Prober and alignment method

Abstract

To provide a prober and an alignment method capable of accurately aligning a transfer arm and a wafer chuck relative to each other.SOLUTION: A prober includes a transport arm 24 for transporting a wafer W, a wafer chuck 34 for holding the wafer W, a needle alignment camera 48 that can move integrally with the wafer chuck 34, a calculation unit 54 that calculates the relative positional relationship between the wafer chuck 34 and the transport arm 24 on the basis of image data of the transport arm 24 photographed by the needle alignment camera 48, and a control unit 58 that corrects the position of at least one of the wafer chuck 34 and the transport arm 24 on the basis of the positional relationship.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a prober for inspecting the electrical characteristics of a plurality of semiconductor devices (chips) formed on a semiconductor wafer.

Background Art

[0002] The semiconductor manufacturing process has a number of processes, and various inspections are performed in various manufacturing processes for quality assurance and yield improvement. For example, at the stage where a plurality of chips of semiconductor devices are formed on a semiconductor wafer, the electrode pads of the semiconductor devices of each chip are connected to a test head, a power supply and test signals are supplied from the test head, and the signals output by the semiconductor devices are measured by the test head to electrically inspect whether they operate normally. Wafer-level inspection is being performed.

[0003] After wafer-level inspection, the wafer is attached to a frame and cut into individual chips by a dicing saw. Only the chips that have been confirmed to operate normally among the cut chips are packaged in the next assembly process, and the malfunctioning chips are excluded from the assembly process. Further, the packaged final product is subjected to a shipping inspection.

[0004] Wafer-level inspection is performed using a prober that brings probes into contact with the electrode pads of each chip on a wafer held by a wafer chuck. The probes are electrically connected to the terminals of the test head, and a power supply and test signals are supplied from the test head to each chip via the probes, and the output signals from each chip are detected by the test head to measure whether they operate normally.

[0005] By the way, when inspecting a wafer with a prober, it is necessary to supply (load) the wafer to be inspected to the wafer chuck and recover (unload) the inspected wafer from the wafer chuck. The supply and recovery of the wafer are performed by a loader unit. In this specification, the whole including the prober and the loader unit will be referred to as a "prober".

[0006] Generally, the loader section in a prober includes a load port on which a wafer cassette is placed, and a wafer transfer unit that transfers wafers between a wafer chuck and the wafer cassette. The wafer transfer unit has a transfer arm, inserts the tip of the transfer arm into the wafer cassette to take out a wafer, and transfers it to the wafer chuck.

[0007] In recent years, multi-stage probers equipped with a plurality of measurement sections have emerged. In a multi-stage prober, a wafer chuck is arranged in each measurement section (stage), and inspections of wafers held by the wafer chucks in each measurement section can be performed simultaneously. In a prober where the stages are adjacent to and connected to each other like this, the adjustment of the transfer between the transfer arm and the wafer chuck is a burden on the work due to the limited space.

[0008] In response to such problems, Patent Document 1 describes a prober that measures the outer shape of a wafer loaded on a wafer chuck with an alignment camera and adjusts the transfer position by obtaining the difference between the center position of the wafer chuck and the center position of the wafer.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, it is assumed that the transfer position of the prober described in Patent Document 1 has been adjusted in advance to such an extent that the wafer does not protrude from the wafer chuck. For this reason, there is a problem that adjustment of the transfer position by visual inspection by an operator is necessary immediately after the assembly of the apparatus.

[0011] The present invention has been made in view of such circumstances, and an object thereof is to provide a prober that automates the adjustment of the transfer position of a wafer from a transfer arm to a wafer chuck or the transfer position from the wafer chuck to the transfer arm, and achieves high speed and high precision.

Means for Solving the Problems

[0012] In order to achieve the above object, the following invention is provided.

[0013] A prober according to a first aspect of the present invention includes a transfer arm for transferring a wafer, a wafer chuck for receiving and holding the wafer from the transfer arm, a camera having a known relative first positional relationship with the wafer chuck, and based on the first positional relationship and the image data of the transfer arm captured by the camera, a calculation unit that calculates a relative second positional relationship between a first position of the transfer arm when delivering the wafer to the wafer chuck and a second position of the wafer chuck when receiving the wafer, and a control unit that corrects at least one of the first position and the second position based on the second positional relationship.

