Prosecution Insights
Last updated: April 19, 2026
Application No. 18/645,681

OPTICAL APPARATUS AND METHOD OF PREVENTING CONTAMINATION OF OPTICAL APPARATUS

Non-Final OA §103§112
Filed
Apr 25, 2024
Examiner
OESTREICH, MITCHELL T
Art Unit
2872
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Lasertec Corporation
OA Round
1 (Non-Final)
74%
Grant Probability
Favorable
1-2
OA Rounds
2y 10m
To Grant
95%
With Interview

Examiner Intelligence

Grants 74% — above average
74%
Career Allow Rate
292 granted / 395 resolved
+5.9% vs TC avg
Strong +22% interview lift
Without
With
+21.5%
Interview Lift
resolved cases with interview
Typical timeline
2y 10m
Avg Prosecution
24 currently pending
Career history
419
Total Applications
across all art units

Statute-Specific Performance

§101
0.5%
-39.5% vs TC avg
§103
37.4%
-2.6% vs TC avg
§102
28.2%
-11.8% vs TC avg
§112
30.8%
-9.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 395 resolved cases

Office Action

§103 §112
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Examiner Notes Examiner cites particular columns and line numbers in the references as applied to the claims below for the convenience of the applicant. Although the specified citations are representative of the teachings in the art and are applied to the specific limitations within the individual claim, other passages and figures may apply as well. It is respectfully requested that, in preparing responses, the applicant fully consider the references in entirety as potentially teaching all or part of the claimed invention, as well as the context of the passage as taught by the prior art or disclosed by the examiner. Priority As required by M.P.E.P. 201.14(c), acknowledgement is made of applicant’s claim for priority based on the application filed on April 28th, 2023 (JP 2023-074735). Receipt is acknowledged of certified copies of papers submitted under 35 U.S.C. 119(a)-(d), which papers have been placed of record in the file. Information Disclosure Statement As required by M.P.E.P. 609, the applicant’s submissions of the Information Disclosure Statements dated April 25th, 2024, October 9th, 2024, and February 20th, 2025 are acknowledged by the examiner and the cited references have been considered in the examination of the claims now pending. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. Claim 3, 4, 9, and 10 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, regards as the invention. Regarding claims 3 and 9, these claims recite the limitation “remote plasma generation apparatus” which is unclear and renders the claims unclear and thus indefinite. Specifically, it is unclear what makes a plasma generation apparatus “remote”. Accordingly, for the purpose of examining the claims currently pending, this limitation will be interpreted to mean “plasma generation apparatus”. Regarding claims 4 and 10, these claims depend on a rejected base claim and are therefore rejected for at least the reasons stated supra. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claim(s) 1-12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kusunose et al. (US 2021/0373447 A1) in view of Schulz et al. (US 2010/0033819 A1). Regarding claim 1, Kusunose teaches an optical apparatus comprising: a light source configured to generate light including EUV light (See, e.g., light source 201 in Fig. 3 and paragraph [0030] which explains it is a EUV light source); a chamber in which a target object to be irradiated with the light is disposed (See, e.g., chamber 100 and sample 40 in Fig. 3); an optical element provided in the chamber in order to guide the light (See, e.g., optical system 16 in Fig. 3); an introducing unit (See, e.g., introduction unit 300 in Fig. 3 which introduces helium or hydrogen gas into the chamber); a power supply configured to apply a negative voltage to the optical element in the chamber (See, e.g., power supply 52 in Fig. 3 and paragraph [0051] which explains a negative voltage is applied to the optical element); an ammeter configured to measure an ion current flowing to the optical element (See, e.g., ammeter 51 in Fig. 3 and paragraph [0052] which explains this); and a control unit (See, e.g., control unit 53 in Fig. 3 and paragraphs [0053]-[0054] which explains this. Note here the control unit is controlling the amount of helium and hydrogen that enters the chamber based on the ammeter). Kusunose lacks an explicit disclosure wherein the introducing unit is configured to introduce argon into the chamber (However, note that Kusunose does teach an introducing unit that introduces a helium or hydrogen gas into the chamber) and wherein the control unit is configured to control an introduction amount of the argon according to a measurement of the ammeter (However note that Kusunose does teach a control unit configured to control an introduction amount of helium or hydrogen gas based on a measurement of an ammeter). However, in an analogous field of endeavor Schulz teaches introducing argon that is turned into argon plasma and used to create a nanostructure that protects an optical