Inspection device and inspection method

Abstract

To provide a technique capable of suppressing a power loss of an irradiation device and adjusting the quantity of light over a wide range and with accuracy when inspecting a substrate.SOLUTION: An inspection device includes: a mount base on which a substrate is mounted; an irradiation device which irradiates the substrate mounted on the mount base with inspection light; and a tester for inspecting the substrate which receives the inspection light. The irradiation device comprises: a light-emitting part to which a plurality of LED is connected; a stationary power source part which outputs power to be supplied to the light-emitting part; and a constant current part which is provided between the light-emitting part and the stationary power source part. The stationary power source part includes a plurality of switching power sources for performing switching using a resonant phenomenon. A first constant current source to which power of the plurality of switching power sources is inputted and which adjusts a current for each first resolution and a second constant current source to which power of the plurality of switching power sources is inputted and which adjusts a current for each second resolution smaller than a first resolution, are connected in parallel in the constant current part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an inspection apparatus and an inspection method. [Background technology]

[0002] In the inspection of a substrate having multiple image sensors, the substrate is irradiated with inspection light from a light-emitting unit formed by multiple LEDs to determine whether or not there is a defect in each pixel of the image sensor. In recent years, for reasons such as improving the S / N ratio and reducing power consumption, the development of inspection devices equipped with a light-emitting unit on the mounting table on which the substrate is placed has been progressing. For example, Patent Document 1 discloses an inspection device equipped with a light irradiation mechanism (irradiation device) that irradiates a substrate having multiple image sensors with inspection light from the mounting table side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-106491 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for reducing power loss in an irradiation device and adjusting the amount of light over a wide range with high precision when inspecting a substrate. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided an inspection apparatus for inspecting a substrate, the inspection apparatus including: a mounting table for mounting the substrate; an irradiation device provided on the mounting table and irradiating inspection light onto the substrate placed on the mounting table; and a tester for inspecting the substrate that receives the inspection light, wherein the irradiation device includes a light-emitting unit connected to a plurality of LEDs; a fixed power supply unit that outputs power to be supplied to the light-emitting unit; and a constant current unit provided between the light-emitting unit and the fixed power supply unit and adjusting the amount of current based on the voltage input from the fixed power supply unit and supplying the current to the light-emitting unit, wherein the fixed power supply unit has a plurality of switching power supplies that perform switching using a resonance phenomenon, and the constant current unit has a first constant current source that receives power from the plurality of switching power supplies and adjusts the current to be supplied to the light-emitting unit for a first resolution, and a second constant current source that receives power from the plurality of switching power supplies and adjusts the current to be supplied to the light-emitting unit for a second resolution smaller than the first resolution, connected in parallel. [Effects of the Invention]

[0006] According to one aspect, in inspecting a substrate, it is possible to suppress power loss of an irradiation device and adjust the amount of light over a wide range with high precision. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic vertical cross-sectional view showing the configuration of an inspection device according to an embodiment. [Figure 2] FIG. 2 is a schematic explanatory diagram showing the configuration of a mounting table and an irradiation device. [Figure 3] FIG. 2 is an explanatory diagram illustrating a schematic configuration of a supply circuit of the irradiation device. [Figure 4] 1 is a diagram illustrating the configuration and operation of a switching power supply; [Figure 5] FIG. 2 is a block diagram showing functional blocks of a control body that controls the irradiation device. [Figure 6] 1 is a flowchart illustrating an inspection method according to an embodiment. [Figure 7] FIG. 10 is an explanatory diagram schematically illustrating a supply circuit of an irradiation device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0009] FIG. 1 is a schematic vertical cross-sectional view showing the configuration of an inspection apparatus 1 according to one embodiment. As shown in FIG. 1, the inspection apparatus 1 according to one embodiment performs optical inspection on a substrate having a plurality of image sensors (not shown), which is a device to be inspected. The image sensor of the device to be inspected may be, for example, a CMOS (Complementary Metal Oxide Semiconductor) sensor. The substrate is formed in a perfect circle shape in a plan view, and has a plurality of image sensors arranged in a matrix (hereinafter, the substrate will also be referred to as a wafer W). Note that the substrate is not limited to a wafer W having a plurality of image sensors, and may be a carrier on which image sensors are arranged, a single chip, an electronic circuit board, or the like.

[0010] Each image sensor has a number of pixels corresponding to the resolution, and each pixel has a layered structure in which an on-chip lens, a color filter, a photodiode, and a wiring layer are layered in this order. In other words, the image sensor is configured as a back-illuminated imaging semiconductor device in which a photodiode is arranged on the on-chip lens (incident) side. The wiring layer of the image sensor has a number of wires that input and output electrical signals to and from the circuit elements within the image sensor.

[0011] During inspection, the inspection device 1 places the wafer W with the surface on the on-chip lens side facing the stage 40, while moving the stage 40 to bring the probes 33 into contact with the wiring in the wiring layer of each image sensor. Furthermore, the inspection device 1 irradiates the wafer W with inspection light (hereinafter referred to as inspection light) whose color, light amount (radiant intensity), angle, etc. are controlled from an irradiation device 50 on the side of the stage 40. The inspection device 1 receives the electrical signal of each image sensor at the time of this irradiation using a tester 30, and determines whether each image sensor is good or bad.

[0012] Each of the plurality of pixels may include a plurality of photodiodes for receiving light of a plurality of colors (e.g., RGB), or may include a single photodiode for receiving light of a single color. When inspecting a photodiode that receives light of a plurality of colors, the illumination device 50 may be configured to irradiate inspection light of a single color (e.g., white), or may be configured to irradiate inspection light of a plurality of colors (e.g., red, green, and blue). Hereinafter, to facilitate understanding of the invention, an illumination device 50 that irradiates inspection light of a single color will first be described.

[0013] The inspection device 1 includes a loader 10 for transporting a wafer W, a housing 20 arranged adjacent to the loader 10, a tester 30 arranged above the housing 20, a stage 40 housed within the housing 20, and a controller 80 for controlling each component of the inspection device 1.