[0014] A prober according to a second aspect of the present invention includes a transfer arm for transferring a wafer, a wafer chuck for receiving and holding the wafer from the transfer arm, a camera having a known relative first positional relationship with the wafer chuck, and based on the first positional relationship and the image data of the transfer arm captured by the camera, a calculation unit that calculates a relative second positional relationship between a first position of the transfer arm when receiving the wafer from the wafer chuck and a second position of the wafer chuck when delivering the wafer, and a control unit that corrects at least one of the first position and the second position based on the second positional relationship.

[0015] In a prober according to a third aspect of the present invention, in the first aspect or the second aspect, a reference mark is arranged on the transfer arm, and the calculation unit calculates the second positional relationship based on the position of the reference mark captured by the camera.

[0016] In the probe according to the fourth aspect of the present invention, in the third aspect, a plurality of reference marks are arranged on the transfer arm, and the calculation unit calculates a second positional relationship based on the positions of the plurality of reference marks photographed by the camera.

[0017] In the probe according to the fifth aspect of the present invention, in the fourth aspect, the calculation unit calculates a second horizontal positional relationship based on the average value of the horizontal positions of the plurality of reference marks.

[0018] In the probe according to the sixth aspect of the present invention, in the fourth or fifth aspect, the calculation unit calculates a second vertical positional relationship based on the minimum value of the vertical positions of the plurality of reference marks.

[0019] The probe according to the seventh aspect of the present invention includes a probe card having a plurality of probes in any one of the first to sixth aspects, and the camera is a needle alignment camera for detecting the tip position of the probe.

Advantages of the Invention

[0020] According to the present invention, it is possible to automate the adjustment of the wafer transfer position from the transfer arm to the wafer chuck or from the wafer chuck to the transfer arm, and to achieve high speed and high precision.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiment for Carrying Out the Invention

[0022] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0023] 〔Configuration of Prober〕 FIG. 1 and FIG. 2 are a schematic plan view and a schematic side view of a prober 10 according to the present embodiment. In FIG. 1, the configuration of the wafer transfer unit 22 is schematically shown.

[0024] As shown in FIGS. 1 and 2, the prober 10 includes a loader unit 14 that supplies and recovers a wafer W (see FIG. 2) to be inspected, and a measurement unit 12 disposed adjacent to the loader unit 14. The measurement unit 12 has a plurality of measurement units 16. When the wafer W is supplied from the loader unit 14 to each measurement unit 16, each measurement unit 16 inspects the electrical characteristics of each chip of the wafer W (wafer-level inspection). Then, the wafer W inspected by each measurement unit 16 is recovered by the loader unit 14. The prober 10 includes a control device 50 (see FIG. 4) described later.

[0025] The loader unit 14 has a load port 18 on which a wafer cassette 20 is placed, and a wafer transfer unit 22 that transfers the wafer W between each measurement unit 16 of the measurement unit 12 and the wafer cassette 20.

[0026] The wafer transfer unit 22 includes a transfer arm 24 (see FIG. 2). The transfer arm 24 is composed of a multi-joint robot arm. An adsorption pad (not shown) is provided on the adsorption surface (holding surface) of the transfer arm 24. The transfer arm 24 transfers the wafer W while adsorbing and holding it with this adsorption pad. In the present embodiment, the transfer arm 24 is of a twin-arm type, but is not limited thereto, and for example, a single-arm type may be used.

[0027] On one or more locations on the lower surface (the surface opposite to the suction surface) of the transfer arm 24, alignment reference marks are provided. FIG. 3 is a bottom view of the transfer arm 24. In the example shown in FIG. 3, N reference marks M1, M2, … M N are arranged. Here, the reference marks M1, M2, … M N are each in a cross shape (also referred to as a + shape or a cruciform shape) when viewed in the Z direction, but the shapes of the reference marks M1, M2, … M N are not limited to the cross shape, and may be circular, rectangular, etc., as long as they are shapes recognizable as reference marks.

