Inspection method and inspection device

Abstract

To provide a technique for accurately bringing a needle tip of a probe into contact with an electrode of an inspected body.SOLUTION: An inspection method for inspecting an inspected body by bringing a needle tip of a probe provided in a probe card into contact with an electrode provided in the inspected body, includes the steps of: projecting an optical axis pattern in which a plurality of optical aces is disposed, by a projection section; detecting the optical axis pattern by a photodetection section; imaging a reference image including the optical axis pattern which is projected by the projection section; imaging a measurement image including two or more optical axes in the optical axis pattern which is detected by the photodetection section; and adjusting a placement table on which the inspected body is placed, on the basis of the reference image and the measurement image.SELECTED DRAWING: Figure 13

Description

[Technical field]

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

[0002] For example, the electrical characteristics of a semiconductor device are inspected using an inspection device while the semiconductor device is still in the state of a semiconductor wafer before being divided into individual semiconductor devices. The inspection device has a probe card on which a plurality of probes are provided. The inspection device inspects the semiconductor device by bringing the tips of the probes provided on the probe card into contact with test pads (electrodes) provided on the semiconductor device, supplying electrical signals to the semiconductor device via the probes, and acquiring the electrical signals output from the semiconductor device via the probes. In order to bring the tips of the probes provided on the probe card into contact with the test pads provided on the semiconductor device, it is necessary to accurately adjust the relative positional relationship between the tips of the probes and the test pads.

[0003] For example, Patent Document 1 discloses an inspection device that identifies the position of a probe tip based on an image of the probe tip captured by a camera, and adjusts the position of the tip of each probe needle based on the identified tip position of each probe needle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-102640 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a technique for bringing the tip of a probe into contact with an electrode of a device under test with high precision. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided an inspection method for inspecting an object to be inspected by contacting the tip of a probe provided on a probe card with an electrode provided on the object to be inspected, the inspection method including the steps of: projecting an optical axis pattern in which a plurality of optical axes are arranged by a projection unit; receiving the optical axis pattern by a light receiving unit; capturing a reference image including the optical axis pattern projected by the projection unit; capturing a measurement image including two or more optical axes of the optical axis pattern received by the light receiving unit; and adjusting a mounting table on which the object to be inspected is placed based on the reference image and the measurement image. Effect of the Invention

[0007] According to one aspect, the tip of the probe can be brought into contact with the electrode of the device under test with high precision. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of an inspection device. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an example of a probe camera unit. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing an example of a wafer camera unit. [Figure 4] FIG. 2 is a block diagram showing an example of a hardware configuration of a computer. [Diagram 5] FIG. 2 is a block diagram showing an example of a functional configuration of a control device. [Figure 6] FIG. 4 is a diagram showing an example of a reference image. [Figure 7] FIG. 13 is a diagram showing an example of a measurement image. [Figure 8] FIG. 11 is a diagram illustrating an example of a method for detecting a positional deviation. [Figure 9] FIG. 4 is a diagram showing an example of the relationship between the working distance and the optical axis pattern. [Figure 10] FIG. 13 is a diagram showing an example of luminance adjustment according to a working distance. [Figure 11] 11A and 11B are diagrams illustrating an example of a relationship between an optical axis shift and an optical axis pattern. [Figure 12]FIG. 13 is a diagram illustrating an example of distortion correction. [Figure 13] 1 is a flowchart illustrating an example of an inspection method. [Figure 14] 13 is a flowchart illustrating an example of a mounting table adjustment process. [Figure 15] FIG. 4 is a schematic diagram showing an example of a state of an inspection device. [Figure 16] FIG. 4 is a schematic diagram showing an example of a state of an inspection device. [Figure 17] FIG. 4 is a schematic diagram showing an example of a state of an inspection device. [Figure 18] FIG. 4 is a schematic diagram showing an example of a state of an inspection device. [Figure 19] FIG. 4 is a schematic diagram showing an example of a state of an inspection device. [Figure 20] FIG. 4 is a schematic diagram showing an example of a state of an inspection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment 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 duplicated descriptions may be omitted.

[0010] [Embodiment] An embodiment of the present disclosure is an inspection apparatus for inspecting a semiconductor device, which is an example of an object to be inspected. In this embodiment, the inspection apparatus inspects electrical characteristics of a semiconductor device formed on a semiconductor wafer by contacting needle tips of probes provided on a probe card with test pads provided on the semiconductor wafer.

[0011] Since the testing device performs preheating and testing in a high-temperature environment, minute vibrations occur in the semiconductor wafer and the probe card due to thermal expansion. In addition, since the stage on which the semiconductor wafer is placed is moved to bring the probe tips into contact with the test pads, even if the relative positions of the probe tips and the test pads are adjusted in advance, the positions of the probe tips and the test pads may ultimately be misaligned.

[0012] The inspection device in this embodiment includes two camera units that can move to opposing positions to bring the probe tips into contact with the test pads with high accuracy. The first camera unit projects an optical axis pattern including multiple optical axes toward the second camera unit. The second camera unit receives the optical axis pattern projected from the first camera unit.

