Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Fumio Komatsu

Motosuke Miyoshi

Katsuya Okumura

Kunihiro Miyazaki

Ayako Shimazaki

Hiroshi Motoki

Yasuhiro Kaga

Koji Tsubusaki

Shinichi Ito

Kei Hayasaki

Isahiro Hasegawa

Kei Hattori

Yumiko Miyano

In an operation of a pattern dimension measuring system comprising a stage, an electron gun part, electron lens systems for scanning electron beam on a sample and having a MOL mechanism thereto, a secondary electron detector for detecting secondary electrons and so forth emitted from the sample, and a host computer having a pattern dimension measuring part, the stage is moved at a constant velocity, the coordinates of the stage is measured by a laser interferometer in real time, the variation in working distance of the electron beam is measured in real time by the optical lever system from a focal length measuring part to be fed back to a stage control part and an objective lens. When a pattern serving as an object to be measured reaches a region capable of scanning, the electron beam is scanned in the best focus while moving the scanning start position of the electron beam in synchronism with the constant velocity movement of the stage, so that the SEM image thereof is acquired.

Pattern dimension measuring system and pattern dimension measuring method

A method for measuring a size of fine pattern wherein sizes of a plurality of fine patterns are measured using a scanning electron microscope is disclosed. The measuring method comprises the following procedures of obtaining a secondary electron image while scanning an electron beam on a fine pattern, determining whether or not the secondary electron image thus obtained meets a shape judgment criterion which has been set in advance, and, when the criterion is met as a result of determination processing, measuring a size of the fine pattern but, when the criterion is not met as a result of determination processing, moving to a next measurement area without measuring a size of the fine pattern.

Method for measuring size of fine pattern

A pattern estimating method, wherein during exposure for forming the device pattern, a latent image of a monitor pattern which has the same pitch as an L/S pattern as the device pattern and has a narrower line width than the L/S pattern is formed in a mark area, after developing the device pattern, probing light is applied from a monitor head to the monitor pattern, and under the conditions for preventing generation of diffracted light of first-order or more, the intensity of zero-order light reflected from the monitor pattern is detected, so that the size of the device pattern is estimated on the basis of the prestored relationship between the device pattern size and the zero-order diffracted light intensity.

Pattern estimating method and pattern forming method

An automatic focus control system comprises an electron beam lens column 1, a device control apparatus 2, and a host computer 3. In the host computer 3, an image processing section 32 and so on are provided. In case of measuring the critical dimension of the patterns in the wafer, after performing the global alignment adjustment, the power spectrum is calculated based on the SEM image of each measuring point in the wafer. After that, in case that the high-frequency component is included more than a prescribed standard value, without performing the automatic focus adjustment, the process for the pattern recognition is performed, and in case that the high-frequency component is included less than the standard value, the process for pattern recognition is performed just before the automatic focus adjustment. Therefore, it is possible to decrease the frequency (times) which performs the process for automatic focus adjustment; as a result, the throughput for measuring is improved.

Automatic focus control method and automatic focus control system having

Analog image data a SEM are converted into digital data, and are processed by a spatial filtering processing, histogram processing, threshold value setting, three-valued image data processing, noise reduction and the like. Area of a pattern in the three-valued image data is calculated by a labelling and calculation processing, and a pattern is sequentially detected by comparing the area of the pattern with a reference area value. The comparison and detection of the same or similar patterns repeated in the SEM image are performed by using the area of the pattern, and are not performed by a shape of the pattern, thereby resulting a precise detection at high speed by using a microprocessor. Since it is possible to perform a pattern recognition from the area value even though the pattern does not have a characteristic, it is possible to precisely detect and recognize a pattern image in high speed.

Method and apparatus for processing pattern image data by SEM

To prevent electric charge up from being accumulated on the plane scanned by an electron beam and further to improve the S/N ratio, an electron beam irradiating apparatus comprising: position information signal outputting section for outputting position information signals, in sequence to designate positions at which an electron beam is irradiated on a plane scanned by the electron beam, so as to designate the irradiation positions at random; and irradiation controller for-controlling the electron beam to irradiate the electron beam at the irradiation positions in response to the outputted position information signals. Further, to integrate an photoelectric signal over a sufficient time interval within the period of the pixel clock signal, the electric signal detecting circuit comprises a plurality of sample hold circuits and a selecting circuit for selecting and activating the sample hold circuits in sequence.

Electron beam irradiating apparatus and electric signal detecting

An electron microscope comprises: a electron optical column 5 for allowing an electron beam aligned and focused by a lens 2, 3, 4 to pass therethrough; a specimen chamber 8 for receiving therein a sample 7 which is irradiated with the electron beam passing through the electron optical column; and a separating thin film 6, mounted so as to close an opening of the electron optical column on the side of the specimen chamber, for separating the electron optical column from the specimen chamber in a vacuum level.

Electron microscope

A critical dimension measuring equipment includes a filtering circuit for inputting image data from a SEM and performs spatial filtering processing of the image data, a histogram processing circuit implements histogram processing of the image data, a threshold value detection circuit obtains a threshold value based on a discriminant criteria method, a three-value conversion processing circuits implements three-value conversion of the image data based on the threshold value, a first calculation circuit obtains the area and perimeter of the bottom section of the pattern based on this data, a second calculation circuit obtains the diameters of the patterns based on this data, and a critical shape recognition circuit decide whether the pattern is circular or elliptical based on the critical diameter, calculates the diameter of the circle based on the area if the pattern is circular, and calculating the major axis and the minor axis of the ellipse based on the area and the perimeter if the pattern is elliptical.