[0014] The loader 10 removes the wafer W from a FOUP (Front Opening Unified Pod), not shown, and places the wafer W on the stage 40 that has moved within the housing 20. The loader 10 also removes the inspected wafer W from the stage 40 and stores it in the FOUP.

[0015] The housing 20 is formed into a substantially rectangular box-like shape and has an inspection space 21 therein for inspecting the wafer W. A stage 40 for transporting the wafer W is installed below the inspection space 21. In the inspection space 21, the wafer W is placed on the stage 40 from the loader 10 and moves in three dimensions (X-axis direction, Y-axis direction, and Z-axis direction) by the operation of the stage 40, and the rotation coordinate θ is adjusted.

[0016] A probe card 32 is held in the upper part of the housing 20 via an interface 31. The interface 31 has a performance board and a number of connection terminals (not shown), and is electrically connected to the tester 30 via a test head (not shown). The tester 30 is connected to a controller 80 of the inspection device 1, and inspects the wafer W under the command of the controller 80.

[0017] The probe card 32 has a plurality of probes 33 (probes) that protrude downward into the inspection space 21. During inspection by the inspection device 1, each probe 33 comes into contact with the wiring (including pads and solder bumps) of each image sensor on the wafer W, which has been moved to an appropriate three-dimensional coordinate position by the stage 40. In this contact state, the inspection device 1 performs an optical inspection of each image sensor. Furthermore, the controller 80 inspects all image sensors by moving the stage 40 in the X-axis, Y-axis, and Z-axis directions to shift its position on the wafer W, and then rotating it by θ, thereby repeating the inspection of each image sensor in sequence.

[0018] The stage 40 includes a moving unit 41 (X-axis moving mechanism 42, Y-axis moving mechanism 43, Z-axis moving mechanism 44) that is movable in the X-axis, Y-axis, and Z-axis directions, a mounting table 45, and a stage control unit 49. The housing 20 includes a frame structure 22 that supports the moving unit 41 and mounting table 45 of the stage 40, and the stage control unit 49 in two levels, one above the other. The moving unit 41 moves the mounting table 45 in the X-axis, Y-axis, and Z-axis directions based on power supply from the stage control unit 49. In addition to moving the mounting table 45 in the X-axis, Y-axis, and Z-axis directions, the moving unit 41 is also configured to rotate the mounting table 45 around an axis (the θ direction).

[0019] The mounting table 45 is a device on which the wafer W is directly placed, and holds the wafer W on a mounting surface 45s by an appropriate holding means. An example of the holding means is a suction device 46 that vacuum-sucks the wafer W onto the mounting surface 45s. The mounting table 45 further includes an irradiation device 50 that irradiates the wafer W with inspection light. The configurations of the mounting table 45 and the irradiation device 50 will be described in detail later.

[0020] The stage control unit 49 is connected to the controller 80 and controls the operation of the stage 40 based on commands from the controller 80. The stage control unit 49 includes, for example, an integrated control unit that controls the operation of the entire stage 40, a PLC or motor driver that controls the operation of the moving unit 41, a power supply unit, etc. (all not shown).

[0021] The controller 80 has a control body 81 that controls the entire inspection device 1, and a user interface 85 that is connected to the control body 81. The control body 81 is configured by a computer, a control circuit board, and the like.

[0022] For example, the control unit 81 has a processor 82, a memory 83, an input / output interface (not shown), and an electronic circuit. The processor 82 is a combination of one or more of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), a circuit made up of multiple discrete semiconductors, etc. The memory 83 is an appropriate combination of volatile memory and non-volatile memory (for example, a compact disc, a DVD (Digital Versatile Disc), a hard disk, a flash memory, etc.).

[0023] On the other hand, the user interface 85 may be a keyboard that allows the user to input commands, or a display that visualizes and displays the operating status of the inspection device 1. Alternatively, the user interface 85 may be a touch panel, a mouse, a microphone, a speaker, or other devices.

[0024] Next, the mounting table 45 that supports the wafer W and the irradiation device 50 that irradiates the wafer W with inspection light will be described with reference to Fig. 2. Fig. 2 is a schematic explanatory diagram showing the configuration of the mounting table 45 and the irradiation device 50, where (A) is a side cross-sectional view and (B) is a plan view.

[0025] 2(A) and 2(B), the upper part of the mounting table 45 has a layered structure of an irradiation device 50 in which a diffusion section 51 and a light guide section 52 are layered in this order vertically downward from a mounting surface 45s of the wafer W. The layered structure of the diffusion section 51 and the light guide section 52 is formed in a square shape larger than the diameter of the wafer W in a plan view. The layered structure is installed on the upper surface of a table body 47 of the mounting table 45, which is fixed to a movable body 44a (see FIG. 1) of the Z-axis movement mechanism 44. A temperature control mechanism 48 is provided within the table body 47, and is composed of a flow path through which a refrigerant circulates, a heater, etc.

[0026] The diffusion unit 51 supports the wafer W and transmits and diffuses the inspection light guided from the light guide unit 52 to irradiate the wafer W. The diffusion unit 51 includes a first glass plate 511 having a mounting surface 45s on which the wafer W is placed, and a second glass plate 512 laminated below the first glass plate 511. The first glass plate 511 is made of, for example, porous glass. The second glass plate 512 is made of, for example, low-thermal expansion glass having a thermal expansion coefficient lower than that of porous glass. The lower surface of the first glass plate 511 and the upper surface of the second glass plate 512 are firmly fixed together by a glass adhesive (not shown).

[0027] The second glass plate 512 has a thickness greater than that of the first glass plate 511. A suction flow path 461 of the suction device 46 is formed inside the second glass plate 512, and vacuum-sucks the wafer W when the wafer W is placed on the stage 40. The suction flow path 461 is formed in a lattice, spiral, ring, or other shape along the surface direction (horizontal direction) of the second glass plate 512, and is open on the upper surface side.

