicant failed to suggest a figure
`as selected by this Authority, because this figure better characterizes the invention
`
`[]
`
`b. []
`
`Form PCT/ISA/210 (first sheet) (January 2015)
`
`

`

` INTERNATIONAL SEARCH REPORT
` International application No
`
`PCT/EP2021/078531
`
`A. CLASSIFICATION OF SUBJECT MATTER
`INV. GO3F7/20
`G02B7/18
`ADD.
`
`According to International Patent Classification (IPC) or to both national classification and IPC
`B. FIELDS SEARCHED
`Minimum documentation searched (classification system followed by classification symbols)
`GO3F G02B
`
`Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched
`
`
`Electronic data base consulted during the international search (name of data base and, where practicable, search terms used)
`
`EPO-Internal, WPI Data,
`
`INSPEC
`
`
`Cc. DOCUMENTS CONSIDERED TO BE RELEVANT
`
`Relevant to claim No.
`Category*|Citation of document, with indication, where appropriate, of the relevant passages
`
`(ASML NETHERLANDS BV
`WO 2017/153152 Al
`[NL]) 14 September 2017 (2017-09-14)
`cited in the application
`paragraphs [0025],
`[0034],
`
`[0035]
`
`(ASML NETHERLANDS BV
`DE 10 2013 111801 Al
`[NL]; ZEISS CARL SMT GMBH [DE])
`13 March 2014 (2014-03-13)
`paragraphs [0029]
`—-—
`[0040]
`
`(NIKON CORP [JP])
`EP 1 376 185 A2
`2 January 2004 (2004-01-02)
`paragraphs [0006]
`—-
`[0008]; figures 4, 5a
`
`
`
`
`
`Klaus
`
`03/02/2022
`25 January 2022
`
`Authorized officer
`Name and mailing address of the ISA/
`European Patent Office, P.B. 5818 Patentlaan 2
`NL - 2280 HV Rijswijk
`Tel. (+31-70) 340-2040,
`Fax: (431-70) 340-3016
`Form PGT/ASA/210 (second sheet) (April 2005)
`
`[| Further documents are listed in the continuation of Box C. [x|See patent family annex.
`
`* Special categories of cited documents:
`
`"A" document defining the general state of the art which is not considered
`to be of particular relevance
`"E" earlier application or patent but published onorafter the international
`filing date
`"L" document which may throw doubts on priority claim(s) or which is
`cited to establish the publication date of another citation or other
`special reason (as specified}
`"O" documentreferring to an oral disclosure, use, exhibition or other
`means
`"P" document published prior to the internationalfiling date but later than
`the priority date claimed
`
`"T" later document publishedafter the internationalfiling date or priority
`date and not in conflict with the application but cited to understand
`the principle or theory underlying the invention
`
`"X" documentof particular relevance;; the claimed invention cannot be
`considered novel or cannot be considered to involve an inventive
`step when the documentis taken alone
`"¥" documentof particular relevance;; the claimed invention cannot be
`considered to involve an inventive step when the documentis
`combined with one or more other such documents, such combination
`being obvious to a person skilled in the art
`
`" document member of the samepatent family
`
`Date of the actual completion of the international search
`
`Date of mailing of the international search report
`
`Eisner,
`
`

`

`INTERNATIONAL SEARCH REPORT
`Information on patent family members
`
`
`
`International application No
`PCT/EP2021/078531
`
`Patent family
`member(s
`
`20180122657 A
`2018389 A
`2019033499
`2017153152
`
`1376185
`2005004145
`2005099611
`
`Publication
`date
`
`13-11-2018
`12-09-2017
`31-01-2019
`14-09-2017
`
`02-01-2004
`06-01-2005
`
`
`Patent document
`
`cited in search report
`
`
`
`wo 2017153152
`Al
`
`12-05-2005
`
`Publication
`date
`
`14-09-2017
`
`Form PGTASA/210 (patent family annex) (April 2005)
`
`

`

`PATENT COOPERATION TREATY
`
`From the
`INTERNATIONAL SEARCHING AUTHORITY
`
`To:
`
`PCT
`
`see form PCTASA/220
`
`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING AUTHORITY
`
`(PCT Rule 43b6i/s.1)
`
`
`
`Date of mailing
`see form PCTASA/210 (second sheet)
`(day/monthyear)
`
`Applicant's or agent's file reference
`see form PCTASA/220
`See paragraph 2 below
`
`International application No.
