Wafer transfer arm and wafer transfer system

Abstract

To provide a wafer transfer arm and a wafer transfer system capable of transferring wafers having various thicknesses while suppressing positional deviation of the wafers, suppressing a phenomenon in which the wafers warp at the time of transfer, stably ensuring a load position accuracy of the wafers, and stably unloading the wafers.SOLUTION: A wafer transfer arm includes: a plurality of air discharge ports 13, 14 that open to a lower surface 12 of an arm top plate 11; and a slope part 15 that is provided on the lower surface 12 and slopes outward in a radial direction toward the lower side. When a wafer W is sucked and moved toward the lower surface 12, the slope part 15 can come into contact with an outer peripheral part of the wafer W. The plurality of air discharge ports 13, 14 have an outer air discharge port 13 facing the outer peripheral part of the wafer W from above, and an inner air discharge port 14 disposed radially inward of the outer air discharge port 13. The air pressure discharged from the outer air discharge port 13 is smaller than the air pressure discharged from the inner air discharge port 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wafer transfer arm and a wafer transfer system. This application claims priority to Japanese Patent Application No. 2024-055941, filed on March 29, 2024, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, wafer testing equipment is known that performs functional tests on semiconductor chips mounted on semiconductor wafers (hereinafter sometimes referred to as "wafers") such as silicon wafers. The wafer testing equipment is equipped with a transfer arm that transports the wafer. The wafer transfer arm transports (transfers) the wafer to the upper surface of a chuck and also transports the wafer from the upper surface of the chuck after testing (inspection).

[0003] In this specification, the process of transporting and placing a wafer on the upper surface of the chuck by a transport arm is sometimes referred to as a load process or simply as load, and the process of lifting and transporting a wafer from the upper surface of the chuck by a transport arm is sometimes referred to as an unload process or simply as unload.

[0004] Recently, wafers have become thinner in power devices that use a metal film on the underside of the wafer as an electrode. The wafer diameter (diameter dimension) is also shifting from the conventional 8 inches to 12 inches. For example, in TAIKO (registered trademark) wafers, the thickness of the effective chip formation area, which is located radially inward from the outer periphery of the wafer, is thinner than that of the outer periphery, and the thickness of this effective chip formation area has been reduced to 100 μm or less.

[0005] Patent Document 1 discloses a wafer transfer arm (Bernoulli chuck) that uses Bernoulli's principle to transfer a wafer while holding it by suction from above. A transfer arm using Bernoulli's principle can hold a wafer without contact, which reduces the risk of damaging a thinned wafer during, for example, an unloading process. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2014 / 084228 Summary of the Invention [Problem to be solved by the invention]

[0007] Generally, when loading a wafer onto the top surface of a chuck with a transfer arm, the amount of misalignment (eccentricity) of the wafer in the XY plane (horizontal plane) relative to the transfer arm is measured in advance (pre-alignment) by measuring the outer periphery of the wafer during transfer, and this eccentricity is reflected (corrected) in the transfer position to the chuck. This ensures positional accuracy between the wafer and the chuck, and ensures test (inspection) accuracy.

[0008] However, the thickness of wafers to be inspected in wafer testing equipment varies depending on the device type, and includes thin wafers of 100 μm or less, such as the TAIKO (registered trademark) wafer mentioned above, as well as thick wafers of around 775 μm (normal thickness). When a thick wafer is held by suction and transported using Bernoulli's principle, a strong air pressure is required according to the weight of the wafer, but if a thin wafer is held by suction and transported using the same air pressure, a force that slides the wafer in the horizontal direction is generated, which could cause the wafer to become misaligned during transport.

[0009] Furthermore, with a wafer that has been thinned or enlarged in diameter, a phenomenon occurs in which a portion of the outer periphery of the wafer W sags (a phenomenon in which the wafer W warps) during transport, as shown in Figure 8. Specifically, a pair of sagging portions H occurs at positions that are rotationally symmetrical by approximately 180° about the central axis (wafer central axis) WC of the wafer W. This makes the measurement accuracy of the wafer's outer periphery unstable, making it impossible to ensure the measurement accuracy of pre-alignment during loading (causing variations in the measurement of the eccentricity), and also making it impossible to ensure the positional accuracy between the wafer and the chuck. If the wafer deviates from the upper surface of the chuck by more than a predetermined value during loading, an error is detected and the operation of the device is stopped.

[0010] In addition, electrical testing of wafers also checks their operating status under various temperature conditions. Specifically, a wafer may be loaded onto a heated chuck. When the wafer is placed on the top surface of the heated chuck, it is vacuum-suctioned and held to the chuck, and simultaneously, thermal expansion of the wafer occurs. More specifically, the wafer is subjected to both an adhesive force acting on the underside of the wafer and an expansion force acting radially outward. This can cause the metal film on the underside of the wafer to peel off, and the underside of the wafer to become stuck between the suction holes. This type of sticking can make it difficult to remove the wafer from the top of the chuck when returning it to the cassette after testing (making unloading difficult). If the wafer cannot be unloaded from the top of the chuck, an error is detected and the device operation is stopped.

[0011] The present invention aims to provide a wafer transport arm and wafer transport system that can stably transport wafers of various thicknesses using Bernoulli's principle while suppressing wafer misalignment, that can suppress the phenomenon of wafer warping during transport even for wafers that have been thinned or increased in diameter, that can stably ensure the loading positional accuracy between the wafer and the chuck, and that can stably unload the wafer even if the wafer sticks to the chuck. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides the following means.

[0013] [Aspect 1 of the present invention] a wafer transport arm that uses Bernoulli's principle to hold a wafer by suction from above, the wafer transport arm comprising: an arm top plate centered on a central axis extending in the vertical direction; a plurality of air outlets opening on the underside of the arm top plate; and a sloped portion provided on the underside that slopes radially outward as it extends downward, wherein when the wafer is sucked by Bernoulli's principle and moves close to the underside, the sloped portion is capable of contacting the outer periphery of the wafer, and the plurality of air outlets include an outer air outlet arranged to face the outer periphery of the wafer from above, and an inner air outlet arranged radially inward from the outer air outlet, and wherein the pressure of the air discharged from the outer air outlet is smaller than the pressure of the air discharged from the inner air outlet.

[0014] In the wafer transfer arm of the present invention, a sloped section is provided on the underside of the arm top plate. When air is discharged from the air discharge port and the wafer is sucked upward based on Bernoulli's principle and moves toward the underside of the arm top plate, the outer periphery of the wafer comes into contact with the sloped section. At this time, the outer periphery of the wafer is guided along the inclination of the sloped section and rises, thereby aligning the central axis of the wafer (wafer central axis) so that it is coaxial with (coincides with) the central axis of the arm top plate, thereby aligning the wafer. In other words, the sloped section provides a wafer centering function.

[0015] This minimizes the amount of misalignment (eccentricity) of the wafer in the XY plane (horizontal plane) during transport. Since the wafer is prevented from being significantly misaligned with respect to the arm top plate, the positional accuracy of the wafer placed on the top surface of the chuck is also ensured.

[0016] The arm top plate has a plurality of air outlets for discharging air from the underside thereof, including outer air outlets and inner air outlets. The outer air outlets are arranged so as to overlap the outer periphery of the wafer when viewed from the top-bottom direction. The outer air outlets have a lower air pressure than the inner air outlets. In other words, the inner air outlets have a higher air pressure than the outer air outlets.

[0017] When the wafer being transported by the transport arm has a thickness of, for example, about 775 μm (normal thickness), air is discharged from the inner air outlet with high air pressure. This allows the transport arm to stably suck and hold the wafer and transport it using Bernoulli's principle, even if the wafer is heavy.

[0018] Furthermore, when the wafer being transported by the transport arm has a thickness of, for example, 100 μm or less, air is discharged from the outer air outlet with a low air pressure. This makes it difficult for a force to slide the wafer horizontally relative to the arm top plate to be generated, preventing the wafer from shifting position during transport.

[0019] Furthermore, the outer air outlets are positioned facing the wafer's outer periphery from above. Therefore, even when transporting thinned or large-diameter wafers that are prone to warping, Bernoulli's principle makes it easy to apply negative pressure to the wafer's outer periphery. Because the wafer's outer periphery can be stably sucked and lifted, the phenomenon of part of the wafer's outer periphery sagging (wafer warpage) during transport can be suppressed.

[0020] By preventing warpage of the wafer in this way, the effect (alignment function) of the sloped portion described above can be stably achieved even in wafers that have been made thinner and larger in diameter. Therefore, the accuracy of the loading position between the wafer and the chuck can be stably ensured.

[0021] Furthermore, when unloading a wafer from the chuck, air is discharged from the inner air outlet, which has a high air pressure. This creates a large negative pressure, allowing the wafer to be pulled up from the upper surface of the chuck with a strong force. For example, even if a wafer is loaded onto a heated chuck and the underside of the wafer becomes stuck to the suction holes opening in the upper surface of the chuck, the wafer can be stably removed from the upper surface of the chuck and transferred by the transfer arm.

[0022] As described above, according to the present invention, wafers of various thicknesses can be stably transported while suppressing positional deviation by using Bernoulli's principle, and even for wafers with thin walls or large diameters, the phenomenon of wafer warping during transport can be suppressed. The accuracy of the loading position between the wafer and the chuck can be stably ensured, and even if the wafer sticks to the chuck, the wafer can be stably unloaded. This reduces downtime caused by error detection in the wafer testing device during loading and unloading processes, and allows efficient and stable testing (inspection) of even wafers that are prone to warping.

[0023] [Aspect 2 of the present invention] 2. The wafer transfer arm according to aspect 1, wherein the outer air outlet is disposed radially inside the sloped portion and adjacent to the sloped portion.

[0024] In this case, the outer air outlets can be positioned closer to the outer periphery (periphery) of the wafer, making the above-described effects of the outer air outlets more stable and significantly more pronounced.

[0025] [Embodiment 3 of the present invention] 3. The wafer transfer arm according to aspect 1 or 2, wherein the outer air outlets discharge air radially inward along the lower surface of the arm top plate.

