JP2010133764A - Polarization analyzer, method of detecting abnormality by polarization analysis, method of manufacturing magnetic recording medium, and method of manufacturing semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly and precisely measure a wide range of average film thickness, shape, and physical characteristics of a sample for a polarization analyzer, a method of detecting abnormality by polarization analysis, a method of manufacturing a magnetic recording medium, and a method of manufacturing a semiconductor wafer. <P>SOLUTION: The polarization analyzer includes: a measurement mechanism for measuring spectroscopic optical characteristics on a sample; a stage mechanism capable of adjusting a position where measurement light from the measurement mechanism hits; a stage position detection mechanism for detecting an irradiation position on the sample of the measurement light; a light reception recording mechanism for adding optical characteristics of a prescribed wavelength only when the measurement light is at a preset prescribed region while moving the sample for acquisition and recording; and a polarization analysis mechanism having an analysis function of either an ellopsometer or a scatterometer for analyzing the structure of the surface of the sample based on recording by the light reception recording mechanism. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ellipsometer, an anomaly detection method based on ellipsometry, a method for manufacturing a magnetic recording medium, and a method for manufacturing a semiconductor wafer. For example, a thin film formed on the surface of a sample such as a magnetic recording medium or a semiconductor wafer Further, the present invention relates to a configuration for measuring the thickness, shape, physical characteristics, and the like of a microstructure with higher accuracy and efficiency than normal thinning measurement.

  In the fields of semiconductors and magnetic disks, it is necessary for process management to measure physical properties such as film thickness, line width, and refractive index of thin films and microstructures produced on products by lithography and imprint technologies. .

  For this purpose, optical measurement using ellipsometry, such as an ellipsometer or a scatterometer, is often used (see, for example, Patent Document 1 or Patent Document 2). An ellipsometer or scatterometer applies measurement light with a known polarization state to the sample surface, measures the polarization state of the measurement light reflected from the sample, models the sample, and compares it with the theoretically calculated polarization state. This is a device that measures the film thickness.

  The basic configurations of the ellipsometer and scatterometer are the same, but differ in the method of modeling the sample and comparing it with the theoretically calculated polarization state. In general, an ellipsometer is used for a sample having a flat surface, and a scatterometer is used for a sample having a concavo-convex structure on the surface. The ellipse sorter technique is detailed in Non-Patent Document 1, for example. Regarding the scatterometry technique, for example, Non-Patent Document 2 introduces an outline of the technique.

  FIG. 6 is a basic device configuration diagram of a normal ellipsometer or scatterometer. The basic configuration of the ellipsometer and the scatterometer is the same, a stage 42 having a spindle motor for placing and rotating the sample 41, a light source 43 for irradiating the sample 41 with measurement light 45, and a light source 43 A polarizer 44 that polarizes light into a predetermined polarization state, an analyzer 47 that adjusts the polarization state of the reflected light 46 from the sample 41, a photodetector 48 that receives the reflected light 46 whose polarization state has been adjusted by the analyzer 47, and a stage 42 And a control / analysis PC 50 for analyzing the polarization information from the photodetector 48.

In this case, the size of the measurement light 45 on the sample 41 is usually from several millimeters to several tens of microns. In many apparatuses, in order to increase information used for analysis, a white light source is used as the light source 43 and a spectroscope is used as the light detector 48 to analyze data using polarization states of multiple wavelengths.
In particular, when the sample structure is complicated or when measurement accuracy is required, polarization analysis by spectroscopy is indispensable.

  Monochromator that acquires spectral data while switching wavelengths one wavelength at a time using a polychromator that can collect multiple wavelengths of spectral data at once using a CCD as the detector, or a photomultiplier tube as the detector A meter is used.

  The time for measuring one location on the sample 41 depends on the wavelength range to be measured, but is about several seconds for the polychromator type and several minutes for the monochromator type. Although the polychromator type is high speed, the detection sensitivity is inferior to that of the monochromator type, so that the measurement accuracy is deteriorated and the light detection sensitivity is insufficient. A monochromator type device is used when precise measurement or analysis in a short wavelength region (light intensity is likely to be insufficient) is required for measurement of semiconductors and magnetic disks that are becoming finer.

