WO2011122096A1

WO2011122096A1 - Patterned media defect inspector device and inspection method for stamper for patterned media employing same

Info

Publication number: WO2011122096A1
Application number: PCT/JP2011/052051
Authority: WO
Inventors: 聖岳堀江; 優日下; 優谷中; 滋芹川
Original assignee: 株式会社日立ハイテクノロジーズ
Priority date: 2010-03-30
Filing date: 2011-02-01
Publication date: 2011-10-06
Also published as: JP2011210327A

Abstract

Disclosed is a method for inspection for a stamper for patterned media, which detects problems with a stamper for transferring a finely detailed pattern to photoresist coated upon a sample, in order to classify defects occurring repeatedly in patterned media discs into defects arising from deteriorations from changes over time in the stamper and defects arising from process problems, and to detect defects arising from changes over time in the stamper. The finely detailed pattern of the stamper is transferred upon the photoresist film coated upon the obverse face of the sample, and light is projected thereupon. The reflected light from the sample whereupon the light is projected is spectrally detected, defects are extracted from a detection waveform obtained by the spectral detection, and a discrimination is made, concerning defects occurring in the same location upon a plurality of samples from among the extracted defects, between the defects caused by the stamper and the defects caused by the process of forming the photoresist film pattern. When the number of defects caused by the stamper exceeds a preset number, an alert is issued.

Description

Patterned media defect inspection apparatus and patterned media stamper inspection method using the same

The present invention relates to a defect inspection apparatus for patterned media and a technique for monitoring defects and deterioration caused by changes over time in a patterned media stamper using the same.

In recent years, the capacity of hard disks, which are recording media used in computers, has been increasing. In order to increase the capacity of recorded information, it is indispensable to improve the density of recording on one disc. Patterned media, which is a medium in which a pattern is formed on the disk surface, is promising as a method capable of greatly improving the recording density as compared with conventional disk media.

Regarding the inspection of patterned media, as disclosed in

Patent Documents

1 and 2, it is known to inspect fine pattern defects by spectroscopic inspection. As a stamper defect detection technique, Patent Document 3 discloses a technique for inspecting a stamper defect that detects an optical disc defect and detects a defect repeatedly generated at the same position as a stamper defect.

JP 2009-257993 A JP 2009-150832 A JP 05-072143 A

When a problem occurs in the stamper used in the pattern formation process of the patterned media disk, the defect is continuously transferred to the same location, resulting in a defective disk. In the techniques disclosed in

Patent Documents

1 and 2, it is difficult to distinguish between a defect caused by a stamper and a defect caused by a manufacturing process.

On the other hand, in the technique disclosed in Patent Document 3, a defect that repeatedly occurs at the same position is used as a stamper defect, and a repeated defect caused by a process failure and a repeated defect caused by a stamper deterioration are identified. Was not considered.

An object of the present invention is to identify a defect that has repeatedly occurred on a patterned media disk due to deterioration due to a change in stamper over time and a defect that has occurred due to a process failure, and has occurred due to a change in stamper over time. An object of the present invention is to provide a patterned media defect inspection apparatus for detecting defects and a patterned media stamper inspection method using the same.

In order to achieve the above-described object, in the present invention, a patterned media defect inspection apparatus for detecting a defect of a stamper for transferring a fine pattern to a resist applied on a sample is applied to the resist applied on the surface. An illumination optical system for irradiating a sample with a fine stamper pattern transferred onto the film, a spectroscopic detection optical system for spectrally detecting reflected light from the sample irradiated with light by the illumination optical system, and a spectroscopic detection optical system A defect extracting means for extracting a defect from a detection waveform obtained by spectral detection by means of a defect, a defect caused by a stamper at a same position on a plurality of samples among defects extracted by the defect extracting means, and a resist film A defect data processing unit for discriminating defects caused by the process of forming the pattern, and the number of defects caused by the stamper in the defect data processing unit is set in advance. It was constructed and an output unit that notifies the warning when it exceeds the number.

