JP4690379B2 - Optical microscope system for nano-line sensing using polarizing plate and fast Fourier transform - Google Patents

Description

  The present invention relates to an optical microscope system for sensing nanowires using a polarizing plate and a fast Fourier transform, and more specifically, using an existing optical microscope system to facilitate alignment between a sample for nanowire elements and a pattern. The present invention relates to an optical microscope system for sensing nanowires.

  The present invention was derived from research conducted as an IT new growth dynamic core technology development project of the Information Communication Department and the Information Communication Research Promotion Agency. [Problem unique number: 2006-S-006-01, assignment name: ubiquitous terminal component module. ]

  A process of manufacturing an electronic device using nanowires always requires a photolithography process. In particular, in order to pattern a structure for manufacturing an electronic device, a technique for acquiring a sample image is necessary in order to align the sample and the pattern in the photolithography process.

  The general diameter of the nanowire used for fabricating the nanowire electronic device is several nanometers to several tens of nanometers, and the length thereof is several tens of nanometers to several tens of micrometers or tens of micrometers. When manufacturing electronic devices using relatively thick and long nanowires with a diameter of several tens of nanometers or more and a length of several micrometers, a sample image can be obtained with a general optical microscope. Therefore, the alignment work of the sample and the pattern can be performed using the existing semiconductor process equipment.

  However, when manufacturing electronic devices using thin nanowires with a diameter of 0 to 20 nanometers (especially less than 10 nm or 10 to 20 nm), an image of the nanowire is obtained using an existing optical microscope. Not easy to do. Also, when an electronic device is manufactured using a single carbon nanotube having a thickness of several nanometers, an image of a nanoline can also be obtained using an optical microscope. It's not easy.

  Therefore, in order to solve the above-mentioned problems, when an electronic device is manufactured using a nanowire or carbon nanotube with a small diameter, an optical microscope is used instead of an optical microscope in order to obtain a sample image necessary for the alignment process. A high-resolution microscope such as an atomic microscope (AFM) or an electron microscope (SEM) that has excellent resolution and can clearly obtain a sample image is used.

  However, when the above-described high-resolution microscope is used, it takes a relatively long time to obtain an image of the sample as compared with the optical microscope and the process cost is high, so that commercialization is not easy. In particular, there is a disadvantage that it is not easy to manufacture and commercialize a large-area nanowire element.

US Patent Publication No. 2003-0189202 US Patent Publication No. 2004-0136866 Proc. SPIE, 2004, p. 1500-p. 1507

  The present invention has been made in view of such problems, and the purpose of the present invention is to capture an image of a nanowire or carbon nanotube with a small diameter using an optical microscope used in an existing semiconductor device manufacturing process as it is. An object of the present invention is to provide an optical microscope system for sensing nanowires that can be obtained.

  In addition, another object of the present invention is to enable nano-element alignment and pattern alignment using an optical microscope, thereby shortening the manufacturing process time and reducing the process cost. It is to provide an optical microscope system.

The present invention has been made in order to achieve such an object, and is provided on a light source section that provides light emitted from a light source to a sample for a nanowire device, and on the light path provided from the light source section. is a rotating polarizing plate for polarizing the light, a polarizing plate controller for rotating is electrically coupled to the rotating polarizer the rotating polarizer at a first frequency (f _0), before Symbol for nanowire element an optical microscope for detecting light from the sample Ru are anti Isa, provided the optical microscope, the while rotating the polarizing plate is rotated, CCD camera for storing the image data obtained by photographing the light detected by the optical microscope And extracting the pixels having the second frequency (2f ₀ ) from the pixels of the video data by performing a fast Fourier transform process on the light intensity information contained in the pixels of the video data, Included in sample And a data processing unit for obtaining an image of the nanowire .

The invention according to claim 2 is the invention according to claim 1 , wherein the nanowires differ according to an angle between a formation direction of the nanowires and a polarization axis of light incident on the nanowires. characterized in that it has an optical anisotropy of emission as.

The invention according to claim 3 is the invention according to claim 1 , wherein the polarizing plate controller rotates the rotating polarizing plate at the first frequency ( f ₀ ) of 0.1 to 1 Hz. It is characterized by controlling to.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the polarization axis of light incident on the nanowire element sample is rotated at the second frequency ( 2f _0). ) Is modulated.
Further, in the invention according to claim 5, in the invention according to claim 4, if the light whose polarization axis is rotated at the second frequency (2f ₀ ) is incident on the sample for a nanowire element, The intensity of light reflected from the nanowire is modulated to the second frequency (2f ₀ ).

