JP2016029344A - Inspection device and inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique to simply perform positioning of a solar battery among a plurality of inspection units.SOLUTION: An index unit 45 is provided at a position fixed relative to a solar battery 9 held by a sample table 4, and performs luminescence emission. A luminescence measuring system 5 obtains a luminescence image by photographing the luminescence emission of the index unit 45 and the solar battery 9. A terahertz wave measuring system 2 includes a camera 6 for taking a visible image. A moving stage 3 moves the sample table 4 between the luminescence measuring system 5 and the terahertz wave measuring system 2. An inspection object place setting unit 711 sets an inspection object place of the solar battery 9 inspected in the terahertz wave measuring system 2. A position determination unit 713 determines the position of the inspection object place of the solar battery 9 on the basis of the image of the index unit 45 in the luminescence image and the image of the index unit 45 in the visible image obtained by the camera 6.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for inspecting a solar cell.

  As a technique for inspecting defects and the like of solar cells, EL (Electro-Luminescence) measurement or PL (Photo-Luminescence) measurement is known. In EL measurement, a forward bias voltage is applied to a solar cell to emit EL light, and this is photographed. In the PL measurement, infrared light or the like is irradiated on a solar cell to emit PL light, and this is photographed.

  Recently, as a solar cell inspection method, it has been proposed to measure a terahertz wave radiated from a solar cell in response to irradiation with pulsed light (for example, Patent Document 1). In the terahertz wave measurement, a terahertz wave is emitted from the solar cell by scanning the solar cell with pulsed light. And the defect of a solar cell etc. are test | inspected by measuring the intensity | strength of the emitted terahertz wave.

JP2013-19861A

  By the way, extracting defects that are difficult to detect with the naked eye by EL measurement or PL measurement in advance and setting them as inspection target locations for terahertz wave measurement is effective in reducing inspection time. In particular, even when a wide range of a solar cell is scanned with probe light, it is effective to narrow down the inspection object range in advance by EL measurement or PL measurement because the inspection time may be prolonged.

  When the EL / PL measurement system and the terahertz wave measurement system are provided at different locations, it is necessary to move the solar cell from the EL / PL measurement system to the terahertz wave measurement system after the EL or PL measurement. Then, although it is necessary to specify the inspection target location with high accuracy in the terahertz wave measurement system, it is difficult to specify when the inspection target location cannot be confirmed with the naked eye or the like. Therefore, alignment may be performed by detecting the mark (index) at a fixed position with respect to the solar cell in the same manner in the EL / PL measurement system and the terahertz wave measurement system. However, in order to perform such alignment, it is necessary to separately acquire a visible image in the EL / PL measurement system. In addition, when a visible image cannot be acquired by an image sensor for EL or PL measurement, it is necessary to separately provide a camera for capturing a visible image. For this reason, the technique which performs alignment of a solar cell more easily between different test | inspection parts is calculated | required.

  This invention is made | formed in view of the said subject, Comprising: It aims at providing the technique which aligns a solar cell easily between several test | inspection parts.

  In order to solve the above-described problem, a first aspect is an inspection apparatus that inspects a solar cell, and is fixed to a holding unit that holds the solar cell and the solar cell that is held by the holding unit. A first inspection unit that obtains a luminescence image by photographing the luminescence emission of the indicator unit, the luminescence emission of the indicator unit, and the luminescence emission of the solar cell, and probe light irradiation. A terahertz wave detection unit that detects a terahertz wave emitted from the solar cell according to the second inspection unit, an image acquisition unit that acquires an image of the index unit, the first inspection unit, and the second A moving mechanism that moves the holding unit between the inspection unit, and an inspection target location setting unit that sets an inspection target location of the solar cell to be inspected in the second inspection unit; The inspection object in the solar cell based on the image of the indicator part in the luminescence image acquired in the first inspection part and the image of the indicator part acquired by the image acquisition part in the second inspection part A position specifying unit for specifying the position of the place.

  Moreover, a 2nd aspect is an inspection apparatus which concerns on a 1st aspect, Comprising: The said parameter | index part is provided in the said holding | maintenance part.

