Abstract: In a measuring system, a method for evaluating parameters of a workpiece includes measuring a periodic structure, such as a grating, on the workpiece to produce image data. An orientation of features in the image data, produced by higher order diffractions from the periodic structure, is identified. An orientation of the periodic structure is determined based on the orientation of the features in the image data. The image data is then modified, based on the orientation of the periodic structure, to correlate with, and for comparison to, simulated image data to ascertain parameters of the workpiece. Alternatively, optical components in the measuring system, or the workpiece itself, are adjusted to provide a desired alignment between the optical components and the periodic structure. A microstructure on the workpiece may then be measured, and the resulting image data may be compared to the simulated image data to ascertain parameters of the microstructure.

Abstract: A method and apparatus identifies defects in a sample using photoluminescence with a silicon filter to filter out the primary excitation light from the return light received by the detector. The silicon filter passes the light emitted by the sample in response to the excitation light, while absorbing the lower wavelength excitation light that is reflected by or transmitted through the sample. The silicon filter has introduced impurities that reduce the recombination lifetime which reduces or eliminate photoluminescence in the silicon filter in response to the excitation light, thereby improving the signal to noise ratio of the signal received by the detector.

Abstract: One or more parameters of a sample that includes a textured substrate and one or more overlying films is determined using, e.g., an optical metrology device to direct light to be incident on the sample and detecting light after the incident light interacts with the sample. The acquired data is normalized using reference data that is produced using a textured reference sample. The normalized data is then fit to simulated data that is associated with a model having an untextured substrate and one or more variable parameters. The value(s) of the one or more variable parameters from the model associated with the simulated data having the best fit is reported as measurement result.

Abstract: Asymmetry metrology is performed using at least a portion of Mueller matrix elements, including, e.g., the off-diagonal elements of the Mueller matrix. The Mueller matrix may be generated using, e.g., a spectroscopic or angle resolved ellipsometer that may include a rotating compensator. The Mueller matrix is analyzed by fitting at least a portion of the elements to Mueller matrix elements calculated using a rigorous electromagnetic model of the sample or by fitting the off-diagonal elements to a calibrated linear response. The use of the Mueller matrix elements in the asymmetry measurement permits, e.g., overlay analysis using in-chip devices thereby avoiding the need for special off-chip targets.

Abstract: In an overlay metrology method used during semiconductor device fabrication, an overlay alignment mark facilitates alignment and/or measurement of alignment error of two layers on a semiconductor wafer structure, or different exposures on the same layer. A target is small enough to be positioned within the active area of a semiconductor device combined with appropriate measurement methods, which result in improved measurement accuracy.

Abstract: A sealing ring assembly and an improved method for mounting a sealing ring into an electrochemical cell used for Electrochemical Capacitance Voltage (ECV) profiling measurements. The ring is located in a holder having at least one secondary bore providing fluid communication between a forward face of the holder and the central bore of the ring, directed parallel to but tangentially offset relative to the inner wall of the central bore so as to impart a degree of rotational flow to electrolyte entering the sealing ring through the or each secondary bore which effectively removes gas bubbles and refreshes the electrolyte. The holder facilitates ring removal with a much reduced risk of damage to the delicate sealing surface.

Abstract: The process of modeling a complex two-dimensional periodic structure is improved by selectively truncating the Fourier expansion used in the calculation of resulting scatter signature from the model. The Fourier expansion is selectively truncated by determining the contribution for each harmonic order in the Fourier transform of the permittivity function and retaining the harmonic orders with a contribution that is above a threshold. The Fourier space may be compressed so that only the selected harmonic orders are used, thereby reducing the required memory and calculation times. The compressed Fourier space may be used in a real-time analysis of a sample or to generate a library that is used in the analysis of a sample.

