JP6499856B2 - Image processing apparatus, image output apparatus, and inspection apparatus - Google Patents

Description

  The present invention relates to a technique for processing an image, and particularly to a technique for pseudo-coloring an image having a plurality of gradation values.

  The imaging technique is a technique for measuring a sample by some method, and imaging and visualizing it. For example, in Patent Document 1, a semiconductor sample is scanned with pulsed light, and terahertz waves generated by irradiation with pulsed light are measured. And it describes that the intensity distribution is imaged and displayed on a monitor. In addition, a pseudo color image in which the shades of measured values are expressed in pseudo color is generated, and the difference in the measured values (gradation) is visually easily understood.

  In Patent Document 2, an analog image signal from a CCD camera is converted into an electromagnetic signal, and a process for converting the digital image signal into a pseudo color is performed. At this time, an R-plane, a G-plane, and a B-plane indicating the correspondence relationship between the brightness value and the density prepared in advance are assigned to the brightness value for each pixel of the image, and a pseudo-colored image is generated. .

  Further, Patent Document 3 discloses a color adjustment method for an output image of a laser scanning microscope. Specifically, a color chart with constant brightness and various hues and saturations is output to a CRT monitor. Subsequently, a display color that matches a predetermined fluorescence wavelength by visual observation is designated on the color chart. Then, the hue and saturation for the display color at this time are stored in the data processing apparatus as color conversion parameters. After that, a predetermined fluorescence wavelength in the measurement data of the fluorescence image of the observed sample is corrected by the color conversion parameter and output to a CRT monitor (or color printer). In this way, the same color tone as when visually observed is reproduced by the output device in accordance with the characteristics of each output device.

JP2013-19861A JP 2002-23062 A Japanese Patent Laid-Open No. 11-098372

  However, according to the technology of Patent Document 2, the color planes are limited to those prepared in advance. For this reason, it is not always possible to visually easily understand the portion to be observed. For example, when the measured values of the portions to be observed are relatively similar, if the plane setting is inappropriate, the resulting image will be a small image with little color change. In order to avoid this, it is necessary to prepare several patterns of planes, which is very time-consuming.

  Further, the technique disclosed in Patent Document 3 obtains a color image suitable for each output device, and cannot generate a pseudo color image suitable for a portion of the subject to be observed.

  An object of the present invention is to provide a technique for obtaining a pseudo color image in which a portion to be observed is visually easy to understand.

In order to solve the above problems, a first aspect is an image processing apparatus that processes an image, and an image acquisition unit that acquires a gradation image in which pixel values are expressed by a plurality of gradation values; A corresponding pseudo color information generation unit that generates corresponding pseudo color information indicating a pseudo color corresponding to the gradation value by mixing seed colors with respective density distributions associated with each gradation value; A density command for accepting a change command for continuously changing a gradation value having a specific density for the density distribution of at least one of the plurality of colors, and changing the density distribution according to the change command and allocation changing unit, based on the corresponding false-color information, by converting the tone values in the tone image to the corresponding pseudo-color, and a pseudo-color image generating unit for generating a pseudo-color image, said density distribution The changing unit includes the plurality of colors. In conjunction with the tone value to be the specific concentration for the concentration distribution of one color is changed, to change the concentration distribution of other colors.

  The second aspect is the image processing apparatus according to the first aspect, wherein the density distribution changing unit can continuously change the gradation value at which the density of the at least one color is maximum or minimum. The change command is accepted.

The third aspect includes an image processing apparatus according to any one aspect of the first or second aspect, the plurality of kinds of colors, red, green and blue.

A fourth aspect is an image output apparatus that outputs an image, and includes an image processing apparatus according to any one of the first to third aspects, and an output unit that outputs the pseudo color image. .

The fifth aspect is an inspection apparatus for inspecting a semiconductor sample, the holding unit holding the semiconductor sample, the irradiation unit for irradiating the semiconductor sample held by the holding unit with inspection light, and the inspection A detection unit that detects the intensity of radiated light emitted from the semiconductor sample in response to light irradiation, position information indicating a position in the semiconductor sample based on a detection result of the detection unit, and a position generated at the position By mixing an image acquisition unit that acquires image data in which a gradation value indicating the intensity of the emitted light is recorded, and a plurality of types of colors in each density distribution associated with the gradation value, A corresponding pseudo color information generating unit that generates corresponding pseudo color information indicating a pseudo color corresponding to a tone value; Continuous values By changing the density distribution changing unit for changing the density distribution, based on the corresponding false-color information, by converting the tone values in the image data to the corresponding pseudo color, and generates a pseudo-color image data A pseudo-color image generation unit; and an image output unit that outputs the pseudo-color image, wherein the density distribution changing unit is a floor having the specific density for density distribution of one color among the plurality of colors. The density distribution of other colors is changed in conjunction with the change of the tone value.

According to the image processing apparatus according to the first aspect, the density distribution of each color can be changed continuously, so that the corresponding pseudo color information suitable for the magnitude of the gradation value included in the image can be generated. . For this reason, it is possible to increase the contrast of a portion to be observed and obtain an image that is visually easy to understand.
In addition, the density distribution of another color can be changed in conjunction with the change of the density distribution of one color. For this reason, the changing operation can be simplified.

  Further, according to the image processing apparatus of the second aspect, the density distribution of the color can be dynamically changed by changing the gradation value associated with the maximum density or the minimum density of at least one color.

Further, according to the image processing apparatus of the third aspect, a pseudo color image using almost all colors can be generated by mixing red, green and blue.

Moreover, according to the image output device which concerns on a 4th aspect, the pseudo color image produced | generated by the image processing apparatus can be output by an output part.