  Moreover, a 3rd aspect is an inspection apparatus which concerns on a 2nd aspect, Comprising: The attachment mechanism which attaches the said indicator | index part with respect to the said holding | maintenance part further is provided.

  The fourth aspect is an inspection apparatus according to any one of the first to third aspects, in which the image acquisition unit of the second inspection unit captures a visible image of the index unit. Part.

  A fifth aspect is an inspection apparatus according to any one of the first to third aspects, wherein the image acquisition unit of the second inspection unit is configured to irradiate the probe unit with the probe light. In response, an image based on the terahertz wave generated from the index unit is acquired.

  Moreover, a 6th aspect is an inspection method which test | inspects a solar cell, Comprising: (a) The process of hold | maintaining a solar cell in a holding part, (b) Luminescence light emission of the said solar cell hold | maintained at the said holding part. And (c) said (b) process which acquires the luminescence image by imaging | photography the luminescence light emission of the parameter | index part provided in the position fixed with respect to the said solar cell hold | maintained at the said holding | maintenance part, Thereafter, by detecting a terahertz wave radiated from the solar cell, a step of setting an inspection target portion of the solar cell to be inspected in a second inspection unit for inspecting the solar cell, and (d) b) a step of moving to the second inspection unit after the step; (e) a step of acquiring an image of the indicator portion at the second inspection unit after the step (d); (B) acquired in step A step of identifying the position of the inspection target location in the solar cell based on the image of the indicator portion in the minence image and the image of the indicator portion obtained in the step (e); ) Inspecting the inspection object location specified in the process by the second inspection unit.

  According to the inspection apparatus according to the first to third aspects, the alignment when the second inspection part is moved from the first inspection part, the image of the indicator part in the luminescence image acquired by the first inspection part, and Based on the image of the index part acquired by the second inspection part, it is possible to accurately specify the inspection target part of the solar cell to be inspected by the second inspection part. Therefore, alignment can be performed easily.

  Moreover, according to the inspection apparatus which concerns on a 2nd aspect, the position of the parameter | index part with respect to a solar cell can be fixed by providing a parameter | index part in a holding | maintenance part.

  Moreover, according to the inspection apparatus which concerns on a 3rd aspect, an indicator part can be replaced | exchanged according to the objective.

  Moreover, according to the inspection apparatus which concerns on a 4th aspect, the position of an index part can be specified from the image of the index part in a visible image.

  Moreover, according to the inspection apparatus which concerns on a 5th aspect, the position of a parameter | index part can be pinpointed from the image of the parameter | index part in the image produced | generated based on the terahertz wave.

  Further, according to the inspection method according to the sixth aspect, the alignment when the second inspection unit is moved from the first inspection unit, the image of the index portion in the luminescence image acquired by the first inspection unit, and the second inspection Based on the image of the index part acquired by the part, it is possible to accurately specify the inspection target portion of the solar cell to be inspected by the second inspection part. Therefore, alignment can be performed easily.

It is a schematic side view of the inspection apparatus which concerns on embodiment. It is a schematic plan view which shows the solar cell hold | maintained at the voltage application table of the sample stand. It is a schematic block diagram of a terahertz wave measurement system. 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 of the example of an inspection using an inspection device. It is a figure which shows the EL image of the solar cell, and the EL image after the process based on different LUT.

  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.

<Device configuration>
FIG. 1 is a schematic side view of an inspection apparatus 100 according to the embodiment. The inspection apparatus 100 irradiates a solar cell 9 that is an inspection target, which is a photo device, with pulsed light, and emits electromagnetic waves (mainly having a frequency of 0) from the solar cell 9 in response to the irradiation of the pulsed light. .1 THz to 30 THz) is detected to inspect the inspection object.

  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.

  In FIG. 1 and the subsequent figures, a right-handed XYZ orthogonal coordinate system with the Z-axis direction as the vertical direction and the XY plane as 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 measuring system 2 is a device for detecting a radiated terahertz wave pulse by irradiating a solar cell 9 disposed below with pulsed light from above. The configuration of the terahertz wave measurement system 2 will be described in detail later.

