Abstract: A standardized sample for scatterometry includes four quadrants each including an inner block surrounded by four outer blocks. A pattern of gratings is repeated within each of the blocks using different resolutions and orientations. Each grating within an outer block has a matching grating within the block's pair. A grating and its matching grating are negative images of each other—the pitch and line-size of a grating are equal, respectively to the line size and pitch of the matching grating. The inner block also includes a series of background patterns positioned behind the gratings. These patterns include repeating patterns of hole and repeating line structures. This series of structures cover a large die area, helping to simulate the conditions faced by real-world scatterometers. The various structures feature a high-degree of alignment, allowing rapid verification using SEM or other techniques.

Abstract: A combination metrology tool is disclosed for analyzing samples, and in particular semiconductor samples. The device includes a first measurement module for determining electrical characteristics of the sample. In general, such a measurement module will monitor electrical characteristics to derive information such as carrier lifetimes, diffusion lengths and surface doping. The device also includes a second measurement module for determining compositional characteristics such as layer thickness, index of refraction and extinction coefficient. The second measurement module will include a light source for generating a probe beam which interacts with the sample. A detection system is provided for monitoring either the change in magnitude or polarization state of the probe beam. The output signals from both measurement modules are combined by a processor to more accurately evaluate the sample.

Abstract: An ellipsometer includes a light source for generating a probe beam of polychromatic light for interacting with a sample. A polarizer is used to impart a known polarization state to the probe beam and the polarized probe beam is directed against the sample at a shallow angle of incidence. A rotating compensator is used to impart phase retardations to the polarization state of the reflected probe beam. After passing through the compensator, the probe beam passes through a second polarizer (analyzer). After leaving the analyzer, the probe beam is received by a detector. The detector translates the received probe beam into a signal that includes DC, 2? and 4? signal components (where ? is the angular velocity of the rotating compensator). A processor analyzes the signal using the DC, 2? and 4? components allowing simultaneous evaluation of both critical dimensions and film parameters.

Abstract: A method and apparatus are disclosed for evaluating relatively small periodic structures formed on semiconductor samples. In this approach, a light source generates a probe beam which is directed to the sample. In one preferred embodiment, an incoherent light source is used. A lens is used to focus the probe beam on the sample in a manner so that rays within the probe beam create a spread of angles of incidence. The size of the probe beam spot on the sample is larger than the spacing between the features of the periodic structure so some of the light is scattered from the structure. A detector is provided for monitoring the reflected and scattered light. The detector includes multiple detector elements arranged so that multiple output signals are generated simultaneously and correspond to multiple angles of incidence. The output signals are supplied to a processor which analyzes the signals according to a scattering model which permits evaluation of the geometry of the periodic structure.

Abstract: A combination metrology tool is disclosed which is capable of obtaining both thermal wave and optical spectroscopy measurements on a semiconductor wafer. In a preferred embodiment, the principal combination includes a thermal wave measurement and a spectroscopic ellipsometric measurement. These measurements are used to characterize ion implantation processes in semiconductors over a large dosage range.

Abstract: An ellipsometer includes a light source for generating a probe beam of polychromatic light for interacting with a sample. The probe beam is passed through a first polarizer that imparts a known polarization state to the probe beam. The polarized probe beam is then directed to reflect from the sample. A second illumination source is switched on and off at a predetermined frequency to create an intensity modulated pump beam (the beam may also be chopped). The pump beam is directed normally against the subject producing a small illumination spot within the area illuminated by the probe beam. The pump induces localized changes in the dielectric properties of the subject. The pump-beam induced oscillations are picked up by the portion of the probe beam that is reflected from within the illumination spot of the pump beam.

Abstract: The subject invention relates to a wafer stage, such as may be used in optical wafer metrology instruments. The stage contains a wafer-chuck that can be connected to translation stages for the purpose of clamping and translating the wafer so that a plurality of sites on the wafer surface may be measured. The chuck includes a holder for mounting a reference sample. The holder is movable between a retracted position where the reference sample is held below the chuck surface and an extended position, such as where the surface of the reference sample is co-planar with the wafer surface. Therefore the holder may be installed within the area of the chuck that is utilized for wafer clamping. By this arrangement, the size of the wafer translation system can be reduced minimizing the stage travel and enabling increased spatial resolution, increased wafer throughput and reduced capital equipment and operating costs.

