Inspection method and inspection device

Abstract

The invention provides a technology for enabling the tip of a probe to be in high-precision contact with an electrode of an inspection object. Provided is an inspection method for inspecting an object to be inspected by bringing the tip of a probe provided on a probe card into contact with an electrode provided on the object to be inspected, the inspection method including: projecting, by a projection unit, a spot pattern in which a plurality of spots are arranged; receiving the light spot pattern by the light receiving part; an image capturing unit that captures a reference image including the spot pattern projected by the projection unit; an image capturing unit that captures a measurement image including two or more light spots in the light spot pattern received by the light receiving unit; and adjusting a stage on which the inspection object is placed on the basis of the reference image and the measurement image.

Description

Technical Field

[0001] The invention relates to an inspection method and an inspection device. Background Art

[0002] For example, the inspection device is used to inspect the electrical characteristics of the semiconductor device in the state of the semiconductor wafer before the semiconductor device is divided. The inspection device includes a probe card provided with a plurality of probes. The inspection device makes the needle tips of the probes provided on the probe card contact with the test pads (electrodes) provided on the semiconductor device, provides an electrical signal to the semiconductor device via the probe, and obtains the electrical signal output from the semiconductor device via the probe to inspect the semiconductor device. In order to make the needle tips of the probes provided on the probe card contact with the test pads provided on the semiconductor device, it is necessary to correctly adjust the relative positional relationship between the needle tips of the probes and the test pads.

[0003] For example, Patent Document 1 discloses an inspection device that determines the position of the probe tip based on an image of the probe tip captured by a camera, and adjusts the position of each probe tip based on the determined position of each probe tip.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-102640 Summary of the invention

[0005] <Problems to be Solved by the Invention>

[0006] The present invention provides a technology for bringing a needle tip of a probe into contact with an electrode of an inspection object with high precision.

[0007] <Methods used to solve the problem>

[0008] According to one aspect of the present invention, there is provided an inspection method for inspecting an inspection object by bringing a needle tip of a probe disposed on a probe card into contact with an electrode disposed on the inspection object, and the method includes the following steps: a projection unit projects a light spot pattern in which a plurality of light spots are arranged; a light receiving unit receives the light spot pattern; a reference image including the light spot pattern projected by the projection unit is captured; a measurement image including two or more light spots in the light spot pattern received by the light receiving unit is captured; and based on the reference image and the measurement image, a stage on which the inspection object is placed is adjusted.

[0009] <Effects of the Invention>

[0010] According to one aspect, the needle tip of the probe can be brought into contact with the electrode of the inspection object with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic cross-sectional view showing an example of an inspection device.

[0012] Figure 2 This is a schematic cross-sectional view showing an example of a probe camera unit.

[0013] Figure 3 This is a schematic cross-sectional view showing an example of a wafer camera unit.

[0014] Figure 4 This is a block diagram showing an example of the hardware configuration of a computer.

[0015] Figure 5 This is a block diagram showing an example of the functional configuration of the control device.

[0016] Figure 6 is a diagram showing an example of a reference image.

[0017] Figure 7 It is a diagram showing an example of a measurement image.

[0018] Figure 8 This is a diagram showing an example of a method for detecting a positional shift.

[0019] Fig. 9 This is a diagram showing an example of the relationship between the working distance and the spot pattern.

[0020] Fig.10 This is a diagram showing an example of brightness adjustment according to the working distance.

[0021] Fig.11 This is a diagram showing an example of the relationship between the optical axis deviation and the spot pattern.

[0022] Fig.12 It is a diagram showing an example of distortion correction.

[0023] Fig.13 This is a flowchart showing an example of the inspection method.

[0024] Fig.14 This is a flowchart showing an example of the stage adjustment process.

[0025] Fig.15 This is a schematic diagram showing an example of the state of the inspection device.

[0026] Fig.16 This is a schematic diagram showing an example of the state of the inspection device.

[0027] Fig.17 This is a schematic diagram showing an example of the state of the inspection device.

[0028] Fig.18 This is a schematic diagram showing an example of the state of the inspection device.

[0029] Fig.19 This is a schematic diagram showing an example of the state of the inspection device.

[0030] Fig. 20 This is a schematic diagram showing an example of the state of the inspection device. DETAILED DESCRIPTION

[0031] Hereinafter, the mode for implementing the present invention will be described with reference to the drawings. In each figure, the same components are sometimes given the same reference numerals, and repeated descriptions are omitted.

[0032] [Implementation Method]

[0033] One embodiment of the present invention is an inspection device for inspecting a semiconductor device as an example of an inspection object. In this embodiment, the inspection device inspects electrical characteristics of a semiconductor device formed on a semiconductor wafer by bringing a probe tip provided on a probe card into contact with a test pad provided on the semiconductor wafer.

[0034] Since the inspection device is preheated and inspected in a high temperature environment, the semiconductor wafer and the probe card generate slight vibrations due to thermal expansion. In addition, even if the relative positional relationship between the probe tip and the test pad is adjusted in advance, the position of the probe tip and the test pad may be offset in the end.

[0035] The inspection device in this embodiment includes two camera units, which can be moved to opposite positions so as to make the tip of the probe contact the test pad with high precision. The first camera unit projects a light spot pattern including a plurality of light spots in the direction of the second camera unit. The second camera unit receives the light spot pattern projected from the first camera unit.

