JP2016029345A - Inspection device and inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique to efficiently perform scanning by probe light radiating terahertz waves.SOLUTION: An inspection device 100 inspects a solar battery 9 on which an electrode wiring pattern is formed. The inspection device 100 comprises: a sample table 4 for holding the solar battery 9; a stage driving mechanism 31 for scanning the solar battery 9 by pulse light LP11 by moving the sample table 4 in an X-axis direction and a Y-axis direction; and a terahertz-wave detection unit 23 for detecting a terahertz-wave pulse LT1 radiated by the solar battery 9 in response to the irradiation of the pulse light LP11. In addition, the inspection device 100 comprises: a wiring pattern information acquisition unit 711 for acquiring wiring pattern information 83 indicating the position of a bus-bar electrode 93; and a control unit 7 for controlling the stage driving mechanism 31 so as to scan, by the pulse light LP11, a region of the solar battery 9 excluding at least part of the wiring pattern on the basis of the wiring pattern information 83.SELECTED DRAWING: Figure 4

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, a comparatively wide long bus bar electrode is formed on the surface of a general solar cell for current collection. When pulse light is irradiated on the bus bar electrode, the pulse light is blocked by the bus bar electrode. In such a case, the pulsed light does not reach the optical carrier generation region, and it is difficult to effectively generate the terahertz wave. That is, even if the bus bar electrode is scanned with pulsed light, it may be difficult to obtain data effective for inspection, which may result in a loss of measurement time. For this reason, the technique which test | inspects a solar cell efficiently was calculated | required.

  An object of the present invention is to provide a technique for efficiently performing scanning with probe light that emits terahertz waves.

  In order to solve the above-described problem, a first aspect is an inspection apparatus for inspecting a solar cell on which an electrode wiring pattern is formed, a holding unit that holds a solar cell, and the solar cell that is held by the holding unit A scanning mechanism that scans with a probe light, a detection unit that detects an electromagnetic wave radiated from the solar cell in response to irradiation of the probe light, and wiring pattern information that acquires wiring pattern information indicating a position of the wiring pattern An acquisition unit, and a control unit that controls the scanning mechanism so as to scan an area of the solar cell excluding at least a part of the wiring pattern with the probe light based on the wiring pattern information.

  The second aspect is the inspection apparatus according to the first aspect, wherein the scanning mechanism moves the solar cell relative to the probe light along a main scanning direction parallel to the surface of the solar cell. A main scanning mechanism that moves, and a sub-scanning mechanism that moves the solar cell relative to the probe light in a sub-scanning direction that is parallel to the surface of the solar cell and orthogonal to the main scanning direction. The control unit controls the sub-scanning mechanism so that the wiring pattern is scanned with the probe light except for a portion extending in the main scanning direction.

  According to a third aspect, in the inspection apparatus according to the second aspect, the portion extending in the main scanning direction includes a bus bar electrode portion.

  Moreover, a 4th aspect is an inspection apparatus which concerns on a 3rd aspect, Comprising: It arrange | positions at predetermined intervals along the direction where the said bus-bar electrode in the said solar cell hold | maintained at the said holding | maintenance part is extended. The scanning mechanism further irradiates the probe light in parallel with the main scanning direction, and the detection unit detects the electromagnetic wave radiated in parallel with the main scanning direction.

  Further, a fifth aspect is an inspection apparatus according to any one of the first to fourth aspects, wherein the wiring pattern information acquisition unit captures the solar cell from an image obtained from the image. The wiring pattern information is obtained by detecting the wiring pattern.

  Moreover, a 6th aspect is an inspection method which test | inspects the solar cell by which the wiring pattern of the electrode was formed in the surface, Comprising: (a) The process of hold | maintaining a solar cell with a holding part, (b) Said (a) Based on the wiring pattern information acquired in the step (c) (b), the step of acquiring wiring pattern information indicating the position of the wiring pattern formed on the surface of the solar cell held in the step, Scanning a region of the solar cell excluding at least a part of the wiring pattern with probe light, and detecting an electromagnetic wave radiated from the solar cell in response to irradiation with the probe light.

  According to the inspection apparatus according to the first aspect, it is possible to suppress unnecessary scanning of at least a part of the wiring pattern. For this reason, inspection time can be shortened.

  According to the inspection apparatus according to the second aspect, the number of main scans can be reduced, so that the inspection time can be shortened.

  According to the inspection apparatus according to the third aspect, the bus bar electrode is wider than the finger electrode. Therefore, the inspection time can be shortened by scanning except for the bus bar electrode portion.