[0013] The inspection device adjusts the position and orientation of the mounting table on which the semiconductor wafer is placed, based on the deviation between the optical axis projected from the first camera unit and the optical axis received from the second camera unit (hereinafter also referred to as "optical axis deviation"). The optical axis deviation includes a position deviation in the xy plane (hereinafter also referred to as "position deviation") and a tilt deviation with respect to the z axis (hereinafter also referred to as "tilt deviation"). Therefore, the inspection device can adjust the position of the mounting table in the xy plane and the tilt with respect to the z axis, based on the optical axis deviation.

[0014] The inspection device can detect both the positional deviation and the tilt deviation with high accuracy by using an optical axis pattern including a plurality of optical axes. In one aspect, the inspection device in the present embodiment can bring the needle tips of the probes into contact with the electrodes of the test object with high accuracy.

[0015] <Inspection equipment> An example of an inspection device in this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing an example of an inspection device in this embodiment.

[0016] As shown in Fig. 1, the inspection device 10 has an inspection device main body 20 and a control device 50. The inspection device main body 20 has a hollow housing 21. Approximately in the center of the housing 21, a moving mechanism 23 is provided for moving a mounting table 25 in the vertical direction (z-axis direction shown in Fig. 1) and horizontal directions (directions in an xy plane parallel to the x-axis and y-axis shown in Fig. 1). A semiconductor wafer (hereinafter referred to as wafer W), which is an example of an object to be inspected, is placed on the upper surface of the mounting table 25. The mounting table 25 holds the wafer W placed on its upper surface by suction using a vacuum chuck or the like.

[0017] A probe camera unit 41 (hereinafter also referred to as "PCU" (Probe Camera Unit)) is provided on the side of the mounting table 25. The probe camera unit 41 can move to a position facing a probe card 36 or a wafer camera unit 42 described below. For example, the mounting table 25 is moved by the moving mechanism 23, whereby the probe camera unit 41 provided on the side of the mounting table 25 moves. The moving mechanism 23 is controlled by the control device 50. The amount of movement of the moving mechanism 23 is managed by the control device 50. The position of the probe camera unit 41 within the housing 21 is managed by the control device 50.

[0018] The probe camera unit 41 projects an optical axis pattern in which multiple optical axes are arranged in a predetermined direction. The probe camera unit 41 is provided so as to project the optical axis pattern upward. The probe camera unit 41 captures an image including the projected optical axis pattern (hereinafter also referred to as a "reference image").

[0019] A wafer camera unit 42 (hereinafter also referred to as "WCU" (Wafer Camera Unit)) is provided in the housing 21. The wafer camera unit 42 is movable to a position facing the mounting table 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.

[0020] The wafer camera unit 42 receives the optical axis pattern projected by the probe camera unit 41. The wafer camera unit 42 is provided in the housing 21 at a position facing the probe camera unit 41 so as to receive the optical axis pattern projected from below. The wafer camera unit 42 captures an image (hereinafter also referred to as a "measurement image") including a part of the received optical axis pattern.

[0021] The housing 21 has a substantially circular opening at the top. A test head 30 is provided in 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 units 32 are provided at the position of the frame 22 within the test head 30. The tilt adjustment units 32 are arranged at predetermined intervals around the opening along the frame 22. The tilt adjustment units 32 hold a substantially cylindrical holder 34 from above via a shaft 33 below the frame 22.

[0022] The holder 34 removably holds, at its lower part, a probe card 36 provided with a plurality of probes 38. The plurality of probes 38 provided on the probe card 36 are provided on the probe card 36 so that their needle tips face downward. The probe card 36 shown in Fig. 1 is an example of a cantilever type probe 38, but other shapes of probes such as a vertical needle type may also be used.

[0023] The probe card 36 has a plurality of probes 38 arranged such that when the wafer W placed on the mounting table 25 is moved to a position for testing, the needle tips of the probes 38 come into contact with test pads provided on the wafer W. The probes 38 are connected to wiring provided on the probe card 36. The wiring provided on the probe card 36 is connected to the test head 30 via wiring provided on the holder 34. The test head 30 is connected to an external tester 31.

[0024] When inspecting the wafer W placed on the mounting table 25, the control device 50 moves the probe camera unit 41 and the wafer camera unit 42 to positions where they face each other. The control device 50 adjusts the position and orientation of the mounting table 25 based on a reference image captured by the probe camera unit 41 and a measurement image captured by the wafer camera unit 42. Specifically, the control device 50 controls the position of the mounting table 25 in the xy plane and the inclination of the mounting table 25 with respect to the z axis by the movement mechanism 23 so that the needle tips of the probes 38 and the test pads on the wafer W placed on the mounting table 25 face each other.

[0025] After adjusting the position and orientation of the mounting table 25, the control device 50 raises the mounting table 25 to bring the tips of the probes 38 into contact with the test pads on the wafer W. Then, the control device 50 controls the external tester 31 to output a predetermined electric signal to the test head 30. The test head 30 outputs the electric signal output from the external tester 31 to the probe card 36 via wiring in the holder 34. The electric signal output to the probe card 36 is supplied to the probes 38 via wiring in the probe card 36. The electric signal supplied to the probes 38 is output to the test pads on the wafer W via the probes 38.

