Abstract: An optical inspection device generates a plurality of measured optical data from inspection of a thin film stack. A processor evolves models of theoretical data, which are compared to the measured data, and a "best fit" solution is provided as the result. Each model of theoretical data is represented by an underlying "genotype" which is an ordered list of "genes." Each gene corresponds to a selected thin film parameter of interest. Many such individual genotypes are created thereby forming a "population" of genotypes, which are evolved through the use of a genetic algorithm. Each genotype has a fitness associated therewith based on how much the theoretical data derived therefrom differs from the measured data. Individual genotypes are selected based on fitness, then a genetic operation is performed on the selected genotypes to produce new genotypes. Multiple generations of genotypes are evolved until an acceptable solution is obtained.

Abstract: An optical measurement system for evaluating a reference sample that has at least a partially known composition. The optical measurement system includes a reference ellipsometer and at least one non-contact optical measurement device. The reference ellipsometer includes a light generator, an analyzer and a detector. The light generator generates a beam of quasimonochromatic light having a known wavelength and a known polarization for interacting with the reference sample. The beam is directed at a non-normal angle of incidence relative to the reference sample to interact with the reference sample. The analyzer creates interference between the S and P polarized components in the light beam after the light beam has interacted with reference sample. The detector measures the intensity of the light beam after it has passed through the analyzer.

Abstract: An ellipsometer, and a method of ellipsometry, for analyzing a sample using a broad range of wavelengths, includes a light source for generating a beam of polychromatic light having a range of wavelengths of light for interacting with the sample. A polarizer polarizes the light beam before the light beam interacts with the sample. A rotating compensator induces phase retardations of a polarization state of the light beam wherein the range of wavelengths and the compensator are selected such that at least a first phase retardation value is induced that is within a primary range of effective retardations of substantially 135.degree. to 225.degree., and at least a second phase retardation value is induced that is outside of the primary range. An analyzer interacts with the light beam after the light beam interacts with the sample. A detector measures the intensity of light after interacting with the analyzer as a function of compensator angle and of wavelength, preferably at all wavelengths simultaneously.

Abstract: An optical inspection device generates a plurality of measured optical data from inspection of a thin film stack. A processor evolves models of theoretical data, which are compared to the measured data, and a "best fit" solution is provided as the result. Each model of theoretical data is represented by an underlying "genotype" which is an ordered list of "genes." Each gene corresponds to a selected thin film parameter of interest. Many such individual genotypes are created thereby forming a "population" of genotypes, which are evolved through the use of a genetic algorithm. Each genotype has a fitness associated therewith based on how much the theoretical data derived therefrom differs from the measured data. Individual genotypes are selected based on fitness, then a genetic operation is performed on the selected genotypes to produce new genotypes. Multiple generations of genotypes are evolved until an acceptable solution is obtained.

Abstract: An optical measurement system for evaluating a reference sample that has at least a partially known composition. The optical measurement system includes a reference ellipsometer and at least one non-contact optical measurement device. The reference ellipsometer includes a light generator, an analyzer and a detector. The light generator generates a beam of quasi-monochromatic light having a known wavelength and a known polarization for interacting with the reference sample. The beam is directed at a non-normal angle of incidence relative to the reference sample to interact with the reference sample. The analyzer creates interference between the S and P polarized components in the light beam after the light beam has interacted with reference sample. The detector measures the intensity of the light beam after it has passed through the analyzer.

Abstract: An optical measurement device is disclosed for evaluating the parameters of a sample. The device includes a polychromatic source for generating a probe beam. The probe beam is focused on the sample surface. Individual rays within the reflected probe beam are simultaneously analyzed as a function of the position within the beam to provide information at multiple wavelengths. A filter, dispersion element and a two-dimensional photodetector array may be used so that the beam may be simultaneously analyzed at multiple angles of incidence and at multiple wavelengths. A variable image filter is also disclosed which allows a selection to be made as to the size of the area of the sample to be evaluated.

