Rca Inc.

General Electric Company

Hans P Kleinknecht

Wolfram A Bosenberg

Karl H Knop

Heinrich Meier

Michael T Gale

William Edward Ham

James Kane

Helmut G Kiess

A dimension of an object disposed on a substrate, such as the width of a line of material deposited on a substrate in an integrated circuit manufacturing procedure, is measured by directing a plane wave of electromagnetic energy of predetermined dimensions toward the object at a predetermined angle of incidence. Electromagnetic energy scattered from two predetermined parts or features, such as the edges, of the object are combined so that they produce an interference pattern in space varying between maxima and minima. The characteristics of the interference pattern permit the dimension of the object to be deduced.

Apparatus and method for optical dimension measurement using

An optical imager includes a sensor and a diffraction lenticular array. The sensor includes a substrate of a semiconductor material having a pair of opposed major surfaces and a plurality of photodetectors arranged in a plurality of columns along one of the major surfaces. The diffraction lenticular array includes a plurality of stripes of a material which will diffract the radiation being sensed. The stripes are arranged in a plurality of repetitive patterns with each pattern being formed of a plurality of spaced, parallel stripes extending longitudinally along a column of the detectors. The pattern of the stripes has a large spacing between the stripes at the center of the pattern and smaller spacing at the edges of the pattern. The stripes may be on a separate substrate of a material which is transparent to the radiation being detected or directly on the major surface of the semiconductor substrate.

Optical imager with diffractive lenticular array

A high resolution periodic pattern is formed in a layer of a photosensitive material by means of a beam of light and a lenticular array formed of a plurality of lenslets. The lenticular array is positioned over the layer and the beam of light is directed through the lenticular array onto the layer. The beam of light is scanned across the lenticular array to pass through the individual lenslets which defines the light into a fine beam and thereby exposes a small area of the layer. The beam is shaped to achieve a periodic pattern in the layer as the beam scans across the layer. By moving the layer in synchronism with the scanning, a two dimensional array of the pattern can be obtained.

Method and apparatus for forming large area high resolution patterns

An optical profilometer for surface contours subject to tilt is optically scanned to measure the surface contours. Surface tilt effects are obviated by slitted apertures in the paths of the reflection beams to pass the beams with large surface tilts (on the order of 30.degree.) without loss of sensitivity, accuracy, or precision.

Optical profilometer for steep surface contours with significant surface

An apparatus and method for determining the doping profile of an epitaxial layer of a semiconductor as a function of conductivity (or resistivity) vs. distance (depth) includes modifying a d.c. generated current by a focused laser beam modulated at high frequencies in the order of 20 MHz, and directed in sequence on a point-by-point basis to the layer surface. Photocurrent variations from point-to-point effected by the laser beam striking the layer at each of the sequence of points are detected to provide a signal related to conductivity, (or, if desired, resistivity) of the layer material.

Method and apparatus for determining the doping profile in epitaxial

An automatic photomask alignment system for projection printing includes a monochromatic light source, such as a laser, a series of diffraction patterns which are located on a semiconductor wafer in locations where alignments are to be made, at least one key which is located on a photomask with which the wafer is to be aligned, and a projection lens system. A light beam from the monochromatic light source is directed about the key on the photomask and through the projection lens system onto one of the diffraction patterns on the substrate to provide a pattern of light spots whose intensities at various locations are determined by the relative alignment of the key and the diffraction grating. A step and repeat mechanism is used to move the semiconductor wafer relative to the image of the photomask pattern which is projected onto the wafer while a feedback arrangement, which employs photocells and servo motors for aligning the locations where devices are to be formed on the substrate relative to the photomask, provides the alignment of the projected image with the proper locations for their formation.

Automatic photomask alignment system for projection printing

The image transfer process in integrated circuit (IC) processes such as large scale integrated (LSI) device process manufacturing is monitored by optical measurements on a stage-by-stage basis by measuring a monitor specimen or test sample formed with a diffraction grating of a predetermined pattern having a strip width corresponding to the desired line widths of the wafers or masks being monitored. A beam of monochromatic light is scanned over the test sample to generate diffracted beams of various orders. Line width, line depth, line edge profile process errors can be determined by various combinations of the diffracted beams of the zero, first, second, etc., orders. The test sample is scanned to generate a display for data representing the diffracted beams. The parameter data can be stored for later use for quality control, process monitoring, circuit design parameters, and the like. Moreover, gross process errors are visually discernible on the monitor specimen.