As a change in the polarization state when the measurement light 45 is reflected on the surface of the sample 41 from the detection value by the spectroscope and the polarization state setting information of the polarizer 44 and the analyzer 47 at that time, Ψ (λ), Δ (λ) is detected.
r _p (λ) / r _s (λ) · tan (Ψ (λ)) × exp (iΔ (λ))
Here, r _p (λ) and r _s (λ) are amplitude reflection coefficients at the wavelength λ of p-polarized light and s-polarized light, respectively. Therefore, Ψ (λ) is an angle determined by the amplitude ratio of p-polarized light and s-polarized light in the reflected light 46, and Δ (λ) is a phase difference angle between the p-polarized light and the s-polarized light of the reflected light 46.

By comparing Ψ (λ) and Δ (λ) obtained from the theoretical model calculated by the control / analysis PC 50 with the actually measured Ψ (λ) and Δ (λ), the thin film film of the sample 41 is obtained. Thickness, shape of fine structure, etc. can be obtained.
JP 2005-257475 A JP 2007-133985 A Fujiwara, Spectroscopic ellipsometry, published by Maruzen Shirasaki, shape measurement using a spectroscopic ellipsometer, O plus E, vol. 3,2005

  However, when analysis in the short wavelength region and high-accuracy measurement are required, it is necessary to use a monochromator type device. As described above, it takes several seconds to several minutes to measure one place on the sample. Therefore, there is a problem that a lot of inspection time is required.

  Therefore, when measuring a large-area sample such as a semiconductor wafer or a magnetic disk, it takes a very long time to measure the entire surface.

  FIG. 7 is a conceptual explanatory diagram of the state of thinning measurement. As shown in FIG. 7A, measurement is performed by selecting a predetermined location on the surface of a sample 41 such as a magnetic disk. FIG. 7B is a diagram schematically showing the measurement results at each measurement location. In this case, the case where measurement is performed at eight locations is shown.

  However, when the number of measurement points is small, as shown in FIG. 7A, there is a problem that even when there is a defective portion 51 in a part of the sample 41, it is easy to miss a locally present defective region 51. It was.

  Accordingly, an object of the present invention is to accurately measure a wide range of average film thickness, shape, and physical properties of a sample in a short time using an ellipsometer, a scatterometer, or the like. .

  From one aspect of the present invention, a measurement mechanism that measures spectroscopic optical characteristics on a sample, a stage mechanism that can adjust a position where measurement light from the measurement mechanism hits the sample, and irradiation of the measurement light on the sample A stage position detection mechanism for detecting a position, and acquiring and recording an optical characteristic of a predetermined wavelength only when the measurement light is in a predetermined area on the sample while moving the sample Provided is a polarization analysis device having a light reception recording mechanism and a polarization analysis mechanism having an analysis function of either an ellipsometer or a scatterometer for analyzing the structure of the surface of the sample based on the recording in the light reception recording mechanism. .

  Further, from another aspect of the present invention, the step of irradiating the measurement light while moving the sample with respect to the spectroscopic optical characteristics on the sample, and a predetermined wavelength only when the sample is in a predetermined region on the sample An anomaly detection method by ellipsometry comprising the steps of acquiring and recording by adding optical characteristics and detecting an anomaly of the surface of the sample by analyzing the structure of the surface of the sample based on the recording Is provided.

  Further, from another aspect of the present invention, the step of irradiating the measurement light while moving the sample with the spectroscopic characteristics on the sample made of a magnetic recording medium, and when the sample is in a predetermined region on the sample Acquiring and recording only by adding optical characteristics of a predetermined wavelength, detecting a structural abnormality of the surface of the sample by analyzing the structure of the surface of the sample based on the recording, and detecting the detection There is provided a method of manufacturing a magnetic recording medium, which includes a step of determining a sample in which no abnormality is detected in the process as an acceptable product.