According to a sixth aspect of the present invention, in the first aspect of the present invention, the video data photographed by the CCD camera is stored in a pixel array according to time, and the data processing unit is provided for each pixel by time. By selecting a complex Fourier coefficient ((2f ₀ ) n, m) corresponding to the second frequency (2f ₀ ) by fast Fourier transforming the light intensity information (I (n, m) ₁ ) , the nano It is characterized by obtaining an image of a line.

  According to the present invention, when an electronic device using a nanowire having a diameter of 0 to 20 nm or a carbon nanotube having a thickness of 0 to 10 nm is manufactured, an existing optical microscope is used. Time can be reduced and manufacturing costs can be reduced.

  In addition, since an optical microscope used in an existing semiconductor element process can be utilized, and the process linkage is excellent, an electronic element process using large-area nanowires or carbon nanotubes is possible.

  Furthermore, instead of an expensive electron microscope (or atomic microscope), an image of a nanoline can be obtained using an optical microscope, which can contribute to activation of nanoline research.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram for explaining one embodiment of an optical microscope system for nano-line sensing according to the present invention. An optical microscope system 1 for sensing nanowires according to the present invention includes a light source unit 10 on which a light source is incident and a CCD (Charge Coupled) that captures an image of a light source that is reflected by reaching a sample (not shown) for nanowire elements. Device) An optical microscope 30 provided with a camera 31 and a rotating polarizing plate 20 provided therebetween, and reaches a sample for a nanowire device by a light source incident from a light source unit 10, and passes through a CCD camera 31. The image processing technology that performs fast Fourier transform processing on the optical image (data) of the sample acquired in this way is used.

  With reference to FIG. 1, the optical microscope system 1 for nanowire sensing of this invention is demonstrated more concretely. The optical microscope system 1 for sensing nano-beams includes a light source unit 10 that receives a light source, a rotatable rotating polarizer 20 that polarizes the light source incident from the light source unit 10 in a specific direction, and a rotating polarizer 20. A polarizing plate controller 40 that is electrically connected to the rotating polarizing plate 20 and controls the rotation of the rotating polarizing plate 20, and passes through the rotating polarizing plate 20 and is incident on the sample for the nanowire device and reflected. An optical microscope 30 that detects the optical image of the nano-line using the captured light and an optical microscope 30 provided in one area of the optical microscope 30 to capture the optical image of the nano-line and store the captured image data The CCD camera 31 and the nanowire image data obtained via the CCD camera 31 at high speed. Rie conversion: and a data processing unit 50 to fast Fourier transform by using the (Fast Fourier Transform FFT) method.

  More specifically, the light source unit 10 generates white light and provides it to the sample for nanodevice. The rotating polarizing plate 20 is a device that obtains polarization properties using the fact that the optical isomers have different colors of transmitted light polarized depending on the direction, and polarizes white light provided from the light source unit 10. The light that has passed through the rotating polarizing plate 20 is polarized in a specific direction. When polarized light is incident on the nanowire, it exhibits optical anisotropy in which most of the nanowire emits light depending on the angle between the nanowire formation direction and the polarization axis. When the formation direction of the nanowire and the polarization axis are aligned and the angle between the two is 0 degree, light is emitted to the maximum, and conversely, when it is 90 degrees, the light is emitted to the minimum. By utilizing such optical anisotropy of nanowires, a high-resolution optical microscope system for sensing nanowires according to the present invention is realized.

In this embodiment, the rotation polarizing plate 20 is rotationally controlled using the polarizing plate controller 40. The polarizing plate controller 40 controls the rotating polarizing plate 20 installed between the light source unit 10 and the optical microscope 30 so as to rotate at a frequency f ₀ in the range of 0.1 Hz to ₁ Hz. In general, the optical microscope 30 can detect nanowires of a sample for a nanowire element using a light source provided from the light source unit 10, and a CCD camera 31 provided in the optical microscope 30 has a rotating polarizing plate. A light source that passes through 20 and is reflected by the sample for the nanowire element is photographed.

  In the present embodiment, the position of the CCD camera 31 is formed at the upper part of the eyepiece, but unlike this, it can be installed in the other region of the optical microscope 30 as well as the lower part of the eyepiece. Install remotely. The image data of the sample for the nanowire device obtained through the CCD camera 31 is stored at regular time intervals, and the CCD camera 31 is stored so that the image data can be stored in the data processing unit 50 that processes the data. Remote adjustment. The data processing unit 50 removes noise from the video data captured through the CCD camera 31 using fast Fourier transform, so that the nanowire with a small diameter in the range of 10 to 20 nanometers or carbon with several nanometers is obtained. Images of nanotube samples can be obtained.

