International Business Machines Corporation

Edward V Weber

Donald E Davis

Hans C Pfeiffer

Philip M Ryan

Guenther O Langner

Cecil T Ho

Robert A Simpson

Ollie C Woodard

Werner Stickel

William A Enichen

Jan Rogoyski

Ralph R Trotter

Alan V Hall

Merlyn H Perkins

Richard D Moore

Ken Tze-Kin Chan

Maurice C Williams

John F Loughran

Wallace J Guillaume

Don F Haire

A pattern is aligned and exposed with a lithography system so that chips larger than the deflection field can be formed by exposing M.times.N fields in a mosaic pattern. The method corrects the deflection field to compensate for the orientation of a previous pattern on a substrate and compensates for errors due to height caused by the beam landing non perpendicular to the target. Two basic procedures disclosed are called '3-mark' which are only applicable to 2.times.2 arrays of fields, and 'M.times.N' which covers the general situation, but with slightly less accuracy.

Registration of patterns formed of multiple fields

A dynamic correction arrangement for an electron beam projection/deflection system provides high order correction values for deflection in accordance with a correction equation. Particularly as applied to high accuracy telecentric deflection, the coefficients of terms of the correction equation may be determined by calibration for a small number of test points. Correction values may be stored in a look-up table or computed in real time by using a math co-processor in a processing pipeline. The correction provided corrects landing angle errors through the third order in telecentric projection/deflection systems such as systems utilizing variable axis immersion lenses.

Dynamic compensation of non-linear electron beam landing angle in

A method of forming inspection patterns for inspecting a workpiece, e.g., for electron beam inspection of optical photomasks. The inspection patterns are formed from the workpiece patterns themselves by applying a first positive windage to the workpiece patterns, inverting the first positive windaged workpiece patterns and applying a second positive windage to the inverted first positive windaged workpiece patterns. The inspection patterns so produced will contain the requisite guard band and the requisite overlap of abutting patterns.

Method for generating inspection patterns

An alignment system for registration of a scanning beam in a mask inspection tool. Minimum scan widths (W) in the registration process are attained thereby increasing registration sensitivity. This technique allows initial placement of the E-Beam to be outside the capture range so that the scan on one side is completely off the metal (on glass) and the scan on the other side is completely on the metal. Correction signals are obtained by comparing the backscattered electron signals from the two scans with the magnitude of the signal being indicative of the amount of correction required and the sign being indicative of the direction of correction.

Alignment technique

This describes an automatic defect inspection system as could be applied to metallized masks or other patterns. The system causes each subfield to be individually aligned for inspection irrespective of the previous alignment of the pattern or any other sub-field. This is accomplished by scanning a preselected portion of each sub-field and adjusting the position of the scan based on the resulting signal while scanning a pre-established portion of the sub-field. In this way a portion of each sub-field is used as an alignment mark and stepping errors avoided. Once alignment is achieved a probe, comparable to the size of the minimum defect to be detected is scanned over the sub-field with an overlapping pattern to find defects such as excessive metal, metal in improper places or points where the metal is missing.

Pattern inspection tool - method and apparatus

In electron beam apparatus having a souce of electrons and a target area toward which the electrons are directed, electron beam forming means are provided along the path from the source to the target. These forming means include a first beam shaping member having a first spot shaping aperture therein, a second beam shaping member having a second spot shaping aperture therein, and means focusing the image of the first aperture in the plane of the second aperture to thereby form a composite spot shape defined by the image of the first aperture and the second aperture. Further means are provided for focusing the image of the composite spot in the target area. Preferably, the apertures are square shaped. Thus, by varying the position of the superimposed image of the first aperture with respect to the second aperture, a wide variety of rectangular shaped composite spots with different dimensions is obtainable. This permits the exposure of rectilinear patterns, e.g., in photoresists of integrated circuit fabrication, by the electron beam with a minimum of exposure steps and substantially no exposure overlap. The result is greatly increased speed in the total exposure of such rectilinear areas to the electron beam as well as a minimum of the 'blooming effects' produced by exposure overlap.

Method and apparatus for forming a variable size electron beam

A method and apparatus is described for performing automatic overlay measurements on wafers utilized in semiconductor manufacturing. The overlay measurements are made at selected sites on a given wafer where a single bar pattern has been overlaid over a double bar pattern. The position of the single bar center line with respect to the center line between the double bars is a direct indication of the overlay error of the two patterns. The overlay error is measured in both the X and Y dimensions and is utilized to monitor the overlay error or to produce statistics and correlations to system parameters so that the sources of overlay errors may be identified and the errors eliminated or minimized on subsequent wafers being processed.

Automatic overlay measurements using an electronic beam system as a

A beam of charged particles has its alignment and brightness alternately controlled in accordance with the current of the beam. The measurements of the current and any corrections for alignment or brightness are made when the beam is not applied to a target.

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Poughkeepsie, NY, United States of America

Edward V Weber