  Further, according to still another aspect of the present invention, the step of irradiating the measurement light while moving the sample with the spectral optical characteristics on the sample made of a semiconductor wafer, and when the sample is in a predetermined region on the sample Acquiring and recording only by adding optical characteristics of a predetermined wavelength, detecting a structural abnormality of the surface of the sample by analyzing the structure of the surface of the sample based on the recording, and detecting the detection There is provided a method of manufacturing a semiconductor wafer, which includes a step of determining a sample in which no abnormality is detected in the process as an acceptable product.

  According to the disclosed ellipsometer, the anomaly detection method by ellipsometry, the method for manufacturing a magnetic recording medium, and the method for manufacturing a semiconductor wafer, normal decimation measurement is performed using an ellipsometer, scatterometer, or other ellipsometer. By doing so, it is possible to measure the surface state of the sample in a short time and in a wide range, and it is possible to reduce oversight of local defective portions in the sample.

  Here, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual configuration diagram of an ellipsometer according to an embodiment of the present invention. Basically, a conventional ellipsometer is provided with a shutter, a shutter controller, and a synchronization controller.

  As shown in FIG. 1, the ellipsometer of the embodiment of the present invention includes a stage 12 having a spindle motor for placing and rotating a sample 11, and a white light source 13 for irradiating the sample 11 with measurement light 15. A polarizer 14 that polarizes light from the white light source 13 into a predetermined polarization state, an analyzer 17 that adjusts the polarization state of the reflected light 16 from the sample 11, and a reflected light 16 whose polarization state has been adjusted by the analyzer 17 at a predetermined timing. A shutter 18 that passes only through the light, a spectroscope 19 that receives the reflected light 16 that has passed through the shutter 18, a shutter control unit 20 that controls the opening and closing of the shutter 18, and a synchronization control unit 21 that synchronizes the movement of the stage 12 and the opening and closing of the shutter 18. , Stage control unit 22 for controlling the movement of the stage 12, detecting the movement position of the sample 11 That the position detecting sensor 23, controls the stage controller 22 and the synchronization control unit 21, a control and analysis for PC24 to analyze the polarization information from the spectrometer 19.

  In this case, in the method of modeling the sample 11 in the control / analysis PC 24 and comparing it with a theoretically calculated polarization state, an ellipso having a function corresponding to a model for reflected light from a flat surface is used. Become a meter. On the other hand, a scatterometer is provided with a function corresponding to a model for scattered light from an uneven surface.

  In the ellipsometer of the embodiment of the present invention, the stage 12 including the stage controller 22 serves as a sample moving mechanism that adjusts the position where the measurement light 15 strikes the sample 11. Further, the stage 12 is provided with a position detection sensor 23 as a stage position detection mechanism for detecting where the measurement light 15 is irradiated on the sample 11.

  In the figure, the shutter 18 is provided on the light receiving side. However, the shutter 18 may be provided between the white light source 13 and the polarizer 14, and in this case, the measurement light 15 is applied to the sample only at a predetermined timing. Will be. These timings are controlled by the detection output of the position detection sensor 23 provided on the stage 12.

  Next, an abnormality detection method based on polarization analysis in the embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, after the polarization state of measurement light 15 from a white light source 13 is adjusted by a polarizer 14, the surface of the sample 11 being moved or stationary by a sample moving mechanism comprising a stage 12 having a spindle motor. Is irradiated with measurement light 15. After adjusting the polarization state of the reflected light 16 from the sample 11 with the analyzer 17, the spectroscope 19 detects the polarization state for each wavelength.

  At this time, as shown in FIG. 2A, it is detected where the measurement light 15 is irradiated on the sample 11 based on the signal of the position detection sensor 23 installed in the sample moving mechanism. Based on the detection result, the shutter 18 is opened only when the measurement light 15 hits a predetermined position of the sample 11 and the reflected light 16 from the sample 11 is incident on the spectroscope 19. In addition, in the figure, the example which divides into four area | regions 25-28 and performs a measurement is shown.

