Radiant energy – Inspection of solids or liquids by charged particles – Methods
Reexamination Certificate
2001-03-26
2003-03-18
Anderson, Bruce (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Methods
C250S310000, C250S3960ML, C250S3960ML
Reexamination Certificate
active
06534766
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims benefit of priority under 35USC §119 to Japanese patent application No. 2000-089909, filed on Mar. 28, 2000, the contents of which are incorporated by reference herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a charged particle beam system. More specifically, the invention relates to observation, inspection and measurement using charged particle beams.
2. Description of the Prior Art
A typical process for producing a semiconductor device includes a step of measuring the dimension of a pattern which is formed on a substrate such as a wafer or a reticle. In the measurement of the dimension of such a pattern, a critical dimension measurement SEM (Scanning Electron Microscope) having a length measuring function is usually used for acquiring a top-down image of the pattern to measure pattern widths, hole diameters and so forth in the top-down image.
In recent years, three-dimensional information such as the shape of the sidewall of a pattern, not only such two-dimensional information, is being an important evaluated item in an actual producing process. Conventionally, a cross-section SEM, a review SEM or the like is used for obtaining the three-dimensional information of a pattern.
However, the cross-section SEM takes a lot of time to carry out processing, since a sample must be broken into minute pieces and be mounted on a predetermined jig. In addition, the cross-section SEM is not suitable for an in-line evaluation for carrying out an evaluation in a producing process, since it is a destructive inspection.
On the other hand, the review SEM is a system for causing electron beams to be obliquely incident on a sample to observe the three-dimensional shape of a pattern by slanting a sample table of a scanning electron microscope together with a transporting mechanism. The review SEM is more suitable for an in-line evaluation than the cross-section SEM, since it is not required to process the sample.
However, the motion of the review SEM is slow since the sample table and a stage are mechanically slanted. In addition, since the review SEM is a separate system from the above-described critical dimension measurement SEM, there is the possibility that the number of producing steps may increase. In order to solve this problem, it is considered that a tilted stage is mounted on the critical dimension measurement SEM. However, it is required to provide a complicated stage mechanism in order to slant a sample table, so that there are problems in that the size of the system increases and the positioning accuracy of the stage deteriorates. For that reason, it is difficult to mount the tilted stage on the critical dimension measurement SEM in the present circumstances.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a charged particle beam system and a pattern slant observing method, which can be used for carrying out an in-line evaluation and which have a rapid, high-accuracy slant observing function.
According to the first aspect of the invention, there is provided a charged particle beam system comprising:
a charged particle beam emitting device for generating charged particle beam and for irradiating a sample to be inspected with the charged particle beam; a condenser lens for condensing the charged particle beam; a scanning deflecting device for deflecting the charged particle beam to scan the charged particle beam on the sample; an objective lens for focusing the charged particle beam on the surface of the sample; a slant observing deflecting device, arranged between the objective lens and the sample, for deflecting the charged particle beam to cause the charged particle beam to be obliquely incident on the sample at an optional slant angle from a beam axis of the charged particle beam; a charged particle detector for detecting a secondary charged particle and/or a reflected charged particle which are generated from the sample irradiated with the charged particle beam; and a control part for controlling the slant angle.
According to the present invention, a slant observing deflecting device provided between the objective lens and the sample slants deflects charged particle beams immediately before the charged particle beams are incident on the sample, so that it is possible to acquire a slant image of the surface of the sample while preventing a deterioration of an electron-optics property due to the bending of the trajectory of the beams.
The control part may preferably include an irradiation position shift correcting part for correcting an irradiation position shift caused by the charged particle beam which is obliquely incident on the sample.
By the irradiation position shift correcting part, it is possible to easily correct the observation position of the slant image, so that it is possible to rapidly observe the slant.
It is preferable that the irradiation position shift correcting part has: an irradiation position shift quantity calculating part for calculating a magnitude and a direction of the irradiation position shift on the basis of the slant angle; and a scanning deflection control part for controlling the scanning deflecting device on the basis of the calculated result of the irradiation position shift quantity calculating part to shift the trajectory of the charged particle beam by a distance according to the magnitude of the irradiation position shift in the opposite direction to the direction of the irradiation position shift.
According to the second aspect of the invention, there is provided a charged particle beam system comprising:
a charged particle beam emitting device for generating a charged particle beam and for irradiating a sample to be inspected with the charged particle beam; a condenser lens for condensing the charged particle beam; an objective lens for focusing the charged particle beam on the surface of the sample; a scanning/slant observing deflecting device, arranged between the objective lens and the sample, for deflecting and scanning the charged particle beam and for causing the charged particle beam to be obliquely incident on the sample at an optional slant angle from a beam axis of the charged particle beam; a charged particle detector for detecting a secondary charged particle and/or a reflected charged particle which are generated from the sample irradiated with the charged particle beam; and a control part for controlling the slant angle.
According to the charged particle beam system, it is possible to simultaneously control the scanning deflection and slant observing deflection of electron beams since it has the scanning/slant observing deflecting device.
The charged particle beam system of the second aspect of the invention may advantageously further comprises: an irradiation position shift quantity calculating part for calculating a magnitude and a direction of an irradiation position shift, which occurs when the charged particle beam is obliquely incident on the sample, on the basis of the slant angle; and an irradiation position shift correcting part for controlling the scanning/slant observing deflecting device to correct the irradiation position shift on the basis of the calculated result of the irradiation position shift quantity calculating part.
The charged particle beam system of the second aspect of the invention may preferably further comprise a correction deflecting device, arranged between the condenser lens and the objective lens, for shifting the trajectory of the charged particle beam by a distance according to the magnitude of the position shift in the opposite direction to the direction of the position shift on the basis of the calculated results of the irradiation position shift quantity calculating part to correct the irradiation position shift, the correction deflecting device constituting an irradiation position shift correcting part.
The above mentioned charged particle beam system may further comprise a stage for suppo
Abe Hideaki
Inoue Masahiro
Sugihara Kazuyoshi
Yamazaki Yuichiro
Anderson Bruce
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Hashmi Zia R.
Kabushiki Kaisha Toshiba
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