It is a schematic side view of the inspection apparatus which concerns on embodiment. It is a schematic block diagram of a terahertz wave measurement system. It is a schematic sectional drawing of a solar cell. It is a figure which shows the time waveform of a terahertz wave. It is a block diagram which shows the electrical connection of the control part and other element in a test | inspection apparatus. It is a flowchart which shows operation | movement of an inspection apparatus. It is a flowchart which shows the detail of the production | generation process and output process of a pseudo color image. It is a figure which shows density distribution of each color, and corresponding pseudo color information. It is a figure which shows the relationship of value S, T, U. It is a figure which shows the density distribution of each color after a change, and corresponding pseudo color information. It is a figure which shows the density distribution of each color after a change, and corresponding pseudo color information.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the component described in this embodiment is an illustration to the last, and is not a thing of the meaning which limits the scope of the present invention only to them. In the drawings, the size and number of each part may be exaggerated or simplified as necessary for easy understanding.

<Configuration of inspection device>
FIG. 1 is a schematic side view of an inspection apparatus 100 according to the embodiment. The inspection apparatus 100 includes an apparatus base 1, a terahertz wave measurement system 2, a moving stage 3, a sample stage 4, a luminescence measurement system 5, a camera 6, and a control unit 7. The inspection apparatus 100 is configured to detect radiated light emitted from the semiconductor sample in response to various types of light irradiation and to image the intensity distribution of the radiated light. Specifically, the emitted light includes EL (Electro-Luminescence) light, PL (Photo-Luminescence) light, and terahertz waves.

  In FIG. 1 and the subsequent drawings, a right-handed XYZ orthogonal coordinate system in which the Z-axis direction is the vertical direction and the XY plane is the horizontal plane is appropriately attached to clarify the directional relationship. A plane parallel to the surface of the moving stage 3 is a horizontal plane (XY plane), and a vertical direction perpendicular thereto is a vertical direction (Z-axis direction). Further, when viewed from the luminescence measurement system 5, the side on which the terahertz wave measurement system 2 is arranged is defined as + Y side, and the opposite side is defined as -Y side. When the terahertz wave measurement system 2 side is viewed from the luminescence measurement system 5 side, the right hand side is the + X side and the left hand side is the -X side. Further, the upper side in the Z-axis direction is the + Z side, and the lower side is the -Z side.

  The terahertz wave measurement system 2 irradiates a semiconductor sample with inspection light (inspection light LP11 described later) and detects terahertz waves generated in response to the irradiation of the inspection light. Moreover, the inspection apparatus 100 images the intensity of the detected terahertz wave (electromagnetic wave of 0.1 THz to 30 THz). The configuration of the terahertz wave measurement system 2 will be described in detail later.

  Here, the semiconductor sample is an electronic device (semiconductor device) composed of a transistor, an integrated circuit (IC or LSI), a resistor, a capacitor, or the like using a semiconductor, an image sensor such as a photodiode, a CMOS sensor, or a CCD sensor, It includes electronic devices (photo devices) that utilize the photoelectric effect of semiconductors, such as solar cells or LEDs. The surface of the semiconductor sample is assumed to be flat, but may be formed to be curved.

  In the present embodiment, a case where the solar cell 9 is inspected as a semiconductor sample will be described, but other semiconductor samples can be similarly inspected.

  The moving stage 3 is moved in the X axis direction, the Y axis direction, and the Z axis direction by the stage drive mechanism 31. The stage drive mechanism 31 includes an X-axis direction moving mechanism that moves the moving stage 3 in the X-axis direction, a Y-axis direction moving mechanism that moves the moving stage 3 in the Y-axis direction, and an elevating mechanism that moves the moving stage 3 up and down in the Z-axis direction. It has. Furthermore, the stage drive mechanism 31 includes a rotation mechanism that moves in the rotation direction around the Z axis (θ axis direction).

  The sample stage 4 is attached to the upper surface of the moving stage 3. The sample stage 4 includes a voltage application table 41 and an electrode pin unit 43.

  The voltage application table 41 is made of a material having high electrical conductivity such as copper, and the surface thereof is gold-plated. A plurality of suction holes are formed on the surface of the voltage application table 41. The suction hole is connected to a suction pump, and the back surface of the solar cell 9 is sucked to the voltage application table 41 by driving the suction pump. As a result, the solar cell 9 is fixed to the sample stage 4. A plurality of suction grooves may be provided on the surface of the voltage application table 41, and the plurality of suction holes may be formed in the suction grooves. In this case, since the solar cell 9 is adsorbed along the plurality of adsorption grooves, the solar cell 9 can be firmly fixed. The voltage application table 41 of the sample stage 4 is an example of a holding unit.

  As the moving stage 3 moves in the X-axis direction, Y-axis direction, and Z-axis direction, the solar cell 9 held on the sample stage 4 on the moving stage 3 moves in the X-axis direction, Y-axis direction, and Z-axis direction. Move to each.

  As shown in FIG. 1, the Y-axis direction moving mechanism of the stage drive mechanism 31 moves the moving stage 3 to positions L1, L2, and L3. The position L1 is the position of the moving stage 3 for installing the solar cell 9 on the voltage application table 41. The position L2 is a position on the + Y side from the position L1, and is a position where EL measurement or PL measurement of the solar cell 9 is performed in the luminescence measurement system 5 (first inspection unit). Furthermore, the position L3 is a position on the + Y side from the position L2, and is a position where the terahertz wave measurement of the solar cell 9 is performed.

  The electrode pin unit 43 includes a plurality of conductive electrode pins 431 and a conductive electrode bar 432 that supports the plurality of electrode pins 431.