[0026] In this case, the air discharged from the outer air outlet flows radially inward along the underside of the arm top plate, effectively generating negative pressure between the underside of the arm top plate and the top surface of the wafer, and more stably increasing the suction force.

[0027] [Aspect 4 of the present invention] 4. The wafer transport arm according to aspect 3, wherein the outer air outlet and the inner air outlet are disposed at different positions in the circumferential direction.

[0028] In this case, the air discharged radially inward from the outer air outlet does not pass over the inner air outlet (above the opening hole), which prevents turbulence from occurring in the air discharged from the outer air outlet, making the negative pressure from the outer air outlet more stable.

[0029] [Embodiment 5 of the present invention] 5. The wafer transfer arm according to aspect 3 or 4, further comprising an exhaust port opening on a lower surface of the arm top plate, the exhaust port being disposed radially inward of the outer air outlet.

[0030] In this case, the air discharged from the outer air outlets along the underside of the arm top plate in the radial direction is exhausted from the exhaust ports on the underside, thereby maintaining an appropriate negative pressure (suction force) that draws the wafer closer to the arm top plate.

[0031] [Aspect 6 of the present invention] 6. The wafer transfer arm according to any one of aspects 1 to 5, wherein six sloped portions are provided at equal intervals in the circumferential direction.

[0032] For example, compared to forming the slope portion in a circular ring shape extending around the entire underside of the arm top plate, with the above configuration, each slope portion can be formed in an arc shape using small, easy-to-handle components, making manufacturing easier.

[0033] Furthermore, since six sloped portions are provided at equal intervals in the circumferential direction, the following effects are obtained. For example, even if the outer periphery of the wafer unintentionally sags during transport as shown in Figure 8 and a pair of sagging portions H is positioned between adjacent sloped portions in the circumferential direction (portions where no sloped portions are provided), a pair of non-sagging portions F can contact the sloped portions at positions offset by 90° around the wafer center axis WC from each of the sagging portions H. Therefore, even if the wafer unintentionally warps, the alignment effect of the sloped portions can be easily obtained in at least a predetermined direction (e.g., the X direction or the Y direction) among the XY plane directions (horizontal plane directions).

[0034] [Embodiment 7 of the present invention] The minimum cross-sectional area of ​​the outer air outlet and the piping member that sends air to the outer air outlet is 19.6 mm 2 The wafer transport arm according to any one of aspects 1 to 6, as described above.

[0035] With the above configuration, even when transporting thin wafers that are prone to warping, the air flow rate (L / min) discharged from the outer air outlets is sufficiently ensured, thereby stably suppressing the sagging phenomenon of the wafer's outer periphery. This allows the above-mentioned sloped section to stably achieve the wafer alignment function.

[0036] [Embodiment 8 of the present invention] A wafer transport system comprising: a wafer transport arm according to any one of aspects 1 to 7; a chuck on which a wafer transported by the wafer transport arm is placed; and a control device, wherein the control device controls the discharge of air from either the outer air outlet or the inner air outlet depending on the type and weight of the wafer transported to the chuck.

[0037] In the wafer transport system of the present invention, the control device controls the air discharge so as to obtain the optimum suction force depending on the type (device type, etc.) and weight (thickness, etc.) of the wafer being loaded onto the chuck. For example, the control device determines and executes whether to discharge air (weak air) from the outer air discharge port or air (strong air) from the inner air discharge port depending on the pre-stored data of each wafer.

[0038] Specifically, the control device performs the following control, for example. When the wafer being transported has a thickness of, for example, about 775 μm (normal thickness) and is heavy, the control device controls the air to be discharged from the inner air outlet with a high air pressure. This ensures stable suction force even for heavy wafers, enabling stable wafer transport.

[0039] Furthermore, when the wafer being transported is thin, for example, 100 μm or less in thickness, and the wafer is a type such as a power device with a metal film on its underside, which is light and prone to warping, the control device controls the air to be discharged from the outer air outlets, which have a low air pressure. This makes it difficult for a force to slide the wafer horizontally, even for a light wafer, and prevents the wafer from shifting significantly during transport. Furthermore, the above-mentioned function (action) of the outer air outlets also prevents the wafer from warping. In this way, the control device can automate the transport with suction forces suitable for various types and weights of wafers.

[0040] [Embodiment 9 of the present invention] A wafer transport system according to aspect 8, wherein the control device controls the ejection of air from the inner air outlet when the wafer transport arm lifts the wafer from the upper surface of the chuck.

[0041] In the above configuration, when unloading a wafer from the upper surface of the chuck, the control device controls the air (strong air) to be discharged from the inner air discharge port regardless of the type or weight of the wafer. This provides a strong suction force, allowing the wafer to be stably unloaded even if it has unintentionally become stuck to the upper surface of the chuck.

[0042] [Aspect 10 of the present invention] A wafer transport system according to aspect 8 or 9, wherein the control device stores measurement data of the amount of shift of the wafer placed on the upper surface of the chuck relative to the chuck, and performs control to use the measurement data as a correction value when placing another wafer to be transported thereafter on the upper surface of the chuck.

[0043] The tendency of transported wafers to warp varies among them, even if they are of the same type and weight (for example, differences occur depending on the production lot).The degree of alignment function obtained by the slope section also differs depending on the amount of warp of each wafer.

[0044] Therefore, in the above-described configuration of the present invention, the control device stores measurement data of the positional deviation (shift amount) of the wafer loading position, and uses this measurement data as a correction value (offset value) for the wafer to be subsequently loaded onto the chuck (the offset value is reflected in the transfer position to the chuck). This makes it possible to stably improve the loading position accuracy between the wafer and the chuck, at least for the second (second wafer) or subsequent wafers transferred, regardless of, for example, the production lot.

[0045] [Embodiment 11 of the present invention] A wafer transport system according to aspect 10, wherein the control device stores measurement data of the shift amount in association with the transport angle of the wafer around the wafer central axis, and uses the measurement data as a correction value depending on the transport angle of the wafer around the wafer central axis.

[0046] Probe cards used to test the functionality of semiconductor chips mounted on wafers are attached to wafer testing equipment at an optimal angle, taking into consideration the layout of the electrical circuits and electronic elements on the card substrate and shortening the circuit length. The probe card attachment angle also varies depending on the angle of the electrical test measuring instrument (tester) (left entry, rear entry) and the purpose of the layout of the electrical circuits and electronic elements inside the tester. Specifically, probe card attachment angles are set at four different angles (0°, 90°, 180°, 270°) in 90-degree increments around the center axis of the wafer being tested.

[0047] Furthermore, the wafer to be loaded onto the chuck has a predetermined transport angle around the wafer's central axis corresponding to the probe card's mounting angle. That is, the transport angle around the wafer's central axis is set to four different angles (0°, 90°, 180°, and 270°) in 90-degree increments around the wafer's central axis. Therefore, when transporting a thin wafer that is prone to warping, the angular position of the portion of the wafer that is prone to sagging around the wafer's central axis changes depending on the transport angle. Therefore, the alignment function provided by the sloped section also changes depending on the transport angle.

[0048] Therefore, in the above-described configuration of the present invention, the control device stores measurement data of the positional deviation (shift amount) of the wafer load position in association with the wafer transport angle around the wafer central axis, and uses this measurement data as a correction value (offset value) for the wafer that is subsequently loaded onto the chuck at the same transport angle (the offset value is reflected in the transfer position to the chuck).Since an optimal offset value can be added to the chuck transfer position (XY coordinates) according to each wafer transport angle, the load position accuracy between the wafer and the chuck can be stably improved regardless of the wafer transport angle.

[0049] [Aspect 12 of the present invention] A wafer transport system according to aspect 10 or 11, wherein the control device stores measurement data of the shift amount in association with the type and weight of the wafer, and uses the measurement data as a correction value depending on the type and weight of the wafer.

[0050] The tendency of the wafer to warp during transport is affected by the type of wafer (device type, etc.) and weight (thickness, etc.). The degree of alignment function obtained by the slope section also differs depending on the amount of warpage of each wafer.

[0051] Therefore, in the above-described configuration of the present invention, the control device stores measurement data of the positional deviation (shift amount) of the wafer loading position in association with the type and weight of the wafer being transported, and uses this measurement data as a correction value (offset value) for a wafer of the same type and weight that is subsequently loaded onto the chuck (the offset value is reflected in the transfer position to the chuck). This makes it possible to stably improve the loading position accuracy between the wafer and the chuck regardless of the type and weight of the wafer.

[0052] [Aspect 13 of the present invention] The control device stores the measurement data of the shift amount in association with a predetermined wafer testing device in which a wafer transport arm that places the wafer on the upper surface of the chuck is installed, and then uses the measurement data as a correction value when another wafer is placed on the upper surface of the chuck in the predetermined wafer testing device.

[0053] The accuracy of the loading position between the wafer and the chuck varies between wafer testing machines, even among machines with the same specifications. This is because there are physical differences (slight individual differences) in, for example, the air pressure (air flow rate) discharged from the air outlet of the transfer arm and the alignment function of the slope section.

[0054] Therefore, in the above-described configuration of the present invention, the control device stores measurement data of the positional deviation (shift amount) of the wafer load position in association with a predetermined wafer testing device, and uses this measurement data as a correction value (offset value) for the wafer to be subsequently loaded onto a chuck in the same predetermined wafer testing device (the offset value is reflected in the transfer position to the chuck). Thus, even when multiple wafer testing devices are used, the load position accuracy between the wafer and the chuck can be stably improved in each wafer testing device.

[0055] [Aspect 14 of the present invention] A wafer transport system according to any one of aspects 8 to 13, wherein the control device stores measurement data of the amount of shift of the wafer placed on the upper surface of the chuck relative to the chuck, and, if the measurement data is greater than an allowable value, controls the wafer transport arm to lift the wafer from the chuck and use the measurement data as a correction value when placing the wafer on the upper surface of the chuck again.