  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. It will 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, respectively. 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 the EL measurement or the 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 a later-described index unit 45 is photographed by the camera 6 provided in the terahertz wave measurement system 2 (second inspection unit).

  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 is held along the bus bar electrode 93 that is the surface side electrode of the solar cell 9 held on the sample stage 4. The electrode pin unit 43 includes a plurality of electrode pins 431 that are brought into contact with each of a plurality of index portions 45 described later.

  The sample stage 4 brings the voltage application table 41 into contact with the back side electrode of the solar cell 9, and brings the plurality of electrode pins 431 into contact with the front side electrode of the solar cell 9 (here, a bus bar electrode 93 described later). . 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 of the solar cell 9.

  The luminescence measurement system 5 performs EL (Electro-Luminescence) measurement or PL (Photo-Luminescence) 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. As a result, the luminescence measurement system 5 causes the solar cell 9 to emit EL, and the image sensor 53 captures the EL emission. Thus, an EL image that is a luminescence image is acquired. 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 probe light source 55. The luminescence measurement system 5 causes the solar cell 9 to emit PL using the PL probe light emitted from the PL probe light source 55, and images the PL emission using the image sensor 53. Thereby, a PL image is acquired.

  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.

  FIG. 2 is a schematic plan view showing the solar cell 9 held on the voltage application table 41 of the sample stage 4. As shown in FIG. 2, the voltage application table 41 is provided with a plurality of indicator portions 45. In the present embodiment, the indicator portions 45 are provided at the outer four corners of the region holding the solar cell 9. As described above, each index unit 45 is provided in the voltage application table 41 that holds the solar cell 9. Therefore, each indicator portion 45 is provided at a position fixed with respect to the solar cell 9.

  In addition, you may provide the attachment mechanism which attaches each index part 45 so that removal is possible on the surface of the voltage application table 41 which comprises a holding | maintenance part. Various specific configurations of the attachment mechanism are conceivable. For example, it is conceivable to provide a frame material having a shape that matches the outer peripheral shape of the index portion 45 at a predetermined position in the voltage application table 41. By storing the indicator portion 45 inside the frame member, the indicator portion 45 can be fixed. In addition, a clamp mechanism for fixing the indicator portion 45 to the frame member may be provided. Furthermore, it is conceivable that an adhesive material or the like is provided on the back side of the index portion 45 itself, and the index portion 45 is detachably attached to the voltage application table 41 via the adhesive material.

  The indicator unit 45 is configured to emit luminescence in the luminescence measurement system 5. Specifically, the indicator unit 45 is configured as a general solar cell including an n-type semiconductor layer, a p-type semiconductor layer, a back electrode, and a front electrode. For this reason, the indicator unit 45 emits EL light when a forward bias voltage is applied by the sample stage 4 in the luminescence measurement system 5. The indicator unit 45 emits PL with the PL probe light emitted from the PL probe light source 55. Alternatively, PL light is emitted upon irradiation with the PL probe light. EL light emission or PL light emission of the indicator unit 45 is photographed by the image sensor 53. In the following description, EL emission and PL emission may be simply referred to as “luminescence emission” unless otherwise distinguished.

  As shown in FIG. 2, each indicator portion 45 includes a rectangular solar cell main body 451 and a cross-shaped surface electrode 452 attached to the surface of the solar cell main body 451. In the EL measurement, the electrode pin 431 is brought into contact with the surface electrode 452 and a forward bias voltage is applied to the solar cell body 451. When the indicator 45 emits luminescence, the surface electrode 452 is displayed on the EL image or the PL image as an image of a non-light emitting portion. Therefore, the position of the indicator portion 45 can be accurately specified by detecting the position of the intersection of the cross-shaped portion.

  Of course, the shape of the indicator portion 45 is not limited to that shown in FIG. The shape of the surface electrode 452 may be a specific shape (for example, a circle) other than the cross shape. In this case, it is conceivable to determine the position of the index portion 45 by obtaining the barycentric position or the like of the non-light-emitting portion of the specific shape in the luminescence image.

