JP2008164292A - Probe inspection apparatus, position displacement correction method, information processing apparatus and method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain optimal contact positions of probe needles at all times by appropriately correcting position displacements of the contact positions of the probe needles even in the case that the probe needles come into contact with one electrode pad a plurality of times. <P>SOLUTION: A probe inspection apparatus 100 acquires pre-contact images 51 and post-contact images 52 of a probe needle 8a to each pad 40 of a chip 30 by imaging by a CCD camera 6, extracts differential images 53 between both images by an image processing PC 10, computes the amount of position displacement between the position of the newest needle track 41b and a target position in the differential images 53 for respective thirty pads computes an overall amount of correction of a probe card 8 on the basis of each amount of position displacement, and corrects position displacements by reflecting the amount of correction in inspections of each pad 40 of the chip 30 to be inspected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a probe inspection apparatus that inspects the electrical characteristics of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object, a positional deviation correction method in the probe inspection apparatus, and information used in the probe inspection apparatus The present invention relates to a processing device, an information processing method and a program in the information processing device.

  2. Description of the Related Art Conventionally, a probe inspection apparatus for inspecting electrical characteristics of an electronic device such as a semiconductor chip (hereinafter simply referred to as a chip) formed on a semiconductor wafer (hereinafter also simply referred to as a wafer) is known. In this probe inspection apparatus, the probe needle provided on the probe card is brought into contact with the electrode pad on the chip, the output is measured by applying a predetermined voltage with a tester connected to the probe card, and compared with the expected value. That is, the quality of the chip is determined.

  In this probe inspection, it is important to accurately bring the probe needle into contact with the target position of the electrode pad. If the probe needle comes in contact with the peripheral edge deviated from the center of the electrode pad or a position outside the electrode pad, it leads to an erroneous inspection. In addition, in order to perform a plurality of measurements on one chip, the region on the electrode pad may be used for each of a plurality of measurements, and if the probe needle is displaced from a different region for each measurement and contacts This makes it difficult to measure multiple times.

As a technique for correcting such misalignment of the probe needle, the following Patent Document 1 discloses a probe card stylus trace of a probe card observed with a color camera, and the needle trace is an appropriate position on the electrode pad ( For example, if the position of the needle trace is deviated from an appropriate position, the positional deviation between the center of the needle trace and the center of the electrode pad is eliminated. A method of moving the stage minutely is disclosed. In addition, Patent Documents 2 to 5 listed below also describe techniques related to probe needle alignment.
Japanese Patent Laying-Open No. 2004-63877 (paragraph [0006] etc.) Japanese Patent Publication No. 06-005690 Japanese Patent Publication No. 07-013990 Japanese Patent No. 2575072 Japanese Patent No. 2998441

  By the way, in the probe inspection, a plurality of measurements may be performed for each electrical condition for one electrode pad, and in this case, a plurality of needle marks are attached on the one electrode pad. It becomes. However, in the technology of each of the above-mentioned patent documents, it is impossible to determine which needle trace is the latest needle trace even if an image of such an electrode pad with a plurality of needle traces is taken. Cannot be calculated, and the positional deviation cannot be corrected.

  In view of the circumstances as described above, the object of the present invention is to appropriately correct the displacement of the probe needle contact position even when the probe needle contacts the electrode pad a plurality of times. Is to provide a probe inspection apparatus, a positional deviation correction method in the probe inspection apparatus, an information processing apparatus used in the probe inspection apparatus, an information processing method and a program in the information processing apparatus .

  In order to solve the above-described problem, a probe inspection apparatus according to a main aspect of the present invention is a probe inspection apparatus that inspects the electrical characteristics of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object. Imaging means for imaging the electrode pad before contact of the probe needle with the object to be inspected and the electrode pad after contact with the probe needle; and the imaged image of the electrode pad before contact Is stored as a first image, the captured image of the electrode pad after contact is stored as a second image, and the difference between the stored first image and the second image Difference extraction means for extracting a difference image as a difference image, and a positional deviation between a needle trace position of the probe needle appearing in the extracted difference image and a target position on the electrode pad to which the probe needle should be brought into contact Calculation means for calculating a correction amount for correction, and correction means for correcting the positional deviation by varying a relative position between the object to be inspected and the probe needle based on the calculated correction amount. .

  Here, the inspected object is, for example, a semiconductor wafer on which a plurality of semiconductor chips are formed or other electronic devices. With this configuration, even if the probe needle touches the object to be inspected multiple times, only the latest needle trace can be extracted by extracting the above-mentioned difference image. By doing so, the contact state can always be kept at the optimum position. Therefore, it is possible to prevent a failure in measurement of the electrical characteristics of the inspection object due to poor contact, and as a result, it is possible to improve the yield of the inspection object. The relative position can be changed by the correcting means by, for example, moving the object to be inspected in the X direction or the Y direction on a plane perpendicular to the contact direction of the probe needle. Further, when the object to be inspected is a semiconductor wafer having a plurality of semiconductor chips provided with a plurality of electrode pads, the correction amount calculated for each electrode pad of one semiconductor chip to be inspected at present May be reflected for each electrode pad of another semiconductor chip to be inspected next.