[0056] In the above configuration, the control device retries the loading process when the wafer placed on the upper surface of the chuck is significantly misaligned in the XY plane (horizontal plane) (when the amount of misalignment exceeds a preset tolerance). During this retry, the previous amount of misalignment of the same wafer is used as a correction value, so the amount of misalignment (shift amount) of the reloaded wafer is significantly reduced. This not only reduces the occurrence of operational stoppages due to error determinations in the wafer testing device during the loading process, but also significantly improves the accuracy of the loading position between the wafer and the chuck. [Effects of the Invention]

[0057] According to the wafer transfer arm and wafer transfer system of the above aspects of the present invention, wafers of various thicknesses can be stably transferred while suppressing wafer misalignment using Bernoulli's principle, and even for wafers with thin walls or large diameters, the phenomenon of wafer warping during transfer can be suppressed, the loading position accuracy between the wafer and the chuck can be stably ensured, and even if the wafer sticks to the chuck, the wafer can be stably unloaded. [Brief explanation of the drawings]

[0058] [Figure 1] FIG. 1 is a side view (side cross-sectional view) that schematically shows a wafer transfer arm and a wafer transfer system according to this embodiment. [Figure 2] FIG. 2 is a side view (side cross-sectional view) that schematically shows the function of the slope portion of the wafer transfer arm, and some of the components of the wafer transfer arm are not shown. [Figure 3] FIG. 3 is a bottom view showing the wafer transfer arm, and schematically shows the outflow directions of the air discharged from the outer air discharge port and the inner air discharge port. [Figure 4] FIG. 4 is a bottom view showing the wafer transfer arm, illustrating a state in which the wafer is held by the transfer arm under suction. [Figure 5] FIG. 5 is an enlarged bottom view of part V in FIG. [Figure 6] FIG. 6 is a flowchart showing an example of a loading process performed by the wafer transport system. [Figure 7] FIG. 7 is a side view (side cross-sectional view) that schematically shows a chuck and a wafer provided in a wafer transfer system according to a modified example of the present embodiment. [Figure 8] FIG. 8 is a perspective view that schematically shows a state in which a wafer that is prone to warping is deformed by its own weight (a state in which a drooping portion occurs). [Figure 9] FIG. 9 is a side cross-sectional view that schematically shows a part of a wafer transfer arm of a conventional comparative example 1. As shown in FIG. [Figure 10]FIG. 10 is a side cross-sectional view that schematically shows a part of a wafer transfer arm of a conventional comparative example 2. As shown in FIG. [Figure 11] FIG. 11 is a side cross-sectional view showing a schematic view of a part of a wafer transfer arm according to an embodiment of the present invention. [Figure 12] FIG. 12 shows the striped pattern that is transferred onto the rear surface of the wafer in the conventional comparative example 1 when the wafer transfer arm is not blowing air. [Figure 13] FIG. 13 shows striped patterns that are projected onto the rear surface of a wafer in a conventional comparative example 1 in a state where air is being sprayed from the wafer transfer arm. [Figure 14] FIG. 14 shows stripes and condensation marks that are projected onto the rear surface of a wafer in a conventional comparative example 1 in a state where air is being ejected from the wafer transport arm. [Figure 15] FIG. 15 shows an image taken with a microscope near the condensation mark in FIG. [Figure 16] FIG. 16 shows stripes that are transferred onto the rear surface of a wafer in the conventional comparative example 2 when the wafer transfer arm is not blowing air. [Figure 17] FIG. 17 shows the state of the rear surface of the wafer in the conventional comparative example 2 when air is being ejected from the wafer transfer arm. [Figure 18] FIG. 18 shows stripes that are transferred onto the rear surface of a wafer when air is not being ejected from the wafer transfer arm in the embodiment of the present invention. [Figure 19] FIG. 19 shows the state of the rear surface of the wafer when air is being ejected from the wafer transfer arm in the embodiment of the present invention. [Figure 20] FIG. 20 is a graph showing the amplitude of vibration measured at each point in the X-axis direction of the wafer when air is being ejected from the wafer transport arm in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0059] A wafer transport arm 10, a wafer transport system 20, and a wafer testing device 1 according to one embodiment of the present invention will be described with reference to the drawings. The wafer testing device 1 according to this embodiment is a device that performs functional testing (electrical testing) of semiconductor chips mounted on a semiconductor wafer (wafer) W such as a silicon wafer, and is also called a prober.

[0060] 1, the wafer testing apparatus 1 includes a wafer transfer system 20, a chuck moving means (not shown), a probe card (not shown), and an electrical test measuring instrument (not shown). The wafer transfer system 20 also includes a wafer transfer arm 10, a chuck 21 on whose upper surface 22 a wafer W transferred by the wafer transfer arm 10 is placed, and a control device 25. In this embodiment, the wafer transfer system 20 may be simply referred to as the transfer system 20, and the wafer transfer arm 10 may be simply referred to as the transfer arm 10.

[0061] The transfer arm 10 is substantially disk-shaped, and the central axis C of the transfer arm 10 extends in the vertical direction. That is, in this embodiment, the direction in which the central axis C of the transfer arm 10 extends (axial direction) corresponds to the vertical direction.

[0062] In this embodiment, the direction perpendicular to the central axis C is called the radial direction. Of the radial directions, the direction approaching the central axis C is called the radially inner direction, and the direction away from the central axis C is called the radially outer direction. The direction going around the central axis C is called the circumferential direction.

[0063] First, each of the components of the wafer testing apparatus 1 other than the transfer system 20 will be described. Although not specifically shown, the chuck moving means moves the chuck 21 between a load / unload position where the wafer W is placed on or lifted up from the upper surface 22 of the chuck 21 by the transfer arm 10, and an inspection position where the wafer W held by the chuck 21 is tested (inspected) using a probe card and an electrical test measuring instrument. In addition, the chuck moving means finely adjusts the position of the chuck 21 in the XY plane (horizontal plane) at the load / unload position under the control of a control device 25, which will be described later.

[0064] Specifically, the chuck moving means includes an XY-axis moving means and a Z-axis moving means. The XY-axis moving means moves the chuck 21 in the plane direction of the XY axes, i.e., in the horizontal plane direction (the direction in which a horizontal plane perpendicular to the up-down direction extends). The Z-axis moving means moves the chuck 21 in the up-down direction.

[0065] Although not specifically shown, the probe card is placed directly above the chuck 21 that has been moved to the inspection position and the wafer W that the chuck 21 holds on its upper surface 22. The probe card has a plurality of probes (contact needles) that protrude downward from the probe card. The plurality of probes are placed facing from above the minute terminals of the semiconductor chip provided on the wafer W.

[0066] The probe card is detachably attached to a probe card fixing mechanism (not shown). More specifically, a predetermined probe card corresponding to the semiconductor chip to be inspected provided on the wafer W is appropriately selected from among a plurality of types of probe cards and fixed to the probe card fixing mechanism.

[0067] Although not specifically shown, an electrical test measuring instrument (tester) measures information about the semiconductor chip detected by the probes via a contact spring pin mechanism electrically connected to each probe of the probe card.

[0068] Next, each of the components of the transport system 20 will be described. The transfer arm 10 uses Bernoulli's principle to hold the wafer W by suction from above. As shown in Fig. 1, the transfer arm 10 is disposed above the chuck 21. The transfer arm 10 performs a load process in which the wafer W is transferred and placed on the upper surface 22 of the chuck 21, and an unload process in which the wafer W is lifted up from the upper surface 22 of the chuck 21 after testing.

[0069] The transport arm 10 comprises an arm top plate 11 centered on a central axis C, a plurality of air outlets 13, 14 opening on an underside 12 of the arm top plate 11, a plurality of air pipes 16, 17 supplying air to each of the air outlets 13, 14, a switching valve 18 selectively supplying air to the plurality of air pipes 16, 17, an exhaust port 30 (see Figure 3) opening on the underside 12 of the arm top plate 11, and a slope portion 15 provided on the underside 12 of the arm top plate 11 and sloping radially outward as it extends downward.

[0070] The arm top plate 11 is in the form of a plate that extends in a direction perpendicular to the up-down direction (horizontal direction). In this embodiment, the arm top plate 11 is in the form of a disk centered on a central axis C. The underside 12 of the arm top plate 11 is in the form of a plane that extends in a direction perpendicular to the central axis C.

[0071] The diameter (outer diameter) of the arm top plate 11 is larger than the diameter of the disk-shaped wafer W transported by the transport arm 10. In this embodiment, the diameter of the wafer W is 8 inches or more. Specifically, the wafer W is an 8-inch wafer, a 12-inch wafer, or the like.

[0072] The multiple air discharge ports 13, 14 include an outer air discharge port 13 arranged facing the outer periphery of the wafer W from above, and an inner air discharge port 14 arranged radially inward of the outer air discharge port 13.

[0073] The pressure of the air discharged from the outer air outlet 13 is set lower than the pressure of the air discharged from the inner air outlet 14. In other words, the pressure of the air discharged from the inner air outlet 14 is set higher than the pressure of the air discharged from the outer air outlet 13. The pressure of the air (weak air) discharged from the outer air outlet 13 is, for example, in the range of 80 to 250 kPa, and the pressure of the air (strong air) discharged from the inner air outlet 14 is, for example, in the range of 180 to 500 kPa.

[0074] 3, a plurality of outer air discharge ports 13 are provided. The outer air discharge ports 13 are arranged at intervals in the circumferential direction. In this embodiment, six outer air discharge ports 13 are provided at equal intervals in the circumferential direction.

[0075] Furthermore, a plurality of inner air discharge ports 14 are provided. The plurality of inner air discharge ports 14 are arranged at intervals in the circumferential direction. In this embodiment, six inner air discharge ports 14 are provided at equal intervals in the circumferential direction.

[0076] Furthermore, the outer air discharge ports 13 and the inner air discharge ports 14 are arranged at different positions in the circumferential direction. The outer air discharge ports 13 and the inner air discharge ports 14 are arranged alternately in the circumferential direction.

[0077] 3 and 4, in this embodiment, the outer air outlet 13 is disposed opposite the peripheral edge We, which is located on the outermost side of the outer periphery of the wafer W. As the air flow is indicated by the arrows in Fig. 3, the outer air outlet 13 discharges air radially inward (towards the central axis C) along the lower surface 12 of the arm top plate 11.