[0028] The reference marks M1, M2, … M N are arranged such that the reference position of the transfer arm 24 can be specified. Here, the reference marks M1, M2, … M N are arranged such that the average of the positions of the reference marks M1, M2, … M N becomes the center position of the transfer arm 24. The center position of the transfer arm 24 is the position that coincides with the center position of the wafer W when the wafer is placed on the transfer arm 24 without deviation. Note that the reference position of the transfer arm 24 is not limited to the center position, and any position where the position of the wafer W placed on the transfer arm 24 can be specified is acceptable. The positions of the reference marks M1, M2, … M N in each transfer arm 24 are stored in the memory unit 52.

[0029] Returning to the descriptions of FIGS. 1 and 2, the transfer arm 24 is supported on the X stage 26 via the rotary lifting member 28. The X stage 26 is configured to be movable in the X direction by an X drive mechanism (not shown). Therefore, when the X stage 26 is moved in the X direction by the X drive mechanism, the transfer arm 24 can be moved in the X direction integrally with the X stage 26. Since the X drive mechanism is well-known, detailed description thereof is omitted.

[0030] The rotary lifting member 28 is disposed between the X-stage 26 and the wafer transfer unit 22. The rotary lifting member 28 is configured to be rotatable in the θ direction (around the Z direction) and movable (liftable) in the Z direction by a rotary lifting mechanism (not shown). Therefore, the transfer arm 24 supported on the upper part of the rotary lifting member 28 can rotate and move up and down integrally with the rotary lifting member 28 in accordance with the rotation and lifting of the rotary lifting member 28. Since the rotary lifting mechanism is well-known, a detailed description thereof will be omitted.

[0031] With such a configuration, the wafer transfer unit 22 can move three-dimensionally between the load port 18 and an arbitrary measurement unit 16 by the X drive mechanism and the rotary lifting mechanism, and the transfer arm 24 can access each position. As a result, the wafer W in the wafer cassette 20 is taken out by the transfer arm 24 of the wafer transfer unit 22 and transferred to each measurement unit 16 of the measurement unit 12 while being held on the suction surface of the transfer arm 24. Further, the inspected wafer W after the inspection is returned to the wafer cassette 20 from each measurement unit 16 through the reverse path.

[0032] The measurement unit 12 includes a plurality of measurement units 16. Since the plurality of measurement units 16 constituting the measurement unit 12 in the present embodiment have the same configuration, one of them will be described as a representative.

[0033] As shown in FIG. 2, the measurement unit 16 includes a head stage 30, a probe card 32, a wafer chuck 34, an alignment camera 46, and a needle alignment camera 48.

[0034] The head stage 30 constitutes the upper plate of the housing of the measurement unit 16. An opening for attaching the probe card 32 is formed in the head stage 30, and the probe card 32 is detachably attached and fixed to this opening. The probe card 32 is exchanged according to the wafer W (device) to be inspected.

[0035] On the upper surface of the head stage 30, a plurality of docking plates 38 are provided to fix the test head 36 at a predetermined position. Each docking plate 38 includes a drive cylinder composed of an air cylinder or the like, and a pin member that can move up and down according to the expansion and contraction of the drive cylinder. Thus, in a state where the test head 36 is placed on the plurality of docking plates 38, each docking plate 38 can move the test head 36 between a position where the test head 36 is brought close to the head stage 30 (mounting position) and a position where the test head 36 is separated from the head stage 30 (non-mounting position) by using the drive cylinder and the pin member. When the test head 36 is moved to the mounting position by each docking plate 38, the contact portion 36a of the test head 36 and the probe card 32 are configured to be electrically connected.

[0036] The probe card 32 is provided with a plurality of probes 40 such as cantilevers and spring pins arranged corresponding to the positions of the electrode pads of each chip of the wafer W to be inspected. Each probe 40 is electrically connected to the terminal of the test head 36, and power and test signals are supplied from the test head 36 to each chip through each probe 40, and the output signal from each chip is detected by the test head to measure whether it operates normally. Since the connection configuration between the probe card 32 and the test head 36 is not a main part of the present invention, a detailed description thereof is omitted.