  The position where the index part 45 is provided is not limited to the position shown in FIG. However, as shown in FIG. 2, the indicator portion 45 is provided at two or more different positions on the surface of the voltage application table 41 to specifically identify the positional relationship between each indicator portion 45 and the solar cell 9. it can.

  The indicator portion 45 is preferably made of the same material as that of the solar cell 9, for example, a member having the same band gap as that of the solar cell 9. In this case, the indicator portion 45 can also emit luminescence under the condition that the solar cell 9 emits luminescence.

  The surface-side electrodes formed on the light-receiving surface 91 of the solar cell 9 shown in FIG. 2 are three elongated rectangular plate-like bus bar electrodes 93 extending along one direction, and extend so as to be orthogonal to the bus bar electrodes 93. It is composed of a large number of elongated plate-like finger electrodes 95. The bus bar electrode 93 is formed wider than the finger electrode 95. In addition, as shown in FIG. 2, the solar cell 9 is arrange | positioned so that the longitudinal direction of each bus-bar electrode 93 may follow a Y-axis direction. For this reason, when a voltage is applied to the solar cell 9, the plurality of electrode pins 431 arranged at regular intervals along the Y-axis direction are brought into contact with the respective bus bar electrodes 93.

  FIG. 3 is a schematic configuration diagram of the terahertz wave measurement system 2. The terahertz wave measurement system 2 includes a probe light irradiation unit 22, a terahertz wave detection unit 23, and a delay unit 24.

  The probe 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 B1. One of the divided pulse lights (pulse light LP11) is applied to the solar cell 9. At this time, the probe light irradiation unit 22 performs irradiation of the pulsed light LP11 from the light receiving surface 91 side. In addition, the pulsed light LP11 is applied to the solar cell 9 so that the optical axis of the pulsed 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.

  The photo device such as the solar cell 9 has, for example, a pn junction part in which a p-type semiconductor and an n-type semiconductor are joined. In the vicinity of this pn junction, a depletion layer in which electrons and holes hardly exist is formed in the vicinity of the pn junction by generating a diffusion current in which electrons and holes are diffused and combined with each other. In this region, a force for pulling electrons and holes back to the n-type and p-type regions is generated, so an electric field (internal electric field) is generated inside the photo device.

  If light having energy exceeding the forbidden band width is irradiated to the pn junction, free electrons and free holes generated in the pn junction are left behind by the internal electric field to the n-type semiconductor side. Free holes move to the p-type semiconductor side. In the photo device, this current is extracted to the outside through electrodes attached to the n-type semiconductor and the p-type semiconductor. For example, in the case of a solar cell, the movement of free electrons and free holes generated when light is irradiated to the depletion layer at the pn junction is used as a direct current.

  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 pulse LT1) is generated in proportion to the temporal differentiation of the instantaneously generated photocurrent.

  As shown in FIG. 3, the other pulse light split by the beam splitter B <b> 1 enters the terahertz wave detector 231 of the terahertz wave detection unit 23 via the delay unit 24 as the detection light LP <b> 12. Further, the terahertz wave pulse LT1 generated in response to the irradiation of the pulsed light LP11 is appropriately condensed by a parabolic mirror or the like and is incident on the terahertz wave detector 231.

  As shown in FIG. 1, the pulsed light LP11 is applied to 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 pulse 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 the present embodiment, the irradiation direction of the pulsed light LP11 and the radiation direction of the detected terahertz wave pulse LT1 are the directions in which the plurality of electrode pins 431 are arranged at a predetermined interval (that is, the Y axis). Direction). For this reason, it is possible to prevent the pulse light LP11 that is the probe light from being blocked by the plurality of electrode pins 431, or the generated terahertz wave pulse LT1 from being blocked by the plurality of electrode pins 431.