  In the probe inspection apparatus, when the electrical characteristics are inspected by contact with the probe needle a plurality of times with respect to the electrode pad, the first inspection by the imaging unit in the next inspection of one time. And a storage unit that stores the image stored as the second image in the first inspection as the first image in the next inspection. You may make it.

  Accordingly, since the second image captured at the previous inspection can be used as the first image at the next inspection, it is possible to save the trouble of capturing the first image for each inspection, and the storage means The storage capacity can also be reduced.

  In the probe inspection apparatus, the storage unit may include a unit that deletes the first image after the difference extraction. Thereby, the storage capacity of the storage means can be further reduced.

  In the probe inspection apparatus, the object to be inspected is a semiconductor wafer having a plurality of semiconductor chips provided with a plurality of the electrode pads, and the probe needle is the semiconductor chip in each of the semiconductor chips. There are a plurality of electrode pads so that they can be in contact with the electrode pads at a time, and the imaging means can continuously capture the first and second images of the respective electrode pads of the one semiconductor chip, and the memory The means corresponds to the second image of each of the electrode pads, the first identification information for identifying the one semiconductor chip, and the second identification information for identifying each of the electrode pads of the one semiconductor chip. The calculation means calculates a correction amount for correcting each positional deviation between the needle trace position of each probe needle and each target position on each electrode pad at a time. It may be.

  Thereby, each 1st and 2nd image in each electrode pad is imaged continuously, the position shift in each electrode pad can be corrected at once, and the processing efficiency concerning correction can be improved. Further, in order to store the first and second images of each electrode pad in association with the first and second identification information, respectively, one semiconductor chip is examined while inspecting each electrode pad of the plurality of semiconductor chips. Even when the electrode pads are inspected a plurality of times, the previous second image can be easily called as the next first image with reference to the identification information. As a result, it is possible to efficiently correct the misalignment by omitting the continuous imaging process of the first image and reducing the processing load of the imaging unit and the used capacity of the storage unit. The correction amount calculated in this case is calculated in consideration of not only the X and Y directions but also the movement in the rotation (θ) direction on the plane, and the correction means is based on the correction amount. The displacement is corrected by moving the object to be inspected in at least one of the X, Y, and θ directions on the plane.

  In the probe inspection apparatus, the object to be inspected is a semiconductor wafer having a plurality of semiconductor chips provided with a plurality of the electrode pads, and the probe needle is provided for each of at least two semiconductor chips among the semiconductor chips. A plurality of the at least two semiconductor chips so as to be able to contact each of the electrode pads at a time, and the imaging means includes the first of the electrode pads of the at least two semiconductor chips. Each of the first and second images can be continuously captured, and the storage means includes the first identification information for identifying the second image of each of the electrode pads and the at least two semiconductor chips, respectively. Storing in association with second identification information for identifying each of the electrode pads of the at least two semiconductor chips, The calculating means calculates a correction amount for correcting each position shift between the needle trace position of each probe needle and each target position on each electrode pad in the at least two semiconductor chips at a time. It doesn't matter.

  Thereby, it is possible to correct the positional deviation of each electrode pad of a plurality of semiconductor chips at once, and the correction processing efficiency is further improved. Further, even when the plurality of semiconductor chips are inspected a plurality of times, the previous second image can be easily called as the next first image with reference to the first and second identification information. It is possible to efficiently correct the misalignment by omitting the imaging process of one image.

  A misregistration correction method according to another aspect of the present invention is a misregistration correction method in a probe inspection apparatus that inspects electrical characteristics of the test object by bringing a probe needle into contact with an electrode pad of the test object, Imaging each of the electrode pad before the probe needle contacts the object to be inspected and the electrode pad after the probe needle contact; and imaging the image of the electrode pad before the contact Storing the image of the imaged electrode pad after contact as a second image, and storing the difference between the stored first image and the second image as a difference image And a positional deviation between a probe mark position of the probe needle appearing in the extracted difference image and a target position on the electrode pad to which the probe needle should be brought into contact is corrected. Calculating a correction amount for, and a step of correcting the positional deviation by varying the relative position between the probe needle and the object to be inspected based on the correction amount the calculated.

  An information processing apparatus according to another aspect of the present invention is an information processing apparatus used in a probe inspection apparatus that inspects electrical characteristics of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object, A memory for storing a first image obtained by imaging the electrode pad before contact of the probe needle with the subject and a second image obtained by imaging the electrode pad after contact with the probe needle, respectively. Means, a difference extracting means for extracting a difference between the stored first image and the second image as a difference image, a needle trace position of the probe needle appearing in the extracted difference image, and Calculating means for calculating a correction amount for correcting a positional deviation from a target position on the electrode pad to be brought into contact with the probe needle.