  According to the inspection apparatus which concerns on a 4th aspect, the test which applies a voltage to a solar cell is attained by making an electrode pin contact a bus-bar electrode. In addition, the direction in which the plurality of electrode pins are arranged is parallel to the main scanning direction. For this reason, it can suppress that probe light is interrupted by a plurality of electrode pins, or that generated electromagnetic waves are interrupted by a plurality of electrode pins.

  According to the inspection apparatus according to the fifth aspect, the wiring pattern formed in each solar cell is photographed and detected. For this reason, a wiring pattern position is correctly detectable for every solar cell hold | maintained at the holding | maintenance 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 block diagram which shows the electrical connection of the control part and other element in a test | inspection apparatus. It is a figure which shows the flow of the data processing in an inspection apparatus. It is a schematic plan view which shows the light-receiving surface of a solar cell. It is a figure which shows the test object area | region, wiring pattern area | region, and scanning area | region set on the solar cell. It is a schematic plan view which shows the solar cell scanned with pulsed light. It is a schematic plan view which shows the example of irradiation of another pulsed light notionally. It is the schematic of a terahertz wave intensity distribution image. It is a schematic plan view for demonstrating the example of a setting of a wiring pattern area | region.

  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.

  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, an EL / PL 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 EL / PL 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 EL / PL 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 is a device that irradiates a solar cell 9 disposed below with pulsed light from above and detects radiated terahertz wave pulses. 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 direction, a Y-axis direction moving mechanism that moves the moving stage 3 in the Y-axis direction, and a lifting mechanism that moves the moving stage 3 up and down in the Z-axis direction. I have.

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

  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 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 EL / PL measurement system 5 performs EL (Electro-Luminescence) measurement or PL (Photo-Luminescence) measurement. The EL / PL measurement system 5 performs EL measurement and PL measurement while covering the solar cell 9 with the cover member 51.

  More specifically, the EL / PL 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 EL / PL measurement system 5. As a result, the solar cell 9 is caused to emit EL, and the EL emission is detected by the image sensor 53. 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.

  Further, the EL / PL measurement system 5 includes a PL probe light source 55 in order to perform PL measurement. The EL / PL measurement system 5 causes the solar cell 9 to emit PL with the PL probe light emitted from the PL probe light source 55, and detects the PL emission with the image sensor 53.

  In the inspection apparatus 100, the EL / PL measurement system 5 is not necessarily an essential configuration, and may be omitted. Further, the EL / PL measurement system 5 may be configured to measure only one of EL measurement and PL measurement.

  FIG. 2 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. 2, 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, the plurality of electrode pins 431 prevent the pulsed light LP11 that is the probe light from being blocked 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.

  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. 3 is a block diagram showing 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 73 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 EL / PL measurement system 5, the stage drive mechanism 31, the delay stage drive mechanism 242, and the camera 6, and bus wiring, a network line, or a serial communication line. Connected by such as. 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.

  FIG. 4 is a diagram showing a flow of data processing in the inspection apparatus 100. The wiring pattern information acquisition unit 711, the scanning position determination unit 713, and the image generation unit 715 illustrated in FIG. 4 are functions realized by software as the CPU 71 operates according to the program 75. Note that some or all of these functions may be realized in hardware by a dedicated logic circuit or the like. In the example illustrated in FIG. 4, each data is performed via the storage unit 74, but some or all of each data may be performed via the RAM 73.

  First, in the present embodiment, photographed image data 81 acquired by photographing the solar cell 9 with the camera 6 is stored in the storage unit 74.

  The wiring pattern information acquisition unit 711 acquires wiring pattern information about the solar cell 9. The wiring pattern information is information indicating at least a partial region of the surface-side electrode formed on the light receiving surface 91 of the solar cell 9. Various modes of acquiring the wiring pattern information are conceivable. As an example, the wiring pattern information acquisition unit 711 performs various images such as edge enhancement processing or binarization processing on the captured image data 81 stored in the storage unit 74. Processes are executed as appropriate. Thereby, the wiring pattern formed in the solar cell 9 is detected, and wiring pattern information is acquired.

  FIG. 5 is a schematic plan view showing the solar cell 9 held in the voltage application table 41 of the sample stage 4. The surface-side electrodes formed on the light receiving surface 91 of the solar cell 9 shown in FIG. 5 are two long rectangular plate-like bus bar electrodes 93, 93 extending along one direction, and both of these bus bar electrodes 93, 93. And a plurality of elongated plate-like finger electrodes 95 extending orthogonally to each other.