[0026] The electrical signals output from the test pads on the wafer W are output to the probes 38. The electrical signals output to the probes 38 are output to the test head 30 via wiring in the probe card 36 and wiring in the holder 34. The electrical signals output to the test head 30 are output to the external tester 31.

[0027] The external tester 31 evaluates the electrical characteristics of the wafer W based on the electrical signals output to the test head 30 and the electrical signals output from the test head 30, and outputs the evaluation results to the control device .

[0028] <Probe camera unit> An example of the probe camera unit in this embodiment will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view showing an example of the probe camera unit in this embodiment.

[0029] As shown in FIG. 2, the probe camera unit 41 includes a projection section 61, an illumination section 62, and an imaging section 63 (an example of a first imaging section).

[0030] The projection unit 61 includes a monochromatic light source 64 and a diffractive optical element 65. The monochromatic light source 64 emits strong monochromatic light. The wavelength of the strong monochromatic light may be set arbitrarily. The diffractive optical element 65 diffracts the strong monochromatic light emitted from the monochromatic light source 64 to form a light source pattern including a plurality of light sources. The optical axis pattern formed by the diffractive optical element 65 is projected upward via a prism 66 and a half mirror 67.

[0031] The illumination unit 62 is a bright field illumination that irradiates visible light. The visible light irradiated by the illumination unit 62 is irradiated upward via a mirror 68 and a 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.

[0032] The optical axis pattern emitted from the probe camera unit 41 can be observed at a focal point FP1 by illumination with dark field illuminations 69-1 and 69-2. Note that a working distance WD1 is the distance between the probe camera unit 41 and the focal point FP1.

[0033] The imaging unit 63 captures a reference image including an optical axis pattern formed by a diffractive optical element 65. In this embodiment, the imaging unit 63 captures a reference image including the entire optical pattern. Strong monochromatic light irradiated from a monochromatic light source 64 is branched by a prism 66 in a direction perpendicular to the irradiation direction of the strong monochromatic light. A filter wheel 70 is provided on the imaging unit 63 side of the prism 66, and a mirror 71 and an optical shutter 72 are provided on the opposite side.

[0034] The imaging section 63 images the optical axis pattern reflected by the mirror 71 using a filter wheel 70 and an optical shutter 72. The imaging section 63 can image the optical axis pattern when the optical shutter 72 is open, and can image the upward field of view of the probe camera unit 41 when the optical shutter 72 is closed.

[0035] <Wafer camera unit> An example of the wafer camera unit in this embodiment will be described with reference to Fig. 3. Fig. 3 is a schematic cross-sectional view showing an example of the wafer camera unit in this embodiment.

[0036] As shown in FIG. 3, 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.

[0037] When the probe camera unit 41 and the wafer camera unit 42 are positioned facing each other, an optical axis pattern irradiated from the probe camera unit 41 is incident on the wafer camera unit 42. The wafer camera unit 42 receives the optical axis pattern incident on the wafer camera unit 42 with a light receiving section 81. The light receiving section 81 is, for example, a mirror that reflects the incident optical axis pattern in a direction in which the imaging section 82 can image it.

[0038] The optical axis pattern received by the light receiving unit 81 is imaged by the imaging unit 82 via the half mirror 84 and the prism 85. The working distance WD2 is the distance between the wafer camera unit 42 and the focal point FP2. When the probe camera unit 41 and the wafer camera unit 42 are in an opposing positional relationship and the focal point FP1 shown in Fig. 2 coincides with the focal point FP2 shown in Fig. 3, the imaging unit 82 can precisely image the optical axis pattern.

[0039] The imaging section 82 captures a measurement image including the optical axis pattern detected by the wafer camera unit 42 at a predetermined time interval. In this embodiment, the imaging section 82 captures a measurement image including two or more optical axes among a plurality of optical axes included in the optical axis pattern. For example, the imaging section 82 may capture the optical axis pattern at a higher imaging magnification than that of the imaging section 63 of the probe camera unit 41. The imaging magnification may be set to any magnification higher than 1x, and may be, for example, 2x.

[0040] In this embodiment, the imaging unit 82 has a fixed focal length. The depth of field of the imaging unit 82 is preferably wider than the depth of field of the imaging unit 63.

[0041] The bright field illumination 83 is a bright field illumination that irradiates visible light. The visible light irradiated by the bright field illumination 83 passes through a mirror 86 and merges with the optical axis pattern received by the light receiving unit 81 at a half mirror 84. The optical axis pattern received by the light receiving unit 81 becomes observable at a focus FP2 by irradiation with dark field illuminations 87-1 and 87-2.

[0042] <Hardware configuration> The control device 50 shown in Fig. 1 is realized by, for example, a computer having a hardware configuration as shown in Fig. 4. Fig. 4 is a block diagram showing an example of the hardware configuration of the computer in this embodiment.

[0043] 4, 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 an HDD (Hard Disk Drive) 508, all of which are connected to each other via a bus B. The input device 501 and the output device 502 may be connected and used when necessary.