  The electrode bar 432 holds a plurality of rod-shaped electrode pins 431 so as to stand up along the Z direction at a predetermined interval in the Y-axis direction. In the present embodiment, the electrode bar 432 holds a plurality of electrode pins 431 along the surface side electrode 96 of the solar cell 9 held on the sample stage 4.

  The sample table 4 brings the voltage application table 41 into contact with the back surface side electrode 92 of the solar cell 9 and a plurality of electrode pins 431 on the surface side electrode of the solar cell 9 (here, the surface side electrode 96 described later). Make contact. The voltage application table 41 and the electrode pin unit 43 are electrically connected and apply a voltage between the front surface side electrode and the back surface side electrode 92 of the solar cell 9.

  The luminescence measurement system 5 performs EL measurement or PL measurement. In the following description, the EL measurement and the PL measurement may be simply referred to as “luminescence measurement” unless otherwise distinguished. In the luminescence measurement system 5, the solar cell 9 is covered by the cover member 51, and the luminescence measurement is performed in that state.

  More specifically, the luminescence measurement system 5 includes an image sensor 53 for performing EL measurement. When performing EL measurement, a forward bias voltage is applied to the solar cell 9 via the voltage application table 41 and the electrode pin unit 43 in the luminescence measurement system 5. Thus, the luminescence measurement system 5 causes the solar cell 9 to emit EL, and the EL sensor detects the EL emission. The control unit 7 performs image processing on the signal output from the image sensor 53, thereby generating an EL image that is a luminescence image. For example, the image sensor 53 is preferably capable of detecting light having a wavelength of about 800 nm to 1600 nm, and more preferably capable of detecting light having a wavelength of about 1000 nm to 1400 nm.

  The luminescence measurement system 5 includes a PL inspection light source 55. The luminescence measurement system 5 causes the solar cell 9 to emit PL with the PL inspection light emitted from the PL inspection light source 55, and detects the PL emission with the image sensor 53. Then, the control unit 7 performs image processing on the signal output from the image sensor 53, thereby generating a PL image that is a luminescence image.

  In the following description, each of the EL image and the PL image may be simply referred to as “luminescence image” unless otherwise distinguished.

  The luminescence measurement system 5 is not necessarily provided with a configuration for performing both EL measurement and PL measurement, and may be configured to perform measurement of only one of them. Moreover, the inspection apparatus 100 does not necessarily need to include both the luminescence measurement system 5 of the terahertz wave measurement system 2 and either one may be omitted.

  FIG. 2 is a schematic configuration diagram of the terahertz wave measurement system 2. The terahertz wave measurement system 2 includes an inspection light irradiation unit 22, a terahertz wave detection unit 23, and a delay unit 24.

  The inspection light irradiation unit 22 includes a femtosecond laser 221. The femtosecond laser 221 emits pulsed light (pulsed light LP1) having a wavelength including a visible light region of, for example, 360 nm (nanometers) or more and 1.5 μm (micrometers) or less. As a specific example, linearly polarized pulsed light having a center wavelength of around 800 nm, a period of several kHz to several hundred MHz, and a pulse width of about 10 to 150 femtoseconds is emitted from the femtosecond laser 221. Of course, pulse light in other wavelength regions (for example, visible light wavelengths such as blue wavelength (450 to 495 nm) and green wavelength (495 to 570 nm)) may be emitted.

  The pulsed light LP1 emitted from the femtosecond laser 221 is divided into two by the beam splitter BE1. One of the divided pulse lights (inspection light LP11) is applied to the solar cell 9. At this time, the inspection light irradiation unit 22 irradiates the inspection light LP11 from the light receiving surface 91 side. Further, the inspection light LP11 is applied to the solar cell 9 so that the optical axis of the inspection light LP11 is obliquely incident on the light receiving surface 91 of the solar cell 9. In the present embodiment, the irradiation angle is set so that the incident angle is 45 degrees. However, the incident angle is not limited to such an angle, and can be appropriately changed within the range of 0 to 90 degrees.

  FIG. 3 is a schematic cross-sectional view of the solar cell 9. The solar cell 9 is configured as a solar cell that is based on crystalline silicon, for example. The solar cell 9 includes, in order from the bottom, a flat plate-like back side electrode 92 made of aluminum, a p-type semiconductor layer 93, an n-type semiconductor layer 94, an antireflection film 95, and a lattice-like front side electrode 96. And a pn junction 97. The antireflection film 95 is made of silicon oxide, silicon nitride, titanium oxide, or the like.

  Of the main surfaces on both sides of the solar cell 9, the main surface on the side where the surface-side electrode 96 is provided is a light receiving surface. That is, the solar cell 9 is designed so as to suitably generate power by receiving light from the light receiving surface side. A transparent electrode may be used for the surface side electrode 96.

  The inspection apparatus 100 may be applied to inspection of solar cells other than crystalline silicon (such as amorphous silicon). In the case of an amorphous silicon solar cell, the energy gap is generally larger than the energy gap of 1.2 eV of a crystalline silicon solar cell, such as 1.75 eV to 1.8 eV. In such a case, by setting the wavelength of the femtosecond laser 221 to, for example, 700 μm or less, terahertz waves can be generated satisfactorily in an amorphous silicon solar cell. The same concept can be applied to other semiconductor solar cells (CIGS type, GaAS type, etc.).

  When the portion of the solar cell 9 where the internal electric field exists is irradiated with the inspection light LP11 having energy exceeding the forbidden band width, photocarriers (free electrons and holes) are generated and accelerated by the internal electric field. As a result, a pulsed current is generated, and an electromagnetic wave is generated accordingly. It is known that the internal electric field is generated at, for example, the pn junction 97 or the Schottky junction.

