Abstract:
Systems and methods are disclosed for using ellipsometer configurations to measure the partial Mueller matrix and the complete Jones matrix of a system that may be isotropic or anisotropic. In one embodiment two or more signals, which do not necessarily satisfy any symmetry assumptions individually, are combined into a composite signal which satisfies a symmetry assumption. The individual signals are collected at two or more analyzer angles. Symmetry properties of the composite signals allow easy extraction of overlay information for any relative orientation of the incident light beam with respect to a ID grating target, as well as for targets comprising general 2D gratings. Signals of a certain symmetry property also allow measurement of profile asymmetry in a very efficient manner. In another embodiment a measurement methodology is defined to measure only signals which satisfy a symmetry assumption. An optional embodiment comprises a single polarization element serving as polarizer and analyzer. Another optional embodiment uses an analyzing prism to simultaneously collect two polarization components of reflected light.
Abstract:
A process for measuring both the reflectance and sheet resistance of a thin film, such as a metal film or a doped semiconductor, in a common apparatus comprises: directing a beam of radiation from a radiation source on the common apparatus onto a portion of the surface of the thin film, sensing the amount of radiation reflected from the surface of the thin film, and contacting the surface of the thin film with a sheet resistance measurement apparatus on the apparatus at a portion of the surface of the thin film coincident with or adjacent to the portion of the thin film contacted by the radiation beam to measure the sheet resistance of the thin film. The sheet resistance measurement apparatus may, by way of example, comprise a 4 point probe or an eddy current measurement apparatus. The respective measurements may be carried out either simultaneously or sequentially. By deriving the resistivity of the thin film from the measured reflectance at any particular region of the thin film surface, the thickness of the thin film, at that region of the film, may be obtained by dividing the derived resistivity by the measured sheet resistance for that same region.
Abstract:
Method and apparatus for accurately and instantaneously determining the thermodynamic temperature of remote objects by continuous determination of the emissivity, the reflectivity, and optical constants, as well as the apparent or brightness temperature of the sample with a single instrument. The emissivity measurement is preferably made by a complex polarimeter including a laser that generates polarized light, which is reflected from the sample into a detector system. The detector system includes a beamsplitter, polarization analyzers, and four detectors to measure independently the four Stokes vectors of the reflected radiation. The same detectors, or a separate detector in the same instrument, is used to measure brightness temperature. Thus, the instrument is capable of measuring both the change in polarization upon reflection as well as the degree of depolarization and hence diffuseness. This enables correction for surface roughness of the sample and background radiation, which could otherwise introduce errors in temperature measurement.
Abstract:
The present invention may include loading a diagnostic sample onto a sample stage, focusing light from an illumination source disposed on a multi-axis stage onto the diagnostic sample, collecting a portion of light reflected from a surface of the diagnostic sample utilizing a detector, wherein the illumination source and the detector are optically direct-coupled via an optical system, acquiring a set of diagnostic parameters indicative of illumination source position drift from the diagnostic sample, determining a magnitude of the illumination source position drift by comparing the acquired set of diagnostic parameters to an initial set of parameters obtained from the diagnostic sample at a previously measured alignment condition, determining a direction of the illumination source position drift; and providing illumination source position adjustment parameters configured to correct the determined magnitude and direction of the illumination source position drift to the multi-axis actuation control system of the multi-axis stage.
Abstract:
The present invention may include loading a diagnostic sample onto a sample stage, focusing light from an illumination source disposed on a multi-axis stage onto the diagnostic sample, collecting a portion of light reflected from a surface of the diagnostic sample utilizing a detector, wherein the illumination source and the detector are optically direct-coupled via an optical system, acquiring a set of diagnostic parameters indicative of illumination source position drift from the diagnostic sample, determining a magnitude of the illumination source position drift by comparing the acquired set of diagnostic parameters to an initial set of parameters obtained from the diagnostic sample at a previously measured alignment condition, determining a direction of the illumination source position drift; and providing illumination source position adjustment parameters configured to correct the determined magnitude and direction of the illumination source position drift to the multi-axis actuation control system of the multi-axis stage.
Abstract:
Methods and apparatus for measuring an optical azimuth angle φO of a substrate relative to a plane of detection in scatterometry tools are disclosed. A grating target on a stage of a scatterometry tool may be illuminated and positions of the resulting diffraction orders may be observed. The optical azimuth angle may be determined from the positions of the diffraction orders. Alternatively, polarization-dependent signals of radiation scattered from a line grating may be measured for equal and opposite polarization angles +A and −A. A combination signal may be computed from the polarization-dependent signals obtained at +A and −A and a property of the combination signal may be calculated for several mechanical Azimuth angles φM. A relationship between the optical azimuth angle φO and the mechanical azimuth angle φM may be determined from a behavior of the property as a function of mechanical azimuth angle φM.
Abstract:
A method of measuring a porosity of a film, by measuring a refractive index of the film in a first environment having a first relative humidity to produce a first refractive index measurement. The refractive index of the film is measured in a second environment having a second relative humidity, where the first relative humidity is different from the second relative humidity, to produce a second refractive index measurement. Multiple gases can be used to create the first and second environments. The first refractive index measurement and the second refractive index measurement are input into a model that correlates refractive index to film porosity, to output the porosity of the film.
Abstract:
An illumination subsystem configured to provide illumination for a measurement system includes first and second light sources configured to generate light for measurements in different wavelength regimes. The illumination subsystem also includes a TIR prism configured to be moved into and out of an optical path from the first and second light sources to the measurement system. If the TIR prism is positioned out of the optical path, light from only the first light source is directed along the optical path. If the TIR prism is positioned in the optical path, light from only the second light source is directed along the optical path. Various measurement systems are also provided. One measurement system includes an optical subsystem configured to perform measurements of a specimen using light in different wavelength regimes directed along a common optical path. The different wavelength regimes include vacuum ultraviolet, ultraviolet, visible, and near infrared wavelength regimes.
Abstract:
A method for registering multiple 3D point sets by determining optimal relative positions and orientations of the 3D point sets. Initial values are determined for the rotation matrices corresponding to the relative orientations of reference frames of the 3D point sets. A registration error cost function is optimized on a product manifold of all of the rotation matrices to determine optimal values of the rotation matrices. The optimal values of the rotation matrices are used to determine optimal values for translation vectors corresponding to the relative positions of the reference frames of the 3D point sets. The 3D point sets are registered on a common reference frame using the optimal rotation matrices and the optimal translation vectors.
Abstract:
A method and apparatus for providing facility location plans for a network are disclosed. For example, the method identifies a facility and a number of nearest active clients associated with a minimized cost per unit demand of connecting these clients to this facility. The method then connects the number of nearest active clients to the facility associated with the minimized cost per unit demand. In one embodiment, the method iterates this process with the remaining clients until all demands have been assigned to facilities.