Abstract: Overlay error between two layers on a substrate is measured using an image of an overlay target in an active area of a substrate. The overlay target may be active features, e.g., structures that cause the device to function as desired when manufacturing is complete. The active features may be permanent structures or non-permanent structures, such as photoresist, that are used define the permanent structures during manufacturing. The image of the overlay target is analyzed by measuring the light intensity along one or more scan lines and calculating a symmetry values for the scan lines. Using the symmetry values, the overlay error can be determined.

Abstract: A method of automatically focusing a microscope in which a beam of light is directed from a light source through an objective of the microscope system to an object whereby light is reflected from the surface thereof; reflected light is collected and directed to an imaging system. The incident beam of light is limited in spatial extent by imaging an aperture to form an illumination pupil, the centroid of illumination of the illumination pupil is aligned with the incident optical axis of the instrument. The reflected light is split in the imaging system into at least one pair of images from eccentric sections of an imaging pupil displaced from the optical axis in opposite directions. The separation of the images thereby produced is determined to provide an indication of the object distance. A focusing system implementing the method and a microscope fitted with such a system are also described.

Abstract: Non-contact apparatus and methods for evaluating at least one of the DC (or RF) dielectric constant, the hardness, and Young's Modulus of a dielectric material on a microelectronic workpiece under process and for generating a correlation factor that relates a measured IR spectrum to at least one of the dielectric constant, the hardness, and Young's Modulus of the dielectric material. A specific example of a method comprises measuring a thickness of the dielectric material on the process workpiece, irradiating the process workpiece with an IR source, and collecting and measuring an IR spectrum from the process workpiece. The measured thickness and at least a portion of the measured IR spectrum from the process workpiece are used with the correlation factor to determine at least one of the dielectric constant, the hardness, and Young's Modulus of the dielectric material. The determined value from the correlation factor is then stored and/or displayed.

Abstract: The present disclosure provides methods and apparatus that enable characterization of an electrical property of a semiconductor specimen, e.g., dopant concentration of a near-surface region of the specimen. In exemplary method, a target depth for measurement is selected. This thickness may, for example, correspond to a nominal production thickness of a thin active device region of the specimen. A light is adjusted to an intensity selected to characterize a target region of the specimen having a thickness no greater than the target depth and a surface of the specimen is illuminated with the light. An AC voltage signal induced in the specimen by the light is measured and this AC voltage may be used to quantify an aspect of the electrical property, e.g., to determine dopant concentration, of the target region.

Abstract: In a measuring system, a method for evaluating parameters of a workpiece includes measuring a periodic structure, such as a grating, on the workpiece to produce image data. An orientation of features in the image data, produced by higher order diffractions from the periodic structure, is identified. An orientation of the periodic structure is determined based on the orientation of the features in the image data. The image data is then modified, based on the orientation of the periodic structure, to correlate with, and for comparison to, simulated image data to ascertain parameters of the workpiece. Alternatively, optical components in the measuring system, or the workpiece itself, are adjusted to provide a desired alignment between the optical components and the periodic structure. A microstructure on the workpiece may then be measured, and the resulting image data may be compared to the simulated image data to ascertain parameters of the microstructure.

Abstract: An apparatus and method for improving the accuracy of Electrochemical Capacitance Voltage (ECV) profiling measurements by alerting the operator to the presence of surface films or gas bubbles during the etching process and by using this in-situ monitoring apparatus to determine the true measurement area at the end of the measurement cycle and using the new value to recalculate the data. By making the area measurement integral to the ECV tool, every sample measurement can be corrected for the true measurement area, leading to improved accuracy and eliminating a large source of error.

Abstract: An optical metrology system collects spectral data while scanning over the focal range. The spectral data is evaluated to determine a plurality of peak intensity values for wavelengths in the spectra. The peak intensities are then combined to form the measured spectrum for the sample, which can then be used to determine the sample properties of interest. In one embodiment, the peak intensity is determined based on the measured maximum intensity and a number n of intensity values around the measured maximum intensity, e.g., using curve fitting. If desired, the number n may be varied as a function of wavelength to vary the effective spot size of the metrology system while optimizing noise performance. The peak intensity may also be derived as the measured maximum intensity or through a statistical analysis.