  An information processing method according to another aspect of the present invention is an information processing method in an information processing apparatus used in a probe inspection apparatus that inspects the electrical characteristics of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object. A first image obtained by imaging the electrode pad before contact of the probe needle with the object to be inspected and a second image obtained by imaging the electrode pad after contact with the probe needle. A step of storing each, a step of extracting a difference between the stored first image and the second image as a difference image, a needle trace position of the probe needle appearing in the extracted difference image, Calculating a correction amount for correcting a positional deviation from a target position on the electrode pad to be brought into contact with the probe needle.

  According to another aspect of the present invention, there is provided a program stored in an information processing apparatus for use in a probe inspection apparatus that inspects an electrical characteristic of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object. Storing each of a first image obtained by imaging the electrode pad before contact with the probe needle and a second image obtained by imaging the electrode pad after contact with the probe needle; Extracting the difference between the first image and the second image as a difference image, the needle trace position of the probe needle appearing in the extracted difference image, and the probe needle to be contacted And a step of calculating a correction amount for correcting a positional deviation from the target position on the electrode pad.

  Further, the present invention may be configured as a recording medium recording this program. Here, the storage medium is, for example, a CD (Compact Disc), a DVD (Digital Versatile Disk), a BD (Blu-ray Disc), an HDD (Hard Disk Drive), a flash memory, or the like.

  As described above, according to the present invention, the probe needle contact position is always optimally corrected by appropriately correcting the displacement of the probe needle contact position even when the probe needle contacts the electrode pad a plurality of times. Can be kept in.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a probe inspection apparatus according to an embodiment of the present invention.
As shown in the figure, a probe inspection apparatus 100 includes, for example, a wafer table 2 holding a semiconductor wafer 1 made of silicon (hereinafter also simply referred to as wafer 1), and the wafer table 2 as shown in FIGS. A probe card provided with a stage 3 for moving in the θ direction, a CCD camera 6 for imaging the wafer 1 from above, a light source 7 for illuminating the wafer 1 during imaging by the CCD camera 6, and a plurality of probe needles 8a 8 and an image processing PC (Personal Computer) 10 for controlling the operation of each unit and performing image processing to be described later.

  The wafer 1 is transferred onto the wafer table 2 by a transfer arm (not shown), and is sucked and fixed to the wafer table 2 by suction means such as a vacuum pump (not shown). Instead of directly adsorbing the wafer 1 to the wafer table 2, for example, a tray (not shown) that can hold the wafer 1 is prepared, and the tray 1 is adsorbed and fixed in a state where the wafer 1 is held on the tray. You may make it. When a hole is formed in the wafer 1 or the like, it may be difficult to directly vacuum-suck the wafer, so the suction method using this tray is effective.

  FIG. 3 is a top view of the wafer 1. As shown in the figure, for example, 88 semiconductor chips (die) 30 (hereinafter simply referred to as chips 30) are formed on the wafer 1 in a grid shape. Of course, the number of chips 30 is not limited to 88.

  FIG. 4 is an enlarged top view of each chip 30 of the wafer 1. As shown in the figure, each chip 30 (30a to 30e) is provided with a plurality of bump-like electrode pads 40 (hereinafter simply referred to as pads), for example, along the peripheral edge. In the present embodiment, 12 pads 40 are provided on each side of the chip 30, for a total of 48 pads, but the number of pads 40 is not limited to this. The layout of the pad 40 is not limited to the case where it is provided at the peripheral edge of each chip 30, and may be provided over the entire surface of each chip 30. Each electrode pad 40 is made of a metal such as gold, silver, copper, solder, nickel, or aluminum, and is connected to an integrated circuit formed inside each chip 30.

  The probe card 8 is configured by fixing a plurality of probe needles 8a corresponding to the number and layout of electrode pads of each chip 30 on a substrate. For example, in the present embodiment, 48 probe needles 8a are provided according to the layout of each chip 30 described above. Each probe card 8 is connected to a tester 9, and each probe needle 8a is brought into contact with each pad 40. A voltage is applied to each pad 40 from the tester 9 through each probe needle 8a under various conditions, and the output The electrical characteristics of each chip 30 can be inspected by measuring the value and comparing it with a predetermined expected value.

  Referring again to FIG. 1, the CCD camera 6 is fixed at a predetermined position above the wafer 1 and incorporates a lens, a shutter (not shown), and the like. The CCD camera 6 displays an image of each pad 40 on each chip 30 (an image of a needle mark attached to each pad 40) enlarged by a built-in lens based on a trigger signal output from the image processing PC 10. Then, an image is taken under the flash emitted by the light source 7 and the taken image is transferred to the image processing PC 10. Specifically, the CCD camera 6 is configured to check the electrical characteristics of one chip 30 before contacting each pad 40 with each probe needle 8a (hereinafter referred to as a pre-contact image). Images (hereinafter referred to as post-contact images). Instead of the CCD camera 6, a camera incorporating another image sensor such as a CMOS sensor may be used.

  The light source 7 is fixed at a predetermined position above the wafer 1 and includes, for example, a flash lamp composed of a high-intensity white LED, a xenon lamp, and the like, and a flash lighting circuit that controls lighting of the flash lamp. The light source 7 illuminates each pad 40 of each chip 30 by emitting high-intensity flash light for a predetermined time of, for example, about several microseconds based on the flash signal output from the image processing PC 10.