  Based on the average spectral polarization characteristics when the measurement light 15 acquired by the spectroscope 19 is in a predetermined region on the sample 11, as illustrated in FIG. Recorded as polarization information Ψ (λ) and Δ (λ) at the wavelength. From the polarization information Ψ (λ), Δ (λ), the film thickness, shape, and physical characteristics in the averaged region of the sample 11 are detected.

At this time, when a defective area 29 is detected in the area 26, as shown in FIG. 2C, the area 25 is further subdivided and the same measurement is performed again. Here, an example is shown in which the area 26 is divided into sub-areas 26 ₁ and 26 ₂ . As described above, the detailed position of the defective area 29 can be specified by repeating the detailed measurement while limiting the area.

  FIG. 3 is a flowchart of the abnormality detection method by polarization analysis in the embodiment of the present invention, which summarizes such a series of flows. In this way, instead of simply thinning out, the average measurement of each of the predetermined areas 25 to 28 set in advance while rotating the sample 11 is performed, so that the defective area 29 in the area 26 is efficiently detected without missing it. It becomes possible.

  If the amount of light at a specific wavelength is insufficient for one scan, the predetermined regions 25 to 28 are scanned a plurality of times, and the necessary amount of light is added to detect and record polarization information. The process proceeds to detection and recording of (λ) and Δ (λ).

  In the figure, one round is divided into four, but the number of divisions is arbitrary. However, if the number of divisions is too large, the time required for measurement increases. On the other hand, if the number of divisions is too small, information from the defective area 29 may be thinned out in the average value and overlooked.

  Based on the above, the anomaly detection method by polarization analysis according to the first embodiment of the present invention will be described next with reference to FIG. FIG. 4 is an explanatory diagram of the synchronous measurement when acquiring the data in the area 32 between a and b on the magnetic disk 31 to be the sample 11. In this example, the measurement light 33 is at the position of the white circle in the figure, and the magnetic disk 31 is rotated clockwise in a certain direction. It is assumed that the origin sensor 34 for detecting rotation is installed in the direction of 3 o'clock in FIG.

  While the magnetic disk 31 is rotating, the origin position is detected based on the detection signal of the origin sensor 34. Based on the detection timing of the origin position and the rotation speed of the magnetic disk 31, an area 32 between a and b of the magnetic disk 31 is formed. The shutter is opened at a position at the measurement light position to record the polarization information at the wavelength λ1. If the amount of light is insufficient, the disk is rotated a plurality of times to add the polarization information in the area 32 between a and b, and the process proceeds to the recording of the next wavelength λ2. This is repeated for the wavelengths that require this.

Next, with reference to FIG. 5, the abnormality detection method by the polarization analysis of Example 2 of this invention is demonstrated.
FIG. 5 is an explanatory diagram of a measurement area setting method in the anomaly detection method based on polarization analysis according to the second embodiment of the present invention. To get.

  As described above, by enlarging the average measurement area 35 in the radial direction of the magnetic disk 31, the probability of missing a defective area is greatly reduced. Although the measurement light is moved in the figure, the data acquisition range may be expanded by moving the magnetic disk 31 in the horizontal direction by providing a horizontal movement mechanism on the stage in addition to the disk rotation mechanism. .

  Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the embodiments and examples, and various modifications can be made. For example, in each of the above-described embodiments, the measurement light is adjusted by the shutter so that the measurement light is incident on the spectroscope only when the measurement light is in a predetermined region on the sample, but this is not essential.

  For example, reflected light from all regions on the sample may be intermittently taken into the spectrometer, and optical characteristics of a predetermined wavelength in a predetermined time segment may be added. In this case, the time segment may be determined as appropriate based on the distance from the origin position of the origin sensor, thereby eliminating the need for a shutter mechanism.