Abstract: An optical inspection apparatus is disclosed for generating an ellipsometric output signal at a plurality of wavelengths, each signal being representative of an integration of measurements at a plurality of angles of incidence. A polarized, broad band light beam is focused through a lens onto a sample in a manner to create a spread of angles of incidence. The reflected beam is passed through a quarter-wave plate and a polarizer which creates interference effects between the two polarizations states in the beam. The beam is then passed through a filter which transmits two opposed radial quadrants of the beam and blocks light striking the remaining two quadrants. The beam is then focused and angularly dispersed as function of wavelength. Each element of a one dimensional photodetector array generates an output signal associated with a specific wavelength and represents an integration of the phase-sensitive ellipsometric parameter (.delta.) at a plurality of angles of incidence.

Abstract: An optical measurement device is disclosed for evaluating the parameters of a sample. The device includes a polychromatic source for generating a probe beam. The probe beam is focused on the sample surface. Individual rays within the reflected probe beam are simultaneously analyzed as a function of the position within the beam to provide information at multiple wavelengths. A filter, dispersion element and a two-dimensional photodetector array may be used so that the beam may be simultaneously analyzed at multiple angles of incidence and at multiple wavelengths. A variable image filter is also disclosed which allows a selection to be made as to the size of the area of the sample to be evaluated.

Abstract: An apparatus is disclosed for evaluating thermal and electrical characteristics of a sample. An intensity modulated pump beam is focused onto the surface of a sample at one spot. A non-modulated probe beam is focused onto the sample at a second spot, spaced laterally and vertically from the first spot. The distance between the two spots is at least two microns. The modulated power of the reflected probe beam that is in phase with the pump beam modulation frequency is monitored to provide information about the characteristics of the sample. The apparatus is particularly useful in evaluating the integrity of metal lines and vias in a semiconductor sample.

Abstract: A method and apparatus is disclosed for measuring the thickness or other optical constants of a thin film on a sample. The apparatus includes a laser for generating a linearly polarized probe beam. The probe beam is tightly focused on the sample surface to create a spread of angles of incidence. The reflected probe beam is passed through a quarter-wave plate and linear polarizer before impinging on a quad cell photodetector. The output signals from the photodetector represent an integration of the intensity of individual rays having various angles of incidence. By taking the difference between the sums of the output signals of diametrically opposed quadrants, a value can be obtained which varies linearly with film thickness for very thin films. The subject device can be used in conjunction with other prior devices to enhance sensitivity for thicker films.

Abstract: An approach for increasing the sensitivity of a high resolution measurement device 50 is disclosed. The device includes a laser 52 for generating a probe beam 54 which is tightly focused onto the surface of the sample 58. A detector 66 is provided for monitoring a parameter of the reflected probe beam. In accordance with the subject invention, a spatial filter is provided for reducing the amount of light energy reaching the detector that has been reflected from areas on the surface of the sample beyond the focused spot. The spatial filter includes a relay lens 68 and a blocking member 70 located in the focal plane of the lens. The blocking member 70 includes an aperture 72 dimensioned to block light reflected from the surface of the sample beyond a predetermined distance from the center of the focused spot. In this manner, greater sensitivity to sample characteristics within the highly focused spot is achieved.

Abstract: An apparatus (10) is disclosed for evaluating the size of grains in a metalized layer on a semiconductor sample (12). The apparatus includes a laser (20) for generating a probe beam (22). The probe beam is focused to a diameter of about one micron and scanned over the surface of the sample. Variations in the power of the specularly reflected beam are measured. In one aspect of the subject invention, the spacing between minima in the reflectivity signal is used to give a direct measurement of average grain size. The depth of the minima can be used to derive a distribution of the grain size. For very small grains, a statistical evaluation of the reflectivity signal is performed to derive grain size.

Abstract: An apparatus (10) designed to evaluate ion implantation levels in semiconductor samples (42) is disclosed. The device includes an intensity modulated pump laser beam (22) and a probe beam (62) having a different wavelength than the pump beam. The two laser beams are focused on a coincident spot on the surface of the sample. Detectors (80, 96) are provided for measuring the non-modulated reflected power of the pump and probe beams. In addition, the modulated reflected power of the probe beam, that is in phase with the intensity modulated pump beam, is also measured. These three independent measurements are utilized to derive the implant dosage level in the semiconductor sample.

