JPH04331390A - Electron beam tester - Google Patents

Abstract

PURPOSE:To neutralize a sample charged positively or negatively and prevent the contrast of a secondary electron image from deteriorating by setting up a filament electrode near the upper part of the sample and controlling the voltage of the filament electrode. CONSTITUTION:A filament electrode 6 is set up near the upper part of a sample 7, and the electrode 6 supplies electrons to the sample 7 or sucks electrons from the sample. An electron beam 9 hits on the sample 7; and if an insulating film on the surface of the sample 7 is charged positively, properly accelerated electrons are given to the electrode 6 and supplied to that insulating film thus neutralizing, the sample and recovering the image quality. On the other hand, where excessive electrons are caught on the insulating film on the surface of the sample 7, a proper positive voltage is applied to the electrode 6, the excessive charges are sucked thus neutralizing the sample, and recovering the degraded image quality.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam tester for testing potential changes in a sample.

0002

2. Description of the Related Art An electron beam tester is capable of observing potential changes inside an LSI chip as a potential contrast image or a potential waveform. In conventional electron beam testers, the acceleration voltage of electrons irradiated onto LSI is 1kV.
It only varied in the vicinity.

0003

[Problems to be Solved by the Invention] When testing a sample with an insulating film, the conventional electron beam tester detects problems when electrons are captured in the insulating film or on the surface of the insulating film, or when excessive secondary electrons are emitted. When this happens, problems arise in which the contrast and image quality of the secondary electron image deteriorate.

[0004] Also, in order to prevent deterioration in the quality of secondary electron images,
This has been addressed by making the primary electron acceleration voltage variable around 1 kV, but there is a problem in that some samples cannot be accommodated due to limitations in the variable range.

An object of the present invention is to provide an electron beam tester that prevents a decrease in the contrast of a secondary electron image.

[0006]

Means for Solving the Problems In order to achieve the above object, an electron beam tester according to the present invention includes an electron beam optical system and a filament electrode, the electron beam optical system comprising: A filament electrode is installed near the sample in the sample chamber, and when the sample is positively or negatively charged, it neutralizes the charge by supplying or inhaling electrons, respectively. It is something that brings peace.

[0007]

[Operation] In the sample chamber of the electron beam tester according to the present invention, a filament electrode is provided near the top of the sample for supplying or inhaling electrons to the sample. By supplying or sucking out electrons, respectively, the charge is neutralized and the contrast reduction in the secondary electron image is recovered.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, an electron gun 1,
A deflector 2, an aperture 3, a lens 4, and a scan coil 5 are installed. These electron beam optical systems are the same as conventional ones. Further, 8 is a detector for detecting voltage changes of the sample 7.

In the present invention, a filament electrode 6 is provided near the upper part of the sample 7 in the sample chamber, and the filament electrode 6 supplies electrons to the sample 7 or sucks electrons from the sample 7.

When the insulating film on the surface of the sample 7 becomes positively charged by applying the electron beam 9, an appropriate accelerating voltage is applied to the filament electrode 6 to supply electrons to the insulating film, neutralizing it and lowering the charge. Restore image quality.

On the other hand, if excessive electrons are captured on the insulating film on the surface of the sample 7, applying an appropriate positive voltage to the filament electrode 6 attracts and neutralizes the excess electrons. Recover degraded image quality.

[0014]

[Effects of the Invention] As explained above, the electron beam tester of the present invention neutralizes positively or negatively charged samples by providing a filament electrode near the top of the sample and adjusting the applied voltage. Deterioration in contrast of secondary electron images can be prevented. In addition, since the filament electrode is located near the sample, there is no need to increase the voltage of the filament electrode so much that the response of the filament electrode can be made faster. The effect is that it can also be executed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 Electron gun 2. Deflector 3 Aperture 4 Lens 5 Scan coil 6 Filament electrode 7 Sample 8 Detector 9　Electron beam

Claims (1)

[Claims] 1. An electron beam tester comprising an electron beam optical system and a filament electrode, the electron beam optical system irradiating an electron beam onto a sample in a sample chamber, and the filament electrode irradiating a sample in a sample chamber with an electron beam. 1. An electron beam tester that is installed near a sample and neutralizes the charge by supplying or inhaling electrons when the sample is positively or negatively charged.