[0028] The stage 40 has the main components of the suction device 46 disposed radially outside the second glass plate 512. Specifically, the suction device 46 includes a suction path 463 that communicates with the suction flow path 461 at the outer periphery of the second glass plate 512, a buffer tank 464 provided midway along the suction path 463, and a vacuum pump 465 provided downstream of the suction path 463.

[0029] On the other hand, the first glass plate 511 has the functions of horizontally mounting the wafer W, suctioning the wafer W, and diffusing the inspection light directed toward the wafer W. That is, the first glass plate 511 diffuses the inspection light therein, thereby illuminating the entire mounting surface 45s. The first glass plate 511 also has a plurality of through-holes 462 penetrating between the upper surface (mounting surface 45s) and the lower surface. Each through-hole 462 is connected to a suction channel 461 of the second glass plate 512 below. The suction device 46 applies an appropriate negative pressure to each through-hole 462 via the suction channel 463 and the suction channel 461 by operating the vacuum pump 465 under the control of the controller 80 (see FIG. 1). This allows the stage 40 to suction the wafer W onto the mounting surface 45s and transport the wafer W without misalignment.

[0030] The means by which the stage 40 holds the wafer W is not limited to the above and may have various configurations. For example, the stage 40 may be provided with a misalignment prevention member (not shown) such as an O-ring to prevent the wafer W from being misaligned relative to the mounting surface 45s. The stage 40 may also be provided with a clamp (not shown) to hold the outer periphery of the wafer W. The stage 40 may also be provided with a convex portion (not shown) on the outer periphery of the mounting surface 45s to support the wafer W, and a microlens array (not shown) radially inward of the convex portion. A protective coating (not shown) to protect the on-chip lenses of each image sensor on the wafer W may also be formed on the upper surface of the first glass plate 511 of the stage 40.

[0031] The light guide unit 52 includes a light guide plate 521 that guides the inspection light emitted from the radially outer side to the inside and diffuses the inspection light to allow the entire plate surface to emit light, and a reflective layer 522 that is laminated on the lower surface (the surface opposite the diffusing unit 51) of the light guide plate 521. For example, the light guide plate 521 is formed of a glass plate containing appropriate impurities. The reflective layer 522 reflects the inspection light directed downward from the light guide unit 52 to the upper surface side.

[0032] The irradiation device 50 includes a light-emitting frame 53 into which the four side edges of the light-guiding unit 52 are inserted and which is formed to surround each side edge. As shown in FIG. 2(B), the light-emitting frame 53 is configured to emit inspection light from all four directions (all around) to each side edge of the light-guiding unit 52.

[0033] A circuit board 56 is provided inside the light-emitting frame 53 on each side of the light-emitting frame 53, and an LED module 55 (LED array) having an array of multiple LEDs 54 is mounted on each circuit board 56. In other words, the irradiation device 50 has four circuit boards 56 arranged along the circumferential direction of the light-emitting frame 53. Each circuit board 56 has multiple LEDs 54 (LED modules 55) linearly arranged opposite to the side edge of the light-guiding unit 52. Furthermore, light shields 57 are provided on the upper and lower surfaces of the side edge of the light-guiding unit 52 near the inside of the light-emitting frame 53, and block the inspection light emitted from each LED 54 from traveling anywhere other than the light-guiding unit 52.

[0034] The LED module 55 on each circuit board 56 functions as a light-emitting unit of the illumination device 50, which is composed of multiple LEDs 54 connected in series. The number n of LEDs 54 constituting the LED module 55 is not particularly limited, but may be, for example, in the range of 10 to 100. In this case, the illumination device 50 needs to output a forward voltage of n × Vf from the power supply to the LED module 55. Furthermore, each LED 54 is a current-controlled element, and the amount of light (radiant intensity) is proportional to the current. In image sensor testing, in order for the light-emitting unit to output a target amount of light (e.g., 0.1 Lux to 100,000 Lux), it is necessary to be able to supply a current ranging from low to high, and to precisely adjust the current. However, if a hard-switching power supply that simply switches between high current and high voltage is used as the power supply to supply power to the LED module 55, power loss will be significant.

[0035] Therefore, the irradiation device 50 according to this embodiment realizes appropriate control of voltage and current while suppressing power loss by using a supply circuit 60 that supplies power to the LED module 55. Next, the supply circuit 60 of the irradiation device 50 will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram that schematically shows the configuration of the supply circuit 60 of the irradiation device 50.

[0036] The supply circuit 60 includes an LED module 55, a fixed power supply unit 61 that is the power source for the LED module 55, and a constant current unit 70 that is provided between the LED module 55 and the fixed power supply unit 61 and adjusts the amount of current. The fixed power supply unit 61 is installed, for example, to the side of or inside the moving unit 41 or inside the stage control unit 49, and supplies power to each circuit board 56 of the light-emitting frame 53. The constant current unit 70 is provided, for example, on each circuit board 56.

[0037] The fixed power supply unit 61 employs a low-noise switching power supply 62 (soft switching power supply) to reduce switching power loss. The fixed power supply unit 61 is configured with two switching power supplies 62 connected in series. Specifically, the two switching power supplies 62 are a forward voltage switching power supply 62A that supplies a forward voltage (n×Vf) to the constant current unit 70, and a control switching power supply 62B that supplies a current control voltage Vval to the constant current unit 70.

[0038] FIG. 4 illustrates the configuration and operation of a switching power supply 62, with (A) being a circuit diagram and (B) and (C) being waveform diagrams at turn-off. As shown in FIG. 4(A), each switching power supply 62 employs a ZVS (Zero Voltage Switching) circuit structure, which performs switching when the voltage is zero. Each switching power supply 62 is configured as an LC resonant circuit in which a capacitor 64 is connected in parallel to each of two switching elements 63 (e.g., MOSFETs), and the load (constant current unit 70) serves as inductance. Specifically, each switching power supply 62 includes two power supplies 65A and 65B forming a bridge configuration and two switching elements 63A and 63B. Each switching power supply 62 has a capacitor 64A and a diode 66A connected in parallel to the switching element 63A, and a capacitor 64B and a diode 66B connected in parallel to the switching element 63B.

