Radiant energy – Irradiation of objects or material – Irradiation of semiconductor devices
Reexamination Certificate
2000-09-07
2001-08-14
Berman, Jack (Department: 2881)
Radiant energy
Irradiation of objects or material
Irradiation of semiconductor devices
C250S307000, C250S397000, C250S310000, C250S311000, C250S3960ML, C250S3960ML, C250S306000
Reexamination Certificate
active
06274876
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scanning microscope using a particle beam. More specifically, the present invention relates to an optimum inspection apparatus using a particle beam for performing observation or inspection of a fine dimension and/or an appearance structure of a semiconductor device.
2. Description of the Related Art
A known critical dimension evaluation apparatus using an electron beam as a particle beam acquiring a sample image based on secondary electrons by scanning an electron beam on a semiconductor sample and inspecting a dimension concerning the characteristic pattern for the sample is disclosed in Japanese Patent Application Number 60-161514. A known appearance inspection electron beam apparatus inspecting an abnormality of a sample by comparing an image of a scanning electron microscope with a standard pattern is disclosed in Japanese Patent Application Number 5-258703. A method introduced by these apparatus has high resolution for the image compared to an inspection method using an optical source and is very useful for inspecting a sub-micron semiconductor pattern.
In the prior art apparatus, an optimum focus adjustment of an electron lens system is performed based upon signals from at least 3 sample images obtained by scanning the electron beam on the same sample under different conditions of focusing shift of the electron lens system. In order to reduce the time spent for focus adjustment, a focus adjustment means for detecting a height of a sample using a height sensor using light reflection (Z sensor) and adjusting the focus of an electron lens system based upon a table produced in advance to reduce the deviation of a height of a sample from the standard is indicated in a Japanese patent application number 8-273575. Since there are such problems that a sample surface measured by the Z sensor does not completely accord with an extreme surface of the sample and that has a disadvantage in a reappearance of the focus adjustment due to hysteresis of magnetization in the electron lens system, resolution of the sample image decreased without the focus adjustment using an electron beam scanning.
A method for obtaining a high resolution for a sample image based upon mathematical conversion (integral conversion) of the sample image using a beam profile measured in advance is introduced in a Japanese patent application number 2-181639. However, this method does not consider variation of the beam profile due to variation of the focusing-shift for each spot from which the sample image is taken.
SUMMARY OF THE INVENTION
It is necessary for the above inspection apparatus to improve its throughput since a quantity for an inspection is increased by an improved resolution. However, in the prior art, time spent in adjusting a focus of the beam accompanied with the beam scanning resulting in an extreme deterioration of an inspection throughput was not taken into consideration. There is still a considerable problem that although it is necessary to execute pluralities of electron beam irradiation on a sample for performing a focus compensation, the irradiation causes contamination on the sample which varies the width of wiring circuit in the sample. Further, there is a problem that because excessive irradiation of the electron beam causes the sample to be electrified, the electron beam used to irradiate the sample is affected so that an acquired sample image causes distortion which deteriorates the accuracy of critical dimensional measurement.
An object of the present invention is to provide an inspection apparatus using a particle beam having high resolution and high throughput.
The above-mentioned object of the invention is achieved by performing a blur-separated image calculation in the inspection apparatus having a sample-image-obtaining means which scans the particle beam on a sample and a sample inspection means which uses the numerical operation of a sample image for an inspection. The inspection apparatus has a focusing-shift-detection means which derives the characteristic quantity of a focusing-shift from the sample image, a beam-blur-profile generation means which generates a beam-blur profile, corresponding to a blur of the particle beam, based upon the characteristic quantity of the focusing-shift and a blur-separation means which generates a blur-separated image based upon a separation or a reduction of a component of the beam-blur profile in the sample image.
The focusing-shift-detection means according to the present invention detects a certain spatial frequency of a Fourier spectrum of the sample image as the characteristic quantity of the focusing-shift.
Furthermore, there is provided means for memorizing by correlating the sample image, the beam-blur profile and the blur-separated image and means for displaying simultaneously a set of the sample image, the beam-blur profile and the blur-separated image.
The invention also encompasses an inspection method using the inspection apparatus. The method involves moving a sample to an inspection point for the sample after an adjustment of an astigmatism for the particle beam is completed, acquiring at most two different kinds of sample images by scanning the particle beam for each inspection point of the sample and inspecting the sample based upon the sample images.
The inspection apparatus of the present invention also includes means for producing a first display image acquired by scanning the particle beam on the sample, means for deriving the characteristic quantity of the focusing-shift based upon the first display image, means for producing a second display image based upon the characteristic quantity of the focusing-shift and the first display image and means for inspecting the sample based upon the second display image.
These and other objects, features and advantages of the present invention will become more apparent in view of the following detailed description of the preferred embodiments.
REFERENCES:
patent: 4748407 (1988-05-01), Brunner et al.
patent: 5561611 (1996-10-01), Avinash
patent: 5825912 (1998-10-01), Okubo et al.
patent: 5866905 (1999-02-01), Kakibayashi et al.
patent: 5872862 (1999-02-01), Okubo et al.
patent: 5894124 (1999-04-01), Iwabuchi et al.
patent: 5981947 (1999-11-01), Nakasuji et al.
patent: 60-161514 (1985-08-01), None
patent: 2-181639 (1990-07-01), None
patent: 5-258703 (1993-10-01), None
patent: 8-273575 (1996-10-01), None
Kawanami Yoshimi
Otaka Tadashi
Yoneyama Akio
Berman Jack
Fernandez Kalimah
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
LandOfFree
Inspection apparatus and method using particle beam and the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Inspection apparatus and method using particle beam and the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Inspection apparatus and method using particle beam and the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2532202