element, i.e. prevents contamination (See, e.g., paragraph [0049] which explains this). Accordingly, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the gas and thus plasma of the device of Kusunose to include argon gas/plasma, as taught by Schulz, for the purpose of optimizing the protection of the optical element and/or to enhance the prevention of contamination of the system. Regarding claim 2, Kusunose in view of Schulz teaches the device set forth above and as modified above further teaches wherein the argon introduced into the chamber contains an argon gas (Note as modified above this limitation is met), the introducing unit includes an introducing pipe connected to the chamber (See, e.g., introduction pipe 304 in Fig. 3), the control unit controls a flow rate of the argon gas supplied into the chamber via the introducing pipe (See, e.g., control unit 53 in Fig. 3 and paragraphs [0053]-[0054] which explains this), and the EUV light guided in the chamber converts the argon gas into argon plasma (See, e.g., paragraph [0045] which explains this and note given the modification above this limitation is met). Regarding claim 3, Kusunose in view of Schulz teaches the device set forth above and as modified above further teaches wherein the introducing unit includes: a remote plasma generation apparatus configured to generate argon plasma (See, e.g., plasma generation device 310 in Fig. 3 and paragraphs [0043]-[0045]); an introducing pipe provided between the remote plasma generation apparatus and the chamber (See, e.g., introduction pipe 304 in Fig. 3); and a variable conductance valve provided in the introducing pipe (See, e.g., variable conductance valve 305 in Fig. 3), and the control unit controls conductance of the variable conductance valve to thereby control a flow rate of the argon plasma supplied into the chamber via the introducing pipe (See, e.g., control unit 53 in Fig. 3 and paragraphs [0053]-[0054] which explains this). Regarding claim 4, Kusunose in view of Schulz teaches the device set forth above and as modified above further teaches wherein a cooling mechanism that cools the introducing pipe is provided (See, e.g., cooling mechanism 330 in Fig. 3). Regarding claim 5, Kusunose in view of Schulz teaches the device set forth above and as modified above further teaches wherein the target object is an EUV mask including a pellicle (See, e.g., paragraph [0059] which explains this). Regarding claim 6, Kusunose in view of Schulz teaches the device set forth above and as modified above further teaches wherein the argon introduced into the chamber contains an argon gas (Note in light of the modification above this limitation is met), the light source further generates the light including VUV light (See, e.g., paragraph [0030]), an oblique incidence mirror that reflects the VUV light is provided in the chamber (See, e.g., paragraphs [0076]-[0077] which explain this), the VUV light reflected by the oblique incidence mirror is made incident on the optical element, and the VUV light guided into the chamber converts the argon gas into argon plasma (See, e.g. paragraphs [0077]-[0078] which explain this). Regarding claim 7, Kusunose teaches a method of preventing contamination of an optical apparatus including: a light source configured to generate light including EUV light (See, e.g., light source 201 in Fig. 3 and paragraph [0030] which explains it is a EUV light source); a chamber in which a target object to be irradiated with the light is disposed (See, e.g., chamber 100 and sample 40 in Fig. 3); an optical element provided in the chamber in order to guide the light (See, e.g., optical system 16 in Fig. 3); the method comprising: a step of introducing (See, e.g., introduction unit 300 in Fig. 3 which introduces helium or hydrogen gas into the chamber); a step of applying a negative voltage to the optical element in the chamber (See, e.g., power supply 52 in Fig. 3 and paragraph [0051] which explains a negative voltage is applied to the optical element); a step of measuring an ion current flowing to the optical element (See, e.g., ammeter 51 in Fig. 3 and paragraph [0052] which explains this); and a step of controlling (See, e.g., control unit 53 in Fig. 3 and paragraphs [0053]-[0054] which explains this. Note here the control unit is controlling the amount of helium and hydrogen that enters the chamber based on the ammeter). Kusunose lacks an explicit disclosure wherein the step of introducing introduces argon into the chamber (However, note that Kusunose does teach an introducing unit that introduces a helium or hydrogen gas into the chamber) and wherein the step of controlling includes controlling an introduction amount of the argon according to a measurement result of the ion current (However note that Kusunose does teach a control unit configured to control an introduction amount of helium or hydrogen gas based on a measurement of an ammeter). However, in an analogous field of endeavor Schulz teaches introducing argon that is turned into argon plasma and used to create a nanostructure