[0078] The exhaust port 30 is disposed radially inward of the outer air outlet 13. The exhaust port 30 is also disposed radially inward of the inner air outlet 14. In this embodiment, the exhaust port 30 is disposed radially between the inner air outlet 14 and the central axis C. The exhaust port 30 has a triangular hole shape, and one of the three vertices of this triangle faces radially inward (toward the central axis C).

[0079] The outer air discharge ports 13 and the exhaust ports 30 are arranged at different positions in the circumferential direction. A plurality of exhaust ports 30 are provided. The plurality of exhaust ports 30 are arranged at intervals in the circumferential direction. In this embodiment, six exhaust ports 30 are provided at equal intervals in the circumferential direction.

[0080] The air discharged from the six outer air outlets 13 is concentrated at the central axis C. Furthermore, in order to reduce the force that causes the wafer W to move away from the wafer transfer arm 10 when each air collide, six exhaust ports 30 are provided to exhaust the air after each outer air collision. This maintains an appropriate negative pressure that draws the wafer W closer to the wafer transfer arm 10.

[0081] Furthermore, the inner air discharge port 14 discharges air that flows in a swirling manner (swirls air) toward the entire periphery (all directions) of the opening of the inner air discharge port 14. The opening of the inner air discharge port 14 is shaped like a circular hole.

[0082] 1, the multiple air pipes 16, 17 include outer air pipes 16 that are connected to the outer air outlet 13 and supply air to the outer air outlet 13, and inner air pipes 17 that are connected to the inner air outlet 14 and supply air to the inner air outlet 14. The outer air pipes 16 and the inner air pipes 17 form air flow paths that are independent (separate) from each other. The minimum cross-sectional area of ​​the outer air outlet 13 and the piping member (outer air piping 16) that sends air to the outer air outlet 13 is, for example, 19.6 mm 2 That is said to be the case.

[0083] The switching valve 18 selectively supplies air supplied from an air supply source (not shown) to either the outer air pipe 16 or the inner air pipe 17. In other words, the switching valve 18 selectively supplies air to either the outer air outlet 13 or the inner air outlet 14 via the outer air pipe 16 or the inner air pipe 17.

[0084] 2, the sloped portion 15 is capable of contacting the outer periphery (peripheral edge We) of the wafer W when the wafer W is sucked based on Bernoulli's principle and moves toward the lower surface 12 of the arm top plate 11. As the wafer W moves upward and is guided along the sloped portion 15, the wafer central axis WC of the wafer W approaches the central axis C of the arm top plate 11 (transfer arm 10), and the wafer W is aligned so that these central axes WC and C approximately coincide with each other. Note that air discharge ports 13 and 14, air pipes 16 and 17, a switching valve 18, and the like are not shown in FIG.

[0085] As shown in Figures 3 and 5, in this embodiment, a resin guide member 19 is attached to the underside 12 of the arm top plate 11, and the slope portion 15 is formed on the guide member 19. The guide member 19 is fixed to the outer periphery of the underside 12 by screws or the like. Multiple guide members 19 are provided. The multiple guide members 19 are arranged at intervals in the circumferential direction. In this embodiment, six guide members 19 are provided at equal intervals in the circumferential direction. Each guide member 19 is in the shape of an arc plate extending in the circumferential direction.

[0086] In this embodiment, a slope portion 15 is provided on each guide member 19. That is, a plurality of slope portions 15 are provided. The plurality of slope portions 15 are arranged at intervals in the circumferential direction. In this embodiment, six slope portions 15 are provided at equal intervals in the circumferential direction.

[0087] More specifically, the sloped portion 15 is disposed at the radially inner end of the lower surface of the guide member 19, or at an intermediate portion located between both radial ends of the lower surface of the guide member 19. The sloped portion 15 also extends in an arc shape over the entire length of the guide member 19 extending in the circumferential direction.

[0088] The outer air discharge port 13 opens on the underside 12 by cutting out a portion of the radially inner end of the guide member 19. As shown in Fig. 5, in this embodiment, the opening of the outer air discharge port 13 is a semicircular hole that protrudes radially inward. The outer air discharge port 13 is disposed radially inward of the slope portion 15 and adjacent to the slope portion 15.

[0089] As shown in FIG. 1, the chuck 21 is cylindrical or disk-shaped. The chuck 21 has a diameter (outer diameter) larger than that of the wafer W. The chuck 21 also has a temperature control means (not shown). The temperature control means includes at least a heating means. The temperature control means may also include a cooling means. The temperature control means heats (or cools) the chuck 21 to a predetermined temperature and maintains it at the predetermined temperature.

[0090] The chuck 21 also has an upper surface 22 on which the wafer W is placed and suction holes (not shown) that open to the upper surface 22. The upper surface 22 is flat and extends in a direction perpendicular to the up-down direction (horizontal direction). The suction holes are, for example, circular holes. Although not particularly shown, air suction means such as a vacuum pump is connected to the suction holes via a flow path within the chuck and piping members, etc.

[0091] The wafer W placed on the upper surface 22 of the chuck 21 by the loading process of the transfer arm 10 is sucked by air (vacuum suction) by the air suction means through the suction holes, and is thereby sucked and held on the upper surface 22. That is, the chuck 21 holds the wafer W by vacuum suction. The wafer W, while being sucked and held by the chuck 21, is moved together with the chuck 21 to an inspection position, where it is inspected by a probe card and an electrical test measuring instrument.

[0092] The control device 25 controls the air to be discharged from either the outer air discharge port 13 or the inner air discharge port 14 depending on the type and weight of the wafer W transferred to the chuck 21 .

[0093] Specifically, the control device 25 performs the following control, for example. When the thickness of the wafer W to be transported is, for example, about 775 μm (normal thickness) and the weight of the wafer W is heavy, the control device 25 operates the switching valve 18 and controls the ejection of high-pressure air from the inner air outlet 14 through the inner air piping 17.

[0094] In addition, when the thickness dimension of the wafer W to be transported is thin, for example, 100 μm or less, and the type of wafer W is a power device or the like having a metal film on the underside, and is a wafer W that is light in weight and prone to warping, the control device 25 operates the switching valve 18 and controls the discharge of low-pressure air from the outer air discharge port 13 through the outer air piping 16.

[0095] Furthermore, when the wafer W is lifted from the upper surface 22 of the chuck 21 by the transport arm 10 (i.e., when unloading), the control device 25 controls the air to be discharged from the inner air discharge port 14 regardless of the type or weight of the wafer W.

[0096] The control device 25 also acquires the amount of shift (amount of misalignment) of the wafer W placed on the upper surface 22 of the chuck 21 by the load process relative to the chuck 21 using a measuring device such as a camera or a sensor (not shown), and stores the measurement data. The control device 25 then performs control to use the measurement data as a correction value (offset value) when placing another wafer W to be transported thereafter on the upper surface 22 of the chuck 21. Specifically, the control device 25 adjusts the transfer position (XY coordinates) of the chuck 21 by adding the correction value, and reflects the adjustment in the load process.

[0097] In addition, the control device 25 stores measurement data of the shift amount in association with the transport angle of the wafer W around the wafer central axis WC (for example, four types of angles: 0°, 90°, 180°, and 270° around the wafer central axis WC), and uses the measurement data as a correction value depending on the transport angle of the wafer W around the wafer central axis WC.

[0098] The control device 25 also stores measurement data of the amount of shift in association with the type and weight of the wafer W, and uses the measurement data as a correction value depending on the type and weight of the wafer W.

[0099] In addition, the control device 25 stores the measurement data of the shift amount during the load process in association with a specified wafer testing device 1 in which a transport arm 10 carrying a wafer W on the upper surface 22 of the chuck 21 is provided, and uses the measurement data as a correction value when another wafer W is subsequently placed on the upper surface 22 of the chuck 21 in the same specified wafer testing device 1.

[0100] The control device 25 also stores measurement data of the amount of shift of the wafer W placed on the upper surface 22 of the chuck 21 relative to the chuck 21, and, if the measurement data is greater than a tolerance, performs control to use the measurement data as a correction value when the wafer W is lifted from the chuck 21 by the transfer arm 10 and then placed again on the upper surface 22 of the chuck 21. The tolerance is set in advance depending on, for example, the type of wafer W to be transferred.

[0101] FIG. 6 is a flowchart showing an example of the loading process performed by the wafer transfer system 20 of this embodiment. 6, when air is discharged from the air discharge ports 13 and 14, the transfer arm 10 sucks the wafer W by the negative pressure generated based on Bernoulli's principle (step S01). The wafer W moves upward toward the lower surface 12 of the arm top plate 11 and comes into contact with the sloped portion 15, whereby the wafer W is guided in the XY plane direction (horizontal plane direction) by the sloped portion 15. As a result, the wafer W is aligned (centered) so that the wafer central axis WC and the central axis C of the transfer arm 10 are substantially coaxial (step S02).

[0102] If there is no offset value (correction value) to be added to the transfer position (XY coordinates) of the chuck 21 (step S03: Yes), the control device 25 moves the chuck 21 to the transfer position without adding an offset value (step S05).If there is an offset value to be added to the transfer position of the chuck 21 (step S03: No), the control device 25 adds the offset value to the transfer position (step S04) and moves the chuck 21 to the transfer position (step S05).

[0103] When the air discharge from the air discharge ports 13, 14 is stopped, the wafer W is lowered and placed on the upper surface 22 of the chuck 21 (step S06). A measuring means such as a camera or a sensor measures the shift amount (positional deviation amount) of the wafer W relative to the chuck upper surface 22 (step S07).

[0104] If the shift amount of the wafer W is within the allowable range (step S08: Yes), the control device 25 stores the shift amount as an offset value (step S11) and ends the series of loading processes. The stored offset value is reflected in the next loading process.

