Control system for a plurality of deep ultraviolet optical oscillators

Patent metadata

Field	Value
Publication number	US-12374853-B2
Application number	US-202017612113-A
Country	US
Kind code	B2
Filing date	May 15, 2020
Priority date	May 22, 2019
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

A deep ultraviolet (DUV) optical system includes: an optical source system including: a plurality of optical oscillators; a beam combiner; and a beam control apparatus between the optical oscillators and the beam combiner. The beam combiner is configured to receive and direct light emitted from any of the optical oscillators toward a scanner apparatus as an exposure light beam, and the beam control apparatus is configured to determine whether the beam combiner receives light from a particular one of the optical oscillators. The DUV optical lithography system also includes a control system coupled to the optical source system, the control system configured to: determine whether a condition exists in the DUV optical system, and based on a determination that the condition exists, perform a calibration action in a subset of the optical oscillators.

First claim

What is claimed is:

1. A deep ultraviolet (DUV) optical system comprising:
an optical source system comprising:
a plurality of optical oscillators;
a beam combiner; and
a beam control apparatus between the optical oscillators and the beam combiner, wherein the beam combiner is configured to receive and direct light emitted from any of the optical oscillators toward a scanner apparatus as an exposure light beam, and the beam control apparatus is configured to determine whether the beam combiner receives light from a particular one of the plurality of optical oscillators; and
a control system coupled to the optical source system, the control system configured to:

determine whether a condition exists in the DUV optical system; and
based on a determination that the condition exists, perform a calibration action in a subset of the optical oscillators.

2. The DUV optical system of claim 1 , wherein the calibration action comprises bringing a wavelength of light produced by at least one of the optical oscillators to be within a target range.

3. The DUV optical system of claim 1 , wherein the condition is a time-based condition or an event-based condition.

4. The DUV optical system of claim 3 , wherein the condition is an event-based condition, the control system is coupled to the light source system and the scanner apparatus, the control system is configured to receive a status signal from the DUV optical system, and the control system determines whether the event-based condition exists based on the status signal from the scanner apparatus.

5. The DUV optical system of claim 4 , wherein the status signal comprises information related to an upcoming event in the scanner apparatus, and the control system performs the calibration action based on the information related to the upcoming event.

6. The DUV optical system of claim 5 , wherein the information related to the upcoming event comprises an amount of time until the upcoming event occurs and an indication that identifies the upcoming event, and the control system performs the calibration action before the upcoming event occurs.

7. The DUV optical system of claim 6 , wherein the upcoming event comprises a change in an operating condition of the scanner apparatus, the change in the operating condition comprising a change in a repetition rate of the exposure beam, a change in a power of the exposure beam, or a change in operating mode of the scanner apparatus.

8. The DUV optical system of claim 3 , wherein the condition is a time-based condition, the control system is configured to monitor a status of the DUV optical system, and the control system is configured to determine the condition of the DUV optical system based on the monitored status of the optical source system.

9. The DUV optical system of claim 1 , wherein each optical oscillator comprises a gain medium, the gain medium comprises a gaseous gain medium, the calibration action comprises a refill operation, and the refill operation comprises exchanging the gaseous gain medium in a subset of the optical oscillators.

10. The DUV optical system of claim 1 , wherein the beam control apparatus comprises a beam blocking device for each of the plurality of optical oscillators, and each of the beam blocking devices is coupled to the control system; and
the control system is further configured to control the beam blocking devices to determine whether the beam combiner receives light from a particular one of the optical oscillators.

11. A method of controlling a plurality of optical oscillators in a deep ultraviolet (DUV) optical system, the DUV optical system including a control system, the method comprising:
a step performed by the control system of monitoring the DUV optical system and making a condition determination whether a condition exists;
a step performed by the control system of determining if any of the plurality of optical oscillators are in a waiting state based at least in part on the condition determination; and
a step performed by the control system of performing a calibration action in a subset of the plurality of optical oscillators that are in the waiting state, wherein one or more of the optical oscillators that are not in the waiting state continue to produce an exposure beam while the control system performs the calibration action.

12. The method of claim 11 , wherein the DUV optical system is configured for use with a DUV optical lithography system, and monitoring the DUV optical system comprises receiving a command signal from a scanner apparatus and determining whether the condition exists based on the command signal.

13. The method of claim 11 , wherein, if the condition exists and none of the plurality of optical oscillators are in the waiting state, placing at least one optical oscillator in the waiting state.

14. A method of controlling a plurality of optical oscillators in a deep ultraviolet (DUV) optical lithography system, the DUV optical system including a control system, the method comprising:
a step performed by the control system of receiving a request for an exposure beam configured to provide a requested dose of DUV light to a wafer; a step performed by the control system of making a cold start determination of whether a cold start condition exists; and a step performed by the control system based at least in part on the cold start determination of:
activating more than a nominal number of optical oscillators, the nominal number of optical oscillators being a number of optical oscillators capable of providing the requested dose under steady-state conditions; and
directing a light beam from each of the activated optical oscillators toward a scanner apparatus to provide the exposure beam during a cold start period.

15. The method of claim 14 , wherein, if the cold start condition exists, further comprising:
determining whether the cold start period has ended; and
if the cold start period has ended, deactivating at least one of the activated optical oscillators.

16. A control system comprising:
an interface configured to communicate with a DUV optical system, and wherein the control system is configured to control the DUV optical system by:
determining whether a condition exists in the DUV optical system, and
based on a determination that the condition exists, performing a calibration action in a subset of optical oscillators in the DUV optical system while at least one optical oscillator that is not in the subset of optical oscillators produces an exposure beam.

17. An optical source system comprising:
N optical oscillators, wherein N is an integer number that is greater than or equal to two; a beam combiner configured to produce an exposure beam from one or more light beams received from one or more of the N optical oscillators; and a control system configured to control the plurality of optical oscillators to determine which M of the plurality of optical oscillators produce light for the exposure beam, wherein M is an integer that is greater than or equal to one and is less than or equal to N,
the control system being further configured to determine whether a condition exists in the optical source system, and to perform a calibration action in one or more of the plurality of optical oscillators if the condition exists, and
wherein the calibration action adjusts a property of a light beam emitted by the one of the plurality of optical oscillators, and the property comprises a center wavelength, an energy, or a spectral bandwidth.

18. The optical source system of claim 17 , wherein the beam

Assignees

• Cymer LLC

Inventors

• Zhao Yingbo
• Gillespie Walter Dale
• Thornes Joshua Jon
• Duffey Thomas Patrick
• Mason Eric Anders

Classifications

• G03F7/70041

  by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control · CPC title

• G03F7/7055

  Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption · CPC title

• H01S3/2256

  KrF, i.e. krypton fluoride is comprised for lasing around 248 nm · CPC title

• H01S3/2253

  XeCl, i.e. xenon chloride is comprised for lasing around 308 nm · CPC title

• H01S3/2251

  ArF, i.e. argon fluoride is comprised for lasing around 193 nm · CPC title