[0039] In the case of a hard-switched power supply that does not include a capacitor 64 in the switching element 63, as shown in FIG. 4B, a large power loss occurs when the current is turned off (the period during which the current and voltage are switched). On the other hand, in each switching power supply 62 shown in FIG. 4A, for example, when the switching element 63B is turned off, the current flowing through the switching element 63B is commutated to the capacitor 64B, and the voltage of the capacitor 64B gradually increases. Therefore, as shown in FIG. 4C, the slope of the voltage increase slows according to the capacitance of the capacitor 64B, thereby reducing power loss. On the other hand, when the switching element 63A is turned off, the charge in the capacitor 64B flows through the constant current unit 70. When the switching element 63B is turned on at this time, the voltage of the on-state switching element 63B becomes approximately 0 V, thereby enabling soft switching.

[0040] Returning to FIG. 3, the two switching power supplies 62 (forward voltage switching power supply 62A and control switching power supply 62B) output different voltages. Forward voltage switching power supply 62A outputs a voltage corresponding to the forward voltage Vf of each LED 54 constituting LED module 55 and the number n of LEDs, i.e., a constant voltage of Vf×n. For example, if the forward voltage Vf of each white light LED 54 is 2.7V and the number n of LEDs 54 is 10, forward voltage switching power supply 62A outputs a voltage close to 27V (=10×2.7). In other words, forward voltage switching power supply 62A performs on / off duty control by soft switching so that the voltage becomes approximately 27V.

[0041] On the other hand, control switching power supply 62B outputs a constant voltage for current control in constant current unit 70. The voltage output by control switching power supply 62B depends on the characteristics and number n of each LED 54 and the configuration of constant current unit 70, but is set to, for example, about 0.5 V for each LED 54. Therefore, if the number n of each LED 54 is 10, control switching power supply 62B outputs a voltage that is close to 5 V (= 10 × 0.5 V). In other words, control switching power supply 62B performs on / off duty control by soft switching so that the voltage becomes approximately 5 V.

[0042] Here, each switching power supply 62 utilizes the voltage-current resonance phenomenon to reduce power loss and improve efficiency, but it cannot significantly change the on / off duty of the current. This makes it difficult to widen the current range for adjusting the light intensity of each LED 54. For this reason, the illumination device 50 according to this embodiment is configured to linearly adjust the amount of current supplied to the LED module 55 by applying a dropper circuit to the constant current unit 70 provided between the fixed power supply unit 61 and the LED module 55. In particular, the constant current unit 70 according to this embodiment uses two constant current sources (large constant current source 71A and small constant current source 71B) formed by dropper circuits, thereby enabling wide-ranging and detailed adjustment of the amount of current supplied to each LED 54.

[0043] Although not specifically shown, the dropper circuits constituting each constant current source of the constant current unit 70 are configured by appropriately combining transistors (including MOSFETs), operational amplifiers, resistors, etc. Each constant current source of the constant current unit 70 may be an IC chip incorporating elements and wiring of the dropper circuit, or may be configured by wiring various discrete devices on the circuit board 56.

[0044] For example, the dropper circuit causes the operational amplifier to function as an error amplifier (reference amplifier), and receives the voltage of forward voltage switching power supply 62A as a reference voltage and the voltage of control switching power supply 62B as an input voltage. The output of the operational amplifier is connected to the base of a transistor, which functions as a control element that divides the input voltage. The dropper circuit is also connected to controller 80 via D / A converter 72, and changes the voltage division ratio of the input voltage (e.g., resistance value) in accordance with a command (current command) from controller 80 to adjust the amount of current output from the dropper circuit.

[0045] In principle, the dropper circuit configured in this manner does not generate switching noise, but heat is generated when the transistor, which is the control element, divides the input voltage. However, as described above, the input voltage of the dropper circuit is the voltage of the control switching power supply 62B, so heat generation by the transistor is suppressed compared to the voltage of the forward voltage switching power supply 62A. As a result, the irradiation device 50 can significantly reduce power loss in the constant current unit 70.

[0046] For example, when each LED 54 is white, as described above, the voltage of the forward voltage switching power supply 62A is 27 V and the voltage of the control switching power supply 62B is 5 V. Therefore, the irradiation device 50 can reduce the power loss of the constant current unit 70 to 1 / 5 or less compared to when the fixed power supply unit 61 is configured with a single power supply.

[0047] The constant current unit 70 is configured by connecting a large constant current source 71A and a small constant current source 71B, which have different resolutions, in parallel with the LED module 55. For example, the large constant current source 71A is configured to be able to adjust the current output from the large constant current source 71A with a resolution of 100 mA (100 mA or more). That is, the large constant current source 71A adjusts the current amount in 100 mA increments based on a current command from the controller 80 received via the D / A converter 72A. On the other hand, the small constant current source 71B is configured to be able to adjust the current output from the small constant current source 71B with a resolution of 1 mA (less than 100 mA). That is, the small constant current source 71B adjusts the current amount in 1 mA increments based on a current command from the controller 80 received via the D / A converter 72B.

[0048] As a result, by combining the large constant current source 71A and the small constant current source 71B, the constant current unit 70 can output a wide range of current amounts to the LED module 55. Specifically, the controller 80 determines a large constant current distribution that adjusts the current amount largely (coarsely) and a small constant current distribution that adjusts the current amount little (finely), and outputs current commands to each of the large constant current source 71A and the small constant current source 71B. As a result, the constant current unit 70 supplies to the LED module 55 the current amount that is the sum of the current amount adjusted by the large constant current source 71A (distribution for large constant current) and the current amount adjusted by the small constant current source 71B (distribution for small constant current).

[0049] As an example, when a current of 1.234 A is to be supplied to the LED module 55, the controller 80 causes the large constant current source 71A to output a current of 1.2 A and the small constant current source 71B to output a current of 0.034 A. By allocating the current in this manner, the irradiation device 50 can precisely adjust the current amount in the constant current unit 70 over a wide range.