Optical measurements of fine line parameters in integrated circuit

Optical monitoring of the lateral dimensions of a pattern disposed on a substrate in the form of a wafer or mask is accomplished by testing for the lateral dimensions of a diffraction grating test pattern disposed adjacent the pattern. A beam of monochromatic light such as from a laser is diffracted by the test pattern and detectors determine the intensity of the diffracted beams. The detectors are disposed in a plane orthogonal to the plane of the test pattern and to the direction of the grating lines. The detectors are selectively spaced from each other according to the periodicity d of the grating and the width of the grating lines a is determined from a relationship of the detected intensities of the beams.

Optical line width measuring apparatus and method

A method of optically testing the lateral dimensions of a pattern of material disposed on a substrate comprises applying the material to both the main area of the substrate and a test area on the same substrate, and selectively removing the material from both areas on the substrate simultaneously to form respectively the pattern on the main area and a diffraction grating on the test area. The diffraction grating is exposed to a beam of light, and the intensity of two of the diffracted beams is measured to obtain a ratio signal (I.sub.2 /I.sub.1), which is then utilized to determine the lateral dimensional tolerance of the integrated circuit pattern.

Optically testing the lateral dimensions of a pattern

A method of optically testing electrical parameters of a surface of a semiconductor including carrier mobility and recombination time is disclosed which includes the step of irradiating the surface with a first beam of monochromatic light having a wavelength less than the wavelength corresponding to the band-gap energy of the semiconductor, resulting in the excitation of electrons and holes at the semiconductor surface. The surface is simultaneously irradiated with a second beam of monochromatic light having a wavelength larger than the wavelength corresponding to the band-gap energy of the semiconductor, whereby part of the second beam is reflected from the surface. The intensity of this reflected beam is measured and the magnitude thereof is a measure of the carrier mobility and recombination time at the semiconductor surface.

Optical testing of a semiconductor

An automatic photomask alignment system includes a monochromatic light source, such as a laser, a series of diffraction patterns which are located on a semiconductor substrate and keys which are located on photomasks with which the substrate is to be aligned. A light beam is directed through the key on a photomask onto the diffraction pattern to provide a pattern of light spots whose intensities at various locations are determined by the relative alignment of the mask and the diffraction grating. A feedback arrangement which employs photocells and means for moving the photomasks relative to the substrate provides the alignment of the photomasks with the substrate.

Photomask alignment system

A method of optically measuring the concentration of carriers in a doped region of a semiconductor wafer includes the step of selectively introducing conductivity modifiers into both the wafer and a test substrate simultaneously to form respectively the doped region in the wafer and a diffraction grating pattern in the substrate including periodically-spaced doped strips. The diffraction grating pattern is exposed to a beam of monochromatic light, and the intensity of one of the diffracted beams is measured, whereby the magnitude thereof is a measure of the carrier concentration in the doped region.

Optically measuring the carrier concentration in a semiconductor

A method of optically monitoring the thickness of a layer of material being deposited on a substrate within a reaction chamber comprises forming on a body a diffraction grating profile, exposing the grating profile to a beam of light while depositing the material on both the substrate and the grating profile, whereby the grating profile functions as a relief pattern diffracting the light beam into diffracted beams of various orders, measuring the intensity of the first order (I.sub.1) and second order (I.sub.2) beams to obtain a ratio signal (I.sub.2 /I.sub.1), and then transmitting the ratio signal to processing means for determining the aspect groove width of the relief pattern, whereby the thickness of the depositing layer is determined from a pre-established relationship dependent upon the aspect groove width.

Optically monitoring the thickness of a depositing layer

A technique for optically monitoring the undercutting of a layer of material being selectively etched beneath a pattern of masking material in an etchant comprises forming on a layer of the material being etched a diffraction grating pattern including spaced strips of masking material having a strip width W, exposing the diffraction grating pattern, while positioned in the etchant, to a beam of monochromatic light, whereby the grating pattern together with the layer of material therebeneath functions as a relief pattern which diffracts the beam of light into diffracted beams of various orders, and then monitoring certain of said diffracted beams to determine when a sharp decrease in the intensity thereof occurs, such a sharp decrease indicating an undercutting equal to a distance of W/2.

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Bergdietikon, Switzerland

Hans P Kleinknecht