[0037] The probe 40 has spring characteristics and contacts the electrode pad with a predetermined contact pressure by raising the contact point above the tip position of the probe 40. Further, when an electrical inspection is performed, if the electrode pad is contacted in an overdrive state, the tip of the probe 40 sinks into the surface of the electrode pad, and stitch marks are formed on the surface of the electrode pad, respectively. Note that overdrive refers to a state in which the surface of the wafer W is raised by a predetermined distance (this distance is also referred to as the "overdrive amount") to a position higher than the tip position of the probe 40 so that the electrode pad and the probe 40 are surely contacted, taking into account the inclination between the wafer W and the arrangement surface of the tip of the probe 40, and the variation in the tip position of the probe 40.

[0038] The wafer chuck 34 holds the wafer W. The wafer chuck 34 has a holding surface 34a on which the wafer W to be inspected is placed, and a plurality of suction ports (not shown) are provided on the holding surface 34a. Each suction port is connected to a suction device (not shown) such as a vacuum pump via a suction pipe line (not shown). Therefore, by applying a negative pressure to each suction port using the suction device, the wafer W placed on the wafer chuck 34 (holding surface 34a) is held by vacuum suction.

[0039] Inside the wafer chuck 34, a heating / cooling mechanism (not shown) as a heating / cooling source is provided so that the electrical characteristics of the wafer W to be inspected can be inspected in a high-temperature state (for example, up to 150 °C) or a low-temperature state (for example, as low as -40 °C). As the heating / cooling mechanism, a known appropriate heater / cooler can be adopted. For example, a double-layer structure including a heating layer of a surface heater and a cooling layer provided with a passage for a cooling fluid, or a heating / cooling device having a single-layer structure in which a cooling pipe with a heating heater wound around a heat conductor is buried can be considered. Further, instead of electric heating, a device that circulates a heat fluid may be used, or a Peltier element may be used.

[0040] The wafer chuck 34 is supported by the XY stage 44 via the rotary lifting member 42. The rotary lifting member 42 is configured to be rotatable in the θ direction (around the Z direction) and movable in the Z direction (liftable) by a rotary lifting mechanism (not shown). Therefore, the wafer chuck 34 supported on the upper part of the rotary lifting member 42 can rotate and move up and down integrally with the rotary lifting member 42 in accordance with the rotation and lifting of the rotary lifting member 42. Since the rotary lifting mechanism is well-known, a detailed description thereof will be omitted.

[0041] The XY stage 44 is configured to be movable in the X direction and the Y direction by an XY drive mechanism (not shown). Therefore, the wafer chuck 34 supported by the XY stage 44 via the rotary lifting member 42 can move in the X direction and the Y direction integrally with the XY stage 44. Since the XY drive mechanism is well-known, a detailed description thereof will be omitted.

[0042] The alignment camera 46 is provided for aligning the wafer W on the wafer chuck 34. The alignment camera 46 is attached to the lower surface of the head stage 30 and is disposed at a position displaced horizontally (Y direction) from the probe card 32.

[0043] The alignment camera 48 is provided for detecting the position of the probe 40. The alignment camera 48 is provided on the XY stage 44 and can move in the X direction and the Y direction integrally with the XY stage 44. Further, the alignment camera 48 is configured to be movable in the Z direction by a lifting mechanism (not shown), and it is possible to adjust the focus position of the alignment camera 48 with respect to the imaging object. The relative first positional relationship between the focus position, which is the reference position of the alignment camera 48, and the wafer chuck 34 is known.

[0044] In the probe 10 configured as described above, when performing wafer-level inspection, the XY stage 44 is moved so that the alignment camera 48 is positioned under the probe 40, and the tip position of the probe 40 is detected by the alignment camera 48. The position (X coordinate and Y coordinate) of the tip of the probe 40 in the horizontal plane is detected based on the coordinates of the alignment camera 48, and the height position (Z coordinate) of the tip of the probe 40 is detected at the focal position of the alignment camera 48. This probe position detection process must be performed whenever the probe card 32 is replaced, and is also appropriately performed every time a predetermined number of chips are measured even when the probe card 32 is not replaced. Since a large number of probes 40 are provided on the probe card 32, the tip positions of all the probes 40 are not detected, and usually, the tip positions of specific probes 40 are detected in consideration of work efficiency.

