Probe 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 testing the electrical characteristics of multiple semiconductor devices (chips) formed on a semiconductor wafer. [Background technology]

[0002] The semiconductor manufacturing process involves numerous steps, and various inspections are performed at each stage of the manufacturing process to ensure quality and improve yield. For example, at the stage when multiple semiconductor chips are formed on a semiconductor wafer, wafer-level inspection is performed in which the electrode pads of each semiconductor chip are connected to a test head, power and test signals are supplied from the test head, and the signals output by the semiconductor are measured by the test head to electrically check whether they are functioning correctly.

[0003] After wafer-level inspection, the wafers are mounted on frames and cut into individual chips by a dicer. Only chips that are confirmed to be functioning correctly are packaged in the next assembly process; defective chips are removed from the assembly process. Furthermore, the packaged final products undergo a final inspection before shipment.

[0004] Wafer-level testing is performed using a prober that contacts the electrode pads of each chip on a wafer held in a wafer chuck. The probe is electrically connected to the terminals of a test head, and power and test signals are supplied from the test head to each chip via the probe, while the output signals from each chip are detected by the test head to measure whether they are functioning correctly.

[0005] By the way, when inspecting wafers with a prober, it is necessary to supply (load) the wafer to be inspected into the wafer chuck and to retrieve (unload) the inspected wafer from the wafer chuck. Wafer supply and retrieval are performed in the loader section. In this specification, the entire unit, including the prober and loader section, will be referred to as the "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 a wafer 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 the wafer, and transfers it to the wafer chuck.

[0007] In recent years, multi-stage probers equipped with a plurality of measurement units have emerged. In a multi-stage prober, a wafer chuck is arranged in each measurement unit (stage), and inspections of wafers held by the wafer chucks in each measurement unit can be performed simultaneously. In a prober in which the stages are adjacent to and connected to each other like this, adjustment of the transfer between the transfer arm and the wafer chuck places 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 premised that the transfer position of the prober described in Patent Document 1 is adjusted in advance so 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 device.

[0011] <00001The present invention has been made in view of these circumstances, and aims to provide a prober that automates the adjustment of the wafer transfer position from the transport arm to the wafer chuck or from the wafer chuck to the transport arm, thereby enabling high-speed and high-precision adjustment. [Means for solving the problem]

[0012] To achieve the above objective, the following invention is provided.

[0013] A prober according to a first aspect of the present invention comprises a transport arm for transporting a wafer, a wafer chuck for receiving and holding the wafer from the transport arm, a camera whose first relative positional relationship with the wafer chuck is known, a calculation unit for calculating a second relative positional relationship between a first position of the transport arm when transferring the wafer to the wafer chuck and a second position of the wafer chuck when receiving the wafer, based on the first positional relationship and image data of the transport arm captured by the camera, and a control unit for correcting 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 comprises a transport arm for transporting a wafer, a wafer chuck for receiving and holding a wafer from the transport arm, a camera whose first relative positional relationship with the wafer chuck is known, a calculation unit for calculating a second relative positional relationship between a first position of the transport arm when receiving a wafer from the wafer chuck and a second position of the wafer chuck when handing over a wafer, based on the first positional relationship and image data of the transport arm captured by the camera, and a control unit for correcting at least one of the first position and the second position based on the second positional relationship.

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

[0016] In the fourth aspect of the present invention, the prober, in the third aspect, has a plurality of reference marks arranged on the transport arm, and the calculation unit calculates a second positional relationship based on the positions of the plurality of reference marks captured by the camera.

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

[0018] In the sixth aspect of the present invention, the prober, in the fourth or fifth aspect, calculates a second vertical positional relationship based on the minimum vertical position of a plurality of reference marks.