[0044] The input device 501 is a keyboard, mouse, touch panel, etc., and is used by an operator to input various operation signals. The output device 502 is a display, etc., and displays the results of processing by the computer 500. The communication I / F 507 is an interface that connects the computer 500 to a network. The HDD 508 is an example of a non-volatile storage device that stores programs and data.

[0045] The external I / F 503 is an interface with an external device. The computer 500 can read and / or write data from and to a recording medium 503a such as a Secure Digital (SD) memory card via the external I / F 503. The ROM 505 is an example of a non-volatile semiconductor memory (storage device) in which programs and data are stored. The RAM 504 is an example of a volatile semiconductor memory (storage device) that temporarily holds programs and data.

[0046] The CPU 506 is a calculation device that reads out programs and data from storage devices such as the ROM 505 and the HDD 508 onto the RAM 504 and executes processes, thereby realizing overall control and functions of the computer 500 .

[0047] <Functional configuration> The functional configuration of the control device in this embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of the functional configuration of the control device in this embodiment.

[0048] As shown in FIG. 5, the control device 50 in 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 mounting table adjustment unit 107.

[0049] 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 mounting table adjustment unit 107 are realized, for example, by the CPU 506 shown in FIG. 4 executing a program loaded on the RAM 504.

[0050] The projection control unit 101 controls the probe camera unit 41 to project an optical axis pattern. The projection control unit 101 controls the brightness of the optical axis pattern projected from the probe camera unit 41 to be changed depending on the height of the mounting table 25.

[0051] The light reception control unit 102 controls the wafer camera unit 42 to receive the optical axis pattern projected from the probe camera unit 41. The control for causing the wafer camera unit 42 to receive the optical axis pattern includes control for moving the wafer camera unit 42 to a position where the optical axis pattern can be received.

[0052] The reference image acquisition unit 103 controls the probe camera unit 41 to capture a reference image. The reference image acquisition unit 103 acquires the reference image captured by the probe camera unit 41.

[0053] The measurement image acquisition unit 104 controls the wafer camera unit 42 to capture measurement images at predetermined time intervals. The measurement image acquisition unit 104 acquires the measurement images captured by the wafer camera unit 42. When optical distortion occurs in the measurement image, the measurement image acquisition unit 104 corrects the optical distortion.

[0054] The position detection unit 105 detects a positional deviation in the xy plane of the mounting table 25 based on the reference image acquired by the reference image acquisition unit 103 and the measurement image acquired by the measurement image acquisition unit 104. Specifically, the position detection unit 105 detects the positional deviation based on the relative position of the measurement image in the reference image.

[0055] The tilt detection unit 106 detects a deviation in tilt of the mounting table 25 with respect to the z-axis based on a plurality of measurement images acquired by the measurement image acquisition unit 104. Specifically, the tilt detection unit 106 detects a deviation in tilt based on a position change of the optical axis included in a plurality of measurement images captured before and after the height of the mounting table 25 changes.

[0056] The mounting table adjustment unit 107 performs control to adjust the mounting table 25. The mounting table adjustment unit 107 adjusts the position of the mounting table 25 based on the position deviation detected by the position detection unit 105. The mounting table adjustment unit 107 adjusts the inclination of the mounting table 25 based on the inclination deviation detected by the inclination detection unit 106.

[0057] The mounting table adjustment unit 107 controls the lifting of the mounting table 25 in order to bring the tips of the probes 38 into contact with the test pads on the wafer W. When the mounting table adjustment unit 107 changes the height of the mounting table 25, it notifies the projection control unit 101 of the amount of change in height. The projection control unit 101 adjusts the brightness of the optical axis pattern according to the amount of change in height.

[0058] <Reference image> The reference image in this embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the reference image.

[0059] As shown in Fig. 6, a plurality of optical axes (dots) are captured in the reference image 100. The plurality of optical axes are randomly arranged in the reference image 100. In the reference image 100 shown in Fig. 6, as an example, the plurality of optical axes are arranged so as to be asymmetric with respect to the x-axis and the y-axis. Note that Fig. 6 shows the x-axis and the y-axis in the image coordinate system. The axes along which the plurality of optical axes are asymmetric are not limited to the x-axis and the y-axis, and any axis may be set.

[0060] <Measurement image> The measurement image in this embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of the measurement image.

[0061] The measurement image 200 shown in Fig. 7 is an image of a part of the optical axis pattern captured in the reference image 100 shown in Fig. 6. As shown in Fig. 7, the measurement image 200 has a smaller number of optical axes than the reference image 100, and the number of optical axes is larger than that of the reference image 100.

[0062] <Detection of position deviation> A method for detecting misalignment based on a reference image and a measurement image in this embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram showing an example of the method for detecting misalignment.

[0063] When the probe camera unit 41 and the wafer camera unit 42 are positioned facing each other, if no misalignment occurs, the arrangement of the optical axes captured in the measurement image will match the arrangement of the optical axes near the center of the reference image. On the other hand, if a misalignment occurs, the arrangement of the optical axes captured in the measurement image will not match the arrangement of the optical axes near the center of the reference image. Conversely, if the arrangement of the optical axes captured in the measurement image does not match the arrangement of the optical axes near the center of the reference image, this indicates that a misalignment has occurred.

