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An Optical Microscope Based Locating System for a Scanning Electron Microscope

IP.com Disclosure Number: IPCOM000037842D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Rosenfield, M: AUTHOR

Abstract

Disclosed is a method to facilitate the location of specific areas of interest in a scanning electron microscope.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 61% of the total text.

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An Optical Microscope Based Locating System for a Scanning Electron Microscope

Disclosed is a method to facilitate the location of specific areas of interest in a scanning electron microscope.

Scanning electron microscopes (SEMs) are often used for inspection and metrology of integrated circuit wafers before, during, and after fabrication. In addition, SEMs are used to characterize resist exposure tools by measuring the features exposed and developed in resist. Modern SEMs have computer controlled stages which allow stage coordinates to be stored in memory and which also allow the stage to be positioned to within 10 mm of the desired location. The problem is that it is frequently very difficult to find the desired features at the desired locations, the first time, on the wafers because of poor image contrast at low magnifications. However, these same desired features are often very easy to see when imaged through a conventional optical microscope. This invention solves the problem of locating features in a conventional SEM by installing an optical microscope (or TV imaging system) inside the SEM vacuum chamber at a fixed offset from the electron beam. When activated, the SEM electron detector would be shut off and the optical microscope illumination then turned on. The desired features would be easily located using the optical microscope and stored in the computerized stage memory. The feature locations could then be positioned under the SEM electron beam by movi...