[0019] A prober according to a seventh aspect of the present invention comprises a probe card having a plurality of probes in any one of the first to sixth aspects, and the camera is a pin-alignment camera for detecting the tip positions of the probes. [Effects of the Invention]

[0020] According to the present invention, the adjustment of the wafer transfer position from the transport arm to the wafer chuck or from the wafer chuck to the transport arm can be automated, resulting in higher speed and higher precision. [Brief explanation of the drawing]

[0021] [Figure 1] Schematic plan of the probe [Figure 2] Schematic side view of the prober [Figure 3] Lower view of the transport arm [Figure 4] Functional block diagram showing the main components of the prober's control system. [Figure 5] A flowchart showing the procedure for the handover adjustment process. [Figure 6] Diagram to explain the handover adjustment process. [Figure 7] Diagram to explain the handover adjustment process. [Figure 8]Diagram illustrating the amount of deflection of the transport arm. [Modes for carrying out the invention]

[0022] Preferred embodiments of the present invention will be described below with reference to the attached drawings.

[0023] [Prover configuration] Figures 1 and 2 are schematic plan and side views of the prober 10 according to this embodiment. Figure 1 shows a simplified representation of the wafer transport unit 22.

[0024] As shown in Figures 1 and 2, the prober 10 includes a loader unit 14 for supplying and retrieving wafers W (see Figure 2) to be inspected, and a measurement unit 12 located adjacent to the loader unit 14. The measurement unit 12 has a plurality of measurement sections 16, and when wafers W are supplied from the loader unit 14 to each measurement section 16, each measurement section 16 performs an inspection of the electrical characteristics of each chip on the wafer W (wafer-level inspection). The wafers W inspected by each measurement section 16 are then retrieved by the loader unit 14. The prober 10 also includes a control device 50 (see Figure 4), which will be described later.

[0025] The loader unit 14 includes a load port 18 on which the wafer cassette 20 is placed, and a wafer transport unit 22 that transports the wafer W between each measuring unit 16 of the measuring unit 12 and the wafer cassette 20.

[0026] The wafer transport unit 22 is equipped with a transport arm 24 (see Figure 2). The transport arm 24 is composed of a multi-joint robot arm. The suction surface (holding surface) of the transport arm 24 is provided with suction pads (not shown). The transport arm 24 transports the wafer W while holding it with these suction pads. In this embodiment, a twin-arm type transport arm 24 is used, but it is not limited to this, and for example, a single-arm type may also be used.

[0027] Alignment reference marks are installed at one or more locations on the underside of the transport arm 24 (the side opposite the suction surface). Figure 3 is an underside view of the transport arm 24. In the example shown in Figure 3, there are N reference marks M1, M2, ... M on the underside of the transport arm 24. N These are positioned here. Here, the reference marks M1, M2, ...M N These are cross-shaped (also called + shape or cruciform) when viewed in the Z direction, but the reference marks M1, M2, ...M N The shape is not limited to a cross shape; any shape that can be recognized as a reference mark, such as a circle or rectangle, is acceptable.

[0028] Reference marks M1, M2,…M N The reference position of the transport arm 24 is positioned so that it can be identified. Here, reference marks M1, M2, ... M N These are the standard marks M1, M2, ...M N The positions are arranged such that the average of the positions of the transport arm 24 is the center position of the transport arm 24. The center position of the transport arm 24 is the position that coincides with the center position of the wafer W when the wafer is placed on the transport arm 24 without displacement. Note that the reference position of the transport arm 24 is not limited to the center position, but any position that allows the position of the wafer W placed on the transport arm 24 to be identified. Reference marks M1, M2, ... M N The position of each transport arm 24 is stored in the memory unit 52.

[0029] Returning to the description of Figures 1 and 2, the transport arm 24 is supported on the X-stage 26 via a rotating 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 transport arm 24 can be moved in the X direction together with the X-stage 26. Since the X-drive mechanism is publicly known, a detailed explanation thereof will be omitted.