  As described above, each embodiment of the present invention has been described. However, the abnormality detection method based on the polarization analysis of the first embodiment or the second embodiment is applied to a manufacturing process of a magnetic recording medium or a semiconductor wafer. In this case, the magnetic recording medium or the semiconductor wafer is used as a sample, the abnormality is detected by the above-described polarization analysis, and the magnetic recording medium or the semiconductor wafer in which no abnormality is detected is determined to be an acceptable product and shipped.

It is a notional block diagram of the ellipsometer of embodiment of this invention. It is explanatory drawing of the abnormality detection method by the polarization analysis of embodiment of this invention. It is a flowchart of the abnormality detection method by the polarization analysis in embodiment of this invention. It is explanatory drawing of the synchronous measurement in Example 1 of this invention. It is explanatory drawing of the setting method of the measurement area | region in the abnormality detection method by the polarization analysis of Example 2 of this invention. It is a basic apparatus block diagram of the conventional ellipsometer or scatterometer. It is a conceptual explanatory drawing of the situation of thinning measurement.

Explanation of symbols

11 Sample 12 Stage 13 White light source 14 Polarizer 15 Measurement light 16 Reflected light 17 Analyzer 18 Shutter 19 Spectrometer 20 Shutter control unit 21 Synchronization control unit 22 Stage control unit 23 Position detection sensor 24 PC for control and analysis
25 to 28 areas 26 ₁ and 26 ₂ sub areas 29 defective area 31 magnetic disk 32 area 33 measuring light 34 origin sensor 35 average measuring area 41 sample 42 stage 43 light source 44 polarizer 45 measuring light 46 reflected light 47 analyzer 48 photodetector 49 Stage control unit 50 PC for control and analysis
51 Defect area

Claims (7)

A measurement mechanism for measuring the spectroscopic characteristics on the sample;
A stage mechanism capable of adjusting the position where the measurement light from the measurement mechanism hits the sample;
A stage position detection mechanism for detecting an irradiation position of the measurement light on the sample;
A light receiving recording mechanism that acquires and records an optical characteristic of a predetermined wavelength only when the measurement light is in a predetermined region set in advance on the sample while moving the sample;
An ellipsometer having an ellipsometer or scatterometer analyzing function that analyzes the structure of the surface of the sample based on recording in the light receiving recording mechanism. The light receiving and recording mechanism includes a spectroscope,
The ellipsometer according to claim 1, further comprising a shutter for adjusting the measurement light so that the measurement light enters the spectroscope only when the measurement light is in a predetermined region on the sample. The ellipsometer according to claim 2, wherein the light receiving and recording mechanism includes a synchronization control mechanism that controls the spectroscope and the shutter in synchronization with the stage mechanism. Irradiating measurement light while moving the sample with respect to the spectroscopic characteristics on the sample; and
Obtaining and recording by adding optical characteristics of a predetermined wavelength only when in a predetermined area on the sample; and
And detecting the structural abnormality of the surface of the sample by analyzing the structure of the surface of the sample based on the recording. Divide the sample into predetermined areas, and divide the area determined to have a high possibility of structural abnormality into smaller areas based on the results of average measurement in each divided area. The abnormality detection method by polarization analysis according to claim 4, further comprising a step of performing detailed measurement. Irradiating measurement light while moving the sample with respect to spectroscopic characteristics on the sample made of a magnetic recording medium; and
Obtaining and recording by adding optical characteristics of a predetermined wavelength only when in a predetermined area on the sample; and
Detecting structural abnormality of the surface of the sample by analyzing the structure of the surface of the sample based on the recording; and
A method of manufacturing a magnetic recording medium, comprising: determining a sample that does not detect an abnormality in the detection step as an acceptable product. Irradiating measurement light while moving the sample with the spectroscopic characteristics on the sample made of a semiconductor wafer; and
Obtaining and recording by adding optical characteristics of a predetermined wavelength only when in a predetermined area on the sample; and
Detecting structural abnormality of the surface of the sample by analyzing the structure of the surface of the sample based on the recording; and
A method of manufacturing a semiconductor wafer, comprising: determining a sample that does not detect abnormality in the detection step as an acceptable product.

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