[0036] The inspection device adjusts the position and posture of the stage on which the semiconductor wafer is placed based on the offset between the optical axis projected by the first camera unit and the optical axis received by the second camera unit (hereinafter also referred to as "optical axis offset"). The optical axis offset includes the position offset in the xy plane (hereinafter also referred to as "position offset") and the tilt offset relative to the z axis (hereinafter also referred to as "tilt offset"). Therefore, the inspection device can adjust the position of the stage in the xy plane and the tilt relative to the z axis based on the optical axis offset.

[0037] By using a light spot pattern including a plurality of light spots, the inspection apparatus can detect both positional displacement and tilt displacement with high accuracy. In one aspect, the inspection apparatus in the present embodiment allows the tip of the probe to contact the electrode of the inspection object with high accuracy.

[0038] <Inspection equipment>

[0039] Reference Figure 1An example of the inspection device in this embodiment will be described. Figure 1 This is a schematic cross-sectional view showing an example of the inspection device in this embodiment.

[0040] like Figure 1 As shown, the inspection device 10 includes an inspection device body 20 and a control device 50. The inspection device body 20 has a hollow housing 21. A moving mechanism 23 is provided in the approximate center of the housing 21, wherein the moving mechanism 23 is used to move the stage 25 in the up and down direction ( Figure 1 z-axis direction shown) and lateral direction ( Figure 1 The semiconductor wafer (hereinafter referred to as wafer W) as an example of the inspection object is placed on the upper surface of the stage 25. The stage 25 uses a vacuum chuck or the like to absorb and hold the wafer W placed on the upper surface.

[0041] A probe camera unit 41 (hereinafter also referred to as "PCU" (Probe Camera Unit)) is provided on the side of the stage 25. The probe camera unit 41 can be moved to a position opposite to the probe card 36 or the wafer camera unit 42 described later. For example, by moving the stage 25 using the moving mechanism 23, the probe camera unit 41 provided on the side of the stage 25 moves. The moving mechanism 23 is controlled by the control device 50. The movement amount of the moving mechanism 23 is managed by the control device 50. The position of the probe camera unit 41 in the housing 21 is managed by the control device 50.

[0042] The probe camera unit 41 projects a light spot pattern in which a plurality of light spots are arranged in a predetermined direction. The probe camera unit 41 is configured to project the light spot pattern upward. The probe camera unit 41 captures an image (hereinafter also referred to as a "reference image") containing the projected light spot pattern.

[0043] A wafer camera unit 42 (hereinafter also referred to as “WCU”) is provided in the housing 21. The wafer camera unit 42 can be moved to a position facing the stage 25 or the probe camera unit 41. The position of the wafer camera unit 42 in the housing 21 is managed by the control device 50.

[0044] The wafer camera unit 42 receives the light spot pattern projected by the probe camera unit 41. The wafer camera unit 42 is provided in the housing 21 at a position opposite to the probe camera unit 41 so as to receive the light spot pattern projected from below. The wafer camera unit 42 captures an image (hereinafter also referred to as a "measurement image") including a portion of the received light spot pattern.

[0045] The housing 21 has a substantially circular opening at the top. A test head 30 is provided at the opening of the housing 21. The test head 30 is fixed to a frame 22 provided along the periphery of the opening. A plurality of tilt adjustment parts 32 are provided at positions of the frame 22 within the test head 30. The tilt adjustment parts 32 are provided at predetermined intervals along the periphery of the opening. The tilt adjustment parts 32 hold a substantially cylindrical holder 34 below the frame 22 from above via a shaft 33.

[0046] The holder 34 detachably holds a probe card 36 provided with a plurality of probes 38 at its lower portion. The plurality of probes 38 provided on the probe card 36 are provided on the probe card 36 with their tips facing downward. Figure 1 The illustrated probe card 36 is an example of a cantilever-type probe 38 , but probes of other shapes such as a vertical needle type may also be used.

[0047] A plurality of probes 38 are provided on the probe card 36 so that when the wafer W placed on the stage 25 is moved to a position for inspection, the needle tips of the probes 38 contact the test pads provided on the wafer W. The probes 38 are connected to wiring provided in the probe card 36. The wiring provided in the probe card 36 is connected to the test head 30 via wiring provided in the holder 34. The test head 30 is connected to an external tester 31.

[0048] When detecting the wafer W placed on the stage 25, the control device 50 moves the probe camera unit 41 and the wafer camera unit 42 to positions opposite to each other. The control device 50 adjusts the position and posture of the stage 25 based on the reference image captured by the probe camera unit 41 and the measurement image captured by the wafer camera unit 42. Specifically, the control device 50 controls the position of the stage 25 on the xy plane and the inclination of the stage 25 relative to the z-axis by moving the mechanism 23 so that the needle tip of the probe 38 and each test pad on the wafer W placed on the stage 25 are in a relative positional relationship.

[0049] After adjusting the position and posture of the stage 25, the control device 50 raises the stage 25 so that the needle tip of the probe 38 contacts each test pad on the wafer W. Then, the control device 50 controls the external tester 31 to output a predetermined electrical signal to the test head 30. The test head 30 outputs the electrical signal output from the external tester 31 to the probe card 36 via the wiring in the holder 34. The electrical signal output to the probe card 36 is provided to the probe 38 via the wiring in the probe card 36. The electrical signal provided to the probe 38 is output to the test pad on the wafer W via the probe 38.