[0030] The rotating lifting member 28 is positioned between the X-stage 26 and the wafer transport unit 22. The rotating lifting member 28 is configured to be rotatable in the θ direction (around the Z direction) and movable (up and down) in the Z direction by a rotating lifting mechanism (not shown). Therefore, the transport arm 24, supported on the upper part of the rotating lifting member 28, is able to rotate and move up and down together with the rotating lifting member 28 in accordance with the rotation and movement of the rotating lifting member 28. Since the rotating lifting mechanism is publicly known, a detailed explanation thereof is omitted.

[0031] With this configuration, the wafer transport unit 22 can move three-dimensionally between the load port 18 and any measurement unit 16 by means of an X-drive mechanism and a rotational lifting mechanism, and the transport arm 24 can access each position. As a result, the wafer W in the wafer cassette 20 is picked up by the transport arm 24 of the wafer transport unit 22 and transported to each measurement unit 16 of the measurement unit 12 while being held by the suction surface of the transport arm 24. After the inspection is completed, the inspected wafer W is returned to the wafer cassette 20 from each measurement unit 16 via the reverse path.

[0032] The measurement unit 12 is equipped with multiple measurement sections 16. Since the multiple measurement sections 16 constituting the measurement unit 12 in this embodiment have similar configurations, one of them will be described as representative.

[0033] As shown in Figure 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 headstage 30 constitutes the upper plate of the housing of the measurement unit 16. The headstage 30 has an opening for attaching a probe card 32, and the probe card 32 is detachably attached and fixed to this opening. The probe card 32 is replaced depending on the wafer W (device) to be inspected.

[0035] Multiple docking plates 38 are provided on the upper surface of the head stage 30 to fix the test head 36 in a predetermined position. Each docking plate 38 is equipped with a drive cylinder, such as an air cylinder, and a pin member that can move up and down in accordance with the extension and retraction of the drive cylinder. As a result, when the test head 36 is placed on multiple docking plates 38, each docking plate 38 can move the test head 36 between a position close to the head stage 30 (mounted position) and a position away from the head stage 30 (unmounted position) using the drive cylinder and pin member. When the test head 36 is moved to the mounted position by each docking plate 38, the contact portion 36a of the test head 36 and the probe card 32 are electrically connected.

[0036] The probe card 32 is equipped with multiple probes 40, such as cantilevers and spring pins, which are arranged to correspond to the positions of the electrode pads on each chip of the wafer W to be tested. Each probe 40 is electrically connected to the terminals of the test head 36, and power and test signals are supplied from the test head 36 to each chip via each probe 40, and the output signals from each chip are detected by the test head to measure whether they are functioning correctly. Note that the connection configuration between the probe card 32 and the test head 36 is not a key part of the present invention, so a detailed explanation is omitted.

[0037] The probe 40 has spring properties and makes contact with the electrode pad with a predetermined contact pressure by raising the contact point above the tip position of the probe 40. Furthermore, when the electrode pad is in an overdrive state during electrical testing, the tip of the probe 40 will sink into the surface of the electrode pad, forming needle marks on the surface of the electrode pad. Overdrive refers to a state in which the surface of the wafer W is raised by a predetermined distance (this distance is also called the "overdrive amount") above the tip position of the probe 40, taking into account the inclination between the wafer W and the alignment surface of the tip of the probe 40, as well as variations in the tip position of the probe 40, so that the electrode pad and the probe 40 make reliable contact.

[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 the holding surface 34a is provided with a plurality of suction ports (not shown). Each suction port is connected to a suction device (not shown), such as a vacuum pump, via a suction conduit (not shown). Therefore, by applying 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) is provided as a heating / cooling source so that the electrical characteristics of the wafer W to be inspected can be tested at high temperatures (e.g., up to 150°C) or low temperatures (e.g., down to -40°C). As the heating / cooling mechanism, any known suitable heater / cooler can be used. For example, a double-layer structure consisting of a heating layer of a surface heater and a cooling layer with passages for a cooling fluid, or a single-layer heating / cooling device with a cooling tube embedded in a heat conductor wrapped around a heating element, are all conceivable. Furthermore, instead of electric heating, a system that circulates a thermal fluid may be used, or a Peltier element may be used.