[0064] 8, measurement image 201 is a measurement image captured near the center of reference image 100. Measurement image 202 is a measurement image captured near the upper right corner of reference image 100. When measurement image 201 is captured by wafer camera unit 42, it indicates that no positional deviation has occurred. On the other hand, when measurement image 202 is captured by wafer camera unit 42, it indicates that a positional deviation has occurred.

[0065] As an example, the position detection unit 105 can detect the positional deviation by using template matching. Specifically, the position detection unit 105 estimates the relative position of the measurement image 200 in the reference image 100 by template matching, and detects the distance between the estimated relative position and the center position of the reference image 100 as the positional deviation.

[0066] Contrast correction A method for correcting the contrast of a reference image and a measurement image in this embodiment will be described with reference to FIGS.

[0067] When the distance between the probe camera unit 41 and the wafer camera unit 42 coincides with the sum of their respective working distances, WD1+WD2 (in other words, when the focal point FP1 of the probe camera unit 41 coincides with the focal point FP2 of the wafer camera unit 42), the contrast of the optical axis pattern included in the measurement image becomes the highest. On the other hand, when the focal point FP1 of the probe camera unit 41 does not coincide with the focal point FP2 of the wafer camera unit 42, the contrast of the optical axis pattern included in the measurement image becomes low.

[0068] FIG. 9 is a diagram showing an example of the relationship between the working distance and the optical axis pattern. As shown in FIG. 9, when the focus is matched (left edge of the paper), the edge of the optical axis included in the measurement image is fine and the contrast is high. On the other hand, when the mounting table 25 is raised from the state where the focus is matched, the working distance WD2 of the wafer camera unit 42 becomes shorter, and the focal point FP1 is out of the depth of field. In this case, the edge of the optical axis included in the measurement image becomes blurred and the contrast becomes low (center of the paper). Similarly, when the mounting table 25 is lowered from the state where the focus is matched, the working distance WD2 of the wafer camera unit 42 becomes longer, and the focal point FP1 is out of the depth of field. In this case, the edge of the optical axis included in the measurement image becomes blurred and the contrast becomes low (right edge of the paper).

[0069] In this embodiment, when the height of the mounting table 25 is changed from the in-focus state, control is performed to adjust the brightness of the optical axis pattern according to the amount of change in the height of the mounting table 25. When the contrast of the optical axis pattern included in the measurement image is low, increasing the brightness of the projected optical axis pattern makes the edge of the optical axis finer and improves the contrast.

[0070] Fig. 10 is a diagram showing an example of brightness adjustment according to the working distance. As shown in Fig. 10, when the focus coincides with the working distance (±0 mm), the current value is set to the basic current value (1x), and when the working distance becomes longer by lowering the mounting table 25 (+1 mm), the current value is overdriven to three times the basic current value. Similarly, when the working distance becomes shorter by raising the mounting table 25 (-1 mm), the current value is overdriven to three times the basic current value. At this time, it is preferable to adjust the overdrive magnification to be larger as the change amount (absolute value) of the working distance becomes larger.

[0071] By adjusting the brightness of the optical axis pattern according to the amount of change in the height of the mounting table 25, it is possible to capture a high-contrast measurement image even while the mounting table 25 is rising or falling. Furthermore, by using a high-contrast measurement image, it is possible to accurately detect the positional deviation and tilt deviation of the mounting table 25.

[0072] <Detection of tilt deviation> A method for detecting tilt deviation using a measurement image in this embodiment will be described with reference to Fig. 11. Fig. 11 is a diagram showing an example of the relationship between optical axis deviation and optical axis pattern.

[0073] 11, when the optical axis projected by the probe camera unit 41 and the optical axis received by the wafer camera unit 42 coincide (no optical axis misalignment), the position of the optical axis does not change before and after the mounting table 25 is raised. On the other hand, when the optical axis projected by the probe camera unit 41 and the optical axis received by the wafer camera unit 42 do not coincide (optical axis misalignment), the position of the optical axis changes before and after the mounting table 25 is raised. In FIG. 11, the solid lines indicate the edges of each observed optical axis, the dotted lines indicate the edges of each optical axis before the mounting table is raised, and the + symbol indicates the center position of each optical axis.

[0074] As an example, the tilt detection unit 106 calculates the amount of change in the position of each optical axis by comparing the center position of each optical axis in the measurement image captured before changing the height of the mounting table 25 with the center position of each optical axis in the measurement image captured after changing the height of the mounting table 25. The tilt detection unit 106 averages the amount of change in the center position of each optical axis and detects the average value as the tilt deviation.

[0075] Distortion correction Distortion correction in this embodiment will be described with reference to Fig. 12. Fig. 12 is a diagram showing an example of distortion correction.

[0076] In the inspection device 10, preheating and testing are performed in a high-temperature environment, so optical distortion may occur in the measurement image captured by the wafer camera unit 42. The optical distortion can be corrected as follows.