`Internationalfiling date (daysmonthyear)
`Priority date (daysnonth/year)
`PCT/EP2021/078531
`14.10.2021
`10.11.2020
`
`
`
`
`
` FOR FURTHER ACTION
`
`
`
`
`Applicant
`ASML NETHERLANDS B.V.
`
`
`International Patent Classification (IPG) or both national classification and IPC
`INV. GO3F7/20 GO02B7/A8
`
`OOO
`
`1.
`
`This opinion contains indications relating to the following items:
`
`XX] Box No.|
`C1 Box No.|
`L] Box No.III
`C1 Box No. IV
`bd Box No. V
`
`Box No. VI
`
`Basis of the opinion
`Priority
`Non-establishment of opinion with regard to novelty, inventive step and industrial applicability
`Lackof unity of invention
`Reasoned statement under Rule 48b6i/s.1(a)(i) with regard to novelty, inventive step and industrial
`applicability; citations and explanations supporting such statement
`Certain documentscited
`
`Box No. Vil
`
`Certain defects in the international application
`
`Box No. Vill Certain observations on the international application
`
`2.
`
`FURTHER ACTION
`
`If ademand for international preliminary examination is made, this opinion will usually be considered to be a
`written opinion of the International Preliminary Examining Authority ("IPEA") except that this does not apply where
`the applicant chooses an Authority other than this one to be the IPEA and the chosen IPEAhasnotifed the
`International Bureau under Rule 66.1is(b) that written opinions of this International Searching Authority
`will not be so considered.
`
`If this opinion is, as provided above, considered to be a written opinion of the IPEA, the applicant is invited to
`submit to the IPEA a written reply together, where appropriate, with amendments, before the expiration of 3 months
`from the date of mailing of Form PCTASA220 or before the expiration of 22 months from the priority date,
`whichever expires later.
`
`For further options, see Form PCTASA220.
`
`
`Date of completion of
`Name and mailing address of the ISA:
`this opinion
`see form
`PCTASA210
`
`d) European Patent Office
`
`Form PCTASA/237 (Cover Sheet) (January 2015)
`
`
`
` Authorized Officer
`
`Eisner, Klaus
`
`i »)
`
`%®Perey
`ugad®™
`
`D-80298 Munich
`Tel. +49 89 2399 - 0
`"roe a9530"
`Telephone No. +49 89 2399-0
`Fax: +49 89 2399 - 4465
`
`
`
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING AUTHORITY
`
`International application No.
`PCT/EP2021/078531
`
`Box No.| Basis of the opinion
`
`1. With regard to the language, this opinion has been established on the basis of:
`
`the international application in the language in which it wasfiled.
`
`a translation of the international application into , which is the language of a translation furnished for the
`purposesof international search (Rules 12.3(a) and 23.1 (b)).
`
`This opinion has been established taking into account the rectification of an obvious mistake authorized
`by or notified to this Authority under Rule 91 (Rule 43bis.1(a))
`
`With regard to any nucleotide and/or amino acid sequencedisclosedin the international application, this
`opinion has been established on the basis of a sequencelisting:
`
`i O
`
`a.
`
`LU forming part of the international application asfiled:
`
`C1
`
`in the form of an Annex CST.25 textfile.
`
`C1 on paper or in the form of an image file.
`
`b.
`
`OO furnished together with the international application under PCT Rule 13ter.1(a) for the purposesof
`international search only in the form of an Annex C/ST.25textfile.
`
`c.
`
`OU furnished subsequent to the international filing date for the purposesof international search only:
`
`C1
`
`in the form of an Annex C/ST.25textfile (Rule 13ter.1(a)).