  The stage 3 includes a motor 4 for moving the X stage 11 and the Y stage 12 along the movement axis 13 (or collectively) in the X direction, the Y direction, the Z direction, and the θ direction, and the X stage 11 and the Y stage. An encoder 5 is provided for determining the moving distance of the stage 12 in each direction. The motor 4 is, for example, an AC servo motor, a DC servo motor, a stepping motor, a linear motor, or the like, and the encoder 5 is, for example, various motor encoders, a linear scale, or the like. Each time the X stage 11 and the Y stage 12 move by a unit distance in the X, Y, Z, and θ directions, the encoder 5 generates an encoder signal that is movement information (coordinate information), and performs image processing on the encoder signal. Output to PC10.

  When inspecting the electrical characteristics of each chip 30, first, the stage 3 is moved in the XY plane so that the chip 30 to be inspected is located directly below each probe needle 8 a of the probe card 8, and then Each probe needle 8a is brought into contact with each pad 40 by moving the stage 3 directly above (Z1 direction), and a voltage is applied from the tester 9 in this state. When the inspection is completed, the stage 3 is moved again downward (Z2 direction) to return to the original state. When the chip 30 to be inspected is changed to another chip 30, the same operation is repeated after the stage 3 is moved on the XY plane by the distance between the chips.

  Further, when each pad 40 of each chip 30 is imaged by the CCD camera 6, the stage 3 is moved on the XY plane so that the CCD camera 6 is positioned directly above the pad 40 to be imaged, and the light source 7. Take an image under the flash of During the inspection with the probe card 8, the CCD camera 6 is retracted to another position so that the wafer 1 and the CCD camera 6 do not come into contact with the stage 3 ascending, and only when imaging is performed. Thus, it is set above the wafer 1.

  The image processing PC 10 receives the encoder signal from the encoder 5, outputs a flash signal to the light source 7 based on the encoder signal, and outputs a trigger signal to the CCD camera 6. Further, the image processing PC 10 outputs a motor control signal for controlling the driving of the motor 4 to the motor 4 at the time of inspection of each chip 30 and at the time of imaging of each pad 40 based on the encoder signal input from the encoder 5.

FIG. 2 is a block diagram showing the configuration of the image processing PC 10.
As shown in the figure, the image processing PC 10 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, an input / output interface 24, an HDD 25, a display unit 26, and an operation input. Each unit 27 is electrically connected to each other via an internal bus 28.

  The CPU 21 comprehensively controls each unit of the image processing PC 10 and performs various calculations in image processing and the like described later. The ROM 22 is a non-volatile memory that stores programs required when the image processing PC 10 is started up and other programs and data that do not require rewriting. The RAM 23 is a volatile memory that is used as a work area for the CPU 21 and temporarily stores various data and programs read from the HDD 25 and the ROM 22.

  The input / output interface 24 connects the operation input unit 27, the motor 4, the encoder 5, the light source 7 and the CCD camera 6 to the internal bus 28, and inputs an operation input signal from the operation input unit 27, and the motor 4. These are interfaces for exchanging various signals with the encoder 5, the light source 7, and the CCD camera 6.

  The HDD 25 has an OS (Operating System), various programs for performing imaging processing and image processing, which will be described later, other various applications, images of each pad 40 captured by the CCD camera 6, and each pad 40. Data indicating the target position for the probe needle 8a to contact and other various data are stored in the built-in hard disk. Note that the various programs for performing the imaging processing and the image processing may be installed from a recording medium such as a CD, a DVD, a BD, or a flash memory in which these programs are recorded.

  The display unit 26 includes, for example, an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), and the like, and displays images captured by the CCD camera 6 and various operation screens for image processing. The operation input unit 27 includes, for example, a keyboard, a mouse, and the like, and inputs an operation from a user in image processing described later.

  Next, the operation of the probe inspection apparatus 100 in this embodiment will be described. When inspecting the electrical characteristics of each chip 30, the probe inspection apparatus 100 corrects this positional deviation when the contact position of each probe needle 8 a with respect to each pad 40 is deviated from a preset target position. Is possible. Hereinafter, the operation related to the positional deviation correction will be mainly described.

  FIG. 5 is a flowchart showing an operation flow when the electrical characteristics of each chip 30 are inspected. In this embodiment, each of the 88 chips 30 shown in FIG. 3 is sequentially inspected. For example, among the chips 30 shown in FIG. 3, the inspection is performed, for example, for each row in order from the leftmost chip 30 in the uppermost row (Y coordinate is maximum). Even when all the inspections for each chip 30 are completed, the same chip 30 may be inspected a plurality of times with different electrical conditions. Therefore, when each chip 30 is inspected, each pad 40 of each chip 30 may already have a needle mark by the probe needle 8a. In the figure, one chip 30 (for example, chip 30a in FIG. 4) of each chip 30 is inspected as an inspection object, and another chip 30 (for example, chip 30e in FIG. 4) before the inspection. Will be described on the assumption that the same inspection is performed.