[0050] The supply circuit 60 also includes a resistor 58 connected in series to the LED module 55, and the controller 80 reads the actual current flowing through the resistor 58 via an A / D converter 59. In other words, the supply circuit 60 functions as an ammeter that measures the actual current supplied to the LED module 55. For example, the controller 80 can accurately adjust the amount of current supplied to the LED module 55 (in other words, the target light intensity of the inspection light) by feeding back the actual current obtained from the resistor 58 when adjusting the amount of current.

[0051] The components of supply circuit 60 (forward voltage switching power supply 62A, control switching power supply 62B, D / A converter 72A, D / A converter 72B, A / D converter 59) and controller 80 are configured to be able to send and receive signals via a serial bus 84. The controller 80 constructs functional blocks as shown in FIG. 5 by having a processor 82 execute a program stored in a memory 83, and controls the operation of irradiation device 50 when inspecting a wafer W. FIG. 5 is a block diagram showing the functional blocks of a control body 81 that controls irradiation device 50.

[0052] Specifically, inside the control body 81, a light amount setting section 91, a current acquisition section 92, a fixed power supply control section 93, and a constant current control section 94 are formed.

[0053] The light intensity setting unit 91 sets the light intensity (radiant intensity) of the inspection light emitted from the plurality of LED modules 55 provided in the light-emitting frame 53 based on the inspection details (recipe) of the wafer W. The light intensity of the inspection light may be set by the user via the user interface 85 (see FIG. 1).

[0054] The current acquisition unit 92 acquires the actual current supplied to each LED module 55 via the resistor 58 and the A / D converter 59 provided in the supply circuit 60 , and outputs the acquired actual current to the constant current control unit 94 .

[0055] The fixed power supply control unit 93 controls the power output timing and switching of each switching power supply 62 (forward voltage switching power supply 62A, control switching power supply 62B). As described above, the irradiation device 50 according to this embodiment adjusts the amount of current in the constant current unit 70. Therefore, the fixed power supply control unit 93 switches the forward voltage Vf×n corresponding to the LED module 55 in the forward voltage switching power supply 62A, without depending on the control of the amount of current supplied to the LED module 55. Furthermore, the fixed power supply control unit 93 switches the current control voltage Vval output to the constant current unit 70 in the control switching power supply 62B, without depending on the control of the amount of current supplied to the LED module 55.

[0056] The constant current control unit 94 calculates the amount of current to be supplied to each LED module 55 based on the light intensity set by the light intensity setting unit 91, and controls the operation of the constant current unit 70 based on the calculated amount of current. To this end, the constant current control unit 94 internally includes a current intensity calculation unit 95, an allocation calculation unit 96, a large constant current control unit 97, and a small constant current control unit 98.

[0057] The current amount calculation unit 95 calculates the amount of current to be supplied to each LED module 55 from the amount of inspection light set by the light amount setting unit 91. For example, the current amount calculation unit 95 stores in advance in memory 83 map information correlating the amount of inspection light with the amount of current, and upon receiving the amount of inspection light from the light amount setting unit 91, the current amount calculation unit 95 refers to the map information to extract the amount of current corresponding to the light amount. Alternatively, the current amount calculation unit 95 may have a function correlating the amount of inspection light with the amount of current, and may calculate the amount of current using the amount of inspection light and the predetermined function.

[0058] The allocation calculation unit 96 appropriately allocates the amount of current supplied from the large constant current source 71A to the LED module 55 and the amount of current supplied from the small constant current source 71B to the LED module 55 based on the amount of current calculated by the current amount calculation unit 95. As described above, the allocation calculation unit 96 allocates the calculated amount of current equal to or greater than 100 mA so that the amount of current is adjusted by the large constant current source 71A, and allocates the calculated amount of current less than 100 mA so that the amount of current is adjusted by the small constant current source 71B.

[0059] The large constant current control unit 97 then commands the large constant current source 71A, via the D / A converter 72A, the amount of current allocated by the allocation calculation unit 96, to the large constant current source 71A. The dropper circuit of the large constant current source 71A adjusts the amount of current based on the current command and supplies it to the LED module 55. Similarly, the small constant current control unit 98 commands the small constant current source 71B, via the D / A converter 72B, the amount of current allocated by the allocation calculation unit 96 to the small constant current source 71B. The dropper circuit of the small constant current source 71B adjusts the amount of current based on the current command and supplies it to the LED module 55.

[0060] Furthermore, the constant current control unit 94 outputs a current command so that the actual current matches the target current amount by adjusting the current amount to be commanded to the large constant current source 71A and the small constant current source 71B using the actual current acquired by the current acquisition unit 92. This allows the control body 81 to more accurately control the amount of inspection light irradiated by the irradiation device 50.

[0061] The inspection device 1 according to this embodiment is basically configured as described above, and its operation (inspection method) will be described below. Fig. 6 is a flowchart showing the inspection method according to one embodiment.

[0062] 6, in inspecting the wafer W, the controller 80 of the inspection apparatus 1 first places the wafer W from the loader 10 onto the stage 40 (step S1). When placing the wafer W on the stage 40, the controller 80 drives the suction device 46 to suction the wafer W onto the placement surface 45s.

[0063] Next, the controller 80 moves the stage 40 horizontally to bring each image sensor to be inspected on the wafer W facing each probe 33, and then raises the stage 40 to bring each probe 33 into contact with the wiring layer of each image sensor (step S2). After each probe 33 has contacted, the inspection device 1 transmits an operation command from the controller 80 to the tester 30 and the irradiation device 50 to start the optical inspection of each image sensor. For example, the tester 30 outputs a bias voltage to each image sensor via each probe 33, activating each image sensor.

[0064] Then, in the optical inspection, the controller 80 emits a set amount of inspection light from the light-emitting frame 53 to the light-guiding unit 52 (step S3). As shown in FIG. 2A, the inspection light that has entered the four side edges of the light-guiding unit 52 from the light-emitting frame 53 travels through the light-guiding unit 52 while being diffused, and is directed from the entire plate surface of the light-guiding unit 52 toward the diffusion unit 51. Furthermore, the inspection light is diffused and transmitted through the diffusion unit 51, and is received by each pixel (photodiode) of each image sensor of the wafer W through the mounting surface 45s.