  The terahertz wave detector 231 includes, for example, a photoconductive switch as an electromagnetic wave detection element. When the terahertz wave pulse 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 pulse LT1 is instantaneously applied to the photoconductive switch. Occur. The current corresponding to the electric field strength is converted into a digital quantity via an I / V conversion circuit, an A / D conversion circuit, or the like. In this way, the terahertz wave detection unit 23 detects the electric field strength of the terahertz wave pulse LT1 that has passed through the solar cell 9 in accordance with the irradiation of the detection light LP12. It is also conceivable to employ another element different from the photoconductive switch, such as a nonlinear optical crystal.

  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 B1 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 pulse LT1 reaches the terahertz wave detector 231 and the time when the detection light LP12 reaches the terahertz wave detector 231. Specifically, the delay stage 241 changes the optical path length of the detection light LP12, thereby delaying the timing (detection timing or sampling timing) at which the terahertz wave detector 231 detects the electric field strength of the terahertz wave pulse LT1. .

  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. For example, an electro-optic element disclosed in Japanese Patent Application Laid-Open No. 2009-175127, which is a patent document, can be used.

  Instead of changing the optical path length of the detection light LP12, the optical path length of the pulsed light LP11 directed to the solar cell 9 or the optical path length of the terahertz wave pulse LT1 emitted from the solar cell 9 may be changed. In any case, the time for the terahertz wave pulse LT1 to reach the terahertz wave detector 231 can be shifted from the time for the detection light LP12 to reach the terahertz wave detector 231. That is, the detection timing of the terahertz wave pulse 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 probe 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 pulsed 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 while moving the solar cell 9, a moving unit that moves the probe light irradiation unit 22 and the terahertz wave detection unit 23 in the XY plane may be provided.

  Also, a scanning mechanism that changes the optical path of the pulsed light LP11 itself may be employed. Specifically, it is conceivable to change the optical path of the pulsed light LP11 along an 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 pulse LT1 emitted 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 of the solar cell 9. Even in this case, the intensity of the terahertz wave pulse LT1 radiated from the solar cell 9 can be increased.

  FIG. 4 is a block diagram illustrating an electrical connection between the control unit 7 and other elements in the inspection apparatus 100. The control unit 7 includes a CPU 71 as an arithmetic device, a read-only ROM 72, a RAM mainly used as a working area of the CPU 71, and a storage unit 74 that is a non-volatile recording medium. 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, and bus wiring, network line, or serial. It is connected via a communication line. The control unit 7 controls the operation of these elements and receives data from these elements.

  The CPU 71 performs arithmetic processing on various data stored in the RAM 73 or the storage unit 74 by reading and executing the program 75 stored in the ROM 72. As described above, the control unit 7 includes the CPU 71, the ROM 72, the RAM 73, and the storage unit 74, and is configured as a general computer.

  The display unit 61 is configured by a liquid crystal display device or the like, and presents various information to the operator. The operation unit 62 is configured as various input devices such as a mouse and a keyboard, and accepts operations for commands given by the operator to the control unit 7. In addition, the display part 61 may be provided with a part or all of the function of the operation part 62 by providing the display part 61 with a touch panel function.

  The CPU 71 functions as an image processing unit 711, an inspection target location setting unit 712, and a position specifying unit 713 by operating according to the program 75.

  The image processing unit 711 has a function of processing a luminescence image. The luminescence image data acquired by the image sensor 53 holds pixel values corresponding to the emission intensity of luminescence emission for each pixel. That is, the luminescence image is an image showing the distribution of luminescence emission intensity. The image processing unit 711 refers to a lookup table (LUT) 741 stored in advance in the storage unit 74 to convert each pixel into a pixel value for colorization. As described above, the image processing unit 711 processes the original luminescence image into a luminescence image in which the emission intensity distribution is expressed in color based on the LUC 741. Further, an LUT 741 in which the original luminescence image is processed into a luminescence image in which the light emission intensity in a specific range is emphasized may be used.