`
`C1 on paper or in the form of an image file (Rule 13ter.1(b) and Administrative Instructions, Section
`713
`
`In addition, in the case that more than one version or copy of a sequencelisting has been filed or furnished,
`the required statements that the information in the subsequent or additional copies is identical to that
`forming part of the application as filed or does not go beyond the application as filed, as appropriate, were
`furnished.
`
`5. Additional comments:
`
`Form PCTASA/237 (January 2015)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING AUTHORITY
`
`International application No.
`PCT/EP2021/078531
`
` Reasoned statement under Rule 436/s.1(a)(i) with regard to novelty, inventive step or
`Box No. V
`industrial applicability; citations and explanations supporting such statement
`
`1. Statement
`
`Novelty (N)
`
`Inventive step (IS)
`
`Industrial applicability (IA)
`
`2. Citations and explanations
`
`see separate sheet
`
`Yes: Claims
`No:
`Claims
`
`Yes: Claims
`No:
`Claims
`
`Yes: Claims
`No:
`Claims
`
`1-15
`16-19
`
`1-15
`16-19
`
`1-19
`
`Form PCTASA/237 (January 2015)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING
`AUTHORITY (SEPARATE SHEET)
`
`International application No.
`
`PCT/EP2021/078531
`
`Re Item V
`
`Reasoned statementwith regard to novelty, inventive step or industrial
`applicability; citations and explanations supporting such statement
`
`1
`
`Reference is madeto the following documents:
`
`D1
`
`D2
`
`D3
`
`WO 2017/153152 A1 (ASML NETHERLANDS BV [NL]) 14
`September 2017 (2017-09-14) cited in the application
`
`DE 10 2013 111801 A1 (ASML NETHERLANDS BV [NL]; ZEISS
`CARL SMT GMBH [DE]) 13 March 2014 (2014-03-13)
`
`EP 1 376 185 A2 (NIKON CORP [JP]) 2 January 2004
`(2004-01-02)
`
`2
`
`The present application does not meet the criteria of Article 33(1) PCT, because
`the subject-matter of claim 16 is not new in the senseofArticle 33(2) PCT.
`
`D1 discloses:
`
`The use of a sub-atmospheric pressure conditioning system
`
`in a lithographic apparatus.
`
`cf. D1, paragraph 25: “Reflector for a projection system of a lithographic
`apparatus using EUV radiation, the reflector comprising a reflector substrate
`and a reflective surface, the substrate having a plurality of coolant channels
`embeddedtherein, the coolant channels being substantially parallel to the
`reflective surface.
`
`cf. D1, paragraph 35: “The coolant supply system is configured to supply water
`at a pressure in the range of from 0.001 to 10 bar.°
`
`Therefore, claim 16 is not new.
`
`Form PCT/ISA/237 (Separate Sheet} (Sheet 1} (EPO-April 2005)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING
`AUTHORITY (SEPARATE SHEET)
`
`International application No.
`
`PCT/EP2021/078531
`
`3
`
`Further novelty objection against claim 16 could be based on the following
`documents:
`
`D2, paragraph 29-40: coolant channel with N2 at a pressure of 0.1 bar to 20 bar
`
`D3, paragraph 6-8: EUV mirror comprising a pipe 32 inside a cooling channel
`30. A gap 36 is formed between the pipe 32 and the inner wall of the channel
`30. The gap 36 is a construed as a conditioning system. The pressure inside the
`gapis a fraction of one atmosphere (paragraph 8).
`
`4
`
`The present application does not meet the criteria of Article 33(1) PCT, because
`the subject-matter of claim 17 is not new in the senseofArticle 33(2) PCT.
`
`D1 discloses:
`
`A method of conditioning a system or sub-system of a
`
`lithographic apparatus, said method including providing a
`
`liguid conditioning fluid at sub-atmospheric pressure to
`
`the system or sub-system to be conditioned.
`
`cf. D1, paragraph 25: EUV reflector comprising coolant channels.
`
`‘The coolant supply system is configured to supply water
`cf. D1, paragraph 35:
`at a pressure in the range of from 0.001 to 10 bar.*
`
`Therefore, claim 17 is not new.
`
`5
`
`D1 further discloses the additional features of claim 18 (cf. D1, paragraph
`25: EUV reflector comprising coolant channels).