In order to achieve the above-described object, the present invention provides a patterned media stamper inspection method for detecting defects in a stamper for transferring a fine pattern onto a resist applied on a sample. Irradiating the sample with the stamper's fine pattern transferred to the resist film, irradiating the sample with light, spectrally detecting the reflected light from the sample irradiated with light, and extracting defects from the detected waveform obtained by spectral detection; Among the extracted defects, the defect caused at the same position on a plurality of samples is distinguished from the defect caused by the stamper and the defect caused by the process of forming the resist film pattern, and the number of defects caused by the stamper is determined in advance. A warning is notified when the set number is exceeded.

In order to achieve the above-described object, the present invention provides a patterned media stamper inspection method for detecting defects in a stamper for transferring a fine pattern onto a resist applied on a sample. Irradiating the sample with the stamper's fine pattern transferred to the resist film, irradiating the sample with light, spectrally detecting the reflected light from the sample irradiated with light, and extracting defects from the detected waveform obtained by spectral detection; Among the extracted defects, the defect caused by the stamper and the defect caused by the process of forming the resist film pattern are discriminated from the state of change over time of the number of defects generated at the same position on a plurality of samples, The defect occurrence position information is output for the defect caused by the discriminated stamper.

According to the present invention, for a defect repeatedly generated at the same location on a plurality of patterned media discs, a defect caused by deterioration due to a change of a stamper with time and a defect caused by a process failure are identified. By detecting defects that have occurred due to changes over time and detecting the occurrence of a stamper life or failure early as a warning or failure, it has become possible to prevent the occurrence of a large number of defects due to the stamper.

It is a figure which shows the pattern formation process of a discrete medium. It is process drawing which shows a nanoimprint process. It is a block diagram which shows the whole structure of a patterned media inspection apparatus. It is sectional drawing of the resist pattern formed on the magnetic film layer. It is a graph which shows the detection output for every spectral wavelength detection channel. It is a flowchart which shows the procedure which detects a defect from spectral waveform data. It is a flowchart which shows the flow of the process which identifies the abnormality of a stamper and the abnormality of a process. It is a front view of the screen which displays the detection result of a stamper abnormality.

First, a process of forming a pattern of a patterned medium (sample) 1 to be inspected in the present invention will be described with reference to FIG. First, thin films such as an underlayer 11, an intermediate layer 12, and a recording layer 13 are formed on the substrate 10 (S101). Next, the resist 14 is applied to the substrate on which the multilayer thin film layer is formed, and the resist is exposed to the nanoimprint by irradiating the exposure light in a state where the stamper on which the fine uneven pattern is formed is pressed against the resist on the substrate. Perform (S102). Next, the shape of the fine pattern of the resist 14 transferred onto the substrate 10 by nanoimprinting is inspected (S103). The substrate that does not pass the inspection is stripped of the resist on the surface and sent to the nanoimprint process of S102 again.

About the board | substrate which passed this test | inspection, the recording layer 13 is etched among the multilayer thin film layers on the board | substrate 10 using the pattern of the resist 14 formed by nanoimprint as a mask, a resist is removed, and a fine pattern is formed (S104). . Next, the nonmagnetic film 15 is formed on the substrate 10 and the fine pattern formed on the recording layer 13 is embedded (S105), and the substrate surface is planarized (CMP (Chemical Mechanical Polishing) process). Then, the nonmagnetic film formed on the substrate 10 is removed leaving the fine pattern portion formed on the recording layer 13 (S106), and the protective film 16 is formed on the surface of the substrate 10 (S107). To do.

Next, the inspection step (S103) for inspecting the fine pattern 14 when it is formed on the substrate 10 by nanoimprinting among the steps shown in FIG. 1 will be described in detail with reference to FIG.

2A shows a state in which a resist film 201 (corresponding to 14 in FIG. 1) is applied on a substrate 203 (corresponding to 10 in FIG. 1) on which a recording layer 202 (corresponding to 13 in FIG. 1) is formed. Then, a state is shown in which the stamper 200 on which a fine pattern to be transferred onto the surface is formed above the substrate 203 is on standby. In FIG. 2, the base layer 11 and the intermediate layer 12 described in FIG. 1 are omitted to simplify the description. Next, as shown in FIG. 2B, the stamper 200 is pressed against the substrate 203 to cause the resist film 201 on the surface to follow the fine pattern formed on the stamper 200. In this state, as shown in FIG. 2C, exposure light is irradiated from the back side of the stamper 200 to expose the resist 201 in a state where the stamper 200 is pressed. When the stamper 200 is peeled from the resist 201 after the resist is exposed and cured, a resist pattern as shown in FIG. 2D is formed on the recording layer 202.