[0077] Fig. 12 is a diagram showing an example of distortion correction. In Fig. 12, the ideal image height corresponds to the position of each optical axis in the optical axis pattern projected from the probe camera unit 41, and the paraxial image height corresponds to the position of each optical axis captured in the measurement image.

[0078] The measurement image acquisition unit 104 corrects the optical distortion based on the position of each optical axis included in the measurement image. By using the measurement image in which the optical distortion has been corrected, the positional deviation and tilt deviation of the mounting table 25 can be detected with high accuracy.

[0079] <Processing Procedure> An inspection method executed by the inspection device 10 in this embodiment will be described with reference to Fig. 13. Fig. 13 is a flow chart showing an example of the inspection method in this embodiment.

[0080] In step S1, the projection control unit 101 of the control device 50 controls the probe camera unit 41 to project an optical axis pattern. The probe camera unit 41 projects, under the control of the control device 50, an optical axis pattern in which a plurality of optical axes are arranged, by the projection unit 61.

[0081] In step S2, the light receiving control unit 102 of the control device 50 controls the wafer camera unit 42 to receive the optical axis pattern projected by the probe camera unit 41. The wafer camera unit 42 starts receiving the optical axis pattern under the control of the control device 50.

[0082] 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. The probe camera unit 41 captures a reference image including an optical axis pattern projected from the projection unit 61 by the imaging unit 63 under the control of the control device 50.

[0083] In step S4, the measurement image acquisition section 104 of the control device 50 controls the wafer camera unit 42 to capture a measurement image. The wafer camera unit 42 captures a measurement image including the optical axis pattern received by the wafer camera unit 42 using the imaging section 82 under the control of the control device 50.

[0084] In step S5, the control device 50 controls the moving mechanism 23 to adjust the mounting table 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 a positional deviation based on the reference image and the measurement image. The position detection unit 105 sends the detected positional deviation to the mounting table adjustment unit 107. Next, the tilt detection unit 106 detects a tilt deviation based on the multiple measurement images. The tilt detection unit 106 sends the detected tilt deviation to the mounting table adjustment unit 107.

[0085] The mounting table adjustment unit 107 receives the positional deviation from the position detection unit 105. Next, the mounting table adjustment unit 107 controls the movement mechanism 23 to move the position of the mounting table 25 in the xy plane so as to eliminate the positional deviation. The mounting table adjustment unit 107 also receives the tilt deviation from the tilt detection unit 106. Next, the mounting table adjustment unit 107 controls the movement mechanism 23 to change the tilt of the mounting table 25 with respect to the z-axis so as to eliminate the tilt deviation.

[0086] In step S6, the mounting table adjustment unit 107 of the control device 50 controls the moving mechanism 23 so that the tips of the probes 38 contact the test pads provided on the wafer W placed on the mounting table 25. The mounting table adjustment unit 107 raises the mounting table 25, the position and orientation of which has been adjusted in step S5, until the tips of the probes 38 contact each test pad on the wafer W.

[0087] When the tips of the probes 38 contact each test pad 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 results of the electrical characteristics of the wafer W from the external tester 31, and outputs the evaluation results.

[0088] <Placement table adjustment process> The mounting table adjustment process (step S5 in FIG. 13) in this embodiment will be described in more detail with reference to FIG. 14 to FIG. 20. FIG. 14 is a flowchart showing an example of the mounting table adjustment process. FIG. 15 to FIG. 20 are schematic diagrams showing an example of the state of the inspection apparatus.

[0089] In step S11, the light-receiving control unit 102 moves the wafer camera unit 42 on a spiral trajectory to a position facing the probe camera unit 41. By moving the wafer camera unit 42 on a spiral trajectory, it becomes possible to detect the optical axis pattern at higher speed. The light-receiving control unit 102 detects the optical axis pattern from the measurement image acquired by the measurement image acquisition unit 104 while moving the wafer camera unit 42. When the optical axis pattern is detected from the measurement image, the light-receiving control unit 102 stops the movement of the wafer camera unit 42.

[0090] 15, the wafer camera unit 42 is provided between the wafer W and the probe card 36. The wafer camera unit 42 moves toward a position facing the probe camera unit 41 provided on the mounting table 25.

[0091] 16, the probe camera unit 41 projects an optical axis pattern along a spiral trajectory in the upward direction. When the wafer camera unit 42 moves to a position facing the probe camera unit 41, the optical axis pattern projected from the probe camera unit 41 enters the wafer camera unit 42. The wafer camera unit 42 detects the optical axis pattern from the incident light.

[0092] Returning to FIG. 14, the explanation will be given. In step S12, the mounting table adjustment unit 107 receives the measurement image from the measurement image acquisition unit 104. Next, the mounting table adjustment unit 107 adjusts the inclination of the mounting table 25 based on the size and contrast of each optical axis included in the measurement image. If there is an inclination deviation between the probe camera unit 41 and the wafer camera unit 42, the size and contrast of each optical axis included in the measurement image will be uneven. The mounting table adjustment unit 107 adjusts the inclination of the mounting table 25 so that the size and contrast of all optical axes included in the measurement image become uniform.