  According to Maxwell's equation, when a change occurs in the current, an electromagnetic wave having an intensity proportional to the time derivative of the current is generated. That is, when a photoexcited carrier generation region such as a depletion layer is irradiated with pulsed light, generation and extinction of a photocurrent occurs instantaneously. An electromagnetic wave pulse (terahertz wave LT1) is generated in proportion to the temporal differentiation of the instantaneously generated photocurrent.

  As shown in FIG. 2, the other pulse light split by the beam splitter BE1 enters the terahertz wave detector 231 of the terahertz wave detection unit 23 via the delay unit 24 as the detection light LP12. Further, the terahertz wave LT1 generated in response to the irradiation of the inspection light LP11 is appropriately condensed by a parabolic mirror or the like, and enters the terahertz wave detector 231.

  As shown in FIG. 1, the inspection light LP11 is irradiated onto the solar cell 9 along the Y-axis direction (in the example of FIG. 1, from the + Y side to the -Y side). Further, the terahertz wave LT1 radiated along the Y-axis direction (in the example of FIG. 1, from the + Y side to the −Y side) is detected by the terahertz wave detector 231. Thus, in this embodiment, the irradiation direction of the inspection light LP11 and the radiation direction of the detected terahertz wave LT1 are the directions in which the plurality of electrode pins 431 are arranged at a predetermined interval (that is, the Y-axis direction). ). Therefore, it is possible to suppress the inspection light LP11 that is the inspection light from being blocked by the plurality of electrode pins 431, or the generated terahertz wave LT1 from being blocked by the plurality of electrode pins 431.

  The terahertz wave detector 231 includes, for example, a photoconductive switch (photoconductive antenna) as an electromagnetic wave detecting element. When the terahertz wave LT1 is incident on the terahertz wave detector 231 and the detection light LP12 is applied to the terahertz wave detector 231, a current corresponding to the electric field strength of the terahertz wave LT1 is instantaneously generated in the photoconductive switch. . The current corresponding to the electric field strength is converted into a digital quantity via a lock-in amplifier (not shown), an I / V conversion circuit, an A / D conversion circuit, and the like. In this manner, the terahertz wave detection unit 23 detects the electric field intensity of the terahertz wave LT1 that has passed through the solar cell 9 in accordance with the irradiation of the detection light LP12. Note that another element different from the photoconductive switch, such as a Schottky barrier diode or a nonlinear optical crystal, may be employed as the detection element.

  The delay unit 24 is an optical device that continuously changes the arrival time of the detection light LP12 to the terahertz wave detector 231. The delay unit 24 includes a delay stage 241 that moves linearly along the incident direction of the detection light LP12 and a delay stage drive mechanism 242 that moves the delay stage 241. The delay stage 241 includes a folding mirror 10M that folds the detection light LP12 in the incident direction. The delay stage driving mechanism 242 translates the delay stage 241 along the incident direction of the detection light LP12 based on the control of the control unit 7. As the delay stage 241 moves in parallel, the optical path length of the detection light LP12 from the beam splitter BE1 to the terahertz wave detector 231 is continuously changed.

  The delay stage 241 changes the difference (phase difference) between the time when the terahertz wave LT1 reaches the terahertz wave detector 231 and the time when the detection light LP12 reaches the terahertz wave detector 231. Specifically, by changing the optical path length of the detection light LP12 by the delay stage 241, the timing (detection timing or sampling timing) at which the terahertz wave detector 231 detects the electric field strength of the terahertz wave LT1 is delayed.

  Note that the arrival time of the detection light LP12 at the terahertz wave detector 231 can be changed by a configuration different from that of the delay stage 241. Specifically, it can be considered to use the electro-optic effect. That is, an electro-optic element whose refractive index changes by changing the applied voltage may be used as the delay element.

  Further, instead of changing the optical path length of the detection light LP12, the optical path length of the inspection light LP11 directed to the solar cell 9 or the optical path length of the terahertz wave LT1 emitted from the solar cell 9 may be changed. In any case, the time for the terahertz wave LT1 to reach the terahertz wave detector 231 can be shifted with respect to the time for the detection light LP12 to reach the terahertz wave detector 231. That is, the detection timing of the terahertz wave LT1 in the terahertz wave detector 231 can be delayed.

  The stage drive mechanism 31 moves the solar cell 9 held on the sample stage 4 attached to the moving stage 3 relative to the inspection light irradiation unit 22 in the XY plane. That is, the inspection apparatus 100 is configured to be able to scan the light receiving surface 91 of the solar cell 9 with the inspection light LP11. Accordingly, in the present embodiment, the stage drive mechanism 31 constitutes a scanning mechanism. However, instead of moving the solar cell 9 or moving the solar cell 9, a moving unit that moves the inspection light irradiation unit 22 and the terahertz wave detection unit 23 in the XY plane may be provided.

  Further, a scanning mechanism that changes the optical path of the inspection light LP11 itself may be employed. Specifically, it is conceivable to change the optical path of the inspection light LP11 along the XY plane parallel to the light receiving surface 91 of the solar cell 9 by a galvano mirror that reciprocally swings. Further, instead of the galvanometer mirror, a polygon mirror, a piezo mirror, or an acoustooptic device may be employed.

  When terahertz wave measurement is performed on the solar cell 9, a reverse bias voltage may be applied to the solar cell 9 via the voltage application table 41 and the electrode pin unit 43 of the sample table 4. Thereby, the intensity of the terahertz wave LT1 radiated from the solar cell 9 can be increased. It is also conceivable that the voltage application table 41 and the electrode bar 432 are short-circuited to short-circuit the front surface side electrode and the back surface side electrode 92 of the solar cell 9. Even in this case, the intensity of the terahertz wave LT1 radiated from the solar cell 9 can be increased.