In the present invention, the pattern of the resist 201 formed on the recording layer 202 as shown in FIG. 2D is checked for its pattern, and the resist 201 is formed on the stamper 200 for forming a pattern. The present invention relates to an inspection apparatus for inspecting a fine pattern state and an inspection method thereof.

Next, the patterned media inspection apparatus according to the present invention will be described with reference to FIG.

The patterned media inspection apparatus according to the present invention includes a θ stage 141 that mounts and rotates a sample (patterned media) 1 to be inspected, a spectral detection optical system 100, a control unit 120, and the spectral detection optical system 100 in a uniaxial direction. And an input / output means 125 for inputting / outputting data to / from the control unit 120.

The spectroscopic detection optical system 100 includes a light source 101 that emits broadband light including deep ultraviolet (DUV) light, a condensing lens 102 that collects light emitted from the light source 101, and an inspection target mounted on the θ stage 141. And a field stop 103 having an opening 1031 for determining a detection field on the patterned medium 1, and a sample 1 to be inspected (the resist 14 pattern formed on the surface in step S102 in FIG. 1). A wavelength selection filter 104 that selects the wavelength of the illumination light, a polarizer 105 that polarizes the illumination light in a specific direction, a half mirror 106 that bends the optical path of the polarized illumination light toward the pattern dodia 1 to be inspected, and illumination. The objective lens 107 for condensing the light on the surface of the patterned medium 1 to be inspected and the light reflected by the surface of the patterned medium 1 are again paired. The reflected light that has been collected by the object lens 107 and transmitted through the half mirror 106 is allowed to pass therethrough, and the aperture 1081 for cutting stray light from the periphery is cut off, and the reflected light that has passed through the aperture 108 is spectrally detected. A spectroscope 109 is provided. The spectroscope 109 is configured by arranging a diffraction grating 110 that diffracts and separates the reflected light that has passed through the aperture 108 and a plurality of detection pixels that detect a spectral waveform diffracted and dispersed by the diffraction grating 110 in a line. And a linear photodetector 111.

The control unit 120 receives the spectral waveform signal detected by the linear photodetector 111 of the spectroscope 109, A / D converts it, outputs a digital signal, and the A / D converted signal. A data processing unit 122 that processes and inspects the pattern shape of the patterned medium 1 to be inspected, a database 123 that stores data indicating the relationship between the spectral waveform signal data and the pattern defect shape, and a control unit that controls the whole 124 is provided. The data processing unit 122 and the control unit 124 are connected to an external input / output unit 125 having a display screen 126.

Next, a method for inspecting the pattern shape formed on the patterned media 1 with the patterned media inspection apparatus having the configuration shown in FIG. 2 will be described.

First, the drive unit 130 is set to the inspection start position under the control of the control unit 124, and the θ stage 141 starts high-speed rotation. With the patterned medium 1 rotated at a high speed by the rotation of the stage 141, the drive unit 130 is moved in one direction (radial direction of the patterned medium 1) at a constant speed. In this state, the light source 101 emits broadband (multi-wavelength) illumination light (for example, a wavelength of 200 to 800 nm) including deep ultraviolet (DUV) light. As the light source 101, an Xe lamp, a halogen lamp, a deuterium lamp, a mercury lamp, or the like can be used.

The light emitted from the light source 101 is condensed at the position of the opening 1031 of the field stop 103 by the condenser lens 102. The image of the light condensed on the opening 1031 of the field stop 103 is formed on the surface of the patterned medium 1 to be inspected by the objective lens 106. The wavelength of the illumination light that has passed through the field stop 103 is selected by the wavelength selection filter 104, and the light having the selected wavelength is used to measure the shape of the pattern formed on the patterned medium 1 by the polarization optical element 105. After being adjusted to a polarization state that can be performed with high sensitivity, a part of the half mirror 106 is reflected in the direction of the objective lens 107, passes through the objective lens 107, and is irradiated onto the patterned medium 1.