  The solar cell 9 is previously installed on the sample stage 4 so that the longitudinal direction of the bus bar electrode 93 is along the Y-axis direction. Further, as shown in the figure, when a voltage is applied to the solar cell 9, a 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.

  The bus bar electrode 93 is formed wider than the finger electrode 95. In the present embodiment, the wiring pattern information acquisition unit 711 acquires the position of the bus bar electrode 93 among the surface side electrodes including the bus bar electrode 93 and the finger electrode 95.

  In the above description, captured image data 81 obtained by capturing with the camera 6 is used to obtain wiring pattern information. However, instead of the captured image data 81, EL image data or PL image data acquired by the image sensor 53 of the EL / PL measurement system 5 may be used. In the solar cell 9, EL light or PL light is not generated from the portion of the bus bar electrode 93, and therefore, the bus bar electrode 93 can be identified from other portions also by the image shown by these. That is, the position of the bus bar electrode 93 can be specified from the EL image or the PL image.

  Further, the position of the bus bar electrode 93 may be specified from CAD data that defines the wiring pattern of the solar cell. However, there may be a case where the bus bar electrode 93 deviates from the ideal position depending on the state of fixation to the sample stage 4. Therefore, the position of the bus bar electrode 93 can be identified with high accuracy by detecting the bus bar electrode 93 based on the captured image data 81, EL image data, or PL image data.

  Returning to FIG. 4, the wiring pattern information 83 indicating the area of the wiring pattern acquired by the wiring pattern information acquisition unit 711 is stored in the storage unit 74. The wiring pattern information 83 is read by the scanning position determination unit 713. The scanning position determination unit 713 determines a position to be scanned with the pulsed light LP11 in the terahertz wave measurement system 2. Specifically, the scanning position determination unit 713 receives an operation command for an area to be inspected (hereinafter referred to as “inspection target area”) desired by the operator via the operation unit 62. The scanning position determination unit 713 determines a position to be scanned with pulsed light (hereinafter referred to as “scanning position”) based on the inspection target region that has received the command and the wiring pattern information 83. The scanning position determination unit 713 stores the scanning position information 85 indicating the determined scanning position in the storage unit 74. The scanning position information 85 is read for the control unit 7 to control the stage driving mechanism 31.

  FIG. 6 is a diagram showing the inspection target region R1, the wiring pattern region R2, and the scanning region R3 set on the solar cell 9. As shown in FIG. FIG. 6 shows a case where the entire area of the solar cell 9 is the inspection target region R1. For such a solar cell 9, the wiring pattern information acquisition unit 711 acquires the area of the bus bar electrode 93 (wiring pattern area R <b> 2) indicated by the wiring pattern information. Then, the scanning position determination unit 713 sets a region obtained by subtracting the wiring pattern region R2 from the inspection target region R1 as a scanning region R3. Then, the scanning position determination unit 713 determines a scanning position based on the scanning region R3.

  In the solar cell 9, when the surface side electrode portion is irradiated with the pulsed light LP <b> 11, the light is blocked by the surface side electrode. For this reason, the pulsed light LP11 does not reach the pn junction (optical carrier generation region), and it is difficult to effectively generate the terahertz wave pulse LT1. Therefore, irradiating the portion of the surface side electrode with the pulsed light LP11 may cause a measurement time loss. Therefore, in the inspection apparatus 100 according to the present embodiment, when the inspection target region R1 specified by the operator includes the wiring pattern region R2 corresponding to the bus bar electrode 93 among the surface-side electrodes, the remainder other than this is excluded. This region is designated as a scanning region R3, and the scanning position is determined. For this reason, according to the inspection apparatus 100, since unnecessary irradiation of the pulsed light LP11 is reduced, the number of main scans can be reduced, and the inspection time can be shortened. For this reason, inspection object field R1 can be inspected efficiently. In particular, the bus bar electrode 93 of the front side electrode is wider than the finger electrode 95. Therefore, it is very effective to scan with the pulsed light LP11 while avoiding the bus bar electrode 93.

  Here, a mechanism for scanning the solar cell 9 with pulsed light in the inspection apparatus 100 will be described. FIG. 7 is a schematic plan view showing the solar cell 9 scanned with the pulsed light LP11. In FIG. 7, the irradiation position of the pulsed light LP11 in the solar cell 9 is conceptually shown as a substantially circular irradiation spot SP1.

