Schlumberger Technologies, Inc.

Fairchild Semiconductor Corporation

Schlumberger Systems & Services, Inc.

P A Crossley

H Keith Nishihara

Neil D Hunt

William I Lehrer

J Martin Tenenbaum

A method for determining alignment and critical dimensions of regions formed on a semiconductor structure during one or more process steps includes the steps of defining a pattern A at a first location on the semiconductor device during a process step, defining a second independent pattern B at the first location on the semiconductor structure during another process step, acquiring an image of the combination A and B of both the first and second patterns, filtering that image to attenuate higher spatial frequencies while preserving lower spatial frequencies, and comparing the sign result of the filtered image with the sign result of a stored image of the individual patterns to determine alignment errors. In the preferred embodiment the step of filtering includes taking the Laplacian of Gaussian convolution of the image and saving the sign of the result. The comparison between the filtered image and the stored image uses the correlation function for the filtered images. Special circuitry is disclosed for performing the method rapidly enough to enable commercial applications.

Mask alignment and measurement of critical dimensions in integrated

An improved lead for surface-mounted electronic components is described. The improved lead includes an opening through the portion of the lead to be placed in contact with the printed circuit board for soldering. The opening, having a diameter approximately equal to the thickness of the lead, enables the detection of correctly-soldered joints using automated inspection equipment. When the lead is correctly soldered, solder is drawn by capillary action into the opening where it forms a meniscus. By automatically detecting the curvature of the meniscus, the quality of the solder joint may be determined.

Lead design to facilitate post-reflow solder joint quality inspection

A method and apparatus for measuring feature dimensions uses selective dark-field illumination to illuminate a target from a single direction at a low angle to the plane of the target. Opposing edges of the target elements are distinguished and captured in separate images. The images are filtered using a Gaussian convolution operator and a Laplacian operator. The signs of the filtered images are correlated at various offsets. The relative displacement of the images which produces the maxium correlation value is used to calculate the average dimension of the target elements.

Method and apparatus for measuring feature dimensions using controlled

A method for directly measuring the area of a topological surface with an arbitrary boundary shape lying in a fixed elevation different from a fixed surrounding surface elevation relies upon binocular stereo vision. Three stereo correlation measurements are made, one over a window entirely within the surface of interest, a second over a window outside the surface of interest and within the surrounding area, and a third over a window fully containing the surface of interest as well as some of the surrounding area. The correlation measured in the third case is the linear sum of the correlation value over each of the first two cases weighted by the proportion of the window that the two surfaces occupy.

Method for directly measuring area and volume using binocular stereo

A photomask for use in manufacturing integrated circuits is fabricated by coating a thin film of organic material, generally a solution of a thermally decomposable hydrocarbon, onto a glass plate and heating it in a reducing atmosphere to convert it into carbon. The carbon layer is masked and etched; for example, in an oxygen plasma, to produce the mask.

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Palo Alto, CA, United States of America

P A Crossley