The reflected light from the patterned medium 1 on which the image of the opening 1031 of the field stop 103 is projected again enters the objective lens 107, and part of the light passes through the half mirror 106 and reaches the stop 108. Here, by adjusting the position of the diaphragm 108, an image of the reflected light from the patterned medium 1 that has passed through the objective lens 107 is formed at the position of the opening 1081 of the diaphragm 108. By matching the size of the aperture 1081 of the aperture 108 to the size of the detection field of view on the patterned medium 1 (the region on which the image of the aperture 1031 of the field aperture 103 is projected) (they need not necessarily be the same size). And may be smaller than the size of the detection visual field), stray light and light that does not form an image on the stop 108 can be blocked.

Reflected light (regularly reflected light) from the detection visual field on the patterned medium 1 that has passed through the aperture 1081 of the stop 108 reaches the diffraction grating 110 of the spectroscopic optical system 109, and the diffraction angle of the diffraction grating 110 depends on the wavelength. Have different spectral waveforms, and the diffracted light separated by the linear photodetector 111 in which a plurality of detection elements are arranged is separated and detected by the respective detection elements. The spectral waveform detection signal detected by the linear photodetector 111 is input to the spectral waveform processing unit 121 of the control unit 120 and A / D converted to obtain a digitized spectral waveform signal. The digitized spectral waveform signal is sent to the data processing unit 122 for processing, and the shape of the pattern formed on the patterned medium 1 to be inspected is inspected.

Next, a pattern shape inspection method executed by the control unit 120 will be described with reference to FIG. First, spectral waveform signal data of a standard sample having a normal concavo-convex pattern and a known pattern shape is acquired (S601) and stored in the database unit 123 (S602). Next, based on the spectral waveform signal data of the standard sample, an uneven pattern shape (as shown in FIG. 4, the height of the pattern of the resist 201 (14) formed on the magnetic film layer 202 (13) is analyzed by electromagnetic wave analysis. The spectral waveform signal when the pattern width, the thickness of the base, etc.) are changed and stored in the database unit 123, and the spectral waveform signal data corresponding to the limit value of the uneven pattern shape change is determined. It is registered in the database unit 123 (S603).

That is, as shown in the graph showing the detection output for each detection channel corresponding to the spectral wavelength of FIG. 5, based on the spectral waveform data 502 obtained by measuring the normal uneven pattern, and the spectral waveform data 502

Spectral waveform data

503 and 504 corresponding to the limit of the allowable shape change of the uneven pattern obtained by the electromagnetic wave analysis is registered in the database unit 123. In FIG. 5, the horizontal axis indicates the channel (ch) number of the linear photodetector 110 corresponding to the detection wavelength, and the channel number corresponds to the detection wavelength. The larger the number, the longer the detection wavelength. Is shown.

The shape of the concavo-convex pattern, for example, how the spectral waveform data changes depending on whether the pattern height changes or the pattern width changes. That is, the spectral waveform data varies depending on the cause of the defect in the uneven pattern shape. Using this characteristic, the relationship between the cause of the irregular pattern shape defect and the characteristic of the spectral waveform data is registered in the database unit 123 in advance, and the spectral waveform data obtained by inspecting the sample to be inspected is stored in the database unit. The distribution characteristics of the wavelength band exceeding the allowable value are obtained by comparing with the spectral waveform data of the standard sample registered in 123, and the cause of the irregular pattern shape defect registered in the database unit 123 and the spectral waveform data The defect of the pattern shape of the sample to be inspected can be detected from the information on the relationship with the characteristics, and the type of the defect can be specified.

Therefore, the inspection target sample having a resist pattern formed on the surface is inspected by the inspection apparatus of FIG. 3 to obtain spectral waveform data (S604), and the spectral waveform data of the inspection target sample is stored in the database unit 123. (S605) The defect is detected by the method described above (S606), and the spectral waveform data of the detected defect is stored together with the position information of the defect (S607). .

In the patterned media inspection apparatus shown in FIG. 3, the configuration in which the spectroscopic detection optical system 100 is moved in one direction by the drive unit 130 while rotating the θ table 140 is shown. However, the θ table 140 is moved in one axis direction. The entire surface of the disk may be inspected by placing it on a movable table and moving it in one axial direction while rotating the θ table 140 with the spectroscopic detection optical system 100 fixed.

A method for monitoring the state of a fine pattern formed on the stamper 200 using such a defect detection method will be described with reference to FIG.