  As described above, it is desirable to prepare not only one type of LUT 741 but also a plurality of different LUTs 741. The image processing unit 711 generates a plurality of luminescence images based on different LUTs 741, thereby causing defects in the solar cell 9 (for example, internal scratches, cracks, film formation defects, film thickness unevenness, crystal grain boundaries, and electrode printing mistakes). Detection of electrode pitting (corrosion), electrode deterioration, electrode disconnection due to peeling, and the like is facilitated. However, the image processing unit 711 is not necessarily required and can be omitted.

  The inspection target location setting unit 712 receives an instruction for designating a location (inspection target location) where terahertz wave measurement is to be performed in the terahertz wave measurement system 2. The inspection target portion is designated by operating the mouse or keyboard of the operation unit 62 by the operator. In the present embodiment, the inspection target location setting unit 712 displays the luminescence image generated by the image processing unit 711 on the display unit 61. Then, the operator operates the operation unit 62 while referring to the luminescence image displayed on the display unit 61 to perform an input for designating the inspection target location where the terahertz wave measurement is performed. The inspection target location setting unit 712 stores inspection target location information indicating the inspection target location in the storage unit 74 in accordance with the input.

  The position specifying unit 713 specifies the position of the inspection target location in the solar cell 9 based on the image of the index unit 45 in the luminescence image and the image of the index unit 45 in the visible image acquired by the camera 6. The camera 6 that captures a visible image is an example of an image acquisition unit.

  Note that some or all of the image processing unit 711, the inspection target location setting unit 712, and the position specifying unit 713 may be realized by hardware by being configured by a dedicated circuit.

<Inspection example>
FIG. 5 is a flowchart of an inspection example using the inspection apparatus 100. The operation of the inspection apparatus 100 in each of the following processes is performed under the control of the control unit 7 unless otherwise specified.

  First, the solar cell 9 is held in the voltage application table 41 (step S11). And the solar cell 9 is moved to the luminescence measurement system 5 (1st test | inspection part) by moving the movement stage 3 (step S12).

  In the luminescence measurement system 5, luminescence measurement is performed on the solar cell 9. Thereby, the luminescence image of the solar cell 9 is acquired (step S13). At this time, since the luminescence emission of the indicator portion 45 is also photographed, a luminescence image including images of the four indicator portions 45 is acquired.

  Next, the image processing unit 711 processes the luminescence image (step S14). Specifically, the image processing unit 711 refers to the LUT 741 to process the original luminescence image into a luminescence image colored according to the emission intensity or a luminescence image in which a specific emission intensity range is emphasized. . The step S14 can be omitted.

  FIG. 6 is a diagram showing EL images i <b> 1 to i <b> 4 after processing based on the EL image i <b> 1 of the solar cell 9 and different LUTs 741. Note that the illustrated EL images i <b> 1 to i <b> 4 are diagrams illustrating a part of the solar cell 9. As illustrated, by generating EL images i <b> 2 to i <b> 4 processed based on different LUTs 741, the EL light emission intensity distribution of the solar cell 9 can be observed from different viewpoints. For this reason, since the detection of the defect candidate location of the solar cell 9 becomes easy, it becomes easy to specify the part which should perform terahertz wave measurement.

  Next, based on the luminescence image, an inspection target location where terahertz wave measurement is to be performed is set (step S15). Specifically, the operator should perform the terahertz wave measurement in a state where the processed luminescence image acquired in step S14 or the original luminescence image acquired in step S13 is displayed on the display unit 61. Perform input to specify the target location. Based on this input, the inspection target location setting unit 712 sets the inspection target location.

  When the setting of the inspection target location is completed, the inspection apparatus 100 drives the stage drive mechanism 31 to move the solar cell 9 from the position of the luminescence measurement system 5 to the position of the terahertz wave measurement system 2 (step S16). Note that step S16 may be executed after step S14 and before step S15.

  The solar cell 9 is photographed by the camera 6. As a result, a visible image including images of the four indicator portions 45 and the solar cell 9 is acquired (step S17). And the location for a test | inspection in the solar cell 9 which moved to the terahertz wave measurement system 2 is specified (step S18).