[0050] The electric signal output from the test pad on the wafer W is output to the probe 38. The electric signal output to the probe 38 is output to the test head 30 via the wiring in the probe card 36 and the wiring in the holder 34. The electric signal output to the test head 30 is output to the external tester 31.

[0051] The external tester 31 evaluates the electrical characteristics of the wafer W based on the electrical signals output to and from the test head 30 , and outputs the evaluation results to the control device 50 .

[0052] 《Probe Camera Unit》

[0053] Reference Figure 2 An example of the probe camera unit in this embodiment will be described. Figure 2 This is a schematic cross-sectional view showing an example of the probe camera unit in this embodiment.

[0054] like Figure 2 As shown, the probe camera unit 41 includes a projection unit 61, an illumination unit 62, and an imaging unit 63 (an example of a first imaging unit).

[0055] The projection unit 61 includes a monochromatic light source 64 and a diffractive optical element 65. The monochromatic light source 64 irradiates strong monochromatic light. The wavelength of the strong monochromatic light can be set arbitrarily. The diffractive optical element 65 forms a light spot pattern including a plurality of light spots by diffracting the strong monochromatic light irradiated from the monochromatic light source 64. The light spot pattern formed by the diffractive optical element 65 is projected upward via a prism 66 and a half mirror 67.

[0056] The illumination unit 62 is a bright field illumination unit that irradiates visible light. The visible light irradiated by the illumination unit 62 is irradiated upward through the reflector 68 and the half mirror 67. The visible light irradiated by the illumination unit 62 merges with the strong monochromatic light irradiated by the monochromatic light source 64 at the half mirror 67.

[0057] Through the illumination of the dark field illumination 69-1 and 69-2, a light spot pattern illuminated from the probe camera unit 41 can be observed at the focal point FP1. It should be noted that the working distance WD1 is the distance between the probe camera unit 41 and the focal point FP1.

[0058] The imaging unit 63 captures a reference image including a light spot pattern formed by the diffractive optical element 65. In the present embodiment, the imaging unit 63 captures a reference image including the entire light spot pattern. The strong monochromatic light irradiated from the monochromatic light source 64 is branched in a direction orthogonal to the irradiation direction of the strong monochromatic light by the prism 66. In the prism 66, a filter wheel 70 is provided on the imaging unit 63 side, and a reflective mirror 71 and an optical shutter 72 are provided on the opposite side.

[0059] The imaging unit 63 uses the filter wheel 70 and the optical shutter 72 to image the light spot pattern reflected by the reflection mirror 71. When the optical shutter 72 is open, the imaging unit 63 can image the light spot pattern, and when the optical shutter 72 is closed, the imaging unit 63 can image the upward field of view of the probe camera unit 41.

[0060] 《Chip Camera Unit》

[0061] Will refer to Figure 3 An example of a wafer camera unit in this embodiment is described. Figure 3 This is a schematic cross-sectional view showing an example of a wafer camera unit in this embodiment.

[0062] like Figure 3 As shown, the wafer camera unit 42 includes a light receiving section 81, an imaging section 82 (an example of a second imaging section), a bright field illumination 83, and dark field illuminations 87-1 and 87-2.

[0063] When the probe camera unit 41 and the wafer camera unit 42 are in a relative positional relationship, the light spot pattern irradiated from the probe camera unit 41 is incident on the wafer camera unit 42. The wafer camera unit 42 receives the light spot pattern incident on the wafer camera unit 42 by the light receiving unit 81. As an example, the light receiving unit 81 is a reflector that reflects the incident light spot pattern in a direction that the imaging unit 82 can image.

[0064] The light spot pattern received by the light receiving unit 81 is photographed by the photographing unit 82 through the half mirror 84 and the prism 85. It should be noted that the working distance WD2 is the distance between the wafer camera unit 42 and the focus FP2. Figure 2 The focal points FP1 and Figure 3 When the focal points FP2 shown are aligned, the imaging unit 82 can finely image the light spot pattern.

[0065] The photographing unit 82 photographs a measurement image including a light spot pattern detected by the wafer camera unit 42 at a predetermined time interval. In the present embodiment, the photographing unit 82 photographs measurement images of two or more light spots among a plurality of light spots included in the light spot pattern. For example, the photographing unit 82 may photograph the light spot pattern at a higher photographing magnification than the photographing unit 63 of the probe camera unit 41. The photographing magnification may be set to any magnification higher than 1, for example, 2.

[0066] In the present embodiment, the focal length of the imaging unit 82 is fixed. The depth of field of the imaging unit 82 can be configured to be wider than the depth of field of the imaging unit 63.

[0067] The bright field illumination 83 is a bright field illumination for irradiating visible light. The visible light irradiated by the bright field illumination 83 passes through the reflector 86 and merges with the light spot pattern received by the light receiving unit 81 at the half mirror 84. The light spot pattern received by the light receiving unit 81 can be observed at the focal point FP2 by irradiating the dark field illumination 87-1 and 87-2.

[0068] <Hardware Structure>

[0069] Figure 1 The control device 50 shown is composed of, for example, Figure 4 Computer implementation of the hardware structure shown. Figure 4 This is a block diagram showing an example of the hardware configuration of a computer in this embodiment.