`
`Therefore, claim 18 is not new.
`
`Form PCT/ISA/237 (Separate Sheet} (Sheet 2} (EPO-April 2005)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING
`AUTHORITY (SEPARATE SHEET)
`
`International application No.
`
`PCT/EP2021/078531
`
`The novelty objection against claims 17 and 18 apply mutatis mutandis to
`lithographic method claim 19.
`
`Claims 1, 5, 9, 10
`
`7.1
`
`D1 is regarded as being the prior art closest to the subject-matter of claims 1,
`5, 9, 10 and discloses:
`
`A conditioning system for a lithographic apparatus, said conditioning system
`being configured to condition one or more optical elements of the lithographic
`apparatus, wherein the conditioning system is configured to have a sub-
`atmospheric pressure at the one or more optical elements
`
`cf. D1, paragraph 25: EUV reflector comprising coolant channels.
`
`‘The coolant supply system is configured to supply water
`cf. D1, paragraph 35:
`at a pressure in the range of from 0.0071 to 10 bar.°
`
`7.2
`
`The subject-matter of claim 1 therefore differs from the D1 conditioning system
`in that the system includes a sub-atmospheric pressure conditioning fluid
`reservoir for storing at least part of the liquid conditioning fluid.
`
`7.2.1
`
`The technical effect of this difference is that sub-atmospheric pressure
`conditioning fluid can be stored in the reservoir.
`
`7.2.2
`
`The problem to be solved by claim 1 may therefore be regarded as howto store
`the sub-atmospheric pressure conditioning fluid.
`
`7.2.3
`
`The solution to this problem proposedin claim 1 of the present application is
`considered as involving an inventive step (Article 33(3) PCT) for the following
`reasons:
`
`Form PCT/ISA/237 (Separate Sheet} (Sheet 3} (EPO-April 2005)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING
`AUTHORITY (SEPARATE SHEET)
`
`International application No.
`
`PCT/EP2021/078531
`
`7.2.3.1
`
`D1 (paragraph 43) discloses that coolant fluid is supplied from coolant supply
`unit and recovered by coolant recovery unit 44. Coolant fluid recovered by
`coolant recovery unit 44 can be recirculated to coolant supply unit 43.
`
`The coolant supply unit 43 can be construed as a ‘conditioning fluid reservoir.
`However, there is no disclosure or suggestion in D1 that the conditioning fluid
`reservoir (coolant supply unit 43) is a sub-atmospheric pressure conditioning
`fluid reservoir.
`
`7.2.3.2
`
`D2 merely discloses a cooling system for e.g. collector mirrors, of EUV
`projection exposure system. The system has a cooling passage passing a
`cooling medium. The cooling passage receives heat from system components
`and discharges the received heat. The cooling medium comprises supercritical
`carbon dioxide and nitrogen, and is selected from a mixture of carbon dioxide
`and a cooling medium component. The cooling medium is provided as a mixture
`of liquid and gaseous phase, and staysin the cooling passage under pressure
`at a range of 50 to 70 bars.
`
`7.2.3.3
`
`D3 discloses (figure 4, 5) an EUV mirror comprising cooling channels formed
`within the mirror member and a coolant pipe of a heat-conductive material
`inserted in each of the channels for passing a cooling fluid inside, its outer wall
`not contacting the wall of the channel but leaving a gap in between. The gap
`contains a gas with high thermal conductivity such as helium whichis
`maintained below atmospheric pressure.
`
`7.2.4
`
`Consequently, the prior art documents would not lead, alone or in combination,
`to the subject-matter of claim 1. Therefore, an inventive step is acknowledged.
`
`7.3
`
`The subject-matter of claim 5 differs from the D1 conditioning system in that the
`system includes a pump downstream of the optical element and a flow restrictor
`upstream of the optical element.
`
`Form PCT/ISA/237 (Separate Sheet} (Sheet 4} (EPO-April 2005)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING
`AUTHORITY (SEPARATE SHEET)
`
`International application No.