When transferring a fine pattern onto a substrate using nanoimprint technology, the cause of a defect that repeatedly occurs at the same location on a plurality of substrates to be sequentially processed is generally caused by a process of forming a fine pattern. The case may be due to deterioration due to aging of the stamper for nanoimprinting. In this case, defects due to the process occur suddenly in a relatively short time, but defects due to deterioration due to the aging of the stamper gradually increase with time. In the present embodiment, by utilizing this difference in characteristics, the method described below will increase the number of defects in the pattern formed on the disk, thereby causing defects due to the process and deterioration due to changes over time of the stamper. A stamper failure was detected by identifying the failure caused.

First, the sample 1 to be inspected, to which a fine pattern is transferred by the stamper 200, is set on the θ table 140 of the inspection apparatus in FIG. 3, and the alignment mark formed on the sample 1 is spectrally detected while the θ table 140 is rotated. Data obtained by detecting with the optical system 100 and processing the detection signal by the spectral waveform processing unit 121 and the data processing unit 122, information on the rotation angle of the θ table 140 and position information on the drive unit 130 at that time Store it (S701).

Next, the entire surface of the sample 1 is inspected by the inspection apparatus of FIG. 3, the processing from S604 to S607 in FIG. 6 is executed to detect defects, and the spectral waveform data of the detected defects and the rotation angle of the θ table 140 are detected. And the position information of the drive unit 130 are obtained (S702) and stored.

Next, the position information of the detected defect and its spectral waveform data are compared with the inspection data (defect positional information and its spectral waveform data) of another substrate that has been previously inspected and stored, and the alignment mark is It is checked whether or not there is the same type of defect at the same position on the substrate when it is used as a reference (S703).

Next, as a result of checking in S703, it is determined whether or not the size or number of defects of the same type determined to exist at the same coordinate exceeds a preset warning setting value (S704). As a result, if the size or number of detected defects does not exceed the preset warning setting value, there is no problem in the process, and the stamper being used can be used normally. If there is a next disk without doing anything, the next disk is inspected (S709).

On the other hand, when the defect size or number exceeds a preset warning setting value, it is determined whether or not the defect size or number exceeds a preset abnormality setting value. (S705). As a result, if it is determined that the defect size or number exceeds the preset abnormal setting value, the warning setting value exceeding is detected in S704 and the abnormality setting value exceeding is detected in S705. (S706), and if it is longer (larger) than the preset time (number of processed samples 1), the life of the stamper gradually deteriorated due to the change with time is detected. As shown in FIG. 8, a defect map 801 indicating the position of the generated defect and stamper information 803 are displayed on the screen 800 (126) of the input / output means 125 as shown in FIG. At the same time, a stamper abnormality signal is output to a nanoimprint apparatus (not shown) that performs the nanoimprint process (S102) shown in FIG. 1 (S707). On the screen 800 (126), as the above-described defect map 801, the position on the sample 1 where the defect corresponding to the stamper defect is detected is detected and associated with the alignment mark position 802 for each defect type. To display. In addition to the stamper information 803, an area 804 for displaying the current state of the stamper and an area 805 for displaying the type of defect detected are provided.

On the other hand, the time from the detection of exceeding the warning set value in S704 to the detection of exceeding the abnormal setting value in S705 (the number of processed samples 1) is shorter than the preset time (the number of processed samples 1) ( In the case where the number of defects is small, it means that a large number of defects have occurred in a short time, and a process abnormality warning is issued from the input / output unit 125 that an abnormality has occurred in the process (S708).

If it is determined in S705 that the size or number of defects does not exceed the preset abnormality set value, a warning notifying that a defect has occurred in the same location is output (S710), and the process ends. .

According to the present embodiment, since the size or number of defects detected at the same location on the disk is checked in two stages, that is, a warning setting value and an abnormal setting value, repeated defects caused by process defects and stamper It is possible to identify and detect repetitive defects that have occurred due to deterioration due to aging, and to detect deterioration due to aging of the stamper at an early stage, thereby preventing a large number of defects due to stampers. became.

The present invention is applied to a defect inspection apparatus for a patterned medium, which is a magnetic recording medium, and an apparatus for monitoring defects and deterioration caused by changes over time of a patterned medium stamper.