  In step S18, the position specifying unit 713 specifies the positions of the four index units 45 included in the luminescence image acquired in step S13 (or the processed luminescence image acquired in step S14). Further, the position specifying unit 713 specifies the positions of the four index units 45 included in the visible image acquired in step S17. Thereby, the inspection object location designated based on the luminescence image can be specified on the visible image.

  When the identification of the inspection target portion is completed, the terahertz wave measurement system 2 performs terahertz wave measurement (step S19). Specifically, the control unit 7 controls the stage drive mechanism 31 so that the inspection target location specified by the position specifying unit 713 is irradiated with the pulsed light LP11. And the pulsed light LP11 which is probe light is irradiated to the test object location of the solar cell 9, and the terahertz wave pulse LT1 radiated | emitted from the solar cell 9 according to it is measured.

  In addition, when the inspection apparatus 100 performs the terahertz wave measurement on the inspection target portion, first, the position (including the orientation and the like) of the solar cell 9 is adjusted based on the position of each index unit 45 included in the visible image ( alignment). Thereby, the positional deviation of the solar cell 9 caused by the conveyance between the luminescence measurement system 5 and the terahertz wave measurement system 2 of the solar cell 9 is corrected. Thereafter, the inspection target portion of the solar cell 9 is irradiated with the pulsed light LP11.

  As described above, according to the inspection apparatus 100 according to the present embodiment, the indicator unit 45 itself is configured to emit luminescence. For this reason, in the luminescence measurement system 5, the apparatus and operation | work which acquire a visible image become unnecessary. For this reason, it is possible to easily perform alignment when the solar cell 9 is moved between the luminescence measurement system 5 and the terahertz wave measurement system 2.

  Although the embodiment has been described above, the present invention is not limited to the above, and various modifications are possible.

  For example, in the above embodiment, the index unit 45 is provided in the holding unit (voltage application table 41) that holds the solar cell 9. However, the indicator part 45 may be provided in the solar cell 9 that is a test sample. In this case, a plurality of thin-film electrodes formed in a predetermined shape such as a cross shape may be provided at an arbitrary position on the light receiving surface 91 of the solar cell 9. In this case, if a forward bias voltage is applied to the solar cell 9 by bringing the electrode pin 431 into contact with the electrode, EL light can be emitted around the electrode. For this reason, the electrode as the index portion can be detected by the image sensor 53 as the non-light emitting portion. In addition, such a thin film electrode as the index portion can be easily formed in the step of providing the bus bar electrode 93 or the finger electrode 95. Of course, you may make it attach the electrode as a parameter | index part to the solar cell 9 later.

  Moreover, in the said embodiment, it demonstrated as what identifies the position of the parameter | index part 45 from a visible image. However, it is also conceivable to specify the position of the index unit 45 from an imaging image obtained by imaging the intensity distribution of terahertz waves, for example, instead of the visible image. For example, the region including each index portion 45 and its periphery is scanned with pulsed light LP11 that is probe light. Thus, it is conceivable that the intensity distribution of the terahertz wave generated from the index unit 45 is imaged and the position of each index unit 45 is specified based on the image. In this case, the probe light irradiation unit 22, the terahertz wave detection unit 23, and the stage drive mechanism 31 constitute an image acquisition unit that acquires an image based on the terahertz wave generated from the index unit 45. In this case, it is possible to omit the camera 6 that captures a visible image.

  Moreover, you may provide the light-shielding member which interrupts luminescence light in the light-receiving surface 91 of the solar cell 9 as an indicator | index part. Also in this case, when the solar cell 9 emits luminescence, the light is blocked by the light blocking member, so that it can be detected by the image sensor 53 as a non-light emitting portion. If, for example, an adhesive tape is employed as the light shielding member, it can be easily attached to the solar cell 9.