`
`PCT/EP2021/078531
`
`7.3.1
`
`The technical effect of this difference is that the pressure at the optical element
`is below atmospheric pressure (application paragraph 21)
`
`7.3.2
`
`The problem to be solved by claim 5 may therefore be regarded as howto
`ensure that the pressure at the optical element is below atmospheric pressure.
`
`7.3.3
`
`The solution to this problem proposedin claim 5 of the present application is
`considered as involving an inventive step (Article 33(3) PCT) for the following
`reasons:
`
`D1 merely discloses (paragraph 35) that the coolant supply system is
`configured to supply water at a pressure in the range of from 0.001 to 10 bar,
`without providing any further details how the sub-atmospheric pressure at the
`optical element is achieved.
`
`D2 and D3 (cf. points 7.2.3.2, 7.2.3.3) do also not provide any teaching which
`could lead in combination with D1 to the subject-matter of claim 5. Therefore,
`an inventive step is acknowledged.
`
`7.4
`
`The subject-matter of claim 9 differs from the D1 conditioning system in that a
`conditioning fluid reservoir is disposed below the optical element such that the
`hydrostatic pressure difference between the optical element and the
`conditioning fluid reservoir reduces the pressure at the optical element to below
`atmospheric pressure.
`
`7.4.1
`
`The technical effect of this difference is that the low pressure is generated by
`utilizing the hydrostatic pressure difference (application paragraph 26)
`
`7.4.2
`
`The problem to be solved by claim 9 may therefore be regarded as how to
`generate the low pressure.
`
`Form PCT/ISA/237 (Separate Sheet} (Sheet 5} (EPO-April 2005)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING
`AUTHORITY (SEPARATE SHEET)
`
`International application No.
`
`PCT/EP2021/078531
`
`7.4.3
`
`The solution to this problem proposedin claim 9 of the present application is
`considered as involving an inventive step (Article 33(3) PCT) for the following
`reasons:
`
`D1 merely discloses (paragraph 35) that the coolant supply system is
`configured to supply water at a pressure in the range of from 0.001 to 10 bar,
`without providing any further details how the sub-atmospheric pressure at the
`optical element is generated.
`
`D2 and D3 (cf. points 7.2.3.2, 7.2.3.3) do also not provide any teaching which
`could lead in combination with D1 to the subject-matter of claim 9. Therefore, an
`inventive step is acknowledged.
`
`7.5
`
`The subject-matter of claim 10 differs from the D1 conditioning system in that
`the system comprises first and second conditioning fluid reservoirs, wherein the
`first and second conditioning fluid reservoirs are in fluid connection with one
`another via a valve which is operable to control the level of conditioning fluid in
`the conditioning fluid reservoir which is in fluid communication with the optical
`element.
`
`7.5.1
`
`The technical effect of this difference is that the static pressure on the optical
`element may be controlled (application paragraph 27)
`
`7.5.2
`
`The problem to be solved by claim 10 may therefore be regarded as how to
`control the static pressure on the optical element.
`
`7.5.3
`
`The solution to this problem proposedin claim 10 of the present application is
`considered as involving an inventive step (Article 33(3) PCT) for the following
`reasons:
`
`Form PCT/ISA/237 (Separate Sheet} (Sheet 6} (EPO-April 2005)
`
`

`

`WRITTEN OPINION OF THE
`INTERNATIONAL SEARCHING
`AUTHORITY (SEPARATE SHEET)
`
`International application No.
`
`PCT/EP2021/078531
`
`D1 merely discloses (paragraph 35) that the coolant supply system is
`configured to supply water at a pressure in the range of from 0.001 to 10 bar,
`without providing any further details how the sub-atmospheric pressure at the
`optical element is controlled.
`
`D2 and D3 (cf. points 7.2.3.2, 7.2.3.3) do also not provide any teaching which
`could lead in combination with D1 to the subject-matter of claim 10. Therefore,
`an inventive step is acknowledged.
`
`8
`
`Claims 2-4, 6-8, 11-15 are dependent on claims 1, 5, 9 or 10 and as such also
`meet the requirements of the PCT with respect to novelty and inventive step.
`
`Form PCT/ISA/237 (Separate Sheet} (Sheet 7} (EPO-April 2005)
`
`