DESCRIPTION OF SYMBOLS 1 ... Patterned medium 100 ... Spectral detection optical system 101 ... Light source 102 ... Condensing lens 103 ... Aperture 104 ... Wavelength selection filter 105 ... Polarization filter 106 ... Half Mirror 107 ... Objective lens 108 ... Aperture 109 ... Spectral optical system 110 ... Diffraction grating 111 ... Linear photodetector 120 ... Control unit 121 ... Spectral waveform processing unit 122 ... Data processing unit 123 ... database unit 124 ... control unit 125 ... input / output unit 130 ... drive unit 140 ... θ table.

Claims

An apparatus for detecting a defect of a stamper for transferring a fine pattern to a resist applied on a sample,
An illumination optical system for irradiating light onto a sample in which a fine pattern of a stamper is transferred to a resist film coated on the surface;
A spectroscopic detection optical system for spectroscopically detecting reflected light from a sample irradiated with light by the illumination optical system;
Defect extraction means for extracting defects from the detection waveform obtained by spectral detection by the spectral detection optical system;
Defect data processing for discriminating defects caused by the stamper and defects caused by the process of forming the resist film pattern from defects extracted by the defect extraction means at the same position on a plurality of samples And
An apparatus for inspecting a defect of a patterned media, comprising: an output unit for notifying a warning when the number of defects caused by the stamper exceeds a preset number in the defect data processing unit.
The defect data processing unit forms a pattern of the resist film and a defect caused by the stamper among defects generated at the same position on the sample repeatedly from a detection waveform obtained by spectral detection by the spectral detection optical system. Discriminating from defects caused by the process to compare the time from when the number of defects occurring at the same coordinate on the sample exceeds the first threshold to the second threshold with a preset time Then, if the time from exceeding the first threshold to exceeding the second threshold is longer than the preset time, it is determined that the defect is caused by the stamper. Defect inspection equipment for patterned media as described.
2. The patterned media defect inspection apparatus according to claim 1, wherein the warning notified by the output unit notifies a stamper replacement time.
The patterned medium according to claim 1, wherein the output unit has a display screen, notifies the warning, and displays information indicating a position where a defect caused by the stamper is generated on the screen. Defect inspection equipment.
A method for detecting a defect of a stamper for transferring a fine pattern to a resist applied on a sample,
Irradiate the sample with a fine stamper pattern transferred to the resist film applied on the surface,
Spectrally detect reflected light from the sample irradiated with the light,
Extract defects from the detected waveform obtained by the spectral detection,
Distinguishing defects caused by the stamper from defects extracted at the same position on a plurality of samples from the extracted defects and defects caused by a process of forming a pattern of the resist film,
An inspection method for a stamper for patterned media, wherein a warning is notified when the number of defects caused by the stamper exceeds a preset number.
Distinguishing defects caused by the stamper from defects generated at the same position on a plurality of samples from the detection waveform obtained by the spectral detection, and defects caused by the process of forming the resist film pattern, When the number of defects occurring at the same position on the plurality of specimens exceeds the first threshold and exceeds the second threshold, the time until the second threshold is exceeded exceeds the first threshold. 6. The method for inspecting a patterned media stamper according to claim 5, wherein a defect caused by the stamper is determined when the time from when the second threshold is exceeded is longer than the preset time.
6. The patterned media stamper inspection method according to claim 5, wherein the warning to be notified notifies a stamper replacement time.
6. The patterned media stamper inspection method according to claim 5, wherein a warning is notified and information indicating a position of occurrence of a defect caused by the stamper is displayed on a screen.
A method for detecting a defect of a stamper for transferring a fine pattern to a resist applied on a sample,
Irradiate the sample with a fine stamper pattern transferred to the resist film applied on the surface,
Spectrally detect reflected light from the sample irradiated with the light,
Extract defects from the detected waveform obtained by the spectral detection,
Among the extracted defects, a defect caused by the stamper from a state of change over time of the number of defects generated at the same position on a plurality of samples, and a defect caused by a process of forming a pattern of the resist film Discriminate,
A method for inspecting a stamper for patterned media, wherein the defect occurrence position information is output for a defect caused by the discriminated stamper.
10. The method for inspecting a stamper for a patterned media according to claim 9, wherein information on the replacement timing of the stamper is notified and information is output based on a defect caused by the discriminated stamper.