  FIG. 4 is a diagram illustrating a time waveform 80 of the terahertz wave LT1. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates electric field strength. Also, in FIG. 4, below the graph showing the time waveform 80, a plurality of detection lights LP <b> 12 having different timings (time t <b> 1 to t <b> 8) reaching the terahertz wave detector 231 by the delay stage 241 are conceptual. Has been shown.

  For example, when the delay stage 241 is adjusted so that the detection light LP12 reaches the terahertz wave detector 231 at time t1, the terahertz wave detector 231 detects the electric field intensity of the value E1. That is, the time t1 corresponds to the phase at which the terahertz wave LT1 becomes the value E1. Similarly, when the detection timing is delayed from time t2 to time t8, the electric field strengths (values E2 to E8) corresponding to the phases are detected.

  By controlling the delay stage 241 and finely changing the detection timing, the electric field strength of each phase of the terahertz wave LT1 is acquired. By plotting the acquired electric field intensity on the graph along the time axis, the time waveform 80 of the terahertz wave LT1 is restored.

  Further, by restoring the time waveform of the terahertz wave LT1, for example, the detection timing (in this case, time t2) at which the electric field intensity of the terahertz wave LT1 is maximized can be found. When the terahertz wave LT1 is detected with the detection timing fixed, the terahertz wave can be easily detected by controlling the delay stage 241 in accordance with the detection timing at which the electric field intensity becomes maximum.

  Note that the arrival time of the detection light LP12 to the terahertz wave detector 231 can be changed by another configuration different from the delay stage 241. Specifically, it can be considered to use the electro-optic effect. That is, an electro-optic element whose refractive index changes by changing the applied voltage may be used as the delay element. For example, an electro-optic element disclosed in Japanese Patent Application Laid-Open No. 2009-175127, which is a patent document, can be used.

  Further, the optical path length of the inspection light LP11 or the optical path length of the terahertz wave LT1 radiated from the solar cell 9 may be changed. Even in this case, the time for the terahertz wave LT1 to reach the terahertz wave detector 231 can be shifted relative to the time for the detection light LP12 to reach the terahertz wave detector 231. That is, the detection timing of the electric field strength of the terahertz wave LT1 in the terahertz wave detector 231 can be delayed.

  The control unit 7 is electrically connected to each unit included in the inspection apparatus 100, and controls the operation of each unit of the inspection apparatus 100 while executing various arithmetic processes.

  FIG. 5 is a block diagram showing an electrical connection between the control unit 7 and other elements in the inspection apparatus 100. The control unit 7 includes a CPU 71, a ROM 72, a RAM 73, and a storage unit 74 that is a nonvolatile recording medium. Thus, the control unit 7 is configured as a general computer.

  The ROM 72 stores basic programs and the like. The RAM 73 is used as a work area when the CPU 71 performs a predetermined process. The storage unit 74 is configured by a non-volatile storage device such as a flash memory or a hard disk device. A program PG1 is installed in the storage unit 74. Various functions (for example, an image acquisition unit 711, a corresponding pseudo color information generation unit 712, a density distribution change unit 713, a pseudo color, and the like are performed by the CPU 71 as a main control unit performing arithmetic processing according to the procedure described in the program PG1. An image generation unit 714 and the like) are realized.

  The image acquisition unit 711 acquires gradation image data in which pixel values are expressed by a plurality of gradation values. Specifically, the gradation image data is recorded in a state in which information indicating the position in the solar cell 9 and information (gradation value) indicating the intensity of the terahertz wave are associated with each other.

  The corresponding pseudo color information generation unit 712 generates the corresponding pseudo color information ED1 indicating the pseudo color corresponding to the gradation value. The corresponding pseudo color information ED1 is generated by mixing a plurality of kinds of colors with respective density distributions associated with the gradation values. In the present embodiment, the plurality of colors are the three primary colors of light, and are red, green, and blue. By mixing these three primary colors, it is possible to generate a full-color pseudo color image in which almost all colors are used.

  The density distribution changing unit 713 receives a change command for continuously changing a specific gradation value having a specific density for at least one of a plurality of types of colors. Then, the density distribution changing unit 713 changes the density distribution of the color according to the contents of the command.

  The pseudo color image generation unit 714 converts the tone value in the image data to the corresponding pseudo color based on the corresponding pseudo color information ED1, and generates pseudo color image data.

  The program PG1 is normally used by being previously stored in a memory such as the storage unit 74, but is recorded in a recording medium such as a CD-ROM or DVD-ROM or an external flash memory (program product). (Or provided by downloading from an external server via a network), and may be additionally or exchanged stored in a memory such as the storage unit 74. Note that some or all of the functions realized in the control unit 7 may be realized in hardware by a dedicated logic circuit or the like.

  The control unit 7 includes each element of the inspection apparatus 100 such as the display unit 61, the operation unit 62, the stage drive mechanism 31, the delay stage drive mechanism 242, the luminescence measurement system 5, the image sensor 53, and the camera 6, bus wiring, and network lines. Alternatively, they are connected via a serial communication line. The control unit 7 controls the operation of these elements and receives data from these elements.

  The display unit 61 constitutes a display device that displays an image such as a liquid crystal display. The display unit 61 is a device that outputs the pseudo color image generated by the pseudo color image generation unit 714. Note that a printing device that prints the pseudo color image on a printing medium such as paper may be provided as the output device.

  The computer constituting the control unit 7 is an image processing apparatus that generates a pseudo color image from a gradation image. Further, an image output device is obtained by adding an output unit such as the display unit 61 to the image processing device.

  The operation unit 62 is an input device configured by, for example, a keyboard and a mouse, and receives various operations (operations such as inputting commands and various data) from the operator. The operation unit 62 may be configured with various switches, a touch panel, and the like.

