Radiant energy – Inspection of solids or liquids by charged particles
Reexamination Certificate
1999-10-13
2001-11-27
Berman, Jack (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
C250S251000, C250S307000, C250S309000
Reexamination Certificate
active
06323484
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an analysis technology of a surface condition of a sample, such as a semiconductor substrate of an integrated circuit device and so on, and more particularly to a sample current spectroscopy surface measurement method and measurement device for inspecting crystallinity of a sample surface.
BACKGROUND OF THE INVENTION
As conventional methods of inspecting crystallinity of a surface of a sample, such as a semiconductor substrate of an integrated circuit device and so on, there are known a low energy electron diffraction (LEED) method and a reflection high energy electron diffraction (RHEED) method, both of which use electron ray or beam, and there is also known a small incident angle X-ray diffraction method which uses X-ray. In each of these methods, electron beam or X-ray is irradiated onto a sample, and a diffraction pattern of scattered electron beam or X-ray is detected to inspect crystallinity of a sample surface. Also, in order to estimate crystallinity of a local area of a sample, there are known a method of performing electron diffraction measurement by using converged electron beam, and a method by using a scanning tunneling microscope which uses a probe.
In a recent semiconductor device having a very high integration degree, it is often required to form a narrow and deep hole in a vertical direction on the surface of a semiconductor element, during a manufacturing process thereof. However, when an aspect ratio of such hole is very large, an analysis of the bottom area of such hole was impossible. This is because, in the conventional diffraction method using electron beam or X-ray, a direction of incidence of electron beam or X-ray onto the surface of a sample and a direction of emanation of detected electrons or X-ray are limited. Also, in the observation method by a scanning tunneling microscope which uses a probe, it was difficult to insert the probe into such hole, and, therefore, an analysis of the bottom area of such hole was difficult because of the structural limitation of the microscope.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to obviate the above-mentioned problems of the prior arts.
It is another object of the present invention to provide a surface measurement apparatus and method in which crystallinity of a surface of a sample can be inspected without detecting electrons or X-ray scattered from the surface of the sample.
It is still another object of the present invention to provide a surface measurement apparatus and method in which analysis of crystallinity of a bottom region of a hole having large aspect ratio and formed on the surface of a sample can be done without detecting electrons or X-ray scattered from the bottom region.
According to one aspect of the present invention, there is provided an apparatus for sample current spectroscopy surface measurement comprising: an electron gun for irradiating an electron beam onto a surface of a sample; a variable voltage source for supplying an acceleration voltage which is variable to change an acceleration energy of said electron beam irradiated from said electron gun onto said surface of said sample; and a sample current measurement means for measuring a sample current which flows into a sample when said electron beam is irradiated from said electron gun onto said surface of said sample; wherein variation of said sample current is detected by measuring said sample current by said sample current measurement means when said acceleration energy of said electron beam irradiated by said electron gun onto said surface of said sample is changed by said variable voltage source.
In the above-mentioned apparatus, it is possible to inspect crystallinity of the surface of the sample by detecting the variation of the sample current.
It is preferable that the above apparatus comprises an electron lens for focusing said electron beam emitted from said electron gun and said electron beam emitted from said electron gun is irradiated onto said surface of said sample after being focused by said electron lens.
It is also preferable that the above apparatus further comprises an electron deflection means for scanning said electron beam emitted from said electron gun, and that the electron beam is irradiated onto and scanned on said surface of said sample by said electron deflection means, and variation of said sample current is detected by using said sample current measurement means in each of measurement points within a scanning region on the surface of the sample while changing said acceleration energy of electrons irradiated onto said surface of said sample from said electron gun by said variable voltage source, thereby inspecting crystallinity of said surface of said sample.
It is also preferable that the above apparatus further comprises a Faraday cup onto which said electron beam from said electron gun is irradiated in place of said surface of said sample; and a Faraday cup current measuring means which measures a current flowing into said Faraday cup when said electron beam is irradiated onto said Faraday cup by said electron gun, and that variation of said current flowing into said Faraday cup is detected by measuring said current flowing into said Faraday cup by said Faraday cup current measuring means when said acceleration energy of said electron beam irradiated onto said Faraday cup by said electron gun is changed by said variable voltage source, and variation of said sample current is detected by measuring said sample current by said sample current measurement means when said acceleration energy of said electron beam irradiated onto said surface of said sample by said electron gun is changed by said variable voltage source, and each sample current value measured by said sample current measurement means is normalized or standardized by using a current value at a corresponding acceleration energy measured by said Faraday cup current measuring means.
It is preferable that the acceleration energy of said electron beam irradiated from said electron gun is changed in a range from 10 to 5000 electron volts by said variable voltage source.
It is possible to further provide a sinusoidal wave voltage generating means, and to superimpose a sinusoidal wave voltage generated by said sinusoidal wave voltage generating means on said acceleration voltage supplied by said variable voltage source, when variation of said sample current is detected by measuring said sample current by said sample current measurement means while changing said acceleration energy of said electron beam irradiated onto said surface of said sample by said electron gun by said variable voltage source.
According to another aspect of the present invention there is provided a method for sample current spectroscopy surface measurement comprising: irradiating an electron beam onto a surface of a sample; and inspecting crystallinity of said surface of said sample by measuring a variation of a sample current flowing into said sample when an acceleration energy of said electron beam irradiated onto said surface of said sample is changed.
It is preferable that the electron beam is focused by an electron lens and irradiated onto a local region on said surface of said sample, thereby crystallinity of said local region on said surface of said sample is inspected.
It is also preferable that the electron beam is focused by an electron lens and scanned on said surface of said sample, and that variation of said sample current is detected in each of measurement points within a scanning region on said surface of said sample while changing said acceleration energy of electrons irradiated onto said surface of said sample, thereby inspecting crystallinity of said surface of said sample.
It is also preferable that the above method further comprises irradiating said electron beam onto a Faraday cup; and variation of a current flowing into said Faraday cup is measured when an acceleration energy of said electron beam irradiated onto said Faraday cup is changed, and variation of sa
Ide Takashi
Itoh Hiroshi
Berman Jack
Fernandez Kalimah
Hutchins, Wheeler & Dittmar
NEC Corporation
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