[0045] Next, a wafer transfer process (wafer load) for transferring the wafer W from the loader unit 14 to the wafer chuck 34 of a predetermined measurement unit 16 is performed. In the wafer transfer process, the wafer W in the wafer cassette 20 is taken out by the transfer arm 24, and the wafer W is transferred and delivered to the wafer chuck 34 of a predetermined measurement unit 16 while being held on the suction surface of the transfer arm 24. At this time, the wafer chuck 34 moves to a predetermined delivery position (the position indicated by the two-dot chain line in FIG. 2) by the movement of the XY stage 44. Then, the wafer W is delivered from the transfer arm 24 to the wafer chuck 34 that has moved to the delivery position, and the wafer W is held by the wafer chuck 34.

[0046] The transfer of the wafer W from the transfer arm 24 to the wafer chuck 34 is performed as follows. For example, a plurality of chuck pins (not shown) provided on the wafer chuck 34 rise from the wafer chuck 34 to support the wafer W conveyed by the transfer arm 24 from below. Then, after the transfer arm 24 retracts, the plurality of chuck pins descend, and the wafer W is placed on the holding surface 34a. Alternatively, the transfer arm 24 may be inverted while the wafer W is held on the suction surface, and the wafer W may be placed on the holding surface 34a. Thus, the position of the wafer W conveyed by the transfer arm 24 needs to be within a certain range in the horizontal and vertical directions from the transfer position of the wafer chuck 34.

[0047] When the wafer W is held by the wafer chuck 34, the alignment camera 46 detects the positions of the electrode pads of each chip on the wafer W. It is not necessary to detect the positions of all the electrode pads of one chip; it is sufficient to detect the positions of some of the electrode pads. Also, it is not necessary to detect the electrode pads of all the chips on the wafer W; the positions of the electrode pads of some chips are detected. Then, the wafer chuck 34 is rotated by the rotation lifting member 42 so that the arrangement direction of the chip electrode pads coincides with the arrangement direction of the probes 40. After that, the wafer chuck 34 is moved by the XY stage 44 so that the electrode pads are positioned directly below the corresponding probes 40. Then, the wafer chuck 34 is lifted by the rotation lifting member 42 to bring the electrode pads into contact with the probes 40. Then, a power supply and a test signal are supplied to the electrode pads from the test head 36 via the contact portion 36a, and the signal output from the electrode pads is detected to confirm whether it operates normally.

[0048] The probe 10 has a function of performing a transfer adjustment process for automatically adjusting the transfer position when the wafer W is transferred between the loader unit 14 and the wafer chuck 34. In this transfer adjustment process, the alignment camera 48 is used to calculate the amount of misalignment between the transfer position of the transfer arm 24 and the transfer position of the wafer chuck 34, and at least one of the transfer position of the transfer arm 24 and the transfer position of the wafer chuck 34 is automatically adjusted so that the amount of misalignment is within the allowable range.

[0049] 〔Configuration of the control device〕 FIG. 4 is a functional block diagram showing the main configuration of the control device 50 of the probe 10. In FIG. 4, only the components related to the transfer adjustment process, which is the main part of the present invention, are shown.

[0050] The control device 50 is realized by a general-purpose computer such as a personal computer or a microcomputer. The control device 50 includes a processor such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and other peripheral circuits, and performs a process of realizing the functions of each part of the control device 50 shown in FIG. 4 by executing a predetermined operation program using these.

[0051] As shown in FIG. 4, the control device 50 functions as a memory unit 52, a calculation unit 54, and a control unit 58.

[0052] The memory unit 52 stores various setting information in the probe 10. Specifically, the memory unit 52 stores the set position of the transfer arm 24 and the set position (reference position) of the wafer chuck 34 as the transfer positions, and also stores the amount of misalignment calculated by the calculation unit 54 described later. Further, the memory unit 52 stores the installation position of the reference mark disposed on the transfer arm 24.

[0053] The calculation unit 54 acquires the image data of the transfer arm 24 captured by the alignment camera 48. Then, the calculation unit 54 performs a position deviation amount calculation process of calculating the amount of position deviation between the wafer transfer position and the transfer position of the wafer chuck 34 based on the image data captured by the alignment camera 48. Further, the calculation unit 54 performs a writing process of storing the amount of position deviation calculated by the position deviation amount calculation process in the memory unit 52.