  As shown in the figure, first, the probe inspection apparatus 100 determines the contact position of the probe needle 8a based on the correction amount calculated in the inspection of the other chip 30 that is the inspection target immediately before the current inspection. Is corrected (step 101). Details of this operation will be described later.

  Subsequently, the CPU 21 of the image processing PC 10 of the probe inspection apparatus 100 determines whether or not an image after contact at the previous inspection is stored in the HDD 25 in the same chip 30 as the current inspection target chip 30. (Step 102). If the previous post-contact image is stored (Yes in step 102), the post-contact image is read from the HDD 25 to be used as the pre-contact image in the current examination (step 103).

  When the image after the previous contact is not stored (that is, when contact is made for the first time with respect to each pad 40 of the one chip 30), the CPU 21 targets the inspection of the wafer 1 to the lower side of the CCD camera 6. The chip 30 is moved, and the CCD camera 6 is caused to capture the pre-contact image of each pad 40 (step 104).

  FIG. 6 is a diagram showing an imaging trajectory of the CCD camera 6 on one chip 30. As shown in the figure, the CPU 21 causes the CCD camera 6 to pick up the imaging position on the chip 30 in the counterclockwise direction, starting from, for example, the uppermost pad 40 on the left side among the pads 40 of the chip 30. The motor drive signal is output to the motor 4 so that the pre-contact images of all the pads 40 are continuously captured. Since the position of the CCD camera 6 itself is fixed at the time of imaging, the stage 3 moves in the opposite direction (clockwise direction) to the locus shown in FIG. The CCD camera 6 continuously flashes images of the pads 40 under the flash from the light source 7 based on the trigger signal output from the CPU 21 in accordance with this movement. Each captured pre-contact image is stored in a buffer area of the RAM 23, for example.

  Subsequently, the CPU 21 retracts the CCD camera 6 from above the chip 30 to be inspected, and then outputs a motor drive signal for moving the stage 3 in the Z1 direction to the motor 4. Each probe needle 8a of the probe card 8 is brought into contact with each pad 40 (step 105). In this state, a voltage is applied from the tester 9 to each pad 40 via the probe needle 8a, and an output value from each pad 40 is measured.

  When the contact and measurement are completed, the CPU 21 moves the chip 30 to be inspected to the lower side of the CCD camera 6 and captures an image after contact of each pad 40 (step 106). That is, in the same manner as the imaging of the pre-contact image, the CPU 21 continuously images each pad 40 after the contact of each probe needle 8a while the CCD camera 6 moves as shown in FIG. The motor drive signal is output to the motor 4 and the trigger signal is output to the CCD camera 6. The image after each contact of each imaged pad 40 is stored in a buffer area of the RAM 23 or the like.

  Next, the CPU 21 extracts the difference between the pre-contact image and the post-contact image of each pad 40 as a difference image (step 107). FIG. 7 is a diagram conceptually showing how the difference image is extracted from one of the pads 40.

  As shown in the figure, the pre-contact image 51 shows that one pad mark 41 a is attached to the pad 40. The needle trace 41a is a needle trace attached by contact in the previous inspection for the chip 30 to be inspected. Further, the post-contact image 52 shows that the pad 40 has another needle trace 41b in addition to the needle trace 41a. The needle trace 41b is a needle trace attached by the contact (step 105 above) in the current examination.

  The CPU 21 extracts the difference image 53 by performing image processing that takes the difference between the pre-contact image 51 and the post-contact image 52. In the difference image 53, only the needle trace 41b in the post-contact image 52 appears. That is, by the extraction process of the difference image 53, even when the chip 30 is contacted a plurality of times, only the latest needle trace can be extracted, and the needle trace which is a correction target of the positional deviation in the current examination. Can be specified. The extraction process of the difference image 53 is performed for all the pads 40 on the chip 30 to be inspected this time.

  Subsequently, the CPU 21 recognizes the needle trace 41b appearing in the extracted difference image 53 for all the pads 40 of the chip 30 to be inspected this time, and this needle trace 41b and a preset target position of the needle trace. (Step 108). This positional deviation is caused by, for example, deterioration over time due to an increase in the number of contacts of each probe needle 8a. Further, in the probe inspection apparatus 100, for example, a test may be performed by applying heat to the pad 40 from the tester 9 via the probe needle 8a (so-called thermal stress inspection). Misalignment may occur.

  FIG. 8 is a diagram conceptually showing a process for calculating the positional deviation amount in one of the pads 40. In the probe inspection apparatus 100 of the present embodiment, for example, the center of the pad 40 is set as the target position of the contact, and this target position data (coordinate data) is stored in the HDD 25 or the like. On the other hand, as shown in the figure, in the difference image 53, the needle trace 41b in the current examination appears at a position shifted in the + direction in the X coordinate and in the − direction in the Y coordinate, where the center of the pad 40 is the origin. Yes. Therefore, there is a positional deviation amount corresponding to the vector a in the figure between the needle trace 41b and the target position. The CPU 21 recognizes the needle trace 41b from the difference image 53 by image processing such as binarization processing, for example, and calculates the positional deviation amount by comparing the target position data with the center coordinates of the needle trace 41b. . The CPU 21 performs this process for all the pads 40 of the chip 30 to be inspected this time.