[0040] The wafer chuck 34 is supported on the XY stage 44 via a rotary lifting member 42. The rotary lifting member 42 is configured to be rotatable in the θ direction (around the Z direction) and movable (up and down) in the Z direction 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 together with the rotary lifting member 42 in accordance with the rotation and movement of the rotary lifting member 42. Since the rotary lifting mechanism is publicly known, a detailed explanation thereof is omitted.

[0041] The XY stage 44 is configured to be movable in the X and Y directions by an XY drive mechanism (not shown). Therefore, the wafer chuck 34, which is supported by the XY stage 44 via the rotating lifting member 42, is able to move in the X and Y directions together with the XY stage 44. Since the XY drive mechanism is publicly known, a detailed explanation thereof is omitted.

[0042] The alignment camera 46 is provided for aligning the wafer W on the wafer chuck 34. The alignment camera 46 is mounted on the underside of the head stage 30 and is positioned horizontally (in the Y direction) offset from the probe card 32.

[0043] The pin alignment camera 48 is provided to detect the position of the probe 40. The pin alignment camera 48 is mounted on the XY stage 44 and is movable in the X and Y directions in conjunction with the XY stage 44. The pin alignment camera 48 is also configured to be movable in the Z direction by a lifting mechanism (not shown), making it possible to align the focal position of the pin alignment camera 48 with the object to be imaged. The pin alignment camera 48 has a known first relative positional relationship between its reference position, which is the focal position, and the wafer chuck 34.

[0044] In the prober 10 configured as described above, when performing wafer-level inspection, the XY stage 44 is moved so that the alignment camera 48 is positioned below the probe 40, and the tip position of the probe 40 is detected by the alignment camera 48. The horizontal position (X and Y coordinates) of the tip of the probe 40 is detected by the coordinates of the alignment camera 48, and the height position (Z coordinate) of the tip of the probe 40 is detected by 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 performed as appropriate each time a predetermined number of chips are measured, even when the probe card 32 is not replaced. Since the probe card 32 is equipped with many probes 40, the tip positions of all probes 40 are not detected, and normally, considering work efficiency, the tip positions of specific probes 40 are detected.

[0045] Next, a wafer transfer process (wafer loading) is performed, in which the wafer W is transferred from the loader unit 14 to the wafer chuck 34 of a predetermined measuring unit 16. In the wafer transfer process, the transfer arm 24 takes out the wafer W from the wafer cassette 20 and, while holding it on the suction surface of the transfer arm 24, transports and transfers the wafer W to the wafer chuck 34 of the predetermined measuring unit 16. At this time, the wafer chuck 34 moves to a predetermined transfer position (the position shown by the dashed line in Figure 2) by the movement of the XY stage 44. Then, the wafer W is transferred from the transfer arm 24 to the wafer chuck 34 that has moved to the transfer position, and the wafer W is held in the wafer chuck 34.

[0046] The transfer of the wafer W from the transport arm 24 to the wafer chuck 34 is performed, for example, by having multiple chuck pins (not shown) provided on the wafer chuck 34 rise from the wafer chuck 34 to support the wafer W being transported by the transport arm 24 from below, and then, after the transport arm 24 retracts, the multiple chuck pins descend to place the wafer W on the holding surface 34a. Alternatively, the transport arm 24 may be inverted while the wafer W is held on the suction surface to place the wafer W on the holding surface 34a. Thus, the position of the wafer W being transported by the transport arm 24 must be within a certain range in the horizontal and vertical directions from the transfer position of the wafer chuck 34.