[0054] The control unit 58 controls the operations of each part of the prober 10. Further, the control unit 58 performs a correction process of correcting at least one of the transfer position (set position) of the transfer arm 24 and the transfer position (set position) of the wafer chuck 34 based on the amount of position deviation stored in the memory unit 52 (that is, the amount of position deviation calculated by the calculation unit 54).

[0055] 〔Transfer adjustment process〕 Next, the transfer adjustment process executed by the prober 10 will be described in detail. FIG. 5 is a flowchart showing the procedure of the transfer adjustment process. The transfer adjustment process is a process executed at the manufacturing stage before the shipment of the prober 10, or at the maintenance stage after the shipment, etc.

[0056] When the transfer adjustment process is started, first, a transfer arm movement process is performed (step S1). In the transfer arm movement process, the control unit 58 controls the operations of each part of the wafer transfer unit 22 (the X stage 26, the rotary lifting member 28, and the transfer arm 24) to move the transfer arm 24 to the design value of the wafer transfer position. At this time, the control unit 58 reads out the set position of the transfer arm 24 stored in the memory unit 52 and controls the transfer arm 24 to move to that set position.

[0057] Next, the calculation process of the reference position of the transfer arm 24 is performed (step S2). In the calculation process of the reference position of the transfer arm 24, first, the control unit 58 controls the operation of the XY stage 44 to move the reference mark of the transfer arm 24 at the wafer transfer position so as to enter the shooting angle of view of the alignment camera 48. In addition, the control unit 58 controls a lifting mechanism (not shown) to align the focal position of the alignment camera 48 with the reference mark. Thereby, the horizontal position and the vertical height of the reference mark can be measured. Here, the alignment camera 48 measures the horizontal position and the vertical height of the reference marks M1, M2,... M N respectively in the horizontal direction and the vertical direction.

[0058] Subsequently, the calculation unit 54 calculates the horizontal position and the vertical height of the center position (an example of the first position), which is the reference position of the transfer arm 24 when the transfer arm 24 transfers the wafer W to the wafer chuck 34, from the horizontal position and the vertical height of the reference mark. Here, the calculation unit 54 calculates the horizontal position and the vertical height of the center position of the transfer arm 24 from the horizontal positions and the vertical heights of the reference marks M1, M2,... M N respectively in the horizontal direction and the vertical direction.

[0059] Next, the correction process of the transfer position is performed (step S3). In the correction process of the transfer position, the calculation unit 54 calculates the deviation amount (an example of the relative second positional relationship) between the wafer transfer position of the wafer chuck 34 and the wafer transfer position of the transfer arm 24. Here, the relative positions (an example of the relative first positional relationship) in the horizontal direction and the vertical direction between the center position of the wafer chuck 34 and the focal position of the alignment camera 48 are known, and the center position (an example of the second position) of the holding surface 34a of the wafer chuck 34 at the wafer transfer position of the wafer chuck 34 when the wafer chuck 34 receives the wafer W is also known. Therefore, the calculation unit 54 calculates, as the deviation amount between the wafer transfer position of the wafer chuck 34 and the wafer transfer position of the transfer arm 24, the deviation amounts in the horizontal direction and the vertical direction between the center position of the transfer arm 24 and the center position of the holding surface 34a of the wafer chuck 34 respectively based on these known values.

[0060] Further, the control unit 58 corrects the wafer transfer position. Here, the control unit 58 corrects the extension amount of the transfer arm 24 or the deviation amount of the wafer chuck 34 with respect to the wafer transfer position. Thereby, the deviation between the center position of the transfer arm 24 during wafer transfer processing and the center position of the holding surface 34a of the wafer chuck 34 can be eliminated.

[0061] In the above embodiment, the case where the wafer W is transferred from the transfer arm 24 to the wafer chuck 34 has been described, but the present invention is not limited to this. The center position (an example of the position 1), which is the reference position of the transfer arm 24 when the transfer arm 24 receives the wafer W from the wafer chuck 34, and the center position of the holding surface 34a of the wafer chuck 34 at the wafer transfer position of the wafer chuck 34 (an example of the second position) when the known wafer chuck 34 transfers the wafer W are calculated. Based on this deviation amount, the control unit 58 corrects the extension amount of the transfer arm 24 or the wafer transfer position of the wafer chuck 34.

