Nanometrics Inc.

Vincent J Coates

Duane C Holmes

Warren Lin

J Evan Grund

Guillermo L Toro-Lira

Stephen B Westrate

A method for determining a value of absolute reflectance of a material at a predetermined wavelength, in the ultraviolet range from its measured reflectance which includes system losses contributed by optics, illumination sources, detectors, etc. The method involves the measurement of reflectance from a known material such as single crystal silicon whose absolute reflectance is well known, dividing the measured value by the absolute value to obtain a system efficiency coefficient at the known wavelength and then, without changing the illumination or optics, measuring the reflectance of the unknown material and applying this coefficient to this measured value to obtain its absolute value.

Method for determining absolute reflectance of a material in the

A feedback method, or automatic gain control circuit, for an image photosensor at the focal plane of an optical system for very narrow linewidth measurements of images having varying intensities such as fluorescing photoresist coated lines. The feedback method includes the steps of measuring the instantaneous intensities of the entire optical beam of radiation with a photodetector and applying the output therefrom to the photosensor to thus normalize its output signal.

Method for normalizing the detection signals of magnified images of

Either resistivity or thickness of conductive thin films may be measured if the other one of the properties is known. The system employs eddy current apparatus including an alternating frequency driving coil, a detector coil mounted in a housing adjacent one surface of the thin film, and circuitry for measuring the signal across the detector coil which senses the field after it is subjected to the eddy currents generated within the conductive film. Precise adjustment of a fixed distance between coils and film surface is important and achievable by positioning the film surface at the focal point of a optical microscope objective lens to which the eddy current apparatus is coupled.

Thickness measurements of thin conductive films

A system for the precise measurement of thin dielectric films on a substrate by directing a plane polarized laser light beam to the film at the Brewster angle of the substrate and by measuring the intensity changes between a measurement from the substrate alone and from the film coated substrate. Accurate thin film measurements in the range of from about 10 to 1,500 Angstroms are possible.

Thin dielectric film measuring system

In a scanning electron microscope, a co-planar, split grid is interposed between an electron bombarded specimen and scintillator. A first positive potential is applied to one element of the split grid and a positive potential, variable with respect to the first potential, is applied to the other grid element for selectively controlling the collection of secondary emission electrons to thereby eliminate uneven secondary electron distribution that may result from various topographical features of the specimen.

Secondary electron emission control in electron microscopes

In scanning electron microscopes the field established between the focusing lens housing at ground potential and the secondary emission electron detector at a positive potential attracts and carries the secondary electrons to the detector. This field is often displaced from the secondary emission source so that much of the emission is attracted to other areas of the microscope and is lost to the detector. To greatly improve detection efficiency, an electron attracting grid at a potential between that on the detector and the focusing lens housing ground reference potential is interposed between the detector and the specimen and positioned so that the new field established between grid and lens housing dips down toward the specimen surface and thus collects substantially all of the secondary emission electrons which then are attracted to higher potential on the detector.

Three-stage secondary emission electron detection in electron microscopes

In making precision measurements with a television camera tube, the inherent scan non-linearity and magnification variations are readily calibrated by painting a grid of known dimensions on the tube face.

Linewidth measuring with linearity calibration of the T.V. camera tube

Very narrow lines, such as integrated circuit conductors, are accurately measured with consistent accuracy using a microscope that projects the image of the narrow object against a slit behind which is a photomultiplier tube. The photomultiplier tube and slit are moved in very small steps under the control of a microcomputer that measures the photomultiplier tube amplitude at each step, eliminates background error due to illumination irregularities, etc., and provides a printout of the line width in micrometers or microinches.

Computerized micromeasuring system and method therefor

A method for determining the precise exposure for a photoresist coating by measuring the coating thickness with a microspectrophotometer that provides data for plotting a nearly sinusoidal curve of percent reflectivity versus wavelength. The nominal exposure derived from the thickness measurement is then corrected to a precise value by extrapolation and normalization of the curve at the photosensitive wavelength of the photoresist.

Growing community of inventors

Palo Alto, CA, United States of America

Vincent J Coates