Critical dimension measuring method and equipment thereof

The fluorescent X-ray generated by elements when an X-ray is total reflected from a substrate surface is detected by a fluorescent X-ray detecting circuit; the fluorescent X-ray peak generated by the substrate element and the fluorescent X-ray peaks generated by contaminative elements are separated by a peak separating circuit; an integral intensity I.sub.0 of the fluorescent X-ray peak generated by the substrate element and integral intensities I of the fluorescent X-ray peaks generated by the contaminative elements are calculated by an integral intensity calculating circuit, respectively; and contaminative element concentrations N=N.sub.0 .multidot.(.eta..sub.0 / I.sub.0).multidot.(I / .eta.) (where N.sub.0 denotes the surface concentration of the substrate; .eta..sub.0 denotes the fluorescent yield of the substrate; and .eta. denotes the fluorescent yield of the contaminative elements) are calculated by a contaminative element concentration calculating circuit on the basis of the calculated integral intensities I.sub.0 and I. The contaminative elements can be analyzed non-destructively without use of any analytical curves, so that it is possible to save much labor required to prepare the analytical curves.

Method and apparatus for analyzing contaminative element concentrations

A contaminating-element analyzing method enables precise identification of contaminating elements and precise calculation of concentrations thereof by eliminating a broad peak waveform due to Rayleigh scattering and Compton scattering and a background waveform from a measured waveform of a contaminated sample. A blank sample or samples are irradiated by an X-ray beam under a constant condition to obtain a plurality of measured waveforms of fluorescent X-rays, and the plurality of measured waveforms are averaged to obtain a blank waveform. Then a contaminated sample is irradiated by the X-ray beam under the same condition as that for the blank sample to obtain a measured waveform of fluorescent X-rays. The blank waveform is subtracted from the measured waveform of contaminated sample, and then the contaminating elements are identified and the concentrations thereof are calculated on the basis of the waveform data after the subtraction process.

Contaminating-element analyzing method

In the method and apparatus for analyzing contaminative element concentrations, a fluorescent X-ray generated by elements when an X-ray is total reflected from the surface of a substrate is detected by a fluorescent X-ray detector; a peak of the fluorescent X-ray generated by a substrate element and peaks of the fluorescent X-ray generated by other contaminative elements are separated from the detected fluorescent X-ray waveform by a peak separating circuit; and the concentrations of the detected contaminative elements are calculated on the basis of the separated peaks by a calculating circuit. In the peak detection, in particular, the peaks of the contaminative elements to be analyzed are detected from the waveform. When other peaks are present within a predetermed number of channels (energy eV) before and after each detected peak, the channel numbers and the signal intensities between the respective peaks are extracted. Further, the a true peak is determined after obtaining the evaluation values of the respective peaks, so that it is possible to separate peaks from the fluorescent X-ray waveform accurately, even if each peak is split in the observed waveform.

A method of extracting a feature of an image, includes: a first step of performing a logarithmic conversion process for each pixel of an image taken by an electron microscope to carry out non-linear image enhancement; a second step of performing an N(N is a predetermined value) valued process for each pixel of the image underwent the logarithmic conversion process, threshold values for the N valued process being obtained by dividing the whole range of gray levels of the pixels by N, and gray level of the pixel being one of N constant gray level values by the N valued process; a third step of performing a partial differentiatial process in X- and Y-directions for each pixel of the image obtained by the second step, to make '0' the gray levels of pixels within the same area divided by the N valued process and make only the boundary between different areas divided by the N valued process to have a certain gray level; and a fourth step of detecting the boundary and extracting a feature of said image.

Method of extracting features of image

Element identification and concentration calculation can be conducted with precision by correcting waveform distortion caused by the energy resolution of a detection system. A smoothing process is effected on a measured waveform of fluorescent X-rays obtained from an object to be measured. A device function of the detection system is obtained for each analytic element, based on the energy resolution of the detection system for a fluorescent X-ray energy value of each analytic element. A deconvolution process is effected on the measured waveform thus smoothed, by using the device functions of the detection system. Analytic elements are identified and concentrations of the analytic elements are obtained from the waveform data after the deconvolution process. The measured waveform is compensated for absorption in a beryllium window prior to smoothing.

Element analyzing method

A contaminating-element analyzing method and an apparatus of the same are disclosed. Differential smoothing process is performed for a measured waveform of a fluorescent X-ray obtained from an object to be measured so as to detect a peak of the measured waveform, the object containing a contaminating element. A model function with variables which are initial parameters with respect to each peak of the measured waveform is provided so as to constitute a model waveform. A nonlinear optimizing process is performed using the method of least squares of the model waveform and the measured waveform so as to decide initial parameters of each model function and to obtain discriminated waveforms. A contaminating element is identified corresponding to each of the discriminated waveforms and obtaining an integrated intensity of a discrete waveform of each of the identified contaminating elements. A background intensity is obtained corresponding to a measured waveform of a fluorescent X-ray obtained from a non-contaminating object which does not contain any contaminating element. The background intensity is subtracted from an integrated intensity of a discrete waveform of each contaminating element.

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Fuchu, Japan

Fumio Komatsu