  As shown in FIG. 7, in the inspection apparatus 100, the stage driving mechanism 31 is driven in a state where the pulsed light LP11 is emitted, and the solar cell 9 is moved in the Y-axis direction. As a result, as indicated by an arrow AR11, the one end portion in the Y axis direction to the other end portion in the scanning region R3 of the solar cell 9 is scanned with the pulsed light LP11. The terahertz wave detector 231 detects the terahertz wave pulse LT1 every time the pulsed light LP11 advances by a predetermined pitch (P1). Hereinafter, this scanning in the Y-axis direction is referred to as main scanning. In this main scanning, the inspection apparatus 100 stores information (terahertz wave intensity information 87) indicating the electric field intensity detected by the terahertz wave detector 231 in the storage unit 74 (see FIG. 4).

  When this main scanning is completed, the inspection apparatus 100 moves the moving stage 3 by a predetermined pitch (P2) in the X-axis direction. Thereby, as indicated by an arrow AR21 in FIG. 7, the irradiation position of the pulsed light LP11 in the solar cell 9 moves along the X-axis direction. Hereinafter, this scanning in the X-axis direction is referred to as sub-scanning. The data acquisition interval (pitch P1) at the time of main scanning and the movement distance (pitch P2) of the irradiation position at the time of sub-scanning can be arbitrarily determined. For example, the beam diameter of the pulsed light LP11 (the diameter of the irradiation spot SP1) For example, the inspection time may be shortened by making it larger than 10 to 100 μm. Alternatively, the solar cells 9 may be inspected with high accuracy by setting the pitches P1 and P2 to be equal to or smaller than the beam diameter of the pulsed light LP11 and averaging the measured values of the terahertz wave pulse LT1.

  After performing the sub-scan, the inspection apparatus 100 moves the solar cell 9 in the direction opposite to the previous main scan while emitting the pulsed light LP11. Thereby, the other end portion in the Y-axis direction in the scanning region R3 is scanned with the pulsed light LP11.

  As described above, the inspection apparatus 100 scans the inspection target region R1 with the pulsed light LP11 by repeatedly performing the main scanning and the sub-scanning. The probe light irradiation unit 22, the moving stage 3, and the stage driving mechanism 31 are a configuration example of a scanning mechanism that scans the solar cell 9 with the pulsed light LP 11.

  As described above, the inspection apparatus 100 does not scan the wiring pattern region R2. This is realized as follows.

  For example, when the n-th main scan (indicated by an arrow AR12) is set to the −X side of the wiring pattern region R2, and the pitch P2 is moved in the next sub-scanning, the irradiation position of the pulsed light LP11 is the wiring position. It is assumed that it overlaps the pattern region R2. In this case, in the sub-scan after the n-th main scan, the inspection apparatus 100 corresponds to the pitch P3 (> P2) corresponding to the width of the wiring pattern region R2 (here, corresponding to the width of the bus bar electrode 93). Just move the irradiation position. Then, the (n + 1) th main scan (arrow AR13) is performed. The scanning position determination unit 713 determines the scanning position so that such scanning is performed. Therefore, as indicated by an arrow AR22 in FIG. 7, sub-scanning is performed in which the irradiation position (irradiation spot SP1) of the pulsed light LP11 is moved by an amount corresponding to the width of the wiring pattern region R2.

  In the example shown in FIG. 7, the scanning region R3 is set so as not to overlap the wiring pattern region R2. For this reason, in the main scanning on both sides of the wiring pattern region R2, the scanning positions are close so that the irradiation spot SP1 of the pulsed light LP11 does not overlap the wiring pattern region R2. However, the scanning position of the pulsed light LP11 is not limited to this.

  FIG. 8 is a schematic plan view conceptually showing another irradiation example of the pulsed light LP11. In the example shown in FIG. 8, the scanning position of the pulsed light LP11 is determined so that the irradiation spot SP1 of the pulsed light LP11 overlaps the wiring pattern region R2. In this case, although it is difficult to generate the terahertz wave pulse LT1 from the portion of the pulsed light LP11 that overlaps the bus bar electrode 93, the end of the bus bar electrode 93 can be inspected.

  FIG. 9 is a schematic diagram of the terahertz wave intensity distribution image i1. The image generation unit 715 (see FIG. 4) generates a terahertz wave intensity distribution image i1 indicating the distribution of the terahertz wave intensity in the solar cell 9 based on the terahertz wave intensity information 87. Then, the inspection apparatus 100 displays the image on the display unit 61 based on an operator command or the like. A terahertz wave intensity distribution image i1 shown in FIG. 9 shows an intensity distribution only in a partial region of the solar cell 9. Thus, according to the terahertz wave intensity distribution image i1, the electric field intensity distribution of the terahertz wave pulse LT1 generated in the solar cell 9 can be visually grasped. Therefore, for example, the defective part of the solar cell 9 can be easily identified.

