Radiant energy – Ionic separation or analysis – With sample supply means
Patent
1997-07-21
1999-03-02
Nguyen, Kiet T.
Radiant energy
Ionic separation or analysis
With sample supply means
H01J 4900
Patent
active
058774963
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a measurement method and apparatus for analyzing surface impurities in a very small region, and more particularly to an apparatus and an analysis method for a surface impurities for use to analyze a surface impurity on an electronic circuit part, a relay contacting surface, an integrated circuit device or any other very small electronic part to analyze a cause of a failure arising from deterioration by contamination.
BACKGROUND ART
A failure in operation of an electronic circuit part, a relay contacting surface, an integrated circuit device such as an IC or an LSI or any other very small electronic part is caused in most cases by a contaminating impurity sticking to the surface.
Contaminating impurities can be roughly divided into the following three:
(1) organic molecules including negative atoms such as oxygen, chlorine or sulfur;
(2) hydrocarbon molecules; and
(3) organic molecules which include both of nitrogen and oxygen.
Since the cause of a failure in operation which takes place is different depending upon the type of the contaminating impurity, it is important and necessary to specify what the contaminating impurity is.
As methods of analyzing a contaminating impurity sticking to the surface of an object, a reflection type infrared absorption method, an ion irradiation mass spectrometry method and a slow electron energy loss analysis method are practically used. However, while those analysis methods are all applied where the analysis surface area for which it is required to perform an analysis is approximately (0.1 mm).sup.2 to (several mm).sup.2, in order to analyze the surface of a chip of a semiconductor device at present, the analysis surface area is required to be on the order lower than (.mu.m).sup.2. Accordingly, any of the analysis methods described above is not suitably used to analyze the surface of an electronic part.
Also a different method is available wherein an electron beam is irradiated upon the surface of a specimen and desorbed molecules are analyzed using a mass spectrograph. In this instance, it is possible to concentrate energy upon a very small region on the order lower than (.mu.m).sup.2 from a relationship of an electron wavelength, and it is possible to analyze the very small region.
From among the conventional analysis methods described above, the reflection type infrared absorption method, the ion irradiation mass spectrometry method and the slow electron energy loss analysis method are not suitable to analyze the surface of an electronic part since the area required for the analysis is large.
The method wherein an electron beam is irradiated and desorbed molecules are analyzed using a mass spectrograph allows an analysis of a very small region. However, the method has a problem in that, where different molecules have an equal mass number (for example, CH.sub.4 and O, CH.sub.4 OH and O.sub.2, and so forth), it cannot be specified what the contaminating impurity is.
DISCLOSURE OF THE INVENTION
The present invention has been made in view of such problems of the prior art as described above, and it is an object of the present invention to provide an analysis method by which a surface impurity in a very small region can be specified.
According to the present invention, an analysis method for a surface impurity in a very small region wherein an electron beam is accelerated with an acceleration voltage and irradiated upon a very small region of a specimen and a mass spectrometry of surface impurity molecules desorbed from the very small region is performed, is characterized in that
the acceleration voltage for accelerating the electron beam is set to a voltage with which desorption of surface contaminating molecules by an ESD effect occurs.
According to the present invention, another analysis method for a surface impurity in a very small region which is performed by an analysis apparatus which has both of an Auger electron spectral diffraction measurement function and a mass spectrometry measurement function and wherein an elect
REFERENCES:
patent: 4393311 (1983-07-01), Feldman et al.
patent: 4968888 (1990-11-01), Appelhans et al.
patent: 5650616 (1997-07-01), Iketaki
Tabuse Kazuhiko
Watanabe Masao
Advantest Corporation
Nguyen Kiet T.
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