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Method for Microscopic Edge Detection

IP.com Disclosure Number: IPCOM000035947D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 13K

Publishing Venue

IBM

Related People

Hall, DR: AUTHOR [+2]

Abstract

Disclosed is a method for analyzing certain types of metrology data from a microscopic system, in order to precisely and accurately locate edges contained in an observed sample.

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Method for Microscopic Edge Detection

Disclosed is a method for analyzing certain types of metrology data from a microscopic system, in order to precisely and accurately locate edges contained in an observed sample.

Several new types of microscopes, such as confocal scanning laser microscopes, or Linnik interferometer-based systems and some conventional "white light" microscopes, record a representation of an object as a three- dimensional array of "pixels". A pixel here can be described as a volume element in space. Each such pixel has values associated with it which describes its X, Y, and Z location values and at least one value describing the interaction of the microscope with the sample at that location. Such an interaction usually is the intensity of light apparently reflected from that pixel, but other phenomena can be used. For convenience, the surface of the sample will be the XY plane, which is perpendicular to the optical axis of the microscope, and the sample will contain a line running in the Y direction. In the simplest case, the problem is to locate the edges of this line. For convenience of description as well as possible actual practice, the data can be averaged over the Y direction so as to afford a twodimensional XZ Y-averaged pixel array.

The change of intensity with Z coordinate ("I vs. Z") plot will generally show a peak maximum whenever Z passes through an interface. We have observed that these peaks appear to be roughly Gaussian in shape in the I(Z) vs. Z, although other function relations between I and Z may also apply. If there are several interfaces, there may be several peaks in the I vs. Z plot. For example, if the structure is a photoresist over a silicon substrate, there will be peaks for the air-to-resist and the resist-to-substrate interfaces. The peak...