[0105] If the shift amount of the wafer W is not within the allowable range (step S08: No), the control device 25 stores the shift amount as the next offset value (step S09) and moves the chuck 21 to the transfer position (step S10). Air is again discharged from the air discharge ports 13, 14, and the transfer arm 10 sucks the wafer W by the negative pressure generated based on Bernoulli's principle (step S01), and the same process as described above is performed (retry process).

[0106] According to the wafer transfer arm 10, wafer transfer system 20, and wafer testing device 1 of the present embodiment described above, the following excellent operational effects can be obtained.

[0107] In the wafer transfer arm 10 of this embodiment, a sloped portion 15 is provided on the underside 12 of the arm top plate 11. When air is discharged from the air discharge ports 13 and 14 and the wafer W is sucked upward by Bernoulli's principle and moves toward the underside 12 of the arm top plate 11, the outer periphery of the wafer W comes into contact with the sloped portion 15. At this time, the outer periphery of the wafer W rises while being guided along the inclination of the sloped portion 15, thereby aligning the central axis of the wafer W (wafer central axis WC) so that it is coaxial with (coincides with) the central axis C of the arm top plate 11, and the wafer W is aligned. In other words, the sloped portion 15 provides a wafer W alignment function.

[0108] This makes it possible to minimize the amount of misalignment (eccentricity) of the wafer W in the XY plane (horizontal plane) during transport. Since the wafer W is prevented from being significantly misaligned with respect to the arm top plate 11, the positional accuracy of the wafer W placed on the chuck upper surface 22 is also ensured.

[0109] Furthermore, the arm top plate 11 has a plurality of air outlets 13, 14 that discharge air from the underside 12 thereof, which include an outer air outlet 13 and an inner air outlet 14. The outer air outlet 13 is disposed so as to overlap with the outer periphery of the wafer W when viewed from the top-bottom direction. The outer air outlet 13 has a lower air pressure than the inner air outlet 14. In other words, the inner air outlet 14 has a higher air pressure than the outer air outlet 13.

[0110] When the thickness of the wafer W to be transported by the transport arm 10 is, for example, about 775 μm (normal thickness), air is discharged from the inner air discharge port 14, which has a high air pressure. This allows the transport arm 10 to stably suck and hold the wafer W and transport it using Bernoulli's principle, even if the wafer W is heavy.

[0111] Furthermore, when the thickness of the wafer W transported by the transport arm 10 is thin, for example, 100 μm or less, air is discharged from the outer air discharge port 13, which has a low air pressure. This makes it difficult for a force to slide the wafer W in the horizontal direction relative to the arm top plate 11 to be generated, and it is possible to prevent the wafer W from shifting position during transport.

[0112] Furthermore, the outer air outlets 13 are disposed to face the outer periphery of the wafer W from above. Therefore, even when transporting a wafer W that is thinned or has a large diameter and therefore prone to warping, it is possible to make it easier for the suction force to act on the outer periphery of the wafer W. Since the outer periphery of the wafer W can be stably sucked and pulled up, it is possible to prevent a part of the outer periphery of the wafer W from sagging (a phenomenon in which the wafer W warps) during transport.

[0113] By preventing warpage of the wafer W in this way, the effect (alignment function) of the slope portion 15 described above can be stably achieved even in wafers W that have been made thinner and larger in diameter. Therefore, the accuracy of the loading position between the wafer W and the chuck 21 can be stably ensured.

[0114] Furthermore, when unloading the wafer W from the chuck 21, air is discharged from the inner air discharge port 14, which has a high air pressure. This provides a high suction force, allowing the wafer W to be pulled up with a strong force from the chuck upper surface 22. For example, even if the wafer W is loaded onto the heated chuck 21 and the suction holes opening in the chuck upper surface 22 become stuck and the lower surface of the wafer W becomes stuck, the wafer W can be stably separated from the chuck upper surface 22 by the transfer arm 10 and transferred.

[0115] As described above, according to this embodiment, Bernoulli's principle can be used to stably transport wafers W of various thicknesses while suppressing misalignment of the wafer W. Even for wafers W that have been thinned or enlarged in diameter, the phenomenon of warping of the wafer W during transport can be suppressed. The accuracy of the loading position between the wafer W and the chuck 21 can be stably ensured, and even if the wafer W adheres to the chuck 21, the wafer W can be stably unloaded. This reduces the occurrence of operational stoppages due to error determinations in the wafer testing device 1 during loading and unloading processes, and allows efficient and stable testing (inspection) of even wafers W that are prone to warping.

[0116] Specifically, in an example of this embodiment, when a flat wafer W of normal thickness that is resistant to warping was placed on the chuck upper surface 22, the positional deviation (shift amount) of the load position was measured. After 180 load processes, the variation in the shift amount in the X direction was kept to within 30 μm, and the variation in the shift amount in the Y direction was kept to within 42 μm. Furthermore, when the positional deviation (shift amount) of the load position when a thin wafer W that is prone to warping was placed on the chuck upper surface 22 was measured, the variation in the shift amount in the X direction was kept within 148 μm and the variation in the shift amount in the Y direction was kept within 155 μm after 180 load processes.

[0117] In this embodiment, the outer air discharge port 13 is disposed radially inside the slope portion 15 and adjacent to the slope portion 15 . In this case, the outer air discharge port 13 can be disposed facing the outermost side (peripheral edge We) of the outer periphery of the wafer W. Therefore, the above-described effects of the outer air discharge port 13 become more stable and particularly remarkable.

[0118] In this embodiment, the outer air outlet 13 discharges air radially inward along the lower surface 12 of the arm top plate 11 . In this case, the air discharged from the outer air discharge ports 13 flows radially inward along the lower surface 12 of the arm top plate 11. This effectively generates negative pressure between the lower surface 12 of the arm top plate 11 and the upper surface of the wafer W, and the suction force is increased more stably.

[0119] In this embodiment, the outer air discharge ports 13 and the inner air discharge ports 14 are arranged at different positions in the circumferential direction. In this case, the air discharged radially inward from the outer air discharge port 13 does not pass over (above the opening hole of) the inner air discharge port 14. This prevents turbulence from occurring in the air discharged from the outer air discharge port 13, making the suction force by the outer air discharge port 13 more stable.

[0120] In this embodiment, the arm top plate 11 is provided with an exhaust port 30 that opens on the lower surface 12 , and the exhaust port 30 is disposed radially inward of the outer air discharge port 13 . In this case, the air discharged from the outer air discharge port 13 radially inward along the lower surface 12 of the arm top plate 11 is exhausted from the exhaust port 30 opening in the lower surface 12. This makes it possible to appropriately maintain the negative pressure (suction force) that draws the wafer W closer to the arm top plate 11. Furthermore, a portion of the air discharged from the inner air discharge port 14 may be exhausted from the exhaust port 30. In this case as well, the effect of maintaining the above-mentioned negative pressure appropriately can be obtained.

[0121] In this embodiment, six slope portions 15 are provided at equal intervals in the circumferential direction. For example, compared to forming the slope portion 15 in a circular ring shape extending around the entire circumference of the underside 12 of the arm top plate 11, with the above configuration, each slope portion 15 can be formed in an arc shape using small, easy-to-handle members (in this embodiment, using guide member 19), making manufacturing easier.

[0122] Furthermore, since six slope portions 15 are provided at equal intervals in the circumferential direction, the following advantageous effects are obtained. For example, even if the outer periphery of the wafer W unintentionally sags as shown in FIG. 8 during transport and a pair of sagging portions H is positioned between adjacent slope portions 15 in the circumferential direction (a portion where no slope portion 15 is provided), a pair of non-sagging portions F can contact the slope portions 15 at positions offset by 90° around the wafer center axis WC from each sagging portion H. Therefore, even if the wafer W unintentionally warps, the alignment effect of the slope portions 15 can be easily obtained in at least a predetermined direction (e.g., the X direction or the Y direction) among the XY plane directions (horizontal plane directions).

[0123] In this embodiment, the minimum cross-sectional area of ​​the outer air outlet 13 and the piping member (outer air piping 16) that sends air to the outer air outlet 13 is 19.6 mm 2 That is said to be the case. According to the above configuration, even when transporting a thin wafer W that is prone to warping, the air flow rate (L / min) discharged from the outer air discharge ports 13 is sufficiently ensured, thereby stably suppressing the sagging phenomenon of the outer periphery of the wafer W. As a result, the above-mentioned slope portion 15 can stably achieve the centering function of the wafer W.

[0124] In addition, the wafer transport system 20 of this embodiment includes the above-mentioned wafer transport arm 10, a chuck 21 on whose upper surface 22 the wafer W transported by the wafer transport arm 10 is placed, and a control device 25, and the control device 25 controls the ejection of air from either the outer air outlet 13 or the inner air outlet 14 depending on the type and weight of the wafer W transported to the chuck 21.

[0125] In the wafer transport system 20 of this embodiment, the control device 25 controls the discharge of air so as to obtain an optimal suction force according to the type (device type, etc.) and weight (thickness, etc.) of the wafer W to be loaded onto the chuck 21. For example, according to the pre-stored specification data of each wafer W, the control device 25 determines and executes whether to discharge air (weak air) from the outer air discharge port 13 or air (strong air) from the inner air discharge port 14.

[0126] Specifically, the control device 25 performs the following control, for example. When the wafer W to be transported has a thickness of, for example, about 775 μm (normal thickness) and is heavy, the control device 25 controls the air to be discharged from the inner air discharge port 14, which has a high air pressure. This ensures stable suction force even for heavy wafers W, allowing the wafers W to be transported stably.

[0127] Furthermore, when the wafer W to be transported has a thin thickness of, for example, 100 μm or less, and the type of wafer W is a power device or the like having a metal film on its underside, and is light in weight and prone to warping, the control device 25 controls the air to be discharged from the outer air outlet 13, which has a low air pressure. As a result, even for a light wafer W, a force that slides the wafer W in the horizontal direction is less likely to be generated, and the wafer W is prevented from shifting significantly during transport. Furthermore, the above-described function (action) of the outer air outlet 13 also prevents the wafer W from warping. In this way, the control device 25 can automate the transport with suction forces suitable for each wafer W of various types and weights.