[0062] Even with this method, the deviation between the center of the holding surface 34a of the wafer chuck 34 and the center of the wafer W during wafer transfer can be eliminated.

[0063] FIG. 6 and FIG. 7 are diagrams for explaining the transfer adjustment process, and are respectively a side schematic view and a top schematic view of the transfer arm 24, the wafer chuck 34, and the alignment camera 48. C shown in FIG. 6 Z is the vertical distance between the focal position, which is the reference position of the alignment camera 48, and the holding surface 34a of the wafer chuck 34, and is a known value. A1, A2,... A shown in FIG. 6 N are the vertical distances between the focal position of the alignment camera 48 and the reference marks M1, M2,... M N respectively, and are values obtained by the Z-direction position of a lift mechanism (not shown) at the position where the alignment camera 48 is in focus on each of the reference marks M1, M2,... M. A shown in FIG. 6 Z and the reference marks M1, M2,... M N respectively.Z is the minimum value of the height (A1 to A of the transfer arm 24 calculated by the calculation unit 54). Also, L shown in FIG. 6 N is the vertical distance between the holding surface 34a of the wafer chuck 34 and the transfer arm 24, and can be obtained by the following formula 1. Z

[0064] L Z = A Z - C Z …(Formula 1) The vector C shown in FIG. 7 XY → (in FIG. 7, there is a "→" above "C XY ") is the horizontal vector from the reference position of the alignment camera 48 to the center O of the holding surface 34a of the wafer chuck 34, and is a known value. B1, B2,... B shown in FIG. 7 N are the horizontal positions of the reference marks M1, M2,... M of the transfer arm 24 detected by the alignment camera 48 respectively. The vector D shown in FIG. 7 N → (in FIG. 7, there is a "→" above "D XY ") is the horizontal vector from the reference position of the alignment camera 48 to the reference position of the transfer arm 24. Here, it is the vector to the center position B of the transfer arm 24 obtained by the average value of B1 to B XY calculated from the reference position of the alignment camera 48. Also, the vector L shown in FIG. 7 N → (in FIG. 7, there is a "→" above "L XY ") is the horizontal vector from the center O of the holding surface 34a of the wafer chuck 34 to the center position B of the transfer arm 24, and can be obtained by the following formula 2. XY → (in FIG. 7, there is a "→" above "L XY ") is the horizontal vector from the center O of the holding surface 34a of the wafer chuck 34 to the center position B of the transfer arm 24, and can be obtained by the following formula 2. XY

[0065] L XY → = D XY → - C XY → …(Formula 2) The control unit 58 adjusts at least one of the center position of the transfer arm 24 and the center position of the holding surface 34a of the wafer chuck 34 so that L XY → and L Z are within the allowable range. Also, the calculation unit 54 calculates L XY → and L​​Z Store it in the memory unit 52.

[0066] Returning to the description of FIG. 5, finally, the correction process of the transfer position described in Patent Document 1 is performed (step S4). That is, the wafer W is transferred to the wafer chuck 34 at the transfer position corrected in step S3, the edge measurement (outer diameter measurement) of the wafer W is performed, and the center position of the wafer W is obtained. Further, the deviation amount from the center of the holding surface 34a of the wafer chuck 34 is calculated, and the extension amount of the transfer arm 24 or the deviation amount is corrected with respect to the wafer transfer position of the wafer chuck 34. Thereby, the deviation between the center of the holding surface 34a of the wafer chuck 34 and the center of the wafer W at the time of wafer transfer can be eliminated.

[0067] According to the present embodiment, based on the image data of the transfer arm 24 captured by the alignment camera 48, the relative second positional relationship between the transfer position of the transfer arm 24 and the transfer position of the wafer chuck 34 is calculated, and based on the calculated second positional relationship, at least one of the transfer position of the transfer arm 24 and the transfer position of the wafer chuck 34 is corrected. Here, the second positional relationship in the horizontal direction is calculated based on the average value of the horizontal positions of the plurality of reference marks M1, M2,... M N and the second positional relationship in the vertical direction is calculated based on the minimum value of the vertical positions of the plurality of reference marks M1, M2,... M N Since the relative positional relationship between the position of the center O of the holding surface 34a of the wafer chuck 34 and the reference position of the alignment camera 48 is known in advance, the appropriate position of the transfer arm 24 with respect to the wafer chuck 34 at the time of wafer transfer can be calculated at high speed and with high accuracy.