[0047] Once the wafer W is held in the wafer chuck 34, the alignment camera 46 detects the position of the electrode pads of each chip on the wafer W. It is not necessary to detect the position of all electrode pads on a chip; detecting the position of some electrode pads is sufficient. Similarly, it is not necessary to detect the electrode pads of all chips on the wafer W; the positions of some electrode pads are detected. The wafer chuck 34 is then rotated by the rotary lifting member 42 so that the arrangement direction of the electrode pads on the chips matches 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. Finally, the wafer chuck 34 is raised by the rotary lifting member 42 to bring the electrode pads into contact with the probes 40. Power and test signals are then supplied to the electrode pads from the test head 36 via the contact section 36a, and the signals output to the electrode pads are detected to confirm that they are functioning correctly.

[0048] The prober 10 is equipped with a function to perform a transfer adjustment process that automatically adjusts 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 needle alignment camera 48 is used to calculate the amount of positional misalignment between the transfer position of the transport arm 24 and the transfer position of the wafer chuck 34, and at least one of the transfer position of the transport arm 24 and the transfer position of the wafer chuck 34 is automatically adjusted so that the amount of positional misalignment is within an acceptable range.

[0049] [Control device configuration] Figure 4 is a functional block diagram showing the main components of the control device 50 of the prober 10. Note that Figure 4 only shows the components related to the transfer adjustment process, which is the main component of the present invention.

[0050] The control device 50 is implemented by a general-purpose computer, such as a personal computer or a microcomputer. The control device 50 is composed of a processor such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array), memory such as ROM (Read Only Memory) or RAM (Random Access Memory), and other peripheral circuits, and performs processing to realize the functions of each part of the control device 50 shown in Figure 4 by executing a predetermined operating program using these components.

[0051] As shown in Figure 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 for the prober 10. Specifically, the memory unit 52 stores the setting position of the transport arm 24 and the setting position (reference position) of the wafer chuck 34 as transfer positions, as well as the amount of positional deviation calculated by the calculation unit 54, which will be described later. Furthermore, the memory unit 52 stores the installation position of the reference mark placed on the transport arm 24.

[0053] The calculation unit 54 acquires image data of the transport arm 24 captured by the alignment camera 48. The calculation unit 54 then performs a positional misalignment calculation process to calculate the amount of misalignment between the wafer transfer position and the wafer chuck 34 based on the image data captured by the alignment camera 48. The calculation unit 54 also performs a write process to store the calculated positional misalignment amount in the memory unit 52.

[0054] The control unit 58 controls the operation of each part of the prober 10. The control unit 58 also performs a correction process to correct at least one of the transfer position (set position) of the transport arm 24 and the transfer position (set position) of the wafer chuck 34 based on the amount of misalignment stored in the memory unit 52 (i.e., the amount of misalignment calculated by the calculation unit 54).

[0055] [Delivery adjustment process] Next, we will explain in detail the handover adjustment process performed by the prober 10. Figure 5 is a flowchart showing the procedure for the handover adjustment process. Note that the handover adjustment process is performed during the manufacturing stage before shipment of the prober 10, or during the maintenance stage after shipment.

[0056] When the transfer adjustment process is initiated, the first step is the transfer arm movement process (step S1). In the transfer arm movement process, the control unit 58 controls the operation of each part of the wafer transfer unit 22 (X stage 26, rotating lifting member 28, and 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 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 that it enters the imaging angle of view of the alignment camera 48. In addition, the control unit 58 controls an elevating 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 and vertical directions 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 and vertical directions between the center position of the transfer arm 24 and the center position of the holding surface 34a of the wafer chuck 34 based on these known values.

[0060] Furthermore, the control unit 58 corrects the wafer transfer position. Here, the control unit 58 corrects the amount of extension of the transport arm 24 or the amount of displacement of the wafer chuck 34 relative to the wafer transfer position. This eliminates the misalignment between the center position of the transport arm 24 and the center position of the holding surface 34a of the wafer chuck 34 during the wafer transfer process.