According to the above-described optical microscope system 1 for sensing nanowires, the polarizing plate controller 40 controls the rotating polarizing plate 20 so as to rotate at a specific frequency f ₀ of 0.1 Hz to 1 Hz. the polarization axis of the linearly polarized light sources is incident to rotate to a frequency of 2f ₀ in. Thus, the angle between the nanowire axis and the polarization axis changes with the frequency of 2f _0, the intensity of light reflected by the nanowire is also modulated to a frequency of 2f _0.

On the other hand, since the sample around the nanowire generally has no or little optical anisotropy, the component modulated to the frequency of 2f ₀ out of the intensity of the light reflected through the surrounding sample is nano. Relatively very small compared to the line. As a result, when a signal modulated at a specific frequency 2f ₀ corresponding to a nanowire is selectively obtained, a signal in the peripheral region without the nanowire is removed, so that the image of the nanowire can be obtained more clearly. Can do.

  As described above, a method for acquiring a nano-line image is a lock-in amplifier (Lock-in) that extracts only a signal having a specific frequency to be used when the specific frequency signal is buried in another noisy environment. in Amplifier) principle.

  The magnification of the optical microscope 30 used in the optical microscope system 1 for sensing nanowires according to the present invention is 1000 to 2500 times, and the nanobeam is obtained using the CCD camera 31 while the rotating polarizing plate 20 rotates. The sample image is stored as a moving image of 30 to 40 frames per second for 2 to 20 seconds. At this time, it is more efficient to use the CCD camera 31 having a pixel number of 640 × 480 pixels or more.

The video data captured by the CCD camera 31 stored for each frame can be displayed in a two-dimensional array composed of pixels of horizontal n ₀ × vertical m ₀ . Each pixel has intensity information I (intensity) of light reflected by the sample for the nanowire element. Therefore, the intensity information of the (n, m) th pixel can be displayed as I (n, m).

  On the other hand, as described above, since each frame is stored at a constant time interval (2 to 20 seconds), the light intensity information I is as shown in FIG. In addition, a three-dimensional array can be displayed.

FIG. 2 is a schematic diagram showing nano-ray image data having a three-dimensional array structure photographed by a CCD camera according to the present invention and an image processing state acquired from this data using a fast Fourier transform method. Referring to FIG. 2, a total of l ₀ [l ₀ = number of CCD image storage frames per second × moving image storage time; sec] is stored on the time axis. In the first frame, if the light intensity information of (n, m) pixels is expressed as I (n, m) _l , the light intensity information of (n, m) pixels is I (N, m) ₁ , I (n, m) ₂ , I (n, m) ₃ ,..., I (n, m) ₁₀ have information. Since each pixel has 10 data on the time axis, frequency information for light intensity information can be obtained for each pixel.

In particular, if a Fourier coefficient corresponding to frequency 2f ₀ is selected for all pixels and a new image is obtained, an image of a nanoline modulated to frequency 2f ₀ can be extracted. Since the time-axis data I (n, m) ₁ , I (n, m) ₂ , I (n, m) ₃ ,..., I (n, m) ₁₀ of each pixel is discrete data, A Fourier coefficient corresponding to the frequency 2f ₀ can be obtained by using a discrete Fourier transform.

However, a calculation process for obtaining Fourier coefficients from 10 pieces of data per pixel (for example, 30 to 40 frames × 2 to 20 seconds) requires a total of 102 calculations, and such calculation is performed for a total of n _0. Xm ₀ (for example, 640 x 480 pixels) pixels must be performed, so that the video processing speed is increased by reducing the number of computations using a fast Fourier transform (FFT). be able to.

In other words, FIG. 2 obtains the complex Fourier coefficient (2f ₀ ) n, m corresponding to the frequency 2f ₀ from the time data per pixel I (n, m) ₁ using the fast Fourier transform, and creates a new image. A schematic diagram for obtaining pixels is shown. At this time, an image image of the nanowire is obtained from the absolute value of the complex Fourier coefficient.

  On the other hand, the phase information of the Fourier coefficient has information with respect to the axial direction of the nanowire. Since the modulation of light reflected from nanowires having different axial directions occurs with a certain time difference, there is a phase difference between the Fourier coefficients. Therefore, the specific phase value of the Fourier coefficient means the axial direction angle of the nanowire corresponding to the specific phase value, so that only the nanowire arranged in the specific direction can be selectively shown in the image.

