Abstract:
An apparatus includes (i) a bright light source for providing an illumination beam at multiple wavelengths selectable with a range from a deep ultraviolet wavelength to an infrared wavelength, (ii) illumination optics for directing the illumination beam towards a sample at selectable sets of angles of incidence (AOI's) or azimuth angles (AZ's) and polarization states to provide spectroscopic ellipsometry, wherein the illumination optics include an apodizer for controlling a spot size of the illumination beam on the sample at each of the selectable AOI/AZ sets, (iii) collection optics for directing an output beam from the sample in response to the illumination beam at each of the selectable AOI/AZ sets and polarization states towards a detector that generates an output signal or image based on the output beam, and (v) a controller for characterizing a feature of the sample based on the output signal or image.
Abstract:
Methods and systems are described herein for producing high radiance illumination light suitable for semiconductor metrology. A cold gas is repeatedly ignited by a pulsed laser to periodically generate accessible, high brightness illumination light generated during each break-down event. The pulse duration and repetition period are set to ignite, but not sustain fully formed plasma. The central plasma core emits high color temperature light before a cooler plasma region forms around the central core. Thus, after ignition, the plasma is extinguished before the arrival of the next laser pulse. The repeated plasma ignition/extinction cycle generates illumination light at high color temperature that is accessible for illumination purposes in a metrology application. In one embodiment, a bulb filled with Xenon gas at 10 atmospheres is repeatedly ignited with a pulsed laser having pulse duration of 10 nanoseconds to generate illumination light with a color temperature of approximately 60,000 Kelvin.
Abstract:
An apparatus includes (i) a bright light source for providing an illumination beam at multiple wavelengths selectable with a range from a deep ultraviolet wavelength to an infrared wavelength, (ii) illumination optics for directing the illumination beam towards a sample at selectable sets of angles of incidence (AOI's) or azimuth angles (AZ's) and polarization states to provide spectroscopic ellipsometry, wherein the illumination optics include an apodizer for controlling a spot size of the illumination beam on the sample at each of the selectable AOI/AZ sets, (iii) collection optics for directing an output beam from the sample in response to the illumination beam at each of the selectable AOI/AZ sets and polarization states towards a detector that generates an output signal or image based on the output beam, and (v) a controller for characterizing a feature of the sample based on the output signal or image.
Abstract:
An apparatus includes (i) a bright light source for providing an illumination beam at multiple wavelengths selectable with a range from a deep ultraviolet wavelength to an infrared wavelength, (ii) illumination optics for directing the illumination beam towards a sample at selectable sets of angles of incidence (AOI's) or azimuth angles (AZ's) and polarization states to provide spectroscopic ellipsometry, wherein the illumination optics include an apodizer for controlling a spot size of the illumination beam on the sample at each of the selectable AOI/AZ sets, (iii) collection optics for directing an output beam from the sample in response to the illumination beam at each of the selectable AOI/AZ sets and polarization states towards a detector that generates an output signal or image based on the output beam, and (v) a controller for characterizing a feature of the sample based on the output signal or image.
Abstract:
A rotatable compensator configured to transmit non-collimated light over a broad range of wavelengths, including ultraviolet, with a high degree of retardation uniformity across the aperture is presented. In one embodiment, a rotatable compensator includes a stack of four individual plates in optical contact. The two thin plates in the middle of the stack are made from a birefringent material and are arranged to form a compound, zeroth order bi-plate. The remaining two plates are relatively thick and are made from an optically isotropic material. These plates are disposed on either end of the compound, zeroth order bi-plate. The low order plates minimize the sensitivity of retardation across the aperture to non-collimated light. Materials are selected to ensure transmission of ultraviolet light. The optically isotropic end plates minimize coherence effects induced at the optical interfaces of the thin plates.
Abstract:
Methods and systems for enhancing the throughput of a metrology system generating measurement signals based on at least two different optical properties of the illumination light are presented. A detector having a two dimensional photosensitive area is subdivided into multiple photosensitive stripes by multiple, independent linear arrays of shift register elements located within the photosensitive area. Charge transfer from pixels within each stripe is directed to a distinct linear array of shift register elements. Each photosensitive stripe is able to resolve an optical property dispersed across the length of each stripe with relatively high resolution. In addition, the detector is able to resolve another optical property dispersed across several photosensitive stripes in a direction orthogonal to each linear array of shift registers at a relatively low resolution.
Abstract:
A rotatable compensator configured to transmit non-collimated light over a broad range of wavelengths, including ultraviolet, with a high degree of retardation uniformity across the aperture is presented. In one embodiment, a rotatable compensator includes a stack of four individual plates in optical contact. The two thin plates in the middle of the stack are made from a birefringent material and are arranged to form a compound, zeroth order bi-plate. The remaining two plates are relatively thick and are made from an optically isotropic material. These plates are disposed on either end of the compound, zeroth order bi-plate. The low order plates minimize the sensitivity of retardation across the aperture to non-collimated light. Materials are selected to ensure transmission of ultraviolet light. The optically isotropic end plates minimize coherence effects induced at the optical interfaces of the thin plates.
Abstract:
A rotatable compensator configured to transmit non-collimated light over a broad range of wavelengths, including ultraviolet, with a high degree of retardation uniformity across the aperture is presented. In one embodiment, a rotatable compensator includes a stack of four individual plates in optical contact. The two thin plates in the middle of the stack are made from a birefringent material and are arranged to form a compound, zeroth order bi-plate. The remaining two plates are relatively thick and are made from an optically isotropic material. These plates are disposed on either end of the compound, zeroth order bi-plate. The low order plates minimize the sensitivity of retardation across the aperture to non-collimated light. Materials are selected to ensure transmission of ultraviolet light. The optically isotropic end plates minimize coherence effects induced at the optical interfaces of the thin plates.
Abstract:
A rotatable compensator configured to transmit non-collimated light over a broad range of wavelengths, including ultraviolet, with a high degree of retardation uniformity across the aperture is presented. In one embodiment, a rotatable compensator includes a stack of four individual plates in optical contact. The two thin plates in the middle of the stack are made from a birefringent material and are arranged to form a compound, zeroth order bi-plate. The remaining two plates are relatively thick and are made from an optically isotropic material. These plates are disposed on either end of the compound, zeroth order bi-plate. The low order plates minimize the sensitivity of retardation across the aperture to non-collimated light. Materials are selected to ensure transmission of ultraviolet light. The optically isotropic end plates minimize coherence effects induced at the optical interfaces of the thin plates.
Abstract:
An apparatus includes (i) a bright light source for providing an illumination beam at multiple wavelengths selectable with a range from a deep ultraviolet wavelength to an infrared wavelength, (ii) illumination optics for directing the illumination beam towards a sample at selectable sets of angles of incidence (AOI's) or azimuth angles (AZ's) and polarization states to provide spectroscopic ellipsometry, wherein the illumination optics include an apodizer for controlling a spot size of the illumination beam on the sample at each of the selectable AOI/AZ sets, (iii) collection optics for directing an output beam from the sample in response to the illumination beam at each of the selectable AOI/AZ sets and polarization states towards a detector that generates an output signal or image based on the output beam, and (v) a controller for characterizing a feature of the sample based on the output signal or image.