Abstract: The present disclosure provides methods and apparatus that enable characterization of an electrical property of a semiconductor specimen, e.g., dopant concentration of a near-surface region of the specimen. In exemplary method, a target depth for measurement is selected. This thickness may, for example, correspond to a nominal production thickness of a thin active device region of the specimen. A light is adjusted to an intensity selected to characterize a target region of the specimen having a thickness no greater than the target depth and a surface of the specimen is illuminated with the light. An AC voltage signal induced in the specimen by the light is measured and this AC voltage may be used to quantify an aspect of the electrical property, e.g., to determine dopant concentration, of the target region.

Abstract: In a measuring system, a method for evaluating parameters of a workpiece includes measuring a periodic structure, such as a grating, on the workpiece to produce image data. An orientation of features in the image data, produced by higher order diffractions from the periodic structure, is identified. An orientation of the periodic structure is determined based on the orientation of the features in the image data. The image data is then modified, based on the orientation of the periodic structure, to correlate with, and for comparison to, simulated image data to ascertain parameters of the workpiece. Alternatively, optical components in the measuring system, or the workpiece itself, are adjusted to provide a desired alignment between the optical components and the periodic structure. A microstructure on the workpiece may then be measured, and the resulting image data may be compared to the simulated image data to ascertain parameters of the microstructure.

Abstract: This disclosure provides methods for measuring asymmetry of features, such as lines of a diffraction grating. On implementation provides a method of measuring asymmetries in microelectronic devices by directing light at an array of microelectronic features of a microelectronic device. The light illuminates a portion of the array that encompasses the entire length and width of a plurality of the microelectronic features. Light scattered back from the array is detected. One or more characteristics of the back-scattered light may be examined by examining data from the complementary angles of reflection. This can be particularly useful for arrays of small periodic structures for which standard modeling techniques would be impractically complex or take inordinate time.

Abstract: An overlay error is determined using a diffraction based overlay target by generating a number of narrow band illumination beams that illuminate the overlay target. Each beam has a different range of wavelengths. Images of the overlay target are produced for each different range of wavelengths. An intensity value is then determined for each range of wavelengths. In an embodiment in which the overlay target includes a plurality of measurement pads, which may be illuminated and imaged simultaneously, an intensity value for each measurement pad in each image is determined. The intensity value may be determined statistically, such as by summing, finding the mean or median of the intensity values of pixels in the image. Spectra is then constructed using the determined intensity value, e.g., for each measurement pad. Using the constructed spectra, the overlay error may then be determined.

Abstract: Scatterometers and methods of using scatterometry to determine several parameters of periodic microstructures, pseudo-periodic structures, and other very small structures having features sizes as small as 100 nm or less. Several specific embodiments of the present invention are particularly useful in the semiconductor industry to determine the width, depth, line edge roughness, wall angle, film thickness, and many other parameters of the features formed in microprocessors, memory devices, and other semiconductor devices. The scatterometers and methods of the invention, however, are not limited to semiconductor applications and can be applied equally well in other applications.

Abstract: A model of a sample with a periodic or non-periodic pattern of conductive and transparent materials is produced based on the effect that the pattern has on TE polarized incident light. The model of the pattern may include a uniform film of the transparent material and an underlying uniform film of the conductive material. When the pattern has periodicity in two directions, the model may include a uniform film of the transparent material and an underlying portion that based on the physical characteristics of the periodic pattern in the TM polarization direction. When the sample includes an underlying periodic pattern that is orthogonal to the top periodic pattern, the sample may be modeled by modeling the physical characteristics of the top periodic pattern and the effect of the bottom periodic pattern. The model may be stored and used to determine a characteristic of the sample.