[0070] like Figure 4 As shown, the computer 500 includes an input device 501, an output device 502, an external I / F (interface) 503, a RAM (random access memory) 504, a ROM (read only memory) 505, a CPU (central processing unit) 506, a communication I / F 507, and a HDD (hard disk drive) 508, etc., which are interconnected via a bus B. It should be noted that the input device 501 and the output device 502 can be connected and utilized when necessary.

[0071] The input device 501 is a keyboard, a mouse, a touch panel, etc., and is used by the operator to input various operation signals. The output device 502 is a display, etc., which displays the processing results of the computer 500. The communication I / F 507 is an interface for connecting the computer 500 to a network. The HDD 508 is an example of a non-volatile storage device that stores programs or data.

[0072] The external I / F 503 is an interface with an external device. The computer 500 can read and / or write to a recording medium 503a such as a SD (Secure Digital) memory card via the external I / F 503. The ROM 505 is an example of a nonvolatile semiconductor memory (storage device) storing a program or data. The RAM 504 is an example of a volatile semiconductor memory (storage device) that temporarily stores a program or data.

[0073] The CPU 506 is a computing device that realizes the control and functions of the entire computer 500 by reading programs or data from a storage device such as the ROM 505 or the HDD 508 to the RAM 504 and executing processing.

[0074] <Functional structure>

[0075] Reference Figure 5 The functional configuration of the control device in this embodiment will be described. Figure 5It is a diagram showing an example of the functional configuration of the control device in this embodiment.

[0076] like Figure 5 As shown, the control device 50 of this embodiment includes a projection control unit 101 , a light receiving control unit 102 , a reference image acquisition unit 103 , a measurement image acquisition unit 104 , a position detection unit 105 , a tilt detection unit 106 , and a stage adjustment unit 107 .

[0077] The projection control unit 101, the light receiving control unit 102, the reference image acquisition unit 103, the measurement image acquisition unit 104, the position detection unit 105, the tilt detection unit 106, and the stage adjustment unit 107 are configured to be configured to be, for example, Figure 4 The CPU 506 shown executes programs loaded on the RAM 504 to achieve this.

[0078] The projection control unit 101 controls so that the probe camera unit 41 projects the spot pattern. The projection control unit 101 controls so that the brightness of the spot pattern projected from the probe camera unit 41 is changed according to the height of the stage 25.

[0079] The light receiving control unit 102 controls the wafer camera unit 42 to receive the light spot pattern projected from the probe camera unit 41. The control for the wafer camera unit 42 to receive the light spot pattern includes control for moving the wafer camera unit 42 to a position where the light spot pattern can be received.

[0080] The reference image acquisition unit 103 performs control so that the probe camera unit 41 captures a reference image. The reference image acquisition unit 103 acquires the reference image captured by the probe camera unit 41 .

[0081] The measurement image acquisition section 104 controls so that the wafer camera unit 42 captures the measurement image at predetermined time intervals. The measurement image acquisition section 104 captures the measurement image captured by the wafer camera unit 42. If optical distortion occurs in the measurement image, the measurement image acquisition section 104 corrects the optical distortion.

[0082] Position detection unit 105 detects a positional deviation of stage 25 on the xy plane based on the reference image acquired by reference image acquisition unit 103 and the measurement image acquired by measurement image acquisition unit 104. Specifically, position detection unit 105 detects a positional deviation based on the relative position of the measurement image in the reference image.

[0083] The tilt detection unit 106 detects the deviation of the tilt of the stage 25 with respect to the z-axis based on the plurality of measurement images acquired by the measurement image acquisition unit 104. Specifically, the tilt detection unit 106 detects the tilt deviation based on the position change of the light spot included in the plurality of measurement images captured before and after the height of the stage 25 changes.

[0084] The stage adjustment unit 107 performs control to adjust the stage 25. The stage adjustment unit 107 adjusts the position of the stage 25 based on the positional deviation detected by the position detection unit 105. The stage adjustment unit 107 adjusts the inclination of the stage 25 based on the inclination deviation detected by the inclination detection unit 106.

[0085] The stage adjustment unit 107 controls the stage 25 to rise so that the needle tip of the probe 38 contacts each test pad on the wafer W. When the stage adjustment unit 107 changes the height of the stage 25, it notifies the projection control unit 101 of the height change. The projection control unit 101 adjusts the brightness of the spot pattern according to the height change.

[0086] 《Benchmark Image》

[0087] Will refer to Figure 6 The reference image in this embodiment will be described. Figure 6 is a diagram showing an example of a reference image.

[0088] like Figure 6 As shown, a plurality of light spots (dots) are captured in the reference image 100. The plurality of light spots are randomly arranged in the reference image 100. As an example, Figure 6 In the reference image 100 shown, the plurality of light spots are arranged asymmetrically with respect to the x-axis and the y-axis. Figure 6 The x-axis and the y-axis in the image coordinate system are shown. The axis about which the plurality of light spots are asymmetric is not limited to the x-axis and the y-axis, and any axis may be set.

[0089] Measuring Images

[0090] Will refer to Figure 7 The measurement image in this embodiment will be described. Figure 7 It is a diagram showing an example of a measurement image.

[0091] Figure 7 The measurement image 200 shown is obtained by Figure 6 The image is obtained by capturing a portion of the light spot pattern captured in the reference image 100 shown in FIG. Figure 7 As shown, in the measurement image 200 , the light spots, which are smaller in number than those in the reference image 100 , are captured larger than those in the reference image 100 .

