Abstract:
Various metrology systems and methods are provided. One metrology system includes a light source configured to produce a diffraction-limited light beam, an apodizer configured to shape the light beam in the entrance pupil of illumination optics, and optical elements configured to direct the diffraction-limited light beam from the apodizer to an illumination spot on a grating target on a wafer and to collect scattered light from the grating target. The metrology system further includes a field stop and a detector configured to detect the scattered light that passes through the field stop. In addition, the metrology system includes a computer system configured to determine a characteristic of the grating target using output of the detector.
Abstract:
A beamsplitter includes a substrate formed from a material transparent to wavelengths of light at least above a selected cutoff wavelength and reflective structures distributed across a surface of the substrate. The reflective structures split incident light having wavelengths above the selected cutoff wavelength into a reflected beam formed from portions of the incident light reflected from the reflective structures and a transmitted beam formed from portions of the incident light transmitted through the substrate. A splitting ratio of a power of the reflected beam to a power of the transmitted beam is based on a ratio of surface area of the reflective surfaces to an area of the incident light on the substrate. Separation distances between neighboring reflective structures are smaller than the cutoff wavelength such that diffracted power of the incident light having wavelengths above the selected cutoff wavelength is maintained below a selected tolerance.
Abstract:
The disclosure is directed to a system and method of controlling spectral attributes of illumination. According to various embodiments, a portion of illumination including an excluded selection of illumination spectra is blocked, while another portion of the illumination including a transmitted selection of illumination spectra is directed along an illumination path. In some embodiments, optical metrology is performed utilizing the spectrally controlled illumination to enhance measurement capability. For instance, the spectral attributes of illumination utilized to analyze different portions of a sample, such as different semiconductor layers, may be selected according to certain measurement characteristics associated with the analyzed portions of the sample.
Abstract:
Metrology targets, design files, and design and production methods thereof are provided. Metrology targets comprising at least one reflection-symmetric pair of reflection-asymmetric structures are disclosed. The structures may or may not be periodic, may comprise a plurality of unevenly-spaced target elements, which may or may not be segmented. The asymmetry may be with respect to target element segmentation or structural dimensions. Also, target design files and metrology measurements of the various metrology targets are disclosed.
Abstract:
Various metrology systems and methods are provided. One metrology system includes a light source configured to produce a diffraction-limited light beam, an apodizer configured to shape the light beam in the entrance pupil of illumination optics, and optical elements configured to direct the diffraction-limited light beam from the apodizer to an illumination spot on a grating target on a wafer and to collect scattered light from the grating target. The metrology system further includes a field stop and a detector configured to detect the scattered light that passes through the field stop. In addition, the metrology system includes a computer system configured to determine a characteristic of the grating target using output of the detector.
Abstract:
A metrology system may include an imaging sub-system including one or more lenses and a detector to image a sample, where the sample includes metrology target elements on two or more sample layers. The metrology system may further include a controller to determine layer-specific imaging configurations of the imaging sub-system to image the metrology target elements on the two or more sample layers within a selected image quality tolerance, where each layer-specific imaging configuration includes a selected configuration of one or more components of the imaging sub-system. The controller may further receive, from the imaging sub-system, one or more images of the metrology target elements on the two or more sample layers generated using the layer-specific imaging configurations. The controller may further provide a metrology measurement based on the one or more images of the metrology target elements on the two or more sample layers.
Abstract:
A beamsplitter includes a substrate formed from a material transparent to wavelengths of light at least above a selected cutoff wavelength and reflective structures distributed across a surface of the substrate. The reflective structures split incident light having wavelengths above the selected cutoff wavelength into a reflected beam formed from portions of the incident light reflected from the reflective structures and a transmitted beam formed from portions of the incident light transmitted through the substrate. A splitting ratio of a power of the reflected beam to a power of the transmitted beam is based on a ratio of surface area of the reflective surfaces to an area of the incident light on the substrate. Separation distances between neighboring reflective structures are smaller than the cutoff wavelength such that diffracted power of the incident light having wavelengths above the selected cutoff wavelength is maintained below a selected tolerance.
Abstract:
A metrology system includes an image device and a controller. The image device includes a spectrally-tunable illumination device and a detector to generate images of a sample having metrology target elements on two or more sample layers based on radiation emanating from the sample in response to illumination from the spectrally-tunable illumination device. The controller determines layer-specific imaging configurations of the imaging device to image the metrology target elements on the two or more sample layers within a selected image quality tolerance in which each layer-specific imaging configuration includes an illumination spectrum from the spectrally-tunable illumination device. The controller further receives one or more images of the metrology target elements on the two or more sample layers generated using the layer-specific imaging configurations. The controller further provides a metrology measurement based on the one or more images of the metrology target elements on the two or more sample layers.
Abstract:
Various metrology systems and methods are provided. One metrology system includes a light source configured to produce a diffraction-limited light beam, an apodizer configured to shape the light beam in the entrance pupil of illumination optics, and optical elements configured to direct the diffraction-limited light beam from the apodizer to an illumination spot on a grating target on a wafer and to collect scattered light from the grating target. The metrology system further includes a field stop and a detector configured to detect the scattered light that passes through the field stop. In addition, the metrology system includes a computer system configured to determine a characteristic of the grating target using output of the detector.