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Direct Measurement Apparatus for Scanning Electron Microscope

IP.com Disclosure Number: IPCOM000053113D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Giuffre, GJ: AUTHOR [+2]

Abstract

A direct measurement arrangement for a scanning electron microscope (SEM) is provided which eliminates the need for making a photograph of the SEM image and recording measurements from the magnified image. The arrangement employs direct measurement via digital readout using the image shift circuits built into a Cambridge Steroscan S150 SEM. With reference to the figure, direct measurement is accomplished by resetting digital up/ down counters 3 via reset button 5. After reset, one edge of the image is aligned to a fixed reticle using the beam offset control arrangement shown at 7. Count push button 9 is then depressed and the second edge of the image is aligned with the fixed reticle. Again, the count button 9 is depressed. Digital readout 11 is calibrated to display the image offset in micron units.

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Direct Measurement Apparatus for Scanning Electron Microscope

A direct measurement arrangement for a scanning electron microscope (SEM) is provided which eliminates the need for making a photograph of the SEM image and recording measurements from the magnified image. The arrangement employs direct measurement via digital readout using the image shift circuits built into a Cambridge Steroscan S150 SEM. With reference to the figure, direct measurement is accomplished by resetting digital up/ down counters 3 via reset button 5. After reset, one edge of the image is aligned to a fixed reticle using the beam offset control arrangement shown at 7. Count push button 9 is then depressed and the second edge of the image is aligned with the fixed reticle. Again, the count button 9 is depressed. Digital readout 11 is calibrated to display the image offset in micron units.

In operation, the voltage from the beam offset control is fed to difference amplifier 13 to remove the -7.5 V component on the input. The output of the difference amplifier determines the output pulse width of linear pulse generator
15. As can be seen, depressing count push button 9 triggers a single pulse from the linear pulse generator. This pulse is used to gate a series of clock pulses from 17 into up/down counters 3. The trailing edge of the linear pulse generator pulse sets up/down flip flop 1 such that the next pulse to count will reverse the direction of counting. When properly calibrated, the diff...