[0065] Here, the irradiation device 50 can emit inspection light with an amount of light appropriately adjusted by the supply circuit 60. Specifically, as shown in Fig. 5 , the fixed power supply control unit 93 operates the forward voltage switching power supply 62A and the control switching power supply 62B, so that the fixed power supply unit 61 outputs a forward voltage Vf×n and a current control voltage Vval that are synchronized with each other to the constant current unit 70.

[0066] At this time, each switching power supply 62 (forward voltage switching power supply 62A, control switching power supply 62B) performs soft switching as described above (see also FIG. 4). This allows the fixed power supply unit 61 to suppress power loss due to switching and reduce noise in the output power. The forward voltage switching power supply 62A can output a substantially constant forward voltage Vf×n to the large constant current source 71A and the small constant current source 71B. The control switching power supply 62B can output a substantially constant current control voltage Vval to the large constant current source 71A and the small constant current source 71B.

[0067] On the other hand, a light intensity setting unit 91 sets the intensity of inspection light based on a recipe for optical inspection. A constant current control unit 94 outputs current commands to each of the large constant current source 71A and the small constant current source 71B based on the set intensity of inspection light and the actual current acquired by a current acquisition unit 92.

[0068] As shown in Figure 3, large constant current source 71A receives a current command via D / A converter 72A and outputs a current amount allocated by the current command based on the input forward voltage Vfxn and current control voltage Vval. Similarly, small constant current source 71B receives a current command via D / A converter 72B and outputs a current amount allocated by the current command based on the input forward voltage Vfxn and current control voltage Vval. As described above, the control elements of large constant current source 71A and small constant current source 71B generate heat in response to the current control voltage Vval, but the amount of heat generated is kept low because the voltage is low. As a result, power loss in constant current unit 70 can be reduced.

[0069] The constant current unit 70 applies two systems, a large constant current source 71A and a small constant current source 71B, thereby enabling wide-ranging and detailed control of the amount of current supplied to the LED module 55. This allows the supply circuit 60 to emit test light of a target intensity from each LED 54 of the LED module 55 with high reproducibility.

[0070] 6, the tester 30 of the inspection device 1 acquires an electrical signal corresponding to the amount of inspection light from the irradiation device 50 from each image sensor on the wafer W via the probe 33 and the probe card 32, and determines whether each image sensor is good or bad (step S4). Specifically, the tester 30 inspects the presence or absence of defects in each pixel of each image sensor based on the acquired electrical signal.

[0071] Optical inspection of the image sensor is performed by changing the intensity of inspection light from the irradiation device 50 multiple times. At this time, the constant current control unit 94 appropriately changes the amount of current output from the constant current unit 70 by changing the current command for the large constant current source 71A and the small constant current source 71B based on the allocation calculated by the allocation calculation unit 96. The constant current unit 70 precisely adjusts the amount of current by combining the large constant current source 71A and the small constant current source 71B, thereby enabling the intensity of the inspection light to accurately match the changed target light intensity.

[0072] After optical inspection of the current image sensor, controller 80 determines whether optical inspection has been performed on all of the multiple image sensors on wafer W (step S5). If there are image sensors that have not yet been inspected, the process returns to step S2, moves stage 40 to bring the uninspected image sensors into contact with probe 33, and then repeats the operations of steps S3 and S4. On the other hand, if inspection of all of the multiple image sensors on wafer W has been completed, the process proceeds to step S6.

[0073] In step S6, the stage 40 is moved and the inspected wafer W is removed from the stage 40 by the loader 10, thereby completing the current inspection.

[0074] By performing the above inspection method, the inspection device 1 can stably irradiate the wafer W with a target amount of inspection light while reducing power loss and noise in the irradiation device 50. This enables the inspection device 1 to inspect each image sensor of the wafer W with high precision and speed. Therefore, for example, the inspection device 1 can prevent inconveniences such as overlooking defects in each pixel of the image sensor during inspection.

[0075] The configuration of the inspection device 1 is not limited to the above embodiment, and various modifications are possible. For example, the irradiation device 50 is an edge type in which the LED module 55 is provided in the light-emitting frame 53 on the side of the mounting table 45, but it may also be a direct type in which the LED module 55 is provided in the mounting table 45 in the stacking direction of the mounting surface 45s. Furthermore, the irradiation device 50 according to the above embodiment is configured to irradiate a single color (white) inspection light, but is not limited to this, and may also be configured to irradiate inspection light of multiple colors (for example, for each of RGB).

[0076] 7 is an explanatory diagram schematically illustrating a supply circuit 60A of an illumination device 50A according to a modified example. As shown in FIG. 7, the illumination device 50A, which irradiates inspection light for each of RGB, forms a supply circuit 60A for irradiating the inspection light for each of the plurality of circuit boards 56 (see FIG. 2(B)) provided in the light-emitting frame 53. The supply circuit 60A includes an LED module 55R including a plurality of red LEDs 54R, an LED module 55G including a plurality of green LEDs 54G, and an LED module 55B including a plurality of blue LEDs 54B, on each circuit board 56. The LED modules 55R, 55G, and 55B may be arranged to extend linearly along the extension direction of the side edge of the light-guiding section 52 and to be parallel to each other.

[0077] Supply circuit 60A includes a fixed power supply unit 61R and a constant current unit 70R that supply power to LED module 55R, a fixed power supply unit 61G and a constant current unit 70G that supply power to LED module 55G, and a fixed power supply unit 61B and a constant current unit 70B that supply power to LED module 55B. Each of fixed power supply units 61R, 61G, and 61B is configured with a forward voltage switching power supply 62A and a control switching power supply 62B, similar to fixed power supply unit 61 in Fig. 3. Each of constant current units 70R, 70G, and 70B is configured with a large constant current source 71A and a small constant current source 71B, similar to constant current unit 70 shown in Fig. 3.