<Inspection of solar cells>
FIG. 6 is a flowchart showing the operation of the inspection apparatus 100. The flowchart shown in FIG. 6 performs an inspection based on the terahertz wave measurement in the terahertz wave measurement system 2 of the inspection apparatus 100. In the following description, it is assumed that each operation of the inspection apparatus 100 is performed under the control of the control unit 7 unless otherwise specified. Moreover, according to the content of each process, a some process may be performed in parallel or the execution order of a some process may be changed suitably.

  First, the solar cell 9 to be inspected is installed in the voltage application table 41 (step S1). At this time, as described above, the solar cell is irradiated with the inspection light LP11 toward the light receiving surface 91 (that is, the main surface on the side receiving sunlight when the solar cell 9 is used). 9 is installed. Then, the stage drive mechanism 31 moves the movable stage 3 to the position L3 so that the solar cell 9 can be inspected in the terahertz wave measurement system 2.

  Subsequently, the electrode pin unit 43 is brought into contact with the front surface side electrode 96, and a reverse bias voltage is applied between the back surface side electrode 92 and the front surface side electrode 96 of the solar cell 9 (step S2). When no reverse bias voltage is applied, step S2 can be omitted.

  Next, the detection timing of the terahertz wave LT1 by the terahertz wave detection unit 23 is set (step S3). Specifically, the control unit 7 controls the delay stage 241 to adjust the position of the folding mirror 10M so that the timing at which the detection light LP12 reaches the terahertz wave detector 231 is fixed at a required detection timing. Is done. Note that the S / N ratio can be increased by setting the detection timing so that the detected terahertz wave intensity is as large as possible. For example, in the case of the time waveform 80 shown in FIG. 4, the terahertz wave LT1 can be detected with the maximum intensity by setting the detection timing to time t3.

  Subsequently, the stage driving mechanism 31 is driven to move the solar cell 9 in a two-dimensional plane. As a result, the inspection target area is scanned with the inspection light LP11 (step S4). Then, the terahertz wave LT1 emitted at each irradiation position of the inspection light LP11 is detected by the terahertz wave detector 231. Information indicating the electric field strength of the detected terahertz wave LT1 is associated with information indicating the generation position (irradiation position) of the terahertz wave LT1, and is appropriately stored in the storage unit 74, the RAM 73, or the like.

  The data obtained in step S4 is gradation image data in which pixel values are expressed by a plurality of gradation values. That is, information indicating the generation position of the terahertz wave LT1 indicates position information of each pixel, and the electric field strength of the terahertz wave LT1 that is multi-value information indicates the pixel value. Based on the gradation image data, a pseudo color image in which the terahertz wave intensity distribution is expressed in a pseudo color (here, red, green, and blue) is generated, and the pseudo color image is an output device 61 or the like. Is output to the outside (step S5). Here, the processing of step S5 (pseudo color image generation processing and output processing) will be described in detail with reference to FIG.

<Pseudo-color image generation processing and output processing>
FIG. 7 is a flowchart showing details of the pseudo color image generation process and output process. First, for each color (red, green and blue), the density distribution associated with the terahertz wave intensity (gradation value) is determined (step S51). In step S51, the density distribution changing unit 713 receives a density distribution change command for each color, and changes the density distribution of the corresponding color based on the change command.

  Subsequently, the corresponding pseudo color information ED1 is generated by mixing the colors in accordance with the density distribution determined in step S51 (step S52). The generated corresponding pseudo color information ED1 is stored in the storage unit 74 or the RAM 73.

  Next, the pseudo color image generation unit 714 generates a pseudo color image (step S53). Specifically, the pseudo color image generation unit 714 performs conversion processing for converting the terahertz wave intensity into a corresponding color (pseudo color) with respect to the terahertz wave intensity image with reference to the corresponding pseudo color information ED1. As a result, a pseudo color image is generated from the terahertz wave intensity image. Then, a pseudo color image is output (step S54).

  Subsequently, it is determined whether or not the pseudo color image generation and output processing is to be ended (step S55). Specifically, this determination is made based on whether or not a change command for changing the color density distribution is input by the operator, or whether a predetermined end processing command is input.

  When the change command is input (No in step S55), the process returns to step S51, and steps S51 to S54 are executed again. Further, when the end processing command is input (Yes in step S55), the generation and output processing of the pseudo color image ends.

  Next, the processing of step S51 (color density distribution determination processing) and the processing of step S52 (processing for generating the corresponding pseudo color information ED1) will be specifically described.

  FIG. 8 is a diagram showing the density distribution of each color and the corresponding pseudo color information ED1. In FIG. 8, the horizontal axis of graphs R1, G1, and B1 indicates the terahertz wave intensity (hereinafter, also simply referred to as “intensity”), and the vertical axis indicates the density of each color. Here, the intensity is a relative value in the range from 0 to 1. In the case of an 8-bit image, the range from 0 to 1 is replaced with 256 gradations from 0 to 255. Graphs R1, G1, and B1 show density distributions corresponding to the intensities for the primary colors red, green, and blue. That is, the graphs R1, G1, and B1 show the assignment of the density of each color to each intensity (gradation value).

  Further, the color chart CC1 shown in FIG. 8 schematically represents the corresponding pseudo color information ED1. In the color chart CC1, the horizontal axis indicates the intensity, and a pseudo color corresponding to the intensity is indicated.

  In this example, red is set to have a minimum density (= 0%) at an intensity of 0 and a maximum density (= 100%) at an intensity of 1.0 as shown in the upper part of FIG. For green, as shown in the middle of FIG. 8, the intensity is set to 0 and 1.0 and the minimum density (= 0%). Further, as shown in the lower part of FIG. 8, the blue color is set to have a maximum density (= 100%) at an intensity of 0 and a minimum density (= 0%) at an intensity of 1.0.