  FIG. 10 is a schematic plan view for explaining an example of setting a wiring pattern region. As shown in FIG. 10, when the entire solar cell 9 is disposed obliquely, or when the bus bar electrode 93 is formed obliquely with respect to the side of the rectangular solar cell 9, the bus bar electrode 93 is In some cases, it is arranged to be inclined with respect to the Y-axis direction.

  For such a bus bar electrode 93, the wiring pattern information acquisition unit 711 may include a rectangular area R2a that includes all the bus bar electrodes 93 and extends in the Y-axis direction as a wiring pattern area. In this case, all of the bus bar electrodes 93 can be removed from the scanning region R3. As a result, main scanning in which the intensity of the terahertz wave pulse LT1 is not acquired is not performed, so that inspection efficiency can be increased. Further, the wiring pattern information acquisition unit 711 may include a rectangular region R2b included in the bus bar electrode 93 and extending in the Y-axis direction as a wiring pattern region. In this case, the peripheral portion of the bus bar electrode 93 can be included in the scanning region R3. Therefore, it is possible to inspect up to the boundary portion of the bus bar electrode 93.

  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.

  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. 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.

DESCRIPTION OF SYMBOLS 100 Inspection apparatus 1 Apparatus stand 2 Terahertz wave measurement system 22 Probe light irradiation part 221 Femtosecond laser 23 Terahertz wave detection part 231 Terahertz wave detector 24 Delay part 3 Moving stage 31 Stage drive mechanism 4 Sample stand 41 Voltage application table 43 Electrode pin Unit 431 Electrode pin 432 Electrode bar 5 EL / PL measurement system 6 Camera 7 Control unit 71 CPU
711 Wiring pattern information acquisition unit 713 Scan position determination unit 715 Image generation unit 74 Storage unit 81 Captured image data 83 Wiring pattern information 85 Scan position information 87 Terahertz wave intensity information 9 Solar cell 91 Light receiving surface 93 Bus bar electrode 95 Finger electrode i1 Terahertz wave Intensity distribution image LP11 Pulse light (probe light)
LT1 Terahertz wave pulse P1 to P3 Pitch R1 Inspection target area R2 Wiring pattern area R3 Scanning area SP1 Irradiation spot

Claims (6)

In an inspection apparatus for inspecting a solar cell on which an electrode wiring pattern is formed,
A holding unit for holding the solar cell;
A scanning mechanism that scans the solar cell held by the holding unit with probe light;
A detection unit for detecting electromagnetic waves radiated from the solar cell in response to irradiation of the probe light;
A wiring pattern information acquisition unit for acquiring wiring pattern information indicating a position of the wiring pattern;
Based on the wiring pattern information, a control unit that controls the scanning mechanism so as to scan a region excluding at least a part of the wiring pattern in the solar cell with the probe light;
An inspection apparatus comprising: The inspection apparatus according to claim 1,
The scanning mechanism is
A main scanning mechanism that relatively moves the solar cell along a main scanning direction parallel to the surface of the solar cell with respect to the probe light;
A sub-scanning mechanism for moving the solar cell relatively in a sub-scanning direction parallel to the surface of the solar cell and perpendicular to the main scanning direction with respect to the probe light;
Including
The said control part is an inspection apparatus which controls the said subscanning mechanism so that it may scan with the said probe light except the part extended in the said main scanning direction among the said wiring patterns. The inspection apparatus according to claim 2,
The inspection apparatus, wherein the portion extending in the main scanning direction includes a bus bar electrode portion. The inspection apparatus according to claim 3,
A plurality of electrode pins arranged at predetermined intervals along the extending direction of the bus bar electrode in the solar cell held by the holding unit,
Further comprising
The scanning apparatus further includes: irradiating the probe light in parallel with the main scanning direction; and the detection unit further includes detecting the electromagnetic wave radiated in parallel with the main scanning direction. The inspection apparatus according to any one of claims 1 to 4,
The wiring pattern information acquisition unit
The inspection apparatus which acquires the said wiring pattern information by detecting the said wiring pattern from the image obtained by image | photographing the said solar cell. An inspection method for inspecting a solar cell having an electrode wiring pattern formed on a surface,
(A) a step of holding the solar cell by the holding unit;
(B) obtaining wiring pattern information indicating the position of the wiring pattern formed on the surface of the solar cell held in the step (a);
(C) Based on the wiring pattern information acquired in the step (b), a region excluding at least a part of the wiring pattern in the solar cell is scanned with probe light, and in response to irradiation with the probe light. Detecting electromagnetic waves emitted from the solar cell;
Including an inspection method.