[0078] Here, the forward voltage Vf of the red LED 54R may be lower than the forward voltages Vf of the green LED 54G and the blue LED 54B, and may be, for example, 1.8 V. Therefore, when the LED module 55R has ten red LEDs 54, the forward voltage switching power supply 62A of the fixed power supply unit 61R supplies a forward voltage Vf×n of 18 V. Therefore, the voltage (e.g., 5 V) of the control switching power supply 62B supplied to the constant current unit 70 is set to a ratio of 5 / 18 (i.e., 1 / 3 or less) of the voltage of the forward voltage switching power supply 62A. Even in this case, heat generation in the control element of the constant current unit 70 is sufficiently suppressed, and power loss can be reduced.

[0079] The supply circuit 60A configured as described above can precisely adjust the light intensity of each of the RGB inspection lights and emit light while suppressing power loss, noise, etc. Therefore, the inspection device 1 can perform inspection with high precision and efficiency even when inspecting each image sensor of the wafer W using inspection lights of multiple colors.

[0080] The technical ideas and effects of the present disclosure explained in the above embodiments will be described below.

[0081] A first aspect of the present disclosure is an inspection apparatus 1 for inspecting a substrate (wafer W), including a mounting table 45 for mounting the substrate, an irradiation device 50 provided on the mounting table 45 and irradiating the substrate mounted on the mounting table 45 with inspection light, and a tester 30 for inspecting the substrate that has received the inspection light, wherein the irradiation device 50 includes a light-emitting unit (LED module 55) to which a plurality of LEDs 54 are connected, a fixed power supply unit 61 that outputs power to be supplied to the light-emitting unit, and a tester 30 provided between the light-emitting unit and the fixed power supply unit 61 and irradiating a current based on a voltage input from the fixed power supply unit 61. and a constant current unit 70 that adjusts the amount of current to be supplied to the light-emitting unit and supplies it to the light-emitting unit, and the fixed power supply unit 61 has a plurality of switching power supplies 62 that perform switching using a resonance phenomenon, and the constant current unit 70 has a first constant current source (large constant current source 71A) that receives power from the plurality of switching power supplies 62 and adjusts the current to be supplied to the light-emitting unit for each first resolution, and a second constant current source (small constant current source 71B) that receives power from the plurality of switching power supplies 62 and adjusts the current to be supplied to the light-emitting unit for each second resolution that is smaller than the first resolution, connected in parallel.

[0082] As described above, the inspection device 1 can significantly reduce switching power loss by applying the switching power supply 62 using the resonance phenomenon to the fixed power supply unit 61. Moreover, the inspection device 1 can adjust the amount of irradiated light over a wide range and with high precision by providing the constant current unit 70 with a first constant current source (large constant current source 71A) that adjusts the current for each first resolution and a second constant current source (small constant current source 71B) that adjusts the current for each second resolution. This allows the inspection device 1 to properly inspect substrates (wafers W), and can promote improvements in the precision and efficiency of substrate inspection.

[0083] The fixed power supply unit 61 also has, as the multiple switching power supplies 62, a forward voltage switching power supply 62A that outputs a voltage that approximates the sum of the forward voltages of the multiple LEDs 54, and a control switching power supply 62B that outputs a voltage for current control of the first constant current source (large constant current source 71A) and the second constant current source (small constant current source 71B). This allows the inspection device 1 to output a constant forward voltage and current control voltage in the fixed power supply unit 61 while suppressing power loss and noise, and to stably adjust the current in the constant current unit 70.

[0084] Furthermore, the voltage output by the control switching power supply 62B is set to ⅓ or less of the voltage output by the forward voltage switching power supply 62A, which allows the inspection device 1 to adjust the current while minimizing heat generation in the control element of the constant current unit 70.

[0085] Furthermore, the first constant current source (large constant current source 71A) can adjust the current in units of 100 mA or more as a first resolution, and the second constant current source (small constant current source 71B) can adjust the current in units of less than 100 mA as a second resolution, which allows the inspection device to adjust the light intensity of the light-emitting element over a wider range and in more detail.

[0086] The inspection device 1 also has a control unit (controller 80) that controls the irradiation device 50. The control unit is communicatively connected to each of the first constant current source (large constant current source 71A) and the second constant current source (small constant current source 71B) via D / A converters 72A and 72B, and the first constant current source and the second constant current source adjust their currents in accordance with current commands output from the control unit. This allows the inspection device 1 to easily adjust the currents in the first constant current source and the second constant current source based on the control of the control unit.

[0087] Furthermore, the control unit (controller 80) calculates the total amount of current to be supplied to the light-emitting units (LED modules 55) based on the light intensity of the light-emitting units set for inspecting the substrate (wafer W), and sets the distribution of the amount of current to be output from the first constant current source (large constant current source 71A) and the amount of current to be output from the second constant current source (small constant current source 71B) from the total amount of current. This allows the inspection device 1 to appropriately distribute the adjustment of the current in the first constant current source and the second constant current source.

[0088] The light-emitting unit (LED module 55) also has a resistor 58 connected in series, and the control unit (controller 80) acquires the actual current flowing through the resistor 58 via an A / D converter 59 and adjusts the overall current amount based on the acquired actual current. This allows the inspection device 1 to adjust the current based on the actual current actually flowing through the light-emitting unit, making it possible to satisfactorily reproduce the light intensity of the irradiation device 50 to the target light intensity.

[0089] Furthermore, the irradiation device 50 can emit light of different colors for each of the plurality of light-emitting units (LED modules 55), and each of the plurality of light-emitting units has a fixed power supply unit 61 and a constant current unit 70. This allows the inspection device 1 to suppress power loss and easily and accurately irradiate inspection light of the target light intensity, even when inspecting a plurality of types of colors.

[0090] Moreover, the irradiation device 50 includes a light guide section 52 facing the mounting surface 45s of the mounting table 45, and a frame (light-emitting frame 53) that surrounds the entire side edge of the light guide section 52, and includes a circuit board 56 inside the frame that has a light-emitting section (LED module 55) and a constant current section 70. This allows the inspection device 1 to irradiate the entire light guide section 52 with inspection light from the surrounding frame, and to allow a target amount of inspection light to enter the substrate (wafer W).