  Further, in this example, the density distribution of each color is set to be changed by designating the intensity (gradation value) that is the maximum density of each color and the terahertz wave intensity (gradation value) that is the minimum density. . Specifically, the density distribution of each color can be changed by designating three intensity values S, T, U.

  The value S is set to an intensity at which red and blue become the minimum density (= 0%). The value T is set to an intensity at which green and blue have the maximum density (= 100%). Furthermore, the value U is set to an intensity at which red and green have the maximum density (= 100%). By changing the values S, T, and U, the intensity at which each color has the maximum density or the minimum density is changed. That is, the values S, T, and U are control parameters for changing the density distribution. As described above, by making it possible to change the gradation value that is the maximum density or the minimum density in the density distribution of each color, the density distribution of each color can be dynamically changed. Therefore, the density distribution of each color can be set appropriately and quickly.

  Note that the values S, T, and U may be specified by directly inputting numerical values, for example. Further, along with at least one of the graphs R1, G1, and B1 as shown in FIG. 8, a line segment indicating the position of the values S, T, and U (for example, a one-dot broken line shown in FIG. indicate. Each value may be specified by accepting an operation for moving the line segment to the left or right along an axis related to intensity (here, the horizontal axis).

  For example, in the example shown in FIG. 8, the values S, T, and U are set to “0.5”, “0.25”, and “0.75”, respectively. For this reason, as shown in the graph R1, with respect to the red density distribution, the intensity is 0 to 0.5 and the minimum density (= 0%), the intensity is 0.5 to 0.75, and the intensity is 0.75. The maximum density (= 100%) is obtained at -1.0.

  Regarding the green density distribution, the intensity is 0 and the minimum density (= 0%), the intensity is increased from 0 to 0.25, the intensity is 0.25 to 0.75, and the maximum density (= 100%). It has become. The density decreases at an intensity of 0.75 to 1.0, and a minimum density at an intensity of 1.0.

  Furthermore, regarding the density distribution of blue, the intensity is 0 to 0.25 and the maximum density (= 100%), the intensity is 0.25 to 0.5 and the density decreases, and the intensity is 0.5 to 1.0 and the minimum density is (= 0%).

  By setting each color to such a density distribution, on the color chart CC1 indicating the corresponding pseudo color information ED1, the intensity is 0 (blue), the intensity is 0.25, the light blue (Aqua), and the intensity is 0.5. It is green (Green), yellow with an intensity of 0.75, and red with an intensity of 1.0. In this case, a gradation in which the pseudo color changes relatively uniformly over the entire intensity is shown.

  For example, the graph R1 shown in FIG. 8 changes in a curved line at an intensity of 0.5 to 0.75. This portion may be linearized as shown by the broken line in FIG. Similarly, the portions of the other graphs G1 and B1 where the concentration increases or decreases may be linearized.

  In this example, each of the values S, T, and U is a control parameter that specifies the intensity at which the density is maximum or minimum for two colors at the same time. For example, when a value S that is a gradation value that becomes the minimum density of red is designated, a gradation value that becomes the minimum density of blue is automatically determined. That is, when the density distribution is changed for one color, the density distribution of the other colors is also changed in conjunction with this. For this reason, the corresponding pseudo color information ED1 can be dynamically changed even with a small change operation. However, the intensity at which the maximum density or the minimum density is obtained can be specified independently for each color.

  Although each value S, T, U can be specified individually, other values may be automatically determined by determining one of the values S, T, U. Specifically, for example, the following conditions (1) to (4) may be set in advance.

(1) T <S <U
(2) S = (T + U) / 2
(3) When S <0.5, UT = S
(4) When S ≧ 0.5, U−T = 1−S

  FIG. 9 is a diagram showing the relationship between the values S, T, and U. FIG. 9 is a graph of the conditions (3) and (4). The horizontal axis indicates the value S, and the vertical axis indicates the difference between the value U and the value T. When the operator designates a value S, for example, the size of T is automatically determined by the condition (2). Further, the value U is automatically determined according to the condition (3) or the condition (4).

  10 and 11 are diagrams showing the density distribution of each color after the change and the corresponding pseudo color information. In the example shown in FIG. 10, the value S is set to 0.2, and the values T and U are set to 0.1 and 0.3, respectively, according to the conditions (1) to (4). . For this reason, the color chart CC1 indicating the corresponding pseudo color information ED1 shows a gradation in which the pseudo color changes sharply in a range where the intensity is relatively small (0 to 0.3). On the other hand, in the example shown in FIG. 11, the value S is set to 0.8, and the values T and U are 0.7 and 0.9, respectively, according to the conditions (1) to (4). Is set to For this reason, the color chart CC1 indicating the corresponding pseudo color information ED1 shows a gradation in which the pseudo color changes sharply in a range where the intensity is relatively large (0.7 to 1). Since the other values T and U are automatically determined by determining the value S in this way, the operation for changing the density distribution of each color can be simplified. Therefore, the corresponding pseudo color information ED1 can be quickly generated. Further, by changing the value S, the pseudo color gradation in the color chart CC1 can be continuously changed.

  For example, in the data acquired in step S4, when the distribution of the terahertz wave intensity is gathered at a relatively small intensity, the value S may be set to a value close to the small intensity. Accordingly, as described with reference to FIG. 10, the pseudo color can be changed abruptly at a relatively small intensity, so that the contrast of the portion that the operator wants to observe can be increased.

  On the other hand, when the distribution of the terahertz wave intensity is gathered at a relatively large intensity, the value S may be set to a value close to the large intensity. As a result, as shown in FIG. 11, the pseudo color can be abruptly changed at a relatively large intensity, so that the contrast of the portion that the operator wants to observe can be increased.