  Next, the CPU 21 calculates a correction amount for the probe card 8 as a whole based on the calculated amount of displacement in each pad 40 (step 109). FIG. 9 is a diagram illustrating a state in which the latest needle traces 41 b are attached to the plurality of pads 40 of the chip 30. In the figure, for convenience of explanation, the needle trace 41a in the previous inspection is not shown. As shown in the figure, the amount of misalignment of the needle marks 41 b in each pad 40 may vary from pad 40 to pad 40. This may occur due to a design error of the probe card 8 or may depend on the progress of aging deterioration or the like for each probe needle 8a. The CPU 21 moves the probe card 8 as a whole so that the amount of positional deviation different for each pad 40 approaches 0 as much as possible, that is, the coordinates of each needle trace 41b and the coordinates of each target position are approximated as much as possible. A correction amount as a quantity is calculated. This calculation is performed by using a known method such as a least square method. This correction amount is calculated in consideration of not only movement of the probe card 8 in the XY direction but also movement in the θ direction. The calculated correction amount data is stored in the HDD 25.

  Subsequently, the CPU 21 erases the data of the pre-contact image 51 from the buffer area of the RAM 23 (step 110). Since the pre-contact image 51 is necessary only for the extraction of the differential image 53, the used capacity of the RAM 23 can be reduced by deleting the pre-contact image 51 after the differential image 53 is extracted. Of course, this erasing process may be performed before the calculation process of each positional deviation amount and correction amount.

  Next, the CPU 21 writes the data of each post-contact image 52 from the buffer area of the RAM 23 to the HDD 25 (step 111). At this time, the CPU 21 stores each post-contact image 52 in the HDD 25 in association with the chip ID for identifying the chip 30 to be inspected this time and the pad ID for identifying each pad 40 of the chip 30. As a result, when the chip 30 to be inspected at this time is to be inspected again later, the post-contact image 52 stored in the HDD 25 is read with reference to the chip ID and the pad ID, and in the second inspection It can be used as the pre-contact image 51. Therefore, the pre-contact image capturing process in step 106 is not necessary, the processing load related to the image capturing process is greatly reduced, and the storage capacity of the RAM 23, HDD 25, etc. is reduced.

  Each post-contact image is stored in, for example, a monochrome BMP (BitMaP) data format. While the use capacity of the HDD 25 is suppressed as much as possible by using a monochrome image instead of a color, the time required for writing to the HDD 25 is shortened by using an uncompressed format. Of course, it may be a color image or an image in a compression format such as JPEG (Joint Photographic Experts Group) or GIF (Graphic Interchange Format).

  Then, the CPU 21 completes the inspection of the chip 30 to be inspected this time (for example, the chip 30a in FIG. 4), and the probe card 8 inspects another chip 30 to be inspected next (for example, the chip 30b in FIG. 4). When the stage 3 moves as described above, as a pre-process for the inspection, the stage 3 is moved based on the correction amount calculated in the step 109, and the positional deviation correction is performed as in the process of the step 101. (Step 112). In this case, when viewed in units of pads 40, for example, the amount of displacement in the pad 40a existing at a predetermined position (for example, the third position from the top of the left side row) on the chip 30a to be inspected this time shown in FIG. Is corrected in the pad 40b that exists at the same position as the pad 40a on the next chip 30b to be inspected. The other chip 30 to be inspected next is usually a chip adjacent to the chip 30 to be inspected this time, but may not be an adjacent chip.

  The CPU 21 repeats the above processing for all the chips 30 to be inspected. As a result, the correction amount calculated in the inspection of the chip 30 that is the previous inspection object can be reflected in feedback control in the inspection of the next chip 30. Further, when the inspection for all the chips 30 of one wafer 1 is completed, the CPU 21 performs the same process for each chip 30 of a different wafer 1 to be inspected next.

  As described above, in the present embodiment, even when a plurality of probe inspections are performed on each pad 40 of each chip 30 and a plurality of needle marks are attached, from the pre-contact image 51 and the post-contact image 52, A difference image 53 is extracted, a positional deviation amount between the position of the latest needle trace 41b and the target position in the differential image 53 is calculated for each pad 40, and a correction amount as a whole of the probe card 8 is calculated from each positional deviation amount. And the correction amount is reflected in the next inspection of the tip 30 to be inspected, so that the contact position of the probe needle 8a can always be kept at the target position.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  In the above-described embodiment, the center position of the pad 40 is the target position of the probe needle 8a. However, the position is not limited to this position. For example, there is a case where one pad 40 is divided into a plurality of regions and used for a plurality of contacts in an inspection under different electrical conditions. FIG. 10 is a diagram showing an image 51 before contact, an image 52 after contact, and a difference image 53 in the inspection in this case.