Abstract: The use of scatterometry measurements is proposed for the evaluation of the implantation or annealing of dopants in a semiconductor. In accordance with the subject method, a probe beam of light illuminates the wafer having the dopants implanted therein. The light reflected from the sample is measured and subjected to a scatterometry analysis. The information derived is correlated to the implant region so that parameters of the implant, such as depth of a junction and lateral spreading of the implant or the dose of implanted ions can be evaluated.

Abstract: A system for characterizing periodic structures on a real time basis is disclosed. A multi-parameter measurement module generates output signals as a function of wavelength or angle of incidence. The output signals are supplied to a parallel processor, which creates an initial theoretical model and calculates the theoretical optical response. The calculated optical response is compared to measured values. Based on the comparison, the model configuration is modified to be closer to the actual measured structure. Thereafter, the complexity of the model is iteratively increased, by dividing the model into layers each having an associated width and height. The model is fit to the data in an iterative manner until a best fit model is obtained which is similar in structure to the periodic structure.

Abstract: A reduced multicubic database interpolation method is provided. The interpolation method is designed to map a function and its associated argument into an interpolated value using a database of points. The database is searched to locate an interpolation cell that includes the function argument. The interpolation cell is used to transform the function argument to reflect translation of the interpolation cell to a unit cell. The interpolated value is then generated as a cubic function using the data points that correspond to vertices of the unit cell. All of the derivatives in the cubic function are simple and the interpolation accuracy order is higher than first-order.

Abstract: A broadband ellipsometer is disclosed with an all-refractive optical system for focusing a probe beam on a sample. The ellipsometer includes a broadband light source emitting wavelengths in the UV and visible regions of the spectrum. The change in polarization state of the light reflected from the sample is arranged to evaluate characteristics of a sample. The probe beam is focused onto the sample using a composite lens system formed from materials transmissive in the UV and visible wavelengths and arranged to minimize chromatic aberrations. The spot size on the sample can be less than 3 mm and the aberration is such that the focal shift over the range of wavelengths is less than five percent of the mean focal length of the system.

Abstract: An optical measurement system for evaluating a reference sample, having at least a partially known composition, includes a reference ellipsometer and at least one non-contact optical measurement device. The ellipsometer includes a light generator, an analyzer, and a detector. The light generator generates a beam of quasi-monochromatic light of known wavelength and polarization, which is directed at a non-normal angle of incidence relative to the reference sample. The analyzer creates interference between S and P polarized components in the beam after interaction with the sample. The detector then measures the intensity of the beam, which a processor uses to determine the polarization state of the beam and, subsequently, an optical property of the reference sample. The processor then can calibrate an optical measurement device by comparing a measured optical parameter from the optical measurement device to the determined optical property from the reference ellipsometer.

Abstract: A system for characterizing periodic structures formed on a sample on a real time basis is disclosed. A spectroscopic measurement module generates output signals as a function of wavelength. The output signals are supplied to a processor for evaluation, which creates an initial theoretical model having a rectangular structure. The processor calculates the theoretical optical response of that sample, which is compared to normalized measured values at each of a plurality of wavelengths. The model configuration is then modified to be closer to the actual measured structure. The processor recalculates the optical response and compares the result to the normalized data. This process is repeated in an iterative manner until a best fit rectangular shape is obtained. Thereafter, the complexity of the model is iteratively increased, and model is iteratively fit to the data until a best fit model is obtained which is similar to the periodic structure.

