Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-05-17
2002-09-03
Sherry, Michael (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C250S310000, C250S311000
Reexamination Certificate
active
06445197
ABSTRACT:
This patent application claims priority based on a Japanese patent application, H11-136214 filed on May 17, 1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electron beam tester, recording medium thereof and a signal data detecting method. More particularly, the present invention relates to the electron beam tester for testing an electric component, the recording medium which stores a program executed by the electron beam tester and the signal data detecting method of detecting data on a signal at a predetermined position of the electric component.
2. Description of the Related Art
In the conventional practice, for example, an electron beam tester is used for testing electric components such as a semiconductor memory and so on. The electron beam tester irradiates an electron beam to an electric component to be tested. Then, by detecting a secondary electron amount generated at the electric component, an electron image of a strobe image of the electric component and a voltage waveform at a predetermined position of the electric component are obtained.
FIGS. 1A
,
1
B and
1
C are provided in order to explain a voltage waveform, obtained by the electron beam tester, at a predetermined position of the electric component. When a signal shown in
FIG. 1A
is supplied to a predetermined position of the electric component, a voltage waveform shown in
FIG. 1A
is supposed to be obtained by the electron beam tester. However, there are occasions where a voltage waveform which is unwantedly deformed with respect to the voltage waveform shown in
FIG. 1A
is obtained instead of the ideal voltage waveform shown in FIG.
1
A. Reasons why such a deformed voltage waveform is obtained are considered to be those as shown in
FIG. 1C
when a signal given contains a signal whose period is displaced, that is, the given signal contains a jitter, or that a signal per se in the electric component is deformed.
However, in the conventional electron beam tester, a problem occurs where a tester cannot distinguish which one of the following actually causes the deformation of the voltage waveform. Namely, such possible two causal factors are:
(1) a signal given contains a jitter, or
(2) a signal per se in the electric component is deformed.
Moreover, recent years required are acquisition and detection of data on the signal at the electric component, such as the data on a voltage fluctuating amount of the signal and data on the phase of jitter in the case with the jitter being contained.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an electron beam tester, recording medium and a signal data detecting method which overcome the above issues in the related art. This object is achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
According to an aspect of the present invention, there is provided an electron beam tester for testing an electric component, the tester comprising: a drive circuit which supplies a signal to the electric component; an electron gun which causes to emanate a secondary electron from the electric component by irradiating the electron beam to a predetermined position of the electric component; a detector which detects an amount of the secondary electron emanated from the electric component; a first variation detecting unit which detects first variation data indicative of a magnitude of a variation amount of the secondary electron, based on the amount of the secondary electron detected by said detector at a predetermined position of the electric component, with a voltage of the secondary electron being constant; a second variation detecting unit which detects second variation data indicative of a magnitude of a variation amount of the secondary electron, based on the amount of the secondary electron detected by said detector at a predetermined position of the electric component, with a voltage fluctuation of the signal being indeterminate; and a voltage fluctuating data detecting unit which detects voltage fluctuating data indicative of a magnitude of voltage fluctuation when the voltage fluctuation of the signal is indeterminate.
In the electron beam tester where the drive circuit supplies to the electron component the signal having a predetermined period, and the voltage fluctuation of the signal is generated by a jitter in which the signal is displaced from the period, the electron beam tester may further comprise: an electron gun control unit comprising a first electron gun control section which instructs said electron gun to irradiate the electron beam synchronized with the first phase in which a voltage of the signal at the predetermined position stays fixed without being affected by the jitter; and a second electron gun control section which instructs said electron gun to irradiate the electron beam synchronized with a second phase in which a voltage of the signal at the predetermined position of the electric component fluctuates due to the jitter.
The first variation detecting unit detects a first variation data indicative of a magnitude of the secondary electron amount, based on the secondary electron amount detected by said detector as a result of the electron beam irradiated from the said electron gun by said first electron gun control section.
The second variation detecting unit detects a second variation data indicative of a magnitude of the secondary electron amount, based on the secondary electron amount detected by said detector as a result of the electron beam irradiated from said electron gun by said second electron gun control section.
The voltage fluctuating data detecting unit detects a magnitude of the voltage at the second phase due to the jitter, based on the first variation data and the second variation data.
The electron beam tester may further comprise: a driver which outputs a desired analysis voltage which serves to control the degree of the secondary electron taken in for detection, in a varying manner, said detector detecting the secondary electron taken in by the analysis voltage; a coincidence analysis voltage detecting unit which detects a coincidence analysis voltage that coincides with a reference secondary electron amount or a slice level set in advance; and a phase determining unit which determines the first phase and the second phase based on the coincidence analysis voltage.
The electron beam tester may further comprise: a driver output control unit which instructs the driver to output a same analysis voltage as the coincidence analysis voltage, at the first phase, detected by the coincidence analysis voltage detecting unit when the electron beam is irradiated from the electron gun by the first electron gun control unit, and which instructs the driver to output a same analysis voltage as the coincidence analysis voltage, at the second phase, detected by the coincidence analysis voltage detecting unit when the electron beam is irradiated from the electron gun by the second electron gun control section.
Moreover, the voltage fluctuating data detecting unit may detect the voltage fluctuating data by subtracting the first variation data from the second variation data.
Moreover, a plurality of phases may be used as the second phase.
The electron beam tester may further comprise a voltage fluctuating amount detecting unit which detects a voltage fluctuating amount due to the jitter at the second phase, based on the voltage fluctuating data.
Moreover, the voltage fluctuating amount detecting unit may detect the voltage fluctuating amount based on relationship between the analysis voltage at the second phase and the secondary electron amount detected by the detector.
The electron beam tester may further comprise a display unit which displays relationship between the voltage fluctuating amount and the second phase of the signal.
The electron beam tester may further comprise: a phase data detecting unit
Advantest Corporation
Patel Paresh
LandOfFree
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