[0093] In step S13, the position detection unit 105 receives the base 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. Next, the position detection unit 105 detects positional deviation based on the base image and the measurement image. Specifically, the position detection unit 105 estimates the relative position of the measurement image in the base image by template matching, and calculates the distance from the estimated relative position to the center position. Then, the position detection unit 105 sends the detected positional deviation to the mounting table adjustment unit 107.

[0094] In step S14, the mounting table adjustment unit 107 receives the positional deviation from the position detection unit 105. Next, the mounting table adjustment unit 107 adjusts the planar position of the mounting table 25 based on the positional deviation.

[0095] In step S15, the control device 50 recognizes the center position of the wafer W by the wafer camera unit 42, and creates three-dimensional data of the wafer W. The control device 50 also recognizes the center position of the probe card 36 by the probe camera unit 41, and creates three-dimensional data of the probe card 36. The control device 50 can recognize the three-dimensional shapes of the probe card 36 and the wafer W based on the center positions and three-dimensional data of the probe card 36 and the wafer W, and can bring the needle tips of the probes 38 into contact with the test pads on the wafer W with higher accuracy.

[0096] 17, the wafer camera unit 42 moves to a position facing the wafer W placed on the mounting table 25 and recognizes the center position of the wafer W. The wafer camera unit 42 captures an image of the wafer W at the position facing 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 creates three-dimensional data of the wafer W.

[0097] 18, the mounting table 25 is moved by the moving mechanism 23 to a position where the probe camera unit 41 and the probe card 36 face each other, and starts to rise. At the position facing the probe card 36, the probe camera unit 41 captures an image of the probe card 36 using the projected optical axis pattern and the filter wheel 70 with the optical shutter 72 closed. The control device 50 recognizes the center position of the probe card 36 based on the image of the probe card 36. The control device 50 also creates high-resolution three-dimensional data of the probe card 36.

[0098] Thereafter, the mounting table adjustment unit 107 moves the mounting table 25 to a position opposite the probe card 36. In addition, the light-receiving control unit 102 moves the wafer camera unit 42 to a position opposite the probe camera unit 41.

[0099] Returning to Fig. 14, in step S16, the measurement image acquisition unit 104 determines whether or not optical distortion occurs in the measurement image. The measurement image acquisition unit 104 detects the position of each optical axis included in the measurement image, and compares the position of each optical axis with the position of the optical axis at the ideal image height, thereby determining whether or not optical distortion occurs.

[0100] If optical distortion occurs (YES), the measurement image acquisition unit 104 advances the process to step S17. On the other hand, if optical distortion does not occur (NO), the measurement image acquisition unit 104 advances the process to step S18.

[0101] In step S17, the measurement image acquisition unit 104 corrects optical distortion of the measurement image based on the difference between the position of each optical axis included in the measurement image and the position of the optical axis at the ideal image height.

[0102] Thereafter, the measurement image acquisition section 104 returns the process to step S16 and repeats step S16 again. The measurement image acquisition section 104 continues correcting the optical distortion until the optical distortion is no longer detected in the measurement image.

[0103] In step S18, the mounting table adjustment unit 107 starts to raise the mounting table 25.

[0104] 19, the mounting table 25 starts to rise by the moving mechanism 23 at a position facing the probe card 36. The wafer camera unit 42 receives the optical axis pattern projected from the probe camera unit 41 at a position facing the probe camera unit 41. The probe camera unit 41 captures measurement images at predetermined time intervals.

[0105] Returning to Fig. 14, an explanation will be given. In step S19, the mounting table adjustment unit 107 notifies the projection control unit 101 of the amount of change in the height of the mounting table 25. The projection control unit 101 adjusts the luminance of the optical axis pattern according to the amount of change in the height of the mounting table 25, and controls the probe camera unit 41 to project the optical axis pattern at that luminance. The probe camera unit 41 changes the luminance of the optical axis pattern under the control of the control device 50.

[0106] 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 optical axis included in the measurement image captured before and after the height of the mounting table 25 changes.

[0107] Next, the tilt detection unit 106 determines whether or not the position of the optical axis has changed. If the position of the optical axis has changed (YES), the tilt detection unit 106 proceeds to step S21. On the other hand, if the position of the optical axis has not changed (NO), the tilt detection unit 106 ends the mounting table adjustment process.

[0108] In step S21, the tilt detector 106 detects the tilt deviation based on the position change of the optical axis detected in step S20. Specifically, the tilt detector 106 calculates the amount of change in the center position of each optical axis included in the measurement image, and detects the average value of the amount of change as the tilt deviation. Then, the tilt detector 106 sends the tilt deviation to the mounting table adjuster 107.

[0109] The mounting table adjustment unit 107 receives the tilt deviation from the tilt detection unit 106. Next, the mounting table adjustment unit 107 adjusts the tilt of the mounting table 25 based on the tilt deviation.

[0110] Thereafter, the control device 50 returns to the process in step S18, and repeats the processes from step S18 to step S20 again. The control device 50 adjusts the tilt deviation until no change in the position of the optical axis occurs as the mounting table 25 rises.