[0092] 《Detection of position deviation》

[0093] Reference Figure 8 A method of detecting positional displacement based on a reference image and a measurement image in this embodiment will be described. Figure 8 This is a diagram showing an example of a method for detecting a positional shift.

[0094] When the probe camera unit 41 and the wafer camera unit 42 are in a relative positional relationship, if there is no positional offset, the configuration of the light spots captured in the measurement image is consistent with the configuration of the light spots near the center of the reference image. On the other hand, if there is a positional offset, the configuration of the light spots captured in the measurement image is inconsistent with the configuration of the light spots near the center of the reference image. Conversely, when the configuration of the light spots captured in the measurement image is inconsistent with the configuration of the light spots near the center of the reference image, it indicates that a positional offset has occurred.

[0095] like Figure 8 As shown, the measurement image 201 is a measurement image obtained by photographing the vicinity of the center of the reference image 100. In addition, the measurement image 202 is a measurement image obtained by photographing the reference image 100 at the upper right than the center. When the wafer camera unit 42 photographs the measurement image 201, it indicates that no positional deviation has occurred. On the other hand, when the wafer camera unit 42 photographs the measurement image 202, it indicates that a positional deviation has occurred.

[0096] For example, the position detection unit 105 may detect the position shift using template matching. Specifically, the position detection unit 105 estimates the relative position of the measurement image 200 in the reference image 100 through template matching and detects the distance between the estimated relative position and the center position of the reference image 100 as the position shift.

[0097] Contrast Correction

[0098] Will refer to Fig. 9 and Fig.10 A method for correcting the contrast between the reference image and the measurement image in this embodiment will be described.

[0099] When the distance between the probe camera unit 41 and the wafer camera unit 42 is consistent with the sum of their respective working distances WD1+WD2 (in other words, when the focus FP1 of the probe camera unit 41 is consistent with the focus FP2 of the wafer camera unit 42), the contrast of the light spot pattern included in the measurement image reaches the highest. On the other hand, when the focus FP1 of the probe camera unit 41 is inconsistent with the focus FP2 of the wafer camera unit 42, the contrast of the light spot pattern included in the measurement image decreases.

[0100] Fig. 9 is a diagram showing an example of the relationship between the working distance and the light spot pattern. Fig. 9As shown, when the focus is consistent (left end of the paper), the edge of the light spot included in the measurement image is fine and the contrast is high. On the other hand, when the stage 25 is raised from the state of consistent focus, the working distance WD2 of the wafer camera unit 42 becomes shorter, and the focus FP1 deviates from the depth of field. In this case, the edge of the light spot included in the measurement image is blurred and the contrast is reduced (center of the paper). Similarly, when the stage 25 is lowered from the state of consistent focus, the working distance WD2 of the wafer camera unit 42 becomes longer, and the focus FP1 deviates from the depth of field. In this case, the edge of the light spot included in the measurement image becomes blurred and the contrast is reduced (right end of the paper).

[0101] In this embodiment, when the height of the stage 25 is changed from the focused state, control is performed to adjust the brightness of the light spot pattern according to the amount of change in the height of the stage 25. When the contrast of the light spot pattern included in the measurement image is low, if the brightness of the projected light spot pattern is increased, the edge of the light spot becomes finer and the contrast is improved.

[0102] Fig.10 FIG. 1 is a diagram showing an example of adjusting brightness according to working distance. Fig.10 As shown, the current value when the focus is consistent with the working distance (±0mm) is set as the basic current value (1 times), and when the stage 25 is lowered to increase the working distance (+1mm), the current value is overdriven to 3 times the basic current value. Similarly, when the stage 25 is raised to shorten the working distance (-1mm), the current value is overdriven to 3 times the basic current value. At this time, the adjustment can be performed in such a way that the larger the change in the working distance (absolute value), the larger the overdrive ratio.

[0103] By adjusting the brightness of the light spot pattern according to the change in the height of stage 25, a high-contrast measurement image can be captured even when stage 25 is raised or lowered. In addition, by using a high-contrast measurement image, positional deviation and tilt deviation of stage 25 can be detected with high accuracy.

[0104] 《Tilt offset detection》

[0105] Will refer to Fig.11 A method of detecting a tilt shift using a measurement image in this embodiment will be described. Fig.11 This is a diagram showing an example of the relationship between the optical axis deviation and the spot pattern.

[0106] like Fig.11As shown in FIG. 1 , when the optical axis projected by the probe camera unit 41 is consistent with the optical axis received by the wafer camera unit 42 (there is no optical axis offset), the position of the light spot does not change before and after the stage 25 is raised. On the other hand, when the optical axis projected by the probe camera unit 41 is inconsistent with the optical axis received by the wafer camera unit 42 (there is an optical axis offset), the position of the light spot changes before and after the stage 25 is raised. It should be noted that Fig.11 In FIG. 1 , the solid line indicates the edge of each light spot observed, the dotted line indicates the edge of each light spot before the stage is raised, and the symbol + indicates the center position of each light spot.

[0107] As an example, the tilt detection unit 106 compares the center position of each light spot in the measurement image captured before the height of the stage 25 is changed with the center position of each light spot in the measurement image captured after the height of the stage 25 is changed, and calculates the amount of change in the position of each light spot. The tilt detection unit 106 averages the amount of change in the center position of each light spot and detects the average value as the tilt offset.