Abstract: A method for improving the measurement of semiconductor wafers is disclosed. In the past, the repeatability of measurements was adversely affected due to the unpredictable growth of a layer of contamination over the intentionally deposited dielectric layers. Repeatability can be enhanced by removing this contamination layer prior to measurement. This contamination layer can be effectively removed in a non-destructive fashion by subjecting the wafer to a cleaning step. In one embodiment, the cleaning is performed by exposing the wafer to microwave radiation. Alternatively, the wafer can be cleaned with a radiant heat source. These two cleaning modalities can be used alone or in combination with each other or in combination with other cleaning modalities. The cleaning step may be carried out in air, an inert atmosphere or a vacuum. Once the cleaning has been performed, the wafer can be measured using any number of known optical measurement systems.

Abstract: An optical measurement system, including a reference ellipsometer and a non-contact optical measurement device, evaluates a sample having at least a partially known composition. The reference ellipsometer includes a light generator to generate a beam of quasi-monochromatic light of known wavelength and polarization, directed at a non-normal angle of incidence to interact with the sample. An analyzer creates interference between S and P polarized components of the reflected beam, the intensity of which is measured by a detector. A processor determines the polarization state using the detected intensity, and determines an optical property of the sample based upon the determined polarization state, the known wavelength, and the composition. The processor calibrates the optical measurement device, used to measure an optical parameter of the sample, by comparing the measured optical parameter from the optical measurement device to the determined optical property from the reference ellipsometer.

Abstract: This invention is an apparatus for imaging metrology, which in particular embodiments may be integrated with a processor station such that a metrology station is apart from but coupled to a process station. The metrology station is provided with a first imaging camera with a first field of view containing the measurement region. Alternate embodiments include a second imaging camera with a second field of view. Preferred embodiments comprise a broadband ultraviolet light source, although other embodiments may have a visible or near infrared light source of broad or narrow optical bandwidth. Embodiments including a broad bandwidth source typically include a spectrograph, or an imaging spectrograph. Particular embodiments may include curved, reflective optics or a measurement region wetted by a liquid. In a typical embodiment, the metrology station and the measurement region are configured to have 4 degrees of freedom of movement relative to each other.

Abstract: A method for modeling diffraction includes constructing a theoretical model of the subject. A numerical method is then used to predict the output field that is created when an incident field is diffracted by the subject. The numerical method begins by computing the output field at the upper boundary of the substrate and then iterates upward through each of the subject's layers. Structurally simple layers are evaluated directly. More complex layers are discretized into slices. A finite difference scheme is performed for these layers using a recursive expansion of the field-current ratio that starts (or has a base case) at the lowermost slice. The combined evaluation, through all layers, creates a scattering matrix that is evaluated to determine the output field for the subject.

Abstract: A stage system is disclosed for supporting and positioning a semiconductor wafer for inspection in an optical metrology device. A chuck for supporting a wafer is mounted to the stage system. The stage system can move the chuck along two linear orthogonal axes. A rotational stage is also provided for rotating the chuck. A mechanism is provided for adjusting the vertical position of a chuck to allow for focusing of the probe beam of the metrology device. The vertical adjustment mechanism is designed so that it does impede the rotational positioning of the chuck.

Abstract: A method and apparatus for evaluating a semiconductor wafer. A combination of a photothermal modulated reflectance method and system with a photothermal IR radiometry system and method is utilized to provide information which can be used to determine properties of semiconductor wafers being evaluated. The system and method can provide for utilizing a common probe source and a common intensity modulated energy source. The system and method further provide an infrared detector for monitoring changes in infrared radiation emitted from a sample, and photodetector for monitoring changes in beam reflected from the sample.

Abstract: An optical measurement system for evaluating a sample has a motor-driven rotating mechanism coupled to an azimuthally rotatable measurement head, allowing the optics to rotate with respect to the sample. A polarimetric scatterometer, having optics directing a polarized illumination beam at non-normal incidence onto a periodic structure on a sample, can measure optical properties of the periodic structure. An E-O modulator in the illumination path can modulate the polarization. The head optics collect light reflected from the periodic structure and feed that light to a spectrometer for measurement. A beamsplitter in the collection path can ensure both S and P polarization from the sample are separately measured. The measurement head can be mounted for rotation of the plane of incidence to different azimuthal directions relative to the periodic structures. The instrument can be integrated within a wafer process tool in which wafers may be provided at arbitrary orientation.