  3A and 3B are video diagrams showing a case where the angle formed between the polarizing plate and the reference axis of the nanowire sample is 0 degree and 90 degrees, and the nanowire element is obtained using the optical system of FIG. The image data of the nanowires that can be obtained from the sample is shown. As described above, θ represents the angle between the polarization axis and the nanoline used as the reference axis, and FIG. 3A shows the case where the angle between the polarization axis and the reference axis of the nanowire sample is 0 °. FIG. 3B shows a case where the angle between the polarization axis and the nanoline reference axis is 90 °.

  In general, light that has passed through the rotary polarizing plate 20 is polarized in a specific direction depending on the rotation angle of the rotary polarizing plate 20. If the polarization axis is horizontal, that is, if the angle between the polarization axis and the reference axis of the nanoline is 0 degrees, the brightness of the nanoline that is parallel to the polarization axis is maximized, The brightness of the nanowire perpendicular to the polarization axis is the lowest. On the other hand, when the polarization axis is vertical, the brightness of the nanowires arranged in the direction aligned with the vertical polarization axis is maximized.

  Referring to FIG. 3A, among the three nanowires a, b, and c, the nanowire a arranged in the direction aligned with the polarization axis shows the maximum brightness, whereas the nanowire 3 has the lowest brightness. Show. Referring to FIG. 3B, among the three nanolines a, b, and c, the brightness of the nanowire a arranged in the direction perpendicular to the polarization axis is the lowest, whereas the brightness of the nanowire c is the maximum. is there.

  The present invention described above can be variously replaced, modified, and changed without departing from the technical idea of the present invention as long as it has ordinary knowledge in the technical field to which the present invention belongs. Therefore, the present invention is not limited to the above-described embodiment and attached drawings.

It is a schematic diagram for demonstrating one Example of the optical microscope system for nano ray sensing which concerns on this invention. It is the schematic which shows the image processing state acquired using the fast Fourier transform method from the nanowire image data of the three-dimensional arrangement structure image | photographed with the CCD camera which concerns on this invention, and this data. FIG. 2 is a video diagram showing a case where an angle formed between a polarizing plate and a reference axis of a nanowire sample is 0 degree, and shows video data of a nanowire that can be obtained from a sample for a nanowire device using the optical system of FIG. ing. FIG. 2 is a video diagram showing a case where an angle formed between a polarizing plate and a reference axis of a nanowire sample is 90 degrees, and shows video data of a nanowire that can be obtained from a sample for a nanowire device using the optical system of FIG. ing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nanoray sensing optical microscope system 10 Light source part 20 Rotating polarizing plate 30 Optical microscope 31 CCD camera 40 Polarizing plate controller 50 Data processing part a, b, c Nanoline

Claims (6)

A light source unit that provides light emitted from the light source to the sample for the nanowire device;
Provided on a path of the light provided from the light source unit, a rotating polarizer for polarizing the light,
A polarizing plate controller electrically connected to the rotating polarizing plate and rotating the rotating polarizing plate at a first frequency (f ₀ );
An optical microscope for detecting light from the front Symbol specimen nanowire element Ru is anti Isa,
Provided optical microscope, while the rotating polarizer is rotated, a CCD camera for storing the image data obtained by photographing the light detected by the optical microscope,
The nanowire element sample is obtained by extracting a pixel having a second frequency (2f ₀ ) from the pixels of the video data by performing a fast Fourier transform process on the light intensity information included in the pixels of the video data. An optical microscope system for sensing nanowires, comprising: a data processing unit for obtaining an image of nanowires contained in the nanowire . The nanowires may in claim 1, characterized in that it comprises an optical anisotropy of emission varied according to the angle between the nanowires polarization axis of the incident light in the forming direction and the nano wire The optical microscope system for nanowire sensing as described. 2. The optical microscope for sensing nanowires according to claim 1 , wherein the polarizing plate controller controls the rotating polarizing plate to rotate at the first frequency ( f ₀ ) of 0.1 to 1 Hz. system. 4. The nanowire sensing device according to claim 3 , wherein the rotation axis of the rotating polarizing plate modulates the polarization axis of light incident on the sample for the nanowire device to the second frequency ( 2f ₀ ) . 5. Optical microscope system. The polarization axis is the second frequency (2f ₀ ) Is incident on the sample for a nanowire device, the intensity of the light reflected from the nanowire is expressed by the second frequency (2f). ₀ 5. The optical microscope system for sensing nanowires according to claim 4, wherein Video data captured by the CCD camera is stored in a pixel array according to time, and the data processing unit performs fast Fourier transform on the time-dependent light intensity information (I (n, m) ₁ ) of each pixel. by selecting the complex Fourier coefficients corresponding to the second frequency _{(2f 0) ((2f 0} ) n, m), for nanowires sensing according to claim 1, characterized in that to obtain an image of the nanowires Optical microscope system.

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