[0128] In this embodiment, the control device 25 controls the air to be discharged from the inner air discharge port 14 when the wafer W is lifted from the upper surface 22 of the chuck 21 by the wafer transfer arm 10 .

[0129] In the above configuration, when unloading the wafer W from the chuck upper surface 22, the control device 25 controls the inner air outlet 14 to discharge air (strong air) regardless of the type or weight of the wafer W. This provides a high suction force, and the wafer W can be stably unloaded even if it has unintentionally become stuck to the chuck upper surface 22.

[0130] In addition, in this embodiment, the control device 25 stores measurement data of the shift amount of the wafer W placed on the upper surface 22 of the chuck 21 relative to the chuck 21, and performs control to use the measurement data as a correction value when another wafer W to be transported thereafter is placed on the upper surface 22 of the chuck 21.

[0131] The likelihood of warping of the transported wafers W varies among the wafers W even if they are of the same type and weight (for example, differences occur depending on the production lot). Furthermore, the degree of alignment function obtained by the slope portion 15 differs depending on the amount of warping of each wafer W.

[0132] Therefore, in the above configuration of this embodiment, the control device 25 stores measurement data of the positional deviation (shift amount) of the loading position of the wafer W, and uses this measurement data as a correction value (offset value) for the wafer W to be subsequently loaded onto the chuck 21 (the offset value is reflected in the transfer position to the chuck 21). This makes it possible to stably improve the loading position accuracy between the wafer W and the chuck 21, at least for the second (second wafer) or subsequent wafers W transported, regardless of, for example, the production lot.

[0133] In addition, in this embodiment, the control device 25 stores measurement data of the shift amount in association with the transport angle of the wafer W around the wafer central axis WC, and uses the measurement data as a correction value depending on the transport angle of the wafer W around the wafer central axis WC.

[0134] The probe card used for functional testing of semiconductor chips mounted on the wafer W is attached to the wafer testing equipment 1 at an optimal attachment angle, taking into consideration the layout area (layout) of the electrical circuits and electronic elements on the card substrate and shortening of the circuit length. The attachment angle of the probe card also varies depending on the angle (left entry, rear entry) of the electrical test measuring instrument (tester) and the purpose of following the layout of the electrical circuits and electronic elements in the tester. Specifically, the attachment angle of the probe card is set to four types (0°, 90°, 180°, 270°) in 90-degree increments around the wafer center axis WC of the wafer W to be tested.

[0135] Furthermore, the wafer W to be loaded onto the chuck 21 has a transfer angle about the wafer central axis WC determined in accordance with the attachment angle of the probe card. That is, the transfer angle of the wafer W about the wafer central axis WC is set to four angles (0°, 90°, 180°, and 270°) in 90-degree increments about the wafer central axis WC. Therefore, when transferring a thin wafer W that is prone to warping, the angular position of the portion H that is prone to sagging about the wafer central axis WC changes depending on the transfer angle. Therefore, the alignment function provided by the slope portion 15 also changes depending on the transfer angle.

[0136] Therefore, in the above configuration of this embodiment, the control device 25 stores measurement data of the positional deviation (shift amount) of the loading position of the wafer W in association with the transport angle of the wafer W around the wafer central axis WC, and uses this measurement data as a correction value (offset value) for the wafer W that is subsequently loaded onto the chuck 21 at the same transport angle (the offset value is reflected in the delivery position to the chuck 21). Because an optimal offset value can be added to the delivery position (XY coordinates) of the chuck 21 according to each transport angle of the wafer W, the loading position accuracy of the wafer W and the chuck 21 can be stably improved regardless of the transport angle of the wafer W.

[0137] In this embodiment, the control device 25 stores measurement data of the shift amount in association with the type and weight of the wafer W, and uses the measurement data as a correction value depending on the type and weight of the wafer W.

[0138] The likelihood of warping of the transported wafers W is affected by the type (device type, etc.) and weight (thickness, etc.) of the wafers W. The degree of alignment function obtained by the slope portion 15 also differs depending on the amount of warping of each wafer W.

[0139] Therefore, in the above configuration of this embodiment, the control device 25 stores measurement data of the positional deviation (shift amount) of the loading position of the wafer W in association with the type and weight of the wafer W to be transported, and uses this measurement data as a correction value (offset value) for a wafer W of the same type and weight to be subsequently loaded onto the chuck 21 (the offset value is reflected in the transfer position to the chuck 21). This makes it possible to stably improve the loading position accuracy of the wafer W and the chuck 21 regardless of the type and weight of the wafer W.

[0140] In addition, in this embodiment, the control device 25 stores the measurement data of the shift amount in association with a specified wafer testing device 1 in which a transport arm 10 carrying a wafer W on the upper surface 22 of the chuck 21 is provided, and then uses the measurement data as a correction value when another wafer W is placed on the upper surface 22 of the chuck 21 in the specified wafer testing device 1.

[0141] The load position accuracy of the wafer W and the chuck 21 varies among wafer testing devices 1. This is because even among wafer testing devices 1 with the same specifications, there are physical differences (slight individual differences) in, for example, the air pressure (air flow rate) discharged from the air discharge ports 13 and 14 of the transfer arm 10 and the alignment function of the slope portion 15.

[0142] Therefore, in the above configuration of this embodiment, the control device 25 stores measurement data of the positional deviation amount (shift amount) of the loading position of the wafer W in association with a predetermined wafer testing apparatus 1, and uses this measurement data as a correction value (offset value) for the wafer W to be subsequently loaded onto the chuck 21 in the same predetermined wafer testing apparatus 1 (the offset value is reflected in the transfer position to the chuck 21). As a result, even when multiple wafer testing apparatuses 1 are used, the loading position accuracy of the wafer W and the chuck 21 can be stably improved in each wafer testing apparatus 1.

[0143] In addition, in this embodiment, the control device 25 stores measurement data of the shift amount of the wafer W placed on the upper surface 22 of the chuck 21 relative to the chuck 21, and if the measurement data is larger than the allowable value, controls the transport arm 10 to lift the wafer W from the chuck 21 and use the measurement data as a correction value when placing the wafer W on the upper surface 22 of the chuck 21 again.

[0144] In the above configuration, the control device 25 retries the loading process when the wafer W placed on the upper surface 22 of the chuck 21 is significantly misaligned in the XY plane direction (horizontal plane direction) (when the amount of misalignment exceeds a preset tolerance). During this retry, the amount of misalignment of the wafer W from the previous time is used as a correction value, so the amount of misalignment (shift amount) of the reloaded wafer W is significantly reduced. Therefore, not only is it possible to prevent the wafer testing device 1 from stopping operation due to an error judgment during the loading process, but the accuracy of the loading position between the wafer W and the chuck 21 is also significantly improved.

[0145] Specifically, in an example of this embodiment, the loading process was retried using a thin wafer W that is prone to warping, and the positional deviation (shift amount) of the reloaded wafer W was measured. After 850 load processes, the variation in the shift amount in the X direction was kept within 60 μm, and the variation in the shift amount in the Y direction was kept within 39 μm.

[0146] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, as described below. In the illustrations of the modified examples, the same components as those in the above-described embodiment are given the same reference numerals, and the following mainly describes the differences.

[0147] In the above embodiment, the case where the wafer W is a disk-shaped wafer with a certain thickness and a flat bottom surface is subjected to the loading and unloading processes has been described, but the present invention is not limited to this. 7 is a side view (side cross-sectional view) schematically showing a chuck 21 and a wafer W provided in a wafer transfer system 20 according to a modified example of the above-described embodiment. Note that components of the transfer system 20 other than those described above are omitted from the illustration.

[0148] 7, in this modification, the wafer W has a thick portion 101 that is arranged on the outer periphery of the wafer W and has an annular plate-shaped thick portion 101, and a thin portion 102 that is arranged radially inward of the thick portion 101 and has a disk-like shape that is thinner than the thick portion 101. The thin portion 102 has a chip formation effective area 103 whose diameter is smaller than that of the thin portion 102. The wafer W in this modification is, for example, a TAIKO (registered trademark) wafer.

[0149] The chuck 21 also has a circular concave step portion 22a located on the outer periphery of the upper surface 22 of the chuck 21, and a convex surface 22b located radially inward of the step portion 22a on the upper surface 22, protruding upward from the step portion 22a, on which the thin portion 102 of the wafer W is placed. The diameter of the convex surface 22b is smaller than the diameter of the thin portion 102 and equal to or greater than the diameter of the effective chip formation area 103.

[0150] More specifically, the upper surface 22 of the chuck 21 has a multi-step shape (two-step convex shape) including a convex surface 22b and a step portion 22a, corresponding to the multi-step shape of the lower surface of the wafer W. In order to stably load a wafer W having such a shape onto the chuck upper surface 22, the diameter of the convex surface 22b must be smaller than the diameter of the thin portion 102 of the wafer W. Furthermore, when testing semiconductor chips on the wafer W, the diameter of the effective chip formation area 103 must be equal to or smaller than the diameter of the convex surface 22b. Therefore, in order to secure a large chip formation effective area 103 and increase the number of effective chips (gross number) (i.e., to increase the profit margin per wafer), it is necessary to make the diameter dimension of the convex surface 22b closer to the diameter dimension of the thin portion 102 of the wafer W.

[0151] In this regard, in this modified example, similar to the above-described embodiment, the positional accuracy of the wafer W placed on the chuck upper surface 22 by the transfer arm 10 is stably ensured. Therefore, it is possible to make the diameter dimension of the convex surface 22b closer to the diameter dimension of the thin-walled portion 102 of the wafer W, and it is possible to increase the area of ​​the convex surface 22b. By increasing the area of ​​the convex surface 22b, it is possible to increase the effective chip formation area 103 of the wafer W. By increasing the effective chip formation area 103, the number of effective chips (gross number) increases, and it is possible to increase the profit margin per wafer W (per wafer unit).