that protects an optical element, i.e. prevents contamination (See, e.g., paragraph [0049] which explains this). Accordingly, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the gas and thus plasma of the method of Kusunose to include argon gas/plasma, as taught by Schulz, for the purpose of optimizing the protection of the optical element and/or to enhance the prevention of contamination of the system. Regarding claim 8, Kusunose in view of Schulz teaches the method set forth above and as modified above further teaches wherein an introducing pipe is connected to the chamber (See, e.g., introduction pipe 304 in Fig. 3), in the step of introducing argon into the chamber, the argon introduced into the chamber contains an argon gas (Note this limitation is met in view of the modification above), in the step of controlling an introduction amount of the argon according to a measurement result of the ion current, a flow rate of the argon gas supplied into the chamber via the introducing pipe is controlled according to the measurement result (See, e.g., control unit 53 in Fig. 3 and paragraphs [0053]-[0054] which explains this), and the EUV light guided in the chamber converts the argon gas into argon plasma (See, e.g., paragraph [0045] which explains this and note given the modification above this limitation is met). Regarding claim 9, Kusunose in view of Schulz teaches the method set forth above and as modified above further teaches wherein the optical apparatus includes: a remote plasma generation apparatus configured to generate argon plasma (See, e.g., plasma generation device 310 in Fig. 3 and paragraphs [0043]-[0045]); an introducing pipe provided between the remote plasma generation apparatus and the chamber (See, e.g., introduction pipe 304 in Fig. 3); and a variable conductance valve provided in the introducing pipe (See, e.g., variable conductance valve 305 in Fig. 3), in the step of introducing argon into the chamber, the argon introduced into the chamber contains the argon plasma (Note this limitation is met in view of the modification above), and in the step of controlling an introduction amount of the argon according to a measurement result of the ion current, conductance of the variable conductance valve is controlled according to the measurement result to control a flow rate of the argon plasma supplied into the chamber via the introducing pipe (See, e.g., control unit 53 in Fig. 3 and paragraphs [0053]-[0054] which explains this). Regarding claim 10, Kusunose in view of Schulz teaches the method set forth above and as modified above further teaches wherein a cooling mechanism that cools the introducing pipe is provided (See, e.g., cooling mechanism 330 in Fig. 3). Regarding claim 11, Kusunose in view of Schulz teaches the method set forth above and as modified above further teaches wherein the target object is an EUV mask including a pellicle (See, e.g., paragraph [0059] which explains this). Regarding claim 12, Kusunose in view of Schulz teaches the method set forth above and as modified above further teaches wherein the light source further generates the light including VUV light (See, e.g., paragraph [0030]), an introducing pipe is connected to the chamber (See, e.g., introduction pipe 304 in Fig. 3), an oblique incidence mirror that reflects the VUV light is provided in the chamber (See, e.g., paragraphs [0076]-[0077] which explain this), the VUV light reflected by the oblique incidence mirror is made incident on the optical element (See, e.g. paragraphs [0077]-[0078] which explain this), in the step of introducing argon into the chamber, the argon introduced into the chamber contains an argon gas (Note this limitation is met in light of the modification above), in the step of controlling an introduction amount of the argon according to a measurement result of the ion current, a flow rate of the argon gas supplied into the chamber via the introducing pipe is controlled according to the measurement result (See, e.g., control unit 53 in Fig. 3 and paragraphs [0053]-[0054] which explains this), and the VUV light guided into the chamber converts the argon gas into argon plasma (See, e.g. paragraphs [0077]-[0078] which explain this).. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to Mitchell Oestreich whose telephone number is (571)270-7559. The examiner can normally be reached M-F 7:00-11:00 MT. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Bumsuk Won can be reached at 571-272-2713. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /MITCHELL T OESTREICH/Examiner, Art Unit 2872 /BUMSUK WON/Supervisory Patent Examiner, Art Unit 2872
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Prosecution Timeline

Apr 25, 2024
Application Filed
Mar 20, 2026
Non-Final Rejection — §103, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
74%
Grant Probability
95%
With Interview (+21.5%)
2y 10m
Median Time to Grant
Low
PTA Risk
Based on 395 resolved cases by this examiner. Grant probability derived from career allow rate.

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