Abstract: A fault detection and classification system for wafer etching, tool cleaning, and other fabrication processes employs exhaust gas composition data from a Fourier transform infrared spectrometer in addition to machine-state and other process-state data. Process control may be initiated based upon the classification of a fault.

Abstract: An implementation of sensor-driven run-to-run process control for semiconductor wafer fabrication integrates a robust, automated Fourier transform infrared reflectometer onto a wafer fabrication cluster tool. Cell controller software integrates an adaptive run-to-run controller, process tool recipe upload and download through a SECS port, sensor control, data archiving, and a graphical user interface.

Abstract: A fast and practical method for the analysis of patterned samples of semiconductor integrated circuits, and other materials, determines the thickness and composition of layers fabricated during manufacture. The method employs a measurement spot that is sufficiently large to irradiate areas of two or more different regions of the sample that result from its patterned features, generally at replicable locations. In carrying out the method, one or more of reflectance, transmittance, and radiance spectrance is measured, and the various parameters characterizing the thickness and composition in the patterned areas are obtained using, for example, a model-based analysis of the polarization and amplitude of the emanating radiation, the model parameters being iteratively adjusted to achieve a match with measured values.

Abstract: A moving mirror interferometer consists of a back-to-back double mirror, operatively interposed in the paths of beams from a beamsplitter/parallel reflecting mirror combiner, and a corner cube retroreflector. One beam component from the combiner is directed toward the retroreflector, and arrives therefrom at one side of the double mirror rotated 180.degree. about its central axis; the other component from the combiner arrives at the opposite side of the double mirror without axial rotation. Alignment in the interferometer is insensitive to shearing or tilting of the optical components; the components may be semi-rigidly mounted for resilient deflection, so as to isolate them against distortion of the supporting structure, and dynamic beam path-length variation may optimally be produced by moving the corner cube retroreflector, the back-to-back double mirror, or both.

Abstract: The method determines the thickness and the free carrier concentration of at least one layer of a structure. An exposed surface of the structure is irradiated using spectral radiation, and the measured reflectance spectrum is compared to a calculated spectrum. Using algorithms that include terms representative of complex refractive indices, layer thickness, dielectric constants, and free carrier concentrations, values are iteratively assigned to the thickness and free carrier concentration parameters so as to produce a best fit relationship between the compared spectra, and to thereby determine those parameters.

Abstract: A multiplicity of one-piece flexure plates are assembled in pairs to provide a support system on which a retroreflector may be mounted for reciprocal motion. Combined with balance bodies, the flexure plates provide a support system having portions that are dynamically and statically balanced with one another, irrespective of orientation, so as to thereby immunize the unit against extraneous forces. The motion transfer assembly is especially adapted for use to support a moving retroreflector in a two-arm interferometer that may further include a beamsplitter assembly constructed from a one-piece, integrally formed body, the body having convergent, optically flat planar surfaces of specular reflectance, and means for adjustably mounting a beamsplitter therein. The spectrometer is of modular construction, and employs an integrated clocking sub-assembly as well as a light-weight voice-coil motor.

Abstract: The method and apparatus effect reversal of a body moving at constant velocity, such as an interferometer reflector, by applying a retrograde electromagnetic force that varies in direct proportion to the distance the body has travelled past the point at which turn around is commenced. Circuitry employed is switched between proportional and integral control configurations, the latter permitting sine-wave oscillation to occur in a servo control loop during reversal.

Abstract: A folded-path gas cell employs an elliptical concave mirror in confronting relationship to two substantially spherical concave mirrors. At least one of the spherical mirrors, and usually both, are formed with an added cylindrical component to increase orthogonal focii coincidence and thereby to increase the radiation energy throughput characteristic of the cell.

Abstract: Corrective factors are applied so as to remove anomalous features from the signal generated by a photoconductive detector, and to thereby render the output signal highly linear with respect to the energy of incident, time-varying radiation. The corrective factors may be applied through the use of either digital electronic data processing means or analog circuitry, or through a combination of those effects.

Abstract: The method and apparatus of the invention permit in situ determinations to be made of the temperature and optical constants of a substrate surface that is being treated, by measurements of radiance, reflectance and transmittance. These determinations in turn provide, at any given instant during processing, compositional and other information, thereby affording highly effective feedback control of the processing conditions. The apparatus comprises an integrated, small and relatively inexpensive instrument for process monitoring.

Abstract: The method and apparatus of the invention effects compression of an analog electrical signal (e.g., representing an interferogram) by introducing into it a component that is a cubic function thereof, normally as a nonlinear negative signal in a feedback loop of an Op Amp. The compressed signal will most desirably be digitized and then digitally decompressed so as to produce a signal that emulates the original.

Abstract: The apparatus and method permit simultaneous and precise determination of the temperature and spectral emittance, over a wide spectral region, of a hot sample. Radiance, and hemispherical reflectance and transmittance measurements are employed, and FT-IR technology is advantageously applied. Reflectance and (where necessary) transmittance measurements are utilized to determine the fraction of incident radiation, of selected wavelength, that is absorbed by the sample, in turn establishing a spectral emittance value. Taken with the measured radiance at the same wavelength, the spectral emittance value will provide a quantity that can be matched with the spectral radiance of a theoretical black body, again at the selected wavelength, to thereby derive the temperature of the hot sample; this in turn enables determination of the spectral emittance of the sample over a desired spectral range.