  As shown in FIG. 5A, in the pre-contact image 51, the needle mark 41a is attached to the region 80a among the four regions 80a to 80d of the pad 40. This is a needle mark attached at the time of the previous inspection of the chip 30. At the time of this previous inspection, the center position of the region 80a is set as the target position.

  As shown in FIG. 4B, the post-contact image 52 has a needle mark 41b around the boundary between the region 80b and the region 80c. However, in this inspection, since the center position of the region 80b becomes the target position, there is a positional deviation between the target position and the needle trace 41b.

  Therefore, as shown in FIG. 5C, the CPU 21 shifts the position of the needle mark 41b at the center position of the region 80b in each pad 40 of the other chip 30 to be inspected next to the chip 30. The amount is calculated, and the correction amount is calculated based on the positional deviation amount of each pad 40.

  In the above-described embodiment, the probe card 8 has the probe needle 8a so as to correspond to the contact to each pad 40 of one chip. However, the probe card 8 contacts the pads 40 of the plurality of chips 30 at a time. The present invention can also be applied to a case where an inspection is performed using a probe card 8 having a corresponding probe needle 8a. In this case, the CCD camera 6 continuously images each pad 40 for each chip 30, and the CPU 21 calculates the amount of positional deviation in each pad 40 for each chip 30, and each positional deviation amount corresponds to each of the plurality of chips 30. The correction amount of the probe card 8 as a whole is calculated so that the pad 40 approaches 0 as much as possible.

  In the above-described embodiment, the post-contact image 52 is stored in the HDD 25. However, if the capacity of the RAM 23 is sufficient, the post-contact image 52 is stored in the RAM 23 without being stored in the HDD 25. May be. Thereby, the writing time and reading time of the post-contact image 52 can be shortened to improve the processing efficiency.

  In the above-described embodiment, the chip ID and the pad ID are stored in the HDD 25 of the image processing PC 10. However, the chip ID and the pad ID are managed together with the wafer ID for identifying each wafer 1. The server may be prepared separately.

  In the embodiment described above, images before and after contact are prepared for all the pads 40 of the chip 30 to be inspected, and the correction amount is calculated based on the positional deviation amount in all the pads 40. Alternatively, the images before and after the contact may be captured only for an arbitrary number (for example, four) of pads 40, and the correction amount may be calculated based on the positional deviation amount of the arbitrary number of pads 40. Thereby, it is possible to reduce the processing load related to the imaging process, the difference image extraction process, the correction amount calculation process, and the like, and to shorten the processing time. In addition, the user may arbitrarily set the number of pads 40 to be subjected to correction amount calculation processing via the operation input unit 27 or the like. However, it is preferable to use all the pads 40 as processing targets from the viewpoint of improving the accuracy of correcting the positional deviation amount. Even with such processing, the processing time can be shortened by continuously performing high-speed scanning imaging of each pad 40 with the CCD camera 6.

  In the above-described embodiment, the latest needle trace is detected by capturing images before and after contact when the probe needle 8a contacts each pad 40 of each chip 30 and extracting a difference image from both images. However, for example, the state of each pad 40 at the moment of contact with the probe needle 8a may be captured by a separately provided camera. As a result, even if the pad 40 had a needle mark before that, the latest contact position can be grasped and the amount of displacement can be calculated as long as the captured image exists. The burden will be reduced.

It is the figure which showed the structure of the probe test | inspection apparatus which concerns on one Embodiment of this invention. It is the block diagram which showed the structure of PC for image processing in one Embodiment of this invention. It is a top view of the wafer in one embodiment of the present invention. It is an enlarged top view of each chip | tip of the wafer in one Embodiment of this invention. 5 is a flowchart showing a flow of operations in the case where the electrical characteristics of each chip are inspected in an embodiment of the present invention. In one Embodiment of this invention, it is the figure which showed the imaging locus of the CCD camera on one chip | tip. It is the figure which showed notionally the mode that a difference image is extracted in one Embodiment of this invention. It is the figure which showed notionally the calculation process of the amount of positional deviation in one Embodiment of this invention. It is the figure which showed a mode that the latest needle trace was attached to the some pad of the chip | tip in one Embodiment of this invention. In other embodiment of this invention, it is the figure which showed the image before contact, the image after contact, and a difference image at the time of dividing one pad into a some area | region and setting the target position of a contact for every area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Stage 4 ... Motor 5 ... Encoder 6 ... CCD camera 7 ... Light source 8 ... Probe card 8a ... Probe needle 9 ... Tester 10 ... Image processing PC
14 ... Lens 21 ... CPU
23 ... RAM
25 ... HDD
30 ... Semiconductor chip (chip, die)
40 ... Electrode pad (pad)
DESCRIPTION OF SYMBOLS 41 ... Needle trace 51 ... Image before contact 52 ... Image after contact 53 ... Difference image 100 ... Probe inspection apparatus

Claims (9)

