Target control in extreme ultraviolet lithography systems using aberration of reflection image
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsTing-Ya CHENG, Han-Lung CHANG, Shi-Han SHANN, Li-Jui CHEN, Yen-Shuo SU
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Abstract
A method of controlling an extreme ultraviolet (EUV) lithography system is disclosed. The method includes irradiating a target droplet with EUV radiation, detecting EUV radiation reflected by the target droplet, determining aberration of the detected EUV radiation, determining a Zernike polynomial corresponding to the aberration, and performing a corrective action to reduce a shift in Zernike coefficients of the Zernike polynomial.
Claims20
A method of controlling an extreme ultraviolet (EUV) lithography system, the method comprising:
- irradiating a target droplet with laser radiation;
- detecting laser radiation reflected by the target droplet;
- determining aberration of the detected laser radiation;
- determining a Zernike polynomial corresponding to the aberration;
- and
- performing a corrective action to reduce a shift in at least one of Zernike coefficients of the Zernike polynomial.
An apparatus for extreme ultraviolet (EUV) lithography, comprising:
- a droplet generator configured to generate target droplets;
- an EUV radiation source for generating EUV radiation including an excitation radiation source, excitation radiation from the excitation radiation source interacting with the target droplets;
- a final focus module configured to:
- detect the excitation radiation reflected by the target droplet;
- determine aberration of the detected excitation radiation;
- generate a plurality of Zernike polynomials;
- determine one or more Zernike polynomials from the plurality of Zernike polynomials that correspond to the aberration;
- and
- perform a corrective action to reduce a shift in at least one of Zernike coefficients of the one or more Zernike polynomials.
A non-transitory, computer-readable medium comprising computer readable instructions stored in a memory which, when executed by a processor of a computer direct the computer to control a final focus module of an extreme ultraviolet (EUV) lithography apparatus to perform a method, the method comprising:
- detecting excitation radiation reflected by a target droplet;
- determining aberration of the detected excitation radiation;
- generating a plurality of Zernike polynomials;
- determining one or more Zernike polynomials from the plurality of Zernike polynomials that correspond to the aberration;
- determining a shift in at least one of Zernike coefficients of the one or more Zernike polynomials;
- and
- detecting a change in a beam profile of the excitation radiation based on the shift in the Zernike coefficients.
Dependencies are inferred from the claim text.