Kla Corporation

Kla Tencor Corporation

Haifeng Huang

Rui-Fang Shi

Damon Floyd Kvamme

Daniel C Wack

Eric Vella

Joseph Walsh

Dan Wack

Mitchell Lindsay

Robert Kestner

Amrish Kelkar

An optical system with aberration correction is disclosed. The optical system may include an illumination source. The optical system may include a detector. The optical system may include one or more collection optics configured to image a sample onto the detector based on illumination from the illumination source. The optical system may include two or more aberration correction plates located in one or more pupil planes of the one or more collection optics. The two or more aberration correction plates may provide at least partial correction of two or more linearly-independent aberration terms. Any particular one of the two or more aberration correction plates may have a spatially-varying thickness profile providing a selected amount of correction for a single particular aberration term of the two or more linearly-independent aberration terms.

Correcting aberration and apodization of an optical system using correction plates

To calibrate a TDI photomask inspection tool, a photomask with a plurality of distinctly patterned regions is loaded into the tool. The plurality of distinctly patterned regions is successively illuminated with an EUV beam of light. While illuminating respective distinctly patterned regions, respective instances of imaging of the respective distinctly patterned regions are performed using a TDI sensor in the inspection tool. While performing the respective instances of imaging, a reference intensity detector is used to measure reference intensities of EUV light collected from the photomask. Based on the results of the respective instances of imaging and the measured reference intensities of EUV light, linearity of the TDI sensor is determined.

EUV in-situ linearity calibration for TDI image sensors using test photomasks

An acousto-optic modulator (AOM) laser frequency shifter system includes a laser configured to generate an incident beam, a first optical splitter optically coupled to the laser and configured to split the incident beam into at least one portion of the incident beam, at least one phase-shift channel optically coupled to the first optical splitter and configured to generate at least one frequency-shifted beam with an acousto-optic modulator (AOM) from the at least one portion of the incident beam received from the first optical splitter, and a second optical splitter configured to receive the at least one frequency-shifted beam from the at least one phase-shift channel and configured to direct the at least one frequency-shifted beam to an interferometer configured to acquire an interferogram of a sample with the at least one frequency-shifted beam.

Fast phase-shift interferometry by laser frequency shift

Reference and test waves are directed in a common path mode in a fiber tip diffraction interferometer. A first fiber can be used to generate the reference wave and a second fiber can be used to generate the test wave. Each fiber can include a single mode fiber tip that defines a wedge at an end without a coating on end surface or a tapered fiber tip. The fiber tip diffraction interferometer can include an aplanatic pupil imaging lens or system disposed to receive both the test wave and the reference wave and a sensor configured to receive both the test wave and the reference wave.

Common path mode fiber tip diffraction interferometer for wavefront measurement

Disclosed are methods and apparatus for measuring and controlling polarization for inspection of a semiconductor sample. The method includes (i) setting up an inspection system in a specific mode of operation, (ii) incrementing a first waveplate of the system through a plurality of rotations while keeping a second waveplate of the system static, (iii) measuring an intensity signal from non-patterned areas of the sample for each rotation of the first waveplate, (iv) incrementing the second waveplate through a plurality of rotations while keeping the first waveplate static (v) measuring an intensity signal from non-patterned areas of the sample for each rotation of the second waveplate, (vi) generating a model of a plurality of polarization and waveplate parameters for the system to simulate the intensity signals that were measured for each rotation of the first and/or second waveplate, and (vii) determining the polarization and waveplate parameters for the system based on the model and a polarization state on photomask plane based on the polarization and waveplate parameters.

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Livermore, CA, United States of America

Haifeng Huang