A probe inspection apparatus for inspecting the electrical characteristics of the object to be inspected by bringing a probe needle into contact with an electrode pad of the object to be inspected,
Imaging means for imaging each of the electrode pad before contact of the probe needle to the object to be inspected and the electrode pad after contact of the probe needle;
Storage means for storing the imaged image of the electrode pad before contact as a first image, and storing the imaged image of the electrode pad after contact as a second image;
Difference extraction means for extracting a difference between the stored first image and the second image as a difference image;
A calculation means for calculating a correction amount for correcting a positional deviation between a needle trace position of the probe needle appearing in the extracted difference image and a target position on the electrode pad to be brought into contact with the probe needle;
A probe inspection apparatus comprising: correction means for correcting the positional deviation by varying a relative position between the object to be inspected and the probe needle based on the calculated correction amount. The probe inspection apparatus according to claim 1,
When the inspection of the electrical characteristics by contact with the probe needle is performed a plurality of times on the electrode pad, the imaging unit controls the imaging of the first image in the next inspection of one time. Further comprising a regulating means to
The storage means stores the image stored as the second image in the first inspection as the first image in the next inspection. The probe inspection apparatus according to claim 2,
The probe inspection apparatus according to claim 1, wherein the storage unit includes a unit that deletes the first image after the difference extraction. The probe inspection apparatus according to claim 2,
The object to be inspected is a semiconductor wafer having a plurality of semiconductor chips provided with a plurality of the electrode pads,
A plurality of the probe needles exist so as to be able to contact each electrode pad of one semiconductor chip among the semiconductor chips at a time,
The imaging means can continuously capture the first and second images of the electrode pads of the one semiconductor chip,
The storage means includes the second image of each electrode pad, first identification information for identifying the one semiconductor chip, and second identification information for identifying each electrode pad of the one semiconductor chip. Is stored in association with
The calculation means calculates a correction amount for correcting each positional deviation between the needle trace position of each probe needle and each target position on each electrode pad at a time. . The probe inspection apparatus according to claim 1,
The object to be inspected is a semiconductor wafer having a plurality of semiconductor chips provided with a plurality of the electrode pads,
A plurality of the probe needles are present for each of the at least two semiconductor chips so as to be able to contact each electrode pad of each of at least two semiconductor chips of the semiconductor chips at a time,
The imaging means can continuously capture the first and second images of the electrode pads of the at least two semiconductor chips, respectively.
The storage means identifies the second image of each of the electrode pads, first identification information for identifying the at least two semiconductor chips, and a first identification information for identifying the electrode pads of the at least two semiconductor chips, respectively. 2 in association with the identification information of 2,
The calculation means calculates a correction amount for correcting each positional deviation between the needle trace position of each probe needle and each target position on each electrode pad in the at least two semiconductor chips at a time. Probe inspection device characterized by the above. A positional deviation correction method in a probe inspection apparatus for inspecting the electrical characteristics of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object,
Imaging each of the electrode pads before contact of the probe needle to the object to be inspected and the electrode pads after contact of the probe needle;
Storing the imaged image of the electrode pad before contact as a first image and storing the imaged image of the electrode pad after contact as a second image;
Extracting a difference between the stored first image and the second image as a difference image;
Calculating a correction amount for correcting a positional deviation between a needle trace position of the probe needle appearing in the extracted difference image and a target position on the electrode pad with which the probe needle should be brought into contact;
And a step of correcting the positional shift by varying a relative position between the object to be inspected and the probe needle based on the calculated correction amount. An information processing apparatus used in a probe inspection apparatus for inspecting the electrical characteristics of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object,
A memory for storing a first image obtained by imaging the electrode pad before contact of the probe needle with the subject and a second image obtained by imaging the electrode pad after contact with the probe needle, respectively. Means,
Difference extraction means for extracting a difference between the stored first image and the second image as a difference image;
Calculating means for calculating a correction amount for correcting a positional deviation between the needle trace position of the probe needle appearing in the extracted difference image and a target position on the electrode pad to which the probe needle should be brought into contact; An information processing apparatus comprising the information processing apparatus. An information processing method in an information processing apparatus used in a probe inspection apparatus for inspecting electrical characteristics of the inspection object by bringing a probe needle into contact with an electrode pad of the inspection object,
Storing a first image obtained by imaging the electrode pad before contact of the probe needle with the subject and a second image obtained by imaging the electrode pad after contact with the probe needle, respectively; When,
Extracting a difference between the stored first image and the second image as a difference image;
Calculating a correction amount for correcting a positional deviation between a needle trace position of the probe needle appearing in the extracted difference image and a target position on the electrode pad to which the probe needle is to be brought into contact. An information processing method characterized by: In an information processing apparatus used in a probe inspection apparatus for inspecting the electrical characteristics of the inspection object by bringing a probe needle into contact with the electrode pad of the inspection object,
Storing a first image obtained by imaging the electrode pad before contact of the probe needle with the subject and a second image obtained by imaging the electrode pad after contact with the probe needle, respectively; When,
Extracting a difference between the stored first image and the second image as a difference image;
Performing a step of calculating a correction amount for correcting a positional deviation between a needle trace position of the probe needle appearing in the extracted difference image and a target position on the electrode pad to which the probe needle is to be brought into contact. Program to let you.

Images