[0068] According to the present embodiment, since no jig is required by providing the reference mark on the transfer arm 24, it becomes easy to perform it at the time of regular maintenance or adjustment at the time of component replacement even after delivery to the customer.

[0069] In addition, since the measurement can be performed while the device is in operation, it is possible to detect a drive failure of the transfer arm 24 at an early stage by periodically measuring and determining the amount of change from the time of adjustment. .

[0070] Furthermore, by utilizing the fact that measurements can be performed even while the apparatus is in operation, the amount of deflection of the transfer arm 24 when transferring wafers of various masses can be measured, and the height of the wafer chuck 34 at the transfer position (second position) can be lowered by an amount equal to the amount of deflection. FIG. 8 is a diagram for explaining the amount of deflection of the transfer arm 24. Reference numeral 100 in FIG. 8 indicates a state in which a wafer W1 with a relatively small mass is being transferred, and the amount of deflection is also relatively small. On the other hand, reference numeral 102 in FIG. 8 indicates a state in which a wafer W2 with a relatively large mass is being transferred, and the amount of deflection is also relatively large. In this way, the difference in mass of the transferred wafers can be used to determine the position of the reference mark M. M According to the present invention, the vertical position of the reference mark M M By measuring the height of the reference mark and adjusting the height of the wafer chuck 34 at the transfer position in accordance with the measured height of the reference mark, the distance between the wafer chuck 34 and the transfer arm 24 can be appropriately maintained, enabling high-speed transfer while preventing accidents such as contact between the wafer W and the wafer chuck 34.

[0071] Although the embodiment of the present invention has been described above, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the spirit of the present invention. [Explanation of symbols]

[0072] 10…Prober 12…Measuring unit 14...Loader section 16...Measuring part 18…Loading port 20...Wafer cassette 22...wafer transport unit 24...Transport arm 26…X Stage 28...Rotating and lifting member 30…Head stage 32…Probe card 34…Wafer chuck 34a…Holding surface 36…Test head 36a…Contact part 38…Docking plate 40…Probe 42…Rotating lifting member 44…XY stage 46…Alignment camera 48…Needle alignment camera 50…Control device 52…Memory part 54…Calculation part 58…Control part A1…Vertical distance between the focal position of the needle alignment camera and the reference mark M1 A2…Vertical distance between the focal position of the needle alignment camera and the reference mark M2 A N …Vertical distance between the focal position of the needle alignment camera and the reference mark M N and A Z …Height of the transfer arm B1…Horizontal position of the reference mark M1 B2…Horizontal position of the reference mark M2 B N …Horizontal position of the reference mark M N B XY …Center position of the transfer arm C XY →Horizontal vector quantity between the reference position of the needle alignment camera and the center of the holding surface of the wafer chuck D XY →…Horizontal vector quantity L between the reference position of the needle alignment camera and the reference position of the transfer arm XY →…Horizontal vector quantity between the center of the holding surface of the wafer chuck and the center position of the transfer arm L Z …Vertical distance between the holding surface of the wafer chuck and the transfer arm M1…Reference mark M2…Reference mark M​M …reference mark M N …reference mark O…center S1~S4… each step of the handover adjustment process W…wafer

Claims

1. A transfer arm for transferring a wafer; a wafer chuck for holding the wafer; a camera movable integrally with the wafer chuck; a calculation unit that calculates a relative positional relationship between the wafer chuck and the transfer arm based on image data of the transfer arm captured by the camera; a control unit that corrects a position of at least one of the wafer chuck and the transfer arm based on the positional relationship; The prober comprises:

2. A probe card having a plurality of probes, The camera is a camera for detecting a tip position of the probe.

2. The prober of claim 1.

3. taking an image of the transfer arm using a camera that is movable integrally with the wafer chuck; calculating a relative positional relationship between the wafer chuck and the transfer arm based on image data of the transfer arm captured by the camera; correcting a position of at least one of the wafer chuck and the transfer arm based on the positional relationship; The alignment method includes:

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