[0152] The present invention may be combined with the various configurations described in the above-described embodiments and modifications, and may also include additions, omissions, substitutions, and other modifications of the configurations, without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the above-described embodiments, but is limited only by the claims. [Example]

[0153] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0154] <Configuration of the transfer arm for each wafer in the examples and comparative examples> A wafer transfer accuracy confirmation test and a wafer arm interference confirmation test, which will be described later, were carried out using the wafer transfer arm 10 of the embodiment, which is a product of the present invention, and the wafer transfer arms 200 and 300 of the conventional comparative examples 1 and 2. First, the configuration of each transfer arm will be described.

[0155] 9 is a side cross-sectional view schematically showing a portion of a wafer transfer arm 200 of Comparative Example 1. As shown in Fig. 9, the transfer arm 200 of Comparative Example 1 has an air discharge port 214 that opens in a lower surface 212 of an arm top plate 211, and a floating stopper 215 that is provided so as to protrude downward from the outer periphery of the lower surface 212.

[0156] The air discharge port 214 is configured to discharge air diagonally downward from the lower surface 212 of the arm top plate 211. Specifically, the air discharge port 214 discharges air radially outward as it moves downward from the lower surface 212. Arrow A shown in FIG. 9 indicates the direction A in which the air discharged from the air discharge port 214 flows. Furthermore, arrow N shown in FIG. 9 indicates the negative pressure N acting on the wafer W when air is discharged from the air discharge port 214 (the direction in which the negative pressure N acts).

[0157] The floating stopper 215 is disposed facing the peripheral edge We of the wafer W from above. When air is discharged from the air discharge port 214, a negative pressure N acts on the wafer W, and the wafer W moves upward (moves closer to the lower surface 212), the floating stopper 215 can come into contact with the peripheral edge We of the wafer W.

[0158] 10 is a side cross-sectional view schematically showing a portion of a wafer transfer arm 300 of Comparative Example 2. As shown in Fig. 10, the transfer arm 300 of Comparative Example 2 has an air discharge port 314 that opens in a lower surface 312 of an arm top plate 311, and a floating stopper 315 that protrudes downward from the outer periphery of the lower surface 312.

[0159] The air outlet 314 can have the same configuration as the inner air outlet 14 of the transfer arm 10 described in the above embodiment. The air outlet 314 is configured to be able to discharge swirling air (swirl air) from the lower surface 312 of the arm top plate 311 toward the entire periphery (all directions) of the opening of the air outlet 314. That is, swirling air is discharged from the air outlet 314. Arrow A in FIG. 10 indicates the direction A of flow of air discharged from the air outlet 314. The air discharged from the air outlet 314 flows between the lower surface 312 of the arm top plate 311 and the upper surface of the wafer W in the plane direction of the XY axes, i.e., in the horizontal direction (the direction in which a horizontal plane perpendicular to the up-down direction extends). Furthermore, arrow N in FIG. 10 indicates the negative pressure N acting on the wafer W when air is discharged from the air outlet 314 (the direction in which the negative pressure N acts).

[0160] The floating stopper 315 is disposed facing the peripheral edge We of the wafer W from above. When air is discharged from the air discharge port 314, a negative pressure N acts on the wafer W, and the wafer W moves upward (moves closer to the lower surface 312), the floating stopper 315 can come into contact with the peripheral edge We of the wafer W.

[0161] 11 is a side cross-sectional view schematically showing a portion of a wafer transfer arm 10 according to an embodiment. In this embodiment, air is discharged from the outer air discharge port 13 out of the inner air discharge port 14 and outer air discharge port 13 of the transfer arm 10. The outer air discharge port 13 opens on the underside 12 of the arm top plate 11 so as to cut out a portion of the radially inner end of a guide member 19 having a sloped portion 15. Note that the inner air discharge port 14 is not shown in FIG.

[0162] The outer air outlet 13 discharges the air, which has been made into a swirling flow inside the arm top plate 11, radially inward from an opening in the lower surface 12 of the arm top plate 11. Arrow A shown in FIG. 11 indicates the direction A in which the air discharged from the outer air outlet 13 flows. The air discharged from the outer air outlet 13 flows radially inward along the XY plane between the lower surface 12 of the arm top plate 11 and the upper surface of the wafer W. Furthermore, arrow N shown in FIG. 11 indicates the negative pressure N acting on the wafer W when air is discharged from the outer air outlet 13 (the direction in which the negative pressure N acts).

[0163] 10 and 11, in Comparative Example 2 and Example, before air is discharged from the air discharge ports 314, 13, the air is caused to fall vertically inside the arm top plates 311, 11 to generate a swirling flow. That is, the arm top plates 311, 11 have an air flow path that is disposed inside the arm top plates 311, 11 and communicates with the air discharge ports 314, 13, and the air flow path has a swirling flow generating section that swirls the air to generate a swirling flow. This makes it easier for the air discharged from the openings of the air discharge ports 314, 13 to flow along the XY plane due to the centrifugal force caused by the swirling.

[0164] <Wafer transfer accuracy verification test> A wafer W transfer accuracy confirmation test was conducted using the wafer transfer arms 200 and 300 of the conventional wafers of Comparative Examples 1 and 2 and the wafer transfer arm 10 of the example of the present invention. The TAIKO (registered trademark) wafer shown in FIG. 7 was used as the wafer W to be transferred. This wafer W has a circular plate-shaped thick portion 101 located on the outer periphery of the wafer W with a thickness of 750 μm, and a circular plate-shaped thin portion 102 located radially inward from the thick portion 101 with a thickness of 85 μm. Note that detailed illustration of the shape of the TAIKO (registered trademark) wafer near its outer periphery (thick portion 101) is omitted in FIGS. 9 to 11.

[0165] Regarding the transfer of the wafer W, first, the wafer central axis WC of the wafer W was aligned (pre-aligned) with the central axis of the lower surface arm (not shown), and then the wafer W was transferred from the lower surface arm to each transfer arm (upper surface arm) 200, 300, 10. When the wafer W was placed (loaded) from each transfer arm 200, 300, 10 onto the upper surface 22 of the chuck 21, the shift amount (positional deviation amount) of the XY coordinates (X axis and Y axis) relative to the chuck 21 was measured. The number of load processes was also 225 for each of the transfer arms 200, 300, 10. The results are shown in Table 1 below.

[0166] [Table 1]

[0167] From the results in Table 1 above, it was confirmed that the wafer transfer arm 10 of the example had significantly improved wafer W transfer accuracy in both the X-axis and Y-axis compared to the wafer transfer arms 200 and 300 of Comparative Examples 1 and 2. Furthermore, when comparing Comparative Examples 1 and 2, it was confirmed that the transfer accuracy of Comparative Example 2 was superior to that of Comparative Example 1 in both the X-axis and Y-axis.

[0168] <Wafer arm interference confirmation test> An arm interference confirmation test for the wafer W was carried out using the wafer transfer arms 200 and 300 of the above-mentioned conventional comparative examples 1 and 2 and the wafer transfer arm 10 of the example of the product of the present invention. The wafer W used in the test was the TAIKO (registered trademark) wafer.

[0169] Specifically, tests were conducted using the following method to confirm whether the upper surface of the wafer W (hereinafter sometimes referred to as the wafer surface) interferes with (contacts) the lower surfaces 212, 312, 12 of the arm top plates 211, 311, 11 when the wafer W is being transported by each transport arm 200, 300, 10, whether the wafer W is locally deformed, and whether condensation occurs on the wafer W.

[0170] First, the arm top plates 211, 311, 11 of each transfer arm 200, 300, 10 are placed on a table or the like so that the undersides 212, 312, 12 of the arm top plates 211, 311, 11 face vertically upward, and a sheet member with a striped pattern is attached to a wall or the like located to the side of the arm top plates 211, 311, 11. A wafer W is placed on the upward-facing undersides 212, 312, 12 of each arm top plate 211, 311, 11, and air is discharged from each air discharge port 214, 314, 13. In this air discharge state (during air discharge) and in a non-air discharge state (before or after air discharge), the striped patterns and the like reflected on the upward-facing mirror-like underside of the wafer W (hereinafter sometimes referred to as the backside of the wafer) of the wafer W are observed and photographed.

[0171] Figure 12 shows the striped pattern transferred onto the back surface of the wafer when the transfer arm 200 of Comparative Example 1 is not in an air-spraying state, and Figure 13 shows the striped pattern transferred onto the back surface of the wafer when the transfer arm 200 of Comparative Example 1 is in an air-spraying state.

[0172] As shown in Fig. 13, when air was being ejected from the transfer arm 200, striped deformation confirmed that the wafer W was locally deformed. This is thought to be because, as shown in Fig. 9, when air was ejected from the air ejection port 214, a strong negative pressure N was generated in a certain area, causing a localized, sharp deformation in the shape of the wafer W. Such deformation is undesirable as it may damage the device circuits of the wafer W.

[0173] Furthermore, since the stripes on the back surface of the wafer do not disappear when the transfer arm 200 is in the air ejection state, it is believed that vibrations such as those in Comparative Example 2 and the example described below are not occurring in the wafer W, and that the front surface of the wafer is in contact (i.e., interfering) with the underside 212 of the arm top plate 211. Such interference is undesirable, as it may damage and contaminate the device circuits of the wafer W.

[0174] 14 shows stripes and condensation marks M that are projected onto the back surface of the wafer W when air is being ejected by the transfer arm 200 in Comparative Example 1. That is, in Comparative Example 1, condensation marks M of about several millimeters in size were observed near the air ejection port 214 of the wafer W. FIG. 15 shows an image taken with a microscope of the area near the condensation marks M in FIG. 14, in which minute water droplets were observed on the wafer W. Such condensation (water droplets) is undesirable because it can damage the device circuits of the wafer W.

[0175] FIG. 16 shows the striped pattern that appears on the backside of the wafer when the transfer arm 300 of Comparative Example 2 is not blowing air, and FIG. 17 shows the state of the backside of the wafer when the transfer arm 300 of Comparative Example 2 is blowing air.