[0061] In the embodiments described above, the case in which a wafer W is transferred from the transport arm 24 to the wafer chuck 34 has been explained, but the invention is not limited to this. The amount of deviation (an example of a relative second positional relationship) between the center position (an example of position 1), which is the reference position of the transport arm 24 when the transport 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 a second position), which is known, is calculated. Based on this amount of deviation, the control unit 58 corrects the extension amount of the transport arm 24 or the wafer transfer position of the wafer chuck 34.

[0062] This method also eliminates the misalignment between the center of the holding surface 34a of the wafer chuck 34 and the center of the wafer W during wafer transfer.

[0063] Figures 6 and 7 are diagrams illustrating the transfer adjustment process, and are schematic side and top views of the transport arm 24, wafer chuck 34, and needle alignment camera 48, respectively. Z This is the vertical distance between the focal position, which is the reference position of the needle alignment camera 48, and the holding surface 34a of the wafer chuck 34, and is a known value. A1, A2, ...A are shown in Figure 6. N These correspond to the focal position of the needle-aligning camera 48 and the reference marks M1, M2, ...M N This is the vertical distance, and the focal length F of the needle-aligning camera 48. Z And the standard marks M1, M2, ...M N These values ​​are determined by the position in the Z direction of the lifting mechanism (not shown) at the position where the needle-aligning camera 48 is in focus on each of the points shown in Figure 6.Z The height of the transport arm 24 (A1~A) is calculated by the calculation unit 54. N It is the minimum value of L shown in Figure 6. Z This is the vertical distance between the holding surface 34a of the wafer chuck 34 and the transport arm 24, and can be calculated by the following equation 1.

[0064] L Z =A Z -C Z …(Formula 1) Vector C shown in Figure 7 XY →(In Figure 7, "C XY The arrow (→) above the arrow is a horizontal vector from the reference position of the needle 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 Figure 7 N These are the reference marks M1, M2, ... M on the transport arm 24 detected by the needle alignment camera 48. N This is the horizontal position. Vector D shown in Figure 7. XY →(In Figure 7, "D XY The arrow (→) above the arrow is a horizontal vector from the reference position of the needle alignment camera 48 to the reference position of the transport arm 24, and here it is from the reference position of the needle alignment camera 48 to B1~B N The center position B of the transport arm 24 is determined by the average value. XY This is a vector to [the specified point]. Also, the vector L shown in Figure 7 XY →(In Figure 7, "L XY The arrow (→) above the wafer chuck 34 indicates the distance from the center O of the holding surface 34a of the wafer chuck 34 to the center position B of the transport arm 24. XY This is a horizontal vector to and can be calculated using the following equation 2.

[0065] L XY →=D XY →-C XY → …(Formula 2) The control unit 58 is L XY → and L Z The center position of the transport arm 24 and the center position of the holding surface 34a of the wafer chuck 34 are adjusted so that the value falls within the acceptable range. In addition, the calculation unit 54 calculates L XY → and LZ The data is stored in the memory unit 52.

[0066] Returning to the explanation of Figure 5, finally, the transfer position correction process 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 determined. Furthermore, the amount of deviation from the center of the holding surface 34a of the wafer chuck 34 is calculated, and the amount of extension of the transport arm 24 or the amount of deviation relative to the wafer transfer position of the wafer chuck 34 is corrected. This makes it possible to eliminate 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.

[0067] According to this embodiment, a second relative positional relationship between the transfer position of the transfer arm 24 and the transfer position of the wafer chuck 34 is calculated based on image data of the transfer arm 24 captured by the needle alignment camera 48, and at least one of the transfer position of the transfer arm 24 and the transfer position of the wafer chuck 34 is corrected based on the calculated second positional relationship. Here, a plurality of reference marks M1, M2, ... M N Based on the average value of the horizontal position, a second horizontal positional relationship is calculated, and multiple reference marks M1, M2, ... M are used. N A second vertical positional relationship is calculated based on the minimum vertical position. Since the relative positional relationship between 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 transport arm 24 relative to the wafer chuck 34 during wafer transfer can be calculated quickly and with high accuracy.