[0108] Distortion Correction

[0109] Will refer to Fig.12 The distortion correction in this embodiment will be described. Fig.12 It is a diagram showing an example of distortion correction.

[0110] In the inspection device 10, since warm-up and testing are performed in a high-temperature environment, optical distortion may appear in the measurement image captured by the wafer camera unit 42. The optical distortion can be corrected as follows.

[0111] Fig.12 FIG. 1 is a diagram showing an example of distortion correction. Fig.12 In FIG. 4 , the ideal image height corresponds to the position of each light spot in the light spot pattern projected from the probe camera unit 41 , and the paraxial image height corresponds to the position of each light spot captured in the measurement image.

[0112] The measurement image acquisition unit 104 corrects the optical distortion based on the position of each light spot included in the measurement image. By using the measurement image corrected for the optical distortion, the positional deviation and the tilt deviation of the stage 25 can be detected with high accuracy.

[0113] <Processing steps>

[0114] Reference Fig.13 The inspection method executed by the inspection device 10 in this embodiment will be described. Fig.13 This is a flowchart showing an example of the inspection method in this embodiment.

[0115] In step S1, the projection control unit 101 of the control device 50 controls the probe camera unit 41 to project a light spot pattern. Under the control of the control device 50, the probe camera unit 41 projects a light spot pattern in which a plurality of light spots are arranged through the projection unit 61.

[0116] In step S2, the light receiving control section 102 of the control device 50 controls the wafer camera unit 42 to receive the light spot pattern projected by the probe camera unit 41. Under the control of the control device 50, the wafer camera unit 42 starts to receive the light spot pattern.

[0117] In step S3 , the reference image acquisition unit 103 of the control device 50 controls the probe camera unit 41 to capture a reference image. Under the control of the control device 50 , the probe camera unit 41 captures a reference image including the light spot pattern projected from the projection unit 61 via the imaging unit 63 .

[0118] In step S4, the measurement image acquisition unit 104 of the control device 50 controls the wafer camera unit 42 to capture a measurement image. Under the control of the control device 50, the wafer camera unit 42 captures a measurement image including a light spot pattern received by the wafer camera unit 42 through the capturing unit 82.

[0119] In step S5, the control device 50 controls the moving mechanism 23 to adjust the stage 25 based on the reference image captured in step S3 and the measurement image captured in step S4. Specifically, first, the position detection unit 105 detects the position offset based on the reference image and the measurement image. The position detection unit 105 transmits the detected position offset to the stage adjustment unit 107. Next, the tilt detection unit 106 detects the tilt offset based on the plurality of measurement images. The tilt detection unit 106 transmits the detected tilt offset to the stage adjustment unit 107.

[0120] The stage adjustment unit 107 receives the position offset from the position detection unit 105. Then, the stage adjustment unit 107 controls the moving mechanism 23 to move the position of the stage 25 on the xy plane to eliminate the position offset. In addition, the stage adjustment unit 107 receives the tilt offset from the tilt detection unit 106. Then, the stage adjustment unit 107 controls the moving mechanism 23 to change the tilt of the stage 25 with respect to the z-axis to eliminate the tilt offset.

[0121] In step S6, the stage adjustment unit 107 of the control device 50 controls the moving mechanism 23 so that the needle tip of the probe 38 contacts the test pads provided on the wafer W placed on the stage 25. The stage adjustment unit 107 raises the stage 25 whose position and posture are adjusted in step S5 until the needle tip of the probe 38 contacts each test pad on the wafer W.

[0122] When the needle tips of the probes 38 contact the test pads on the wafer W, the control device 50 controls the external tester 31 to evaluate the electrical characteristics of the wafer W. The control device 50 receives the evaluation result of the electrical characteristics of the wafer W from the external tester 31 and outputs the evaluation result.

[0123] 《Stage adjustment processing》

[0124] Reference Figures 14 to 20 The stage adjustment process of this embodiment is further described in detail. Fig.13 Step S5). Fig.14 This is a flowchart showing an example of the stage adjustment process. Figures 15 to 20 This is a schematic diagram showing an example of the state of the inspection device.

[0125] In step S11, the light receiving control unit 102 moves the wafer camera unit 42 to a position opposite to the probe camera unit 41 along the spiral trajectory. By moving the wafer camera unit 42 along the spiral trajectory, the light spot pattern can be detected more quickly. The light receiving control unit 102 detects the light spot pattern from the measurement image acquired by the measurement image acquisition unit 104 while moving the wafer camera unit 42. When the light spot pattern is detected from the measurement image, the light receiving control unit 102 stops the movement of the wafer camera unit 42.

[0126] like Fig.15 As shown, the wafer camera unit 42 is disposed between the wafer W and the probe card 36. The wafer camera unit 42 moves in a direction to a position opposed to the probe camera unit 41 disposed on the stage 25.

[0127] like Fig.16 As shown, the probe camera unit 41 projects a light spot pattern along a spiral trajectory upward. When the wafer camera unit 42 moves to a position opposite to the probe camera unit 41, the light spot pattern projected from the probe camera unit 41 is incident on the wafer camera unit 42. The wafer camera unit 42 detects the light spot pattern from the incident light.