[0176] As shown in Fig. 17, when air is being ejected from the transfer arm 300, the stripes disappear due to the vibration of the wafer W. Specifically, the wafer W vibrates up and down at a high frequency, which makes the stripes that were visible on the back surface of the wafer appear to have disappeared. Furthermore, because the wafer W is vibrating, it can be seen that the front surface of the wafer is separated from the underside 312 of the arm top plate 311 and is out of contact with it, as shown in Fig. 10.

[0177] In Comparative Example 2, air is discharged from the air discharge port 314 in the XY plane direction (horizontal direction), so that the negative pressure N is generated not locally but dispersed over a wide area, which makes it difficult for local deformation of the wafer W to occur. This suppresses damage to the device circuits of the wafer W. Furthermore, since vibration occurs because the wafer surface does not come into contact (interfere) with the underside 312 of the arm top plate 311, suppressing the contact (interference) suppresses damage to and contamination of the device circuits of the wafer W.

[0178] Furthermore, in Comparative Example 2, no condensation marks M were observed on the rear surface of the wafer when air was being ejected by the transfer arm 300. Therefore, damage to the device circuits of the wafer W due to condensation (water droplets) is also suppressed.

[0179] FIG. 18 shows the striped pattern that appears on the rear surface of the wafer when the transfer arm 10 of the embodiment is not injecting air, and FIG. 19 shows the state of the rear surface of the wafer when the transfer arm 10 of the embodiment is injecting air.

[0180] As shown in Figure 19, when air is being ejected from the transfer arm 10, the stripes disappear due to the vibration of the wafer W. Specifically, the wafer W vibrates up and down at a high frequency, which makes it appear that the stripes that were on the back surface of the wafer have disappeared. Furthermore, because the wafer W is vibrating, it can be seen that the front surface of the wafer is separated from the underside 12 of the arm top plate 11 and is out of contact with it, as shown in Figure 11. Note that the vibration of the wafer W is not hindered solely by the contact between the peripheral edge We of the wafer W and the slope portion 15.

[0181] In the embodiment, air is discharged from the outer air discharge ports 13 radially inward along the XY plane direction (horizontal direction), so that the negative pressure N is generated not locally but dispersed over a wide area, thereby making it difficult for local deformation of the wafer W to occur. In particular, when the wafer W is a TAIKO (registered trademark) wafer, air is discharged from near the thick portion 101 on the outer periphery of the wafer W, so deformation of the wafer W is further suppressed. As a result, damage to the device circuits of the wafer W is suppressed. Furthermore, since vibration occurs when the wafer surface does not contact (interfere with) the underside 12 of the arm top plate 11, suppressing the contact (interference) suppresses damage to and contamination of the device circuits of the wafer W.

[0182] Furthermore, in this example, no condensation marks M were observed on the rear surface of the wafer when air was being ejected by the transfer arm 10. Therefore, damage to the device circuits of the wafer W due to condensation (water droplets) is also suppressed.

[0183] Next, the height displacement and its distribution of the wafer backside were observed using a microscope. Specifically, using the transfer arm 200 for the wafer of Comparative Example 1 and the transfer arm 10 for the wafer of Example, the arm top plates 211 and 11 of each transfer arm 200 and 10 were installed on the microscope stage so that the lower surfaces 212 and 12 of the arm top plates 211 and 11 faced vertically upward. A wafer W was placed on these lower surfaces 212 and 12, and the height displacement and its distribution at each part of the wafer backside when air was discharged from each air discharge port 214 and 13 were confirmed. Note that, for the height displacement, the height position of the wafer backside in the non-air discharge state was set as a reference value of 0 μm, and the relative height change (relative change value) of each part of the wafer backside in the air discharge state was measured.

[0184] As a result, in the transfer arm 200 of Comparative Example 1, the MIN value (recess value in the Z-axis direction) near the air outlet 214 of the entire area of ​​the back surface of the wafer was −381.0 μm. The absolute value of this MIN value (381.0 μm) is larger than the height dimension L of the floating stopper 215 (320 μm) shown in FIG. 9, which indicates that the front surface of the wafer is interfering with the lower surface 212 of the arm top plate 211.

[0185] Furthermore, in Comparative Example 1, the height displacement of the wafer rear surface (amount of unevenness in the Z-axis direction) varied greatly in each part of the wafer rear surface. Specifically, in the entire area of ​​the wafer rear surface, the MAX value (value that becomes convex in the Z-axis direction) was 1039.0 μm, and the MIN value was −395.0 μm. This result also revealed that the stress on the wafer W was large.

[0186] On the other hand, in the transfer arm 10 of the example, the MIN value in the entire area of ​​the wafer back surface near the outer air outlet 13 was −308.0 μm. The absolute value of this MIN value (308.0 μm) is smaller than the height dimension of the guide member 19 shown in FIG. 11 = 620 μm, which indicates that the wafer front surface does not interfere with the underside 12 of the arm top plate 11.

[0187] In addition, in the example, the MAX value of the height displacement (the value that is convex in the Z-axis direction) in the entire area of ​​the back surface of the wafer was 669.0 μm, and the MIN value (the value that is concave in the Z-axis direction) was -308.0 μm, and this result also showed that the stress on the wafer W was small.

[0188] In this example, since the wafer W vibrates while air is being ejected, it is difficult to find the focal position using a microscope (because there is also a range of focal depth). For this reason, the following method was used to measure the height displacement of the rear surface of the wafer. That is, the microscope used to observe the wafer backside was moved up and down, and the positions on both the top and bottom sides where the wafer backside began to lose focus while air was being ejected were found. Since the distance between these two sides corresponds to the amplitude of vibration, the midpoint between the top and bottom sides was taken as the focal position (height position).

[0189] 20 is a graph showing the measured amplitude of vibration caused by repeated rising and falling of various parts of the wafer W in the air ejection state of the transfer arm 10 of the embodiment. As shown in the graph of FIG. 20, the maximum value of the vibration amplitude in the X-axis direction of the wafer W in the air ejection state was ±33 μm (width 66 μm), the minimum value was ±1 μm (width 2 μm), and the average value was ±15 μm (width 30 μm). [Industrial Applicability]

[0190] The wafer transfer arm, wafer transfer system, and wafer testing device of the present invention utilize Bernoulli's principle to stably transfer wafers of various thicknesses while suppressing misalignment, and can suppress wafer warping during transfer even for thinned or large-diameter wafers. This stably ensures the accuracy of the loading position between the wafer and the chuck, and allows stable unloading of the wafer even if the wafer sticks to the chuck. This allows for stable wafer inspection and efficient manufacturing. Therefore, the present invention has industrial applicability. [Explanation of symbols]

[0191] 1...wafer testing device, 10...wafer transfer arm, 11...arm top plate, 12...bottom surface, 13...outer air outlet (air outlet), 14...inner air outlet (air outlet), 15...slope portion, 20...wafer transfer system, 21...chuck, 22...top surface, 25...control device, 30...exhaust port, C...center axis, W...wafer, WC...wafer center axis

Claims

1. A wafer transport arm that sucks and holds a wafer from above using negative pressure generated by discharging air, a plurality of air outlets opening on the underside of the arm top plate; a slope portion provided on the lower surface and inclined radially outward as it extends downward, When the wafer is sucked by the negative pressure and moves toward the lower surface, the sloped portion can come into contact with the outer periphery of the wafer, The plurality of air outlets are an outer air outlet disposed opposite the outer periphery of the wafer from above; an inner air outlet disposed radially inward of the outer air outlet, The pressure of the air discharged from the outer air discharge port is set lower than the pressure of the air discharged from the inner air discharge port. Wafer transfer arm.

2. The outer air discharge port is disposed radially inside the slope portion and adjacent to the slope portion.

2. The wafer transfer arm according to claim 1.

3. The outer air outlet discharges air radially inward along the lower surface of the arm top plate.

2. The wafer transfer arm according to claim 1.

4. The outer air discharge port and the inner air discharge port are arranged at different positions in the circumferential direction.

4. The wafer transport arm according to claim 3.

5. Further, an exhaust port is provided on the underside of the arm top plate, The exhaust port is disposed radially inward of the outer air discharge port.

4. The wafer transport arm according to claim 3.

6. Six slope portions are provided at equal intervals in the circumferential direction.

2. The wafer transfer arm according to claim 1.

7. The minimum cross-sectional area of ​​the outer air outlet and the piping member that sends air to the outer air outlet is 19.6 mm ２ It is said that 2. The wafer transfer arm according to claim 1.

8. The wafer transfer arm according to claim 1; a chuck on the upper surface of which the wafer transported by the wafer transport arm is placed; a control device; the control device controls the air to be discharged from either the outer air discharge port or the inner air discharge port depending on the type and weight of the wafer to be transferred to the chuck. Wafer transport system.

9. the control device controls the air to be discharged from the inner air discharge port when the wafer is lifted from the upper surface of the chuck by the wafer transfer arm. The wafer transport system according to claim 8 .

10. the control device stores measurement data of the amount of shift of the wafer placed on the upper surface of the chuck relative to the chuck, and performs control to use the measurement data as a correction value when placing another wafer to be transported thereafter on the upper surface of the chuck. The wafer transport system according to claim 8 .

11. the control device stores measurement data of the shift amount in association with a transport angle of the wafer about the wafer central axis, and uses the measurement data as a correction value according to the transport angle of the wafer about the wafer central axis. The wafer transport system according to claim 10.

12. the control device stores the measurement data of the shift amount in association with the type and weight of the wafer, and uses the measurement data as a correction value according to the type and weight of the wafer. The wafer transport system according to claim 10.

13. the control device stores the measurement data of the shift amount in association with a predetermined wafer testing device in which a wafer transfer arm that places the wafer on the upper surface of the chuck is provided, and thereafter, when another wafer is placed on the upper surface of the chuck in the predetermined wafer testing device, the measurement data is used as a correction value. The wafer transport system according to claim 10.

14. the control device stores measurement data of the amount of shift of the wafer placed on the upper surface of the chuck relative to the chuck, and, if the measurement data is greater than an allowable value, performs control to use the measurement data as a correction value when lifting the wafer from the chuck by the wafer transfer arm and placing the wafer on the upper surface of the chuck again. The wafer transport system according to claim 8 .

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