  Further, when the distribution of the terahertz wave intensity in the portion that the operator wants to observe is relatively uniformly dispersed, the contrast in the pseudo color image can be obtained by making the pseudo color gradation uniform as shown in FIG. Can be increased.

  In the above description, the difference between the value U and the value T is assumed to be changed by the value S. However, fixing to a constant value (for example, 0.2) is not hindered.

  In the above description, the intensity at which each color has the maximum density or the minimum density is set by specifying the values S, T, and U. However, it may be possible to designate an intensity that is a specific intermediate density between the maximum density and the minimum density. It is also possible to specify an intensity that provides a specific intermediate density and determine the density distribution of each color based on the specified intensity.

  Further, as shown in FIG. 8, for example, a plurality of control points P1 and P2 that are movable along the vertical axis (concentration axis) on both the horizontal axis (intensity axis) are set in advance on the graph R1. Alternatively, these movements may be accepted. Then, the density distribution may be changed by deforming the graph R1 so as to pass through the control points P1, P2 after movement. Moreover, you may enable it to increase / decrease arbitrarily the number of the control points which determine the shape of graph R1.

  Further, in the present embodiment, the density distribution of the three colors is set to be changeable, but even if the density distribution of only one or two of the three colors is set to be changeable. Good.

  In the present embodiment, the density distribution of the three colors is set to be changeable, but the corresponding pseudo color information is generated by mixing two colors or four or more colors. It may be.

  Further, the colors mixed for generating the corresponding pseudo color information are not limited to red, green, and blue, but may be other colors. For example, cyan, magenta and yellow may be included.

  The EL image or PL image obtained by EL measurement or PL measurement in the luminescence measurement system 5 is an image in which EL light intensity or PL light intensity is recorded for each position on the solar cell 9. Therefore, it is also possible to appropriately convert the EL light intensity or the PL light intensity into a gradation image expressed in multiple gradations, and to convert this into a pseudo color image using the color chart CC1. At this time, the EL image or the PL image can be suitably formed into a pseudo color image by appropriately changing the density distribution of a plurality of colors and changing the color chart CC1.

  Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention. In addition, the configurations described in the above embodiments and modifications can be appropriately combined or omitted as long as they do not contradict each other.

100 Inspection device 22 Inspection light irradiation part (irradiation part)
23 Terahertz wave detection unit 24 Delay unit 3 Moving stage 31 Stage drive mechanism 4 Sample stage 41 Voltage application table (holding unit)
43 Electrode Pin Unit 5 Luminescence Measurement System 53 Image Sensor 55 PL Probe Light Source (Irradiation Unit)
61 Display section (output section)
62 Operation unit 7 Control unit 71 CPU
711 Image acquisition unit 712 Corresponding pseudo color information generation unit 713 Density distribution change unit 714 Pseudo color image generation unit 74 Storage unit 9 Solar cell (semiconductor sample)
CC1 color chart (corresponding pseudo color information)
ED1 pseudo color information LP11 inspection light LT1 terahertz wave P1, P2 control point PG1 program R1, G1, B1 graph (concentration distribution)

Claims (5)

An image processing apparatus for processing an image,
An image acquisition unit for acquiring a gradation image in which pixel values are expressed by a plurality of gradation values;
A corresponding pseudo color information generating unit that generates corresponding pseudo color information indicating a pseudo color corresponding to the gradation value by mixing a plurality of types of colors with respective density distributions corresponding to the gradation values. When,
For the density distribution of at least one of the plurality of colors, a density command that accepts a change command that can continuously change a gradation value at a specific density and changes the density distribution according to the change command Change part,
Based on the corresponding pseudo color information, the pseudo color image generation unit that generates the pseudo color image by converting the gray scale value in the gray scale image into a corresponding pseudo color;
Equipped with a,
The density distribution changing unit changes the density distribution of another color in conjunction with the change of the gradation value that becomes the specific density for the density distribution of one color among the plurality of colors. An image processing apparatus. The image processing apparatus according to claim 1,
The density distribution changing unit is an image processing apparatus that receives a change command for continuously changing a gradation value at which the density of the at least one color is maximum or minimum. The image processing apparatus according to claim 1 or 2 ,
The image processing apparatus, wherein the plurality of colors include red, green, and blue. An image output device for outputting an image,
The image processing apparatus according to any one of claims 1 to 3 ,
An output unit for outputting the pseudo color image;
An image output apparatus comprising: An inspection apparatus for inspecting a semiconductor sample,
A holding unit for holding a semiconductor sample;
An irradiation unit that irradiates the semiconductor sample held by the holding unit with inspection light;
A detection unit for detecting the intensity of radiation emitted from the semiconductor sample in response to irradiation of the inspection light;
Based on the detection result of the detection unit, an image acquisition unit that acquires position information indicating a position in the semiconductor sample, and image data in which a gradation value indicating the intensity of emitted light generated at the position is recorded;
A corresponding pseudo color information generation unit configured to generate corresponding pseudo color information indicating a pseudo color corresponding to the gradation value by mixing a plurality of types of colors with respective density distributions associated with the gradation value; ,
A density distribution changing unit that changes the density distribution by continuously changing a specific gradation value that is a specific density for the density distribution of at least one of the plurality of colors;
Based on the corresponding pseudo color information, a pseudo color image generation unit that generates pseudo color image data by converting the gradation value in the image data into a corresponding pseudo color;
An image output unit for outputting the pseudo color image;
With
The density distribution changing unit changes the density distribution of the other colors in conjunction with the change of the gradation value that becomes the specific density for the density distribution of one color among the plurality of colors. , Inspection equipment.