[0128] return Fig.14 In step S12, the stage adjustment unit 107 receives the measurement image from the measurement image acquisition unit 104. Next, the stage adjustment unit 107 adjusts the inclination of the stage 25 based on the size and contrast of each light spot included in the measurement image. If there is a tilt offset between the probe camera unit 41 and the wafer camera unit 42, the size and contrast of each light spot included in the measurement image become uneven. The stage adjustment unit 107 adjusts the inclination of the stage 25 so that the size and contrast of all light spots included in the measurement image are uniform.

[0129] In step S13, the position detection unit 105 receives the basic image from the reference image acquisition unit 103. Next, the position detection unit 105 receives the measurement image from the measurement image acquisition unit 104. Subsequently, the position detection unit 105 detects the position shift based on the basic image and the measurement image. Specifically, the position detection unit 105 estimates the relative position of the measurement image in the basic image by template matching, and calculates the distance from the estimated relative position to the center position. Then, the position detection unit 105 transmits the detected position shift to the stage adjustment unit 107.

[0130] In step S14, the stage adjustment unit 107 receives the positional deviation from the position detection unit 105. Next, the stage adjustment unit 107 adjusts the planar position of the stage 25 based on the positional deviation.

[0131] In step S15, the control device 50 uses the wafer camera unit 42 to identify the center position of the wafer W and generates three-dimensional data of the wafer W. In addition, the control device 50 uses the probe camera unit 41 to identify the center position of the probe card 36 and generate three-dimensional data of the probe card 36. Based on the center positions of the probe card 36 and the wafer W and the three-dimensional data, the control device 50 can identify the three-dimensional shapes of the probe card 36 and the wafer W, so that the needle tip of the probe 38 can contact the test pad on the wafer W with higher accuracy.

[0132] like Fig.17 As shown, the wafer camera unit 42 moves to a position opposite to the wafer W placed on the stage 25, and recognizes the center position of the wafer W. The wafer camera unit 42 photographs the wafer W at a position opposite to the wafer W. The control device 50 recognizes the center position of the wafer W based on the image of the wafer W. In addition, the control device 50 generates three-dimensional data of the wafer W.

[0133] like Fig.18 As shown, the stage 25 is moved to a position where the probe camera unit 41 and the probe card 36 are opposite to each other through the moving mechanism 23, and starts to rise. At the position opposite to the probe card 36, with the optical shutter 72 closed, the probe camera unit 41 uses the projected light spot pattern and the filter wheel 70 to photograph the probe card 36. The control device 50 recognizes the center position of the probe card 36 based on the image of the probe card 36. In addition, the control device 50 generates high-resolution three-dimensional data of the probe card 36.

[0134] Thereafter, the stage adjustment unit 107 moves the stage 25 to a position facing the probe card 36 . Furthermore, the light receiving control unit 102 moves the wafer camera unit 42 to a position facing the probe camera unit 41 .

[0135] return Fig.14In step S16, the measurement image acquisition unit 104 determines whether optical distortion occurs in the measurement image. The measurement image acquisition unit 104 detects the position of each light point included in the measurement image and compares the position of each light point with the position of the light point in the ideal image to determine whether optical distortion occurs.

[0136] If optical distortion has occurred (Yes), the measurement image acquisition unit 104 advances the process to step S17. On the other hand, if optical distortion has not occurred (No), the measurement image acquisition unit 104 advances the process to step S18.

[0137] In step S17, the measurement image acquisition unit 104 performs optical distortion correction on the measurement image. The measurement image acquisition unit 104 can correct the optical distortion of the measurement image based on the difference between the position of each light spot included in the measurement image and the position of the light spot in the ideal image.

[0138] After that, the measurement image acquisition section 104 returns the process to step S16 and repeats step S16 again. The measurement image acquisition section 104 continues to correct the optical distortion until the optical distortion in the measurement image is no longer detected.

[0139] In step S18 , the stage adjustment unit 107 starts raising the stage 25 .

[0140] like Fig.19 As shown, the stage 25 starts to rise at a position opposite to the probe card 36 by the moving mechanism 23. The wafer camera unit 42 receives the light spot pattern projected from the probe camera unit 41 at a position opposite to the probe camera unit 41. The probe camera unit 41 captures measurement images at predetermined time intervals.

[0141] return Fig.14 In step S19, the stage adjustment unit 107 notifies the projection control unit 101 of the change in the height of the stage 25. The projection control unit 101 controls the probe camera unit 41 to adjust the brightness of the light spot pattern according to the change in the height of the stage 25, and projects the light spot pattern with the brightness. Under the control of the control device 50, the probe camera unit 41 changes the brightness of the light spot pattern.

[0142] In step S20, the tilt detection unit 106 receives the measurement image from the measurement image acquisition unit 104. Next, the tilt detection unit 106 detects a change in the position of the light spot included in the measurement image captured before and after the height change of the stage 25.

[0143] Subsequently, the tilt detection unit 106 determines whether the position of the light spot has changed. If the position of the light spot has changed ("Yes"), the tilt detection unit 106 advances the process to step S21. On the other hand, if the position of the light spot has not changed ("No"), the tilt detection unit 106 ends the stage adjustment process.

[0144] In step S21, the tilt detection unit 106 detects the tilt offset based on the position change of the light spot detected in step S20. Specifically, the tilt detection unit 106 calculates the change amount of the center position of each light spot included in the measurement image, and detects the average value of the change amount as the tilt offset. Then, the tilt detection unit 106 transmits the tilt offset to the stage adjustment unit 107.