[0068] According to this embodiment, since a reference mark is applied to the transport arm 24, a jig is not required, making it easier to perform regular maintenance and adjustments when replacing parts even after delivery to the customer.

[0069] Furthermore, by taking advantage of the fact that measurements can be taken even while the device is in operation, it is possible to periodically measure and determine the amount of change since the adjustment, thereby enabling early detection of drive malfunctions in the transport arm 24. .

[0070] Furthermore, by taking advantage of the fact that measurements can be performed even while the device is in operation, the amount of deflection of the transport arm 24 when transporting 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 the same height as the amount of deflection. Figure 8 is a diagram illustrating the amount of deflection of the transport arm 24. Figure 8 shows 100, which indicates the state when transporting wafer W1, which has a relatively small mass, and the amount of deflection is also relatively small. On the other hand, Figure 8 shows 102, which indicates the state when transporting wafer W2, which has a relatively large mass, and the amount of deflection is also relatively large. In this way, the reference mark M differs depending on the mass of the wafer being transported. M The vertical position of the reference mark M will be different. According to the present invention, in the needle alignment camera 48, 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 according to the measured height of the reference mark, the distance between the wafer chuck 34 and the transport arm 24 can be appropriately maintained, enabling high-speed transport while preventing accidents such as contact between the wafer W and the wafer chuck 34.

[0071] Although embodiments of the present invention have 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…Prova 12…Measurement unit 14...Loader section 16…Measuring part 18…Load port 20... Wafer cassette 22…Wafer transport unit 24... Transport arm 26…X Stage 28...Rotating and lifting member 30…Headstage 32…Probe card 34… Wafer Chuck 34a...Holding surface 36…Test head 36a... Contact area 38… Docking plate 40…Probe 42...Rotating and lifting member 44…XY Stage 46… Alignment camera 48... Needle alignment camera 50…Control device 52...Memory section 54...Calculation section 58... Control Unit A1…The vertical distance between the focal point of the alignment camera and the reference mark M1. A2…The vertical distance between the focal point of the alignment camera and the reference mark M2. A N ...the focal position of the needle-aligning camera and the reference mark M N The vertical distance from A Z ...height of the transport arm B1...Horizontal position of reference mark M1 B2...Horizontal position of reference mark M2 B N ...Standard Mark M N horizontal position B XY ...center position of the transport arm C XY →The horizontal vector quantity between the reference position of the alignment camera and the center of the wafer chuck's holding surface. D XY →...The horizontal vector quantity L between the reference position of the needle-aligning camera and the reference position of the transport arm. XY →...The horizontal vector quantity between the center of the wafer chuck's holding surface and the center position of the transport arm. L Z ...the vertical distance between the wafer chuck's holding surface and the transport arm M1...Standard mark M2...Standard mark MM ...standard mark M N ...standard mark O…center S1-S4... Each step of the handover adjustment process W...wafer

Claims

1. A transport arm for transporting wafers, A wafer chuck for holding the wafer, A camera that can move integrally with the wafer chuck, A calculation unit calculates the relative positional relationship between the wafer chuck and the transport arm based on image data of the transport arm captured by the camera, A control unit that corrects the position of at least one of the wafer chuck and the transport arm based on the positional relationship, A probe equipped with [this feature].

2. Equipped with a probe card having multiple probes, The camera is a camera for detecting the tip position of the probe. The probe according to claim 1.

3. The steps include: photographing the transport arm with a camera that can move integrally with the wafer chuck, A step of calculating the relative positional relationship between the wafer chuck and the transport arm based on the image data of the transport arm captured by the camera, A step of correcting the position of at least one of the wafer chuck and the transport arm based on the positional relationship, Alignment methods, including those mentioned above.

Images