[0111] 20, the mounting table 25 continues to rise with the positional deviation and inclination deviation adjusted. When the needle tips of the probes provided on the probe card 36 come into contact with the test pads on the wafer W placed on the upper surface of the mounting table 25, the mounting table 25 stops rising. The needle tips of the probes provided on the probe card 36 come into contact with the test pads on the wafer W with high precision.

[0112] <Effects of the embodiment> In the present embodiment, the inspection device 10 projects an optical axis pattern in which multiple optical axes are arranged by the probe camera unit 41, receives the optical axis pattern by the wafer camera unit 42, and adjusts the mounting table 25 on which the wafer W is placed based on a reference image including the optical axis pattern projected by the probe camera unit 41 and a measurement image including two or more optical axes out of the optical axis pattern detected by the wafer camera unit 42. The inspection device 10 can detect the positional deviation and inclination deviation of the mounting table 25 with high accuracy by using an image of the optical axis pattern in which multiple optical axes 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 test object with high accuracy.

[0113] The inspection device 10 in this embodiment may capture a measurement image in a positional relationship in which the probe camera unit 41 and the wafer camera unit 42 face each other. According to this embodiment, the optical axis pattern projected by the probe camera unit 41 can be reliably detected by the wafer camera unit 42.

[0114] The inspection device 10 in this embodiment may capture a measurement image at a larger magnification than the reference image. The inspection device 10 may adjust the position of the mounting table 25 based on the relative position of the measurement image in the reference image. The inspection device 10 may project an optical axis pattern in which the optical axes are arranged asymmetrically with respect to a predetermined axis. According to this embodiment, the positional deviation of the mounting table 25 can be detected with high accuracy.

[0115] The inspection device 10 in this embodiment may adjust the inclination of the mounting table 25 based on the position change of the optical axis included in the multiple measurement images. The inspection device 10 may capture each of the multiple measurement images when the probe camera unit 41 is fixed to the mounting table 25 and the height of the mounting table 25 is different. The inspection device 10 may change the brightness of the optical axis pattern according to the amount of change in the height of the mounting table 25. According to this embodiment, the inclination deviation of the mounting table 25 can be detected with high accuracy.

[0116] [supplement] The configuration of the inspection device 10 in the above-described embodiment is merely an example, and at least a part of the processing performed by the control device 50 may be executed by another information processing device connected to the control device 50 so as to be capable of data communication. For example, the other information processing device connected to the control device 50 so as to be capable of data communication may be a computer that provides a cloud service.

[0117] The embodiments disclosed herein are illustrative and not restrictive in all respects. The embodiments can 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 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]

[0118] W: Wafer 10: Inspection equipment 23: Movement mechanism 25:Placement table 30: Test head 36: Probe card 38: Probe 41: Probe camera unit 42: Wafer camera unit 50: Control device 61: Projection section 62: Lighting department 63: Imaging section 81: Light receiving part 82: Imaging section 101: Projection control unit 102: Light receiving control unit 103: Reference image acquisition unit 104: Measurement image acquisition unit 105: Position detection unit 106: Tilt detection unit 107: Placement table adjustment section

Claims

1. 1. A method for testing an object to be tested by contacting a tip of a probe provided on a probe card with an electrode provided on the object to be tested, comprising: projecting an optical axis pattern in which a plurality of optical axes are arranged by a projection unit; receiving the optical axis pattern by a light receiving unit; capturing a reference image including the optical axis pattern projected by the projection unit; capturing a measurement image including two or more of the optical axes of the optical axis pattern received by the light receiving unit; adjusting a mounting table on which the object to be inspected is placed based on the reference image and the measurement image; An inspection method having the following features.

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

3. The inspection method according to claim 1, The measurement image is captured at a larger magnification than the reference image. Testing method.

4. 4. The inspection method according to claim 1, further comprising: the adjusting step adjusts a position of the mounting table based on a relative position of the measurement image in the reference image. Testing method.

5. The inspection method according to claim 4, The optical axis pattern has the optical axes arranged asymmetrically with respect to a predetermined axis. Testing method.

6. 4. The inspection method according to claim 1, further comprising: the adjusting step adjusts a tilt of the mounting table based on a position change of the optical axis included in the plurality of measurement images. Testing method.

7. 7. The inspection method according to claim 6, the projection unit is fixed to the placement table, The plurality of measurement images are captured when the height of the mounting table is different. Testing method.

8. The inspection method according to claim 7, the projection unit changes the luminance of the optical axis pattern in accordance with an amount of change in height of the placement table. Testing method.

9. 1. A testing device that tests an object to be tested by contacting a tip of a probe provided on a probe card with an electrode provided on the object to be tested, a projection unit that projects an optical axis pattern in which a plurality of optical axes are arranged; a light receiving unit that receives the optical axis pattern; a first imaging unit that captures a reference image including the optical axis pattern projected by the projection unit; A second imaging unit that captures a measurement image including two or more of the optical axes of the optical axis pattern received by the light receiving unit; an adjustment unit that adjusts a mounting table on which the object to be inspected is placed, based on the reference image and the measurement image; An inspection device comprising:

10. 10. The inspection device according to claim 9, The second imaging unit captures the measurement image at a magnification ratio greater than a magnification ratio at which the first imaging unit captures the reference image. Inspection equipment.

Images