[0145] The stage adjustment unit 107 receives the tilt offset from the tilt detection unit 106. Next, the stage adjustment unit 107 adjusts the tilt of the stage 25 based on the tilt offset.

[0146] After that, control device 50 returns the process to step S18, and repeats the process from step S18 to step S20 again. Control device 50 adjusts the tilt offset until the position of the light spot no longer changes with the rise of stage 25.

[0147] like Fig. 20 As shown in FIG. 1 , the stage 25 continues to rise in a state where the position offset and the tilt offset are adjusted. When the needle tip of the probe provided on the probe card 36 contacts the test pad on the wafer W placed on the upper surface of the stage 25, the stage 25 stops rising. The needle tip of the probe provided on the probe card 36 contacts the test pad on the wafer W with high precision.

[0148] <Effects of implementation>

[0149] In the inspection device 10 in the present embodiment, a light spot pattern in which a plurality of light spots are arranged is projected by the probe camera unit 41, the light spot pattern is received by the wafer camera unit 42, and the stage 25 on which the wafer W is placed is adjusted based on a reference image including the light spot pattern projected by the probe camera unit 41 and a measurement image including two or more light spots in the light spot pattern detected by the wafer camera unit 42. The inspection device 10 can detect the positional deviation and tilt deviation of the stage 25 with high accuracy by using an image obtained by photographing the light spot pattern in which a plurality of light spots are arranged. In one aspect, according to the present embodiment, the needle tip of the probe can be brought into contact with the electrode of the inspection object with high accuracy.

[0150] The inspection device 10 in this embodiment can capture a measurement image in a positional relationship in which the probe camera unit 41 and the wafer camera unit 42 are opposed to each other. According to this embodiment, the wafer camera unit 42 can reliably detect the light spot pattern projected by the probe camera unit 41.

[0151] The inspection device 10 in this embodiment can capture the measurement image at a larger magnification than the reference image. The inspection device 10 can adjust the position of the stage 25 based on the relative position of the measurement image in the reference image. The inspection device 10 can project a light spot pattern in which the light spots are asymmetrically arranged with respect to a predetermined axis. According to this embodiment, the positional deviation of the stage 25 can be detected with high accuracy.

[0152] The inspection device 10 of this embodiment can adjust the tilt of the stage 25 based on the position change of the light spot included in the multiple measurement images. When the probe camera unit 41 is fixed to the stage 25 and the height of the stage 25 is different, the inspection device 10 can take multiple measurement images respectively. The inspection device 10 can change the brightness of the light spot pattern according to the change in the height of the stage 25. According to this embodiment, the tilt deviation of the stage 25 can be detected with high accuracy.

[0153] [Replenish]

[0154] The structure of the inspection device 10 of the above embodiment is an example, and at least a part of the processing performed by the control device 50 may be performed by another information processing device connected to the control device 50 in a manner capable of data communication. For example, the other information processing device connected to the control device 50 in a manner capable of data communication may be a computer providing a cloud service.

[0155] The embodiments of the present invention are illustrative in all respects and are not restrictive. The embodiments may be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments may adopt other structures within the scope of non-contradiction, and may also be combined within the scope of non-contradiction.

Claims

1. An inspection method for inspecting an inspection object by bringing a probe tip provided on a probe card into contact with an electrode provided on the inspection object, and comprising the following steps: The projection unit projects a light spot pattern, wherein a plurality of light spots are arranged in the light spot pattern; Receiving the light spot pattern by a light receiving part; capturing a reference image including the light spot pattern projected by the projection unit; capturing a measurement image including two or more of the light spots in the light spot pattern received by the light receiving unit; as well as Based on the reference image and the measurement image, a stage on which the inspection object is placed is adjusted.

2. The inspection method according to claim 1, wherein: The measurement image is captured in a positional relationship in which the projection unit and the light receiving unit are opposed to each other.

3. The inspection method according to claim 1, wherein: The measurement image is captured at a larger capture magnification than that of the reference image.

4. The inspection method according to any one of claims 1 to 3, wherein: In the step of adjusting, the position of the stage is adjusted based on the relative position of the measurement image in the reference image.

5. The inspection method according to claim 4, wherein: In the light spot pattern, the light spots are arranged asymmetrically with respect to a predetermined axis.

6. The inspection method according to any one of claims 1 to 3, wherein: In the step of adjusting, the tilt of the stage is adjusted based on a change in position of the light spot included in a plurality of the measurement images.

7. The inspection method according to claim 6, wherein: The projection unit is fixed on the carrier. The plurality of measurement images are captured respectively when the heights of the stage are different.

8. The inspection method according to claim 7, wherein: The projection unit changes the brightness of the light spot pattern according to a change in the height of the stage.

9. An inspection device for inspecting an inspection object by bringing a needle tip of a probe provided on a probe card into contact with an electrode provided on the inspection object, and comprising: A projection unit projects a light spot pattern, wherein a plurality of light spots are arranged in the light spot pattern; A light receiving part, receiving the light spot pattern; a first photographing unit, for photographing a reference image including the light spot pattern projected by the projection unit; a second photographing unit for photographing a measurement image including two or more of the light spots in the light spot pattern received by the light receiving unit; as well as The adjustment unit adjusts a stage on which the inspection object is placed based on the reference image and the measurement image.

10. The inspection device according to claim 9, wherein: The second imaging unit captures the measurement image at a larger imaging magnification than the imaging magnification used by the first imaging unit to capture the reference image.

Images