Abstract: A method and apparatus are disclosed for evaluating surface and subsurface features in a semiconductor sample. In operation, a periodic energy source is applied to the surface of the semiconductor sample to generate a periodic electron-hole plasma. This plasma interacts with features in the sample as it diffuses. The plasma affects the index of refraction of the sample and the changing plasma density is monitored using a radiation probe. In the preferred embodiment, the radiation probe measures the plasma induced periodic changes of reflectivity of the surface of the sample to yield information about the sample, such as ion dopant concentrations, residue deposits and defects.

Abstract: In an ellipsometric apparatus, a laser is provided for generating a probe beam. The probe beam is passed through a polarization section to give the beam a known polarization state. The probe beam is then tightly focused with a high numerical aperture lens onto the surface of the sample. The polarization state of the reflected probe beam is analyzed. In addition, the angle of incidence of one or more rays in the incident probe beam is determined based the radial position of the rays within the reflected probe beam. This approach provides enhanced spatial resolution and allows measurement over a wide spread of angles of incidence without adjusting the position of the optical components. Multiple angle of incidence measurements are greatly simplified.

Abstract: An apparatus (20) for measuring the thickness of a thin film layer (32) on substrate (28) includes a probe beam of radiation (24) focused substantially normal to the surface of the sample using a high numerical aperture lens (30). The high numerical aperture lens (30) provides a large spread of angles of incidence of the rays within the incident focused beam. A detector (50) measures the intensity across the reflected probe beam as a function of the angle of incidence with respect to the surface of the substrate (28) of various rays within the focused incident probe beam. A processor (52) functions to derive the thickness of the thin film layer based on these angular dependent intensity measurements. This result is achieved by using the angular dependent intensity measurements to solve the layer thickness using variations of the Fresnel equations. The invention is particularly suitable for measuring thin films, such as oxide layers, on silicon semiconductor samples.

Abstract: A method and apparatus are disclosed for evaluating surface and subsurface features in a semiconductor sample. In operation, a periodic energy source is applied to the surface of the semiconductor sample to generate a periodic electron-hole plasma. This plasma interacts with features in the sample as it diffuses. The plasma affects the index of refraction of the sample and the changing plasma density is monitored using a radiation probe. In the preferred embodiment, the radiation probe measures the plasma induced periodic changes of reflectivity of the surface of the sample to yield information about the sample, such as ion dopant concentrations, residue deposits and defects.

Abstract: A method and apparatus are disclosed for evaluating surface and subsurface features in a semiconductor sample. In operation, a periodic energy source is applied to the surface of the semiconductor sample to generate a periodic electron-hole plasma. This plasma interacts with features in the sample as it diffuses. The plasma affects the index of refraction of the sample and the changing plasma density is monitored using a radiation probe. In the preferred embodiment, the radiation probe measures the plasma induced periodic changes of reflectivity of the surface of the sample to yield information about the sample, such as ion dopant concentrations, residue deposits and defects.

Abstract: The subject invention relates to a method and apparatus for identifying and testing the location of areas of interest on a workpiece and specifically, unmasked areas on a semiconductor wafer. In the subject method, the surface of the wafer is scanned with a search beam of radiation. The power of the reflected search beam will be a function of the optical reflectivity of the surface of the sample. Since the optical reflectivity of the unmasked areas are different from the masked areas, the power measurement of the reflected search beam can be used to identify the location of areas to be measured. In the preferred testing procedure, an intensity modulated pump beam is used to periodically excite a region in the identified unmasked area.

Abstract: A method and apparatus is disclosed for detecting defect surface states in any material and in particular semiconductors. In the subject device, a periodic localized excitation is generated at the surface of the sample with an intensity modulated pump laser beam. A probe laser beam is directed to the surface of the sample and changes in the probe beam which are in phase with the modulated pump frequency are detected. In the preferred embodiment, periodic changes in the optical reflectivity of the surface of the sample induced by an intensity modulated excitation beam are detected by measuring the corresponding modulations in the reflected power of the probe beam. Any time dependence of the probe beam modulated reflectance signal is monitored. An evaluation of defect surface states is then made by investigating the time dependence of the magnitude and/or phase of this probe beam modulated reflectance signal.