  In the above embodiment, pulsed light is emitted from the femtosecond laser 221, and pulsed terahertz waves are emitted from the solar cell 9. However, instead of the femtosecond laser 221, it is also possible to use two light sources that emit two continuous lights having slightly different oscillation frequencies (Japanese Patent Laid-Open No. 2013-170864). Specifically, an optical beat signal corresponding to the difference frequency is generated by superimposing two continuous lights by a coupler formed by an optical fiber or the like that is an optical waveguide. Then, by irradiating the solar cell 9 with this optical beat signal, an electromagnetic wave (terahertz wave) corresponding to the frequency of the optical beat signal can be emitted.

  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. Moreover, each structure demonstrated by said each embodiment and each modification can be suitably combined or abbreviate | omitted unless it mutually contradicts.

100 Inspection Equipment 1 Equipment Base 2 Terahertz Wave Measurement System (Second Inspection Department)
22 probe light irradiation unit 221 femtosecond laser 231 terahertz wave detector 23 terahertz wave detection unit 24 delay unit 241 delay stage 242 delay stage driving mechanism 3 moving stage 31 stage driving mechanism (moving mechanism)
DESCRIPTION OF SYMBOLS 4 Sample stand 41 Voltage application table 43 Electrode pin unit 431 Electrode pin 432 Electrode bar 45 Indicator part 451 Solar cell main body 452 Surface electrode 5 Luminescence measurement system (1st test | inspection part)
53 Image sensor 55 PL probe light source 6 Camera (shooting unit)
7 Control unit 71 CPU
711 Image processing unit 712 Inspection target location setting unit 713 Position specifying unit 74 Storage unit 9 Solar cell 91 Light receiving surface 93 Bus bar electrode 95 Finger electrode LP11 Pulse light (probe light)
LP12 detection light LT1 terahertz wave pulse i1 to i4 EL image

Claims (6)

An inspection device for inspecting solar cells,
A holding unit for holding the solar cell;
Provided at a position fixed to the solar cell held by the holding unit, and an indicator unit for emitting luminescence;
A first inspection unit that acquires a luminescence image by photographing the luminescence emission of the indicator unit and the luminescence emission of the solar cell;
A terahertz wave detection unit that detects a terahertz wave emitted from the solar cell in response to irradiation with probe light, and a second inspection unit that includes an image acquisition unit that acquires an image of the index unit;
A moving mechanism for moving the holding unit between the first inspection unit and the second inspection unit;
An inspection object location setting unit for setting an inspection object location of the solar cell to be inspected in the second inspection unit;
The inspection object in the solar cell based on the image of the indicator part in the luminescence image acquired in the first inspection part and the image of the indicator part acquired by the image acquisition part in the second inspection part A position specifying part for specifying the position of the place;
An inspection apparatus comprising: The inspection apparatus according to claim 1,
The inspection apparatus, wherein the index part is provided in the holding part. The inspection apparatus according to claim 2,
An inspection apparatus, further comprising an attachment mechanism for removably attaching the indicator portion to the holding portion. The inspection apparatus according to any one of claims 1 to 3, wherein
The inspection apparatus, wherein the image acquisition unit of the second inspection unit includes an imaging unit that captures a visible image of the index unit. The inspection apparatus according to any one of claims 1 to 3, wherein
The inspection apparatus, wherein the image acquisition unit of the second inspection unit acquires an image based on a terahertz wave generated from the index unit in response to irradiation of the probe light to the index unit. An inspection method for inspecting a solar cell,
(A) a step of holding the solar cell in the holding unit;
(B) Photographing the luminescence emission of the solar cell held by the holding unit and the luminescence emission of the indicator unit provided at a position fixed to the solar cell held by the holding unit Obtaining a luminescence image; and
(C) After the step (b), by detecting a terahertz wave radiated from the solar cell, the inspection target portion of the solar cell to be inspected in the second inspection unit inspecting the solar cell is set Process,
(D) After the step (b), the step of moving to the second inspection unit;
(E) after the step (d), obtaining an image of the indicator portion at the second inspection portion;
(F) Based on the image of the indicator portion in the luminescence image acquired in the step (b) and the image of the indicator portion acquired in the step (e), Identifying the position;
(G) a step of inspecting the inspection target portion specified in the step (f) by the second inspection unit;
Including an inspection method.