[0091] A second aspect of the present disclosure is an inspection method for an inspection device that inspects a substrate (wafer W), including the steps of (a) placing the substrate on a mounting table 45, (b) irradiating the substrate placed on the mounting table 45 with inspection light using an irradiation device 50 provided on the mounting table 45, and (c) inspecting the substrate that has received the inspection light using a tester 30, wherein in the step (b), power is output from a fixed power supply unit 61 having a plurality of switching power supplies 62 that perform switching using a resonance phenomenon to be supplied to a light-emitting unit (LED module 55) to which a plurality of LEDs 54 are connected, A constant current unit 70 provided between the light-emitting unit and fixed power supply unit 61 supplies a current adjusted based on a voltage input from the fixed power supply unit 61 to the light-emitting unit, and the constant current unit 70 has a first constant current source (large constant current source 71A) and a second constant current source (small constant current source 71B) connected in parallel, and the first constant current source receives power from multiple switching power supplies 62 to adjust the current supplied to the light-emitting unit for each first resolution, while the second constant current source receives power from multiple switching power supplies 62 to adjust the current supplied to the light-emitting unit for each second resolution smaller than the first resolution. Even in this case, the inspection method can reduce power loss in the irradiation device 50 and adjust the light intensity over a wide range and with high precision when inspecting a board.

[0092] In addition, in this description, control switching power supply 62B is shared by large constant current source 71A and small constant current source 71B, but in order to improve power supply efficiency, control switching power supply 62B may be divided into one for large constant current source 71A and one for small constant current source 71B.

[0093] The inspection device 1 and inspection method according to the presently disclosed embodiments are illustrative in all respects and are not limiting. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The matters described in the above-described embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent. [Explanation of symbols]

[0094] 1. Inspection equipment 30 Tester 45 Mounting table 50 Irradiation device 54 LED 55 LED modules 61 Fixed power supply section 62 Switching Power Supply 70 Constant current section 71A large constant current source 71B Small constant current source W wafer

Claims

1. An inspection device for inspecting a substrate, a mounting table on which the substrate is placed; an irradiation device provided on the mounting table and configured to irradiate the substrate placed on the mounting table with inspection light; a tester that inspects the substrate that has received the inspection light, The irradiation device is a light emitting unit to which a plurality of LEDs are connected; a fixed power supply unit that outputs power to be supplied to the light-emitting unit; a constant current unit that is provided between the light-emitting unit and the fixed power supply unit and that adjusts the amount of current based on a voltage input from the fixed power supply unit and supplies the current to the light-emitting unit, the fixed power supply unit has a plurality of switching power supplies that perform switching using a resonance phenomenon, the constant current unit includes a first constant current source connected in parallel to receive power from the plurality of switching power supplies and adjust the current supplied to the light-emitting unit for each first resolution, and a second constant current source connected in parallel to receive power from the plurality of switching power supplies and adjust the current supplied to the light-emitting unit for each second resolution smaller than the first resolution; Inspection equipment.

2. The fixed power supply unit includes the plurality of switching power supplies, a forward voltage switching power supply that outputs a voltage that approximates the sum of the forward voltages of the plurality of LEDs; a control switching power supply that outputs a voltage for current control of the first constant current source and the second constant current source, The inspection device according to claim 1 .

3. the voltage output by the control switching power supply is set to 1 / 3 or less of the voltage output by the forward voltage switching power supply; The inspection device according to claim 2 .

4. the first constant current source is capable of adjusting a current in units of 100 mA or more as the first resolution; the second constant current source is capable of adjusting a current in units of less than 100 mA as the second resolution; The inspection device according to any one of claims 1 to 3.

5. a control unit for controlling the irradiation device, the control unit is communicatively connected to each of the first constant current source and the second constant current source via a D / A converter; the first constant current source and the second constant current source adjust currents in response to a current command output from the control unit. The inspection device according to any one of claims 1 to 4.

6. the control unit calculates a total amount of current to be supplied to the light-emitting unit based on the light intensity of the light-emitting unit set during inspection of the board, and sets a distribution of the amount of current to be output from the first constant current source and the amount of current to be output from the second constant current source from the total amount of current. The inspection device according to claim 5 .

7. a resistor connected in series to the light emitting unit; the control unit acquires an actual current flowing through the resistor via an A / D converter, and adjusts the total current amount based on the acquired actual current. The inspection device according to claim 6.

8. the irradiation device is capable of emitting light of different colors for each of the plurality of light-emitting units, The fixed power supply unit and the constant current unit are provided for each of the plurality of light-emitting units. The inspection device according to any one of claims 1 to 7.

9. The irradiation device is a light guide portion facing a mounting surface of the mounting table; a frame surrounding the entire side edge of the light guide portion, a circuit board having the light emitting unit and the constant current unit disposed inside the frame; The inspection device according to any one of claims 1 to 8.

10. An inspection method for an inspection device that inspects a substrate, comprising: (a) placing the substrate on a mounting table; (b) irradiating the substrate placed on the mounting table with inspection light by an irradiation device provided on the mounting table; (c) inspecting the substrate that has received the inspection light by a tester; In the step (b), a fixed power supply unit having a plurality of switching power supplies that perform switching using a resonance phenomenon outputs power to be supplied to a light-emitting unit connected to a plurality of LEDs, and a constant current unit provided between the light-emitting unit and the fixed power supply unit supplies a current adjusted based on a voltage input from the fixed power supply unit to the light-emitting unit; the constant current unit has a first constant current source and a second constant current source connected in parallel, the first constant current source receives power from the plurality of switching power supplies and adjusts the current supplied to the light-emitting unit for each first resolution, and the second constant current source receives power from the plurality of switching power supplies and adjusts the current supplied to the light-emitting unit for each second resolution smaller than the first resolution; Testing method.

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