Wafer transfer arm and wafer transfer system

Abstract

This transfer arm is provided with: 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 that inclines outward in the 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 the outer peripheral part of the wafer W. The plurality of air discharge ports (13, 14) have: an outer air discharge port (13) that faces the outer peripheral part of the wafer W from above; and an inner air discharge port (14) that is disposed inward in the radial direction of the outer air discharge port (13). The pressure of air discharged from the outer air discharge port (13) is smaller than the pressure of air discharged from the inner air discharge port (14).

Description

Wafer transfer arm and wafer transfer system

[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.

[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. Furthermore, wafer diameters (diameter dimensions) are 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 transfers a wafer while suction-holding it from above using Bernoulli's principle. A transfer arm using Bernoulli's principle can hold a wafer without contact, thereby suppressing the problem of damaging a thinned wafer during, for example, an unloading process.

[0006] International Publication No. 2014 / 084228

[0007] Generally, when a wafer is loaded onto the upper surface of a chuck by a transfer arm, the positional deviation (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 the positional accuracy of the wafer and chuck, and ensures the accuracy of testing (inspection).

[0008] However, the thickness of wafers to be inspected in wafer testing equipment varies depending on the device type, etc., and there are thin wafers with thicknesses of 100 μm or less, such as the above-mentioned TAIKO (registered trademark) wafer, and thick wafers with thicknesses of about 775 μm (normal thickness). When a thick wafer is suction-held 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 suction-held and transported using the same air pressure, a force that slides the wafer in the horizontal direction is generated, and there is a risk that the wafer will 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. More specifically, a pair of sagging portions H occurs at positions that are rotationally symmetrical to each other 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 by more than a predetermined value relative to the upper surface of the chuck during loading, an error is detected and the operation of the device is stopped.

[0010] Wafer electrical testing also checks the operating status under various temperature conditions. Specifically, a wafer may be loaded onto a heated chuck. When the wafer is placed on the heated chuck, it is vacuum-suctioned and held to the chuck. At the same time, the wafer undergoes thermal expansion. Specifically, the wafer is subjected to both a vacuum 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 may become stuck between the vacuum holes. This makes it difficult to remove the wafer from the chuck when returning it to the cassette after testing (making unloading difficult). If the wafer cannot be unloaded from the chuck, an error is detected and the device stops operating.

[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.

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

[0013] Aspect 1 of the Present Invention is a wafer transfer arm that uses Bernoulli's principle to hold a wafer by suction from above, 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 section 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 section 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 of 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 to be transported by the transport arm has a thickness of, for example, about 775 μm (normal thickness), air is discharged from the inner air discharge port with a high air pressure, which allows the transport arm to stably suck and hold the wafer by Bernoulli's principle and transport it, even if the wafer is heavy.

[0018] Furthermore, when the wafer to be 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, which makes it difficult for a force to slide the wafer horizontally relative to the arm top plate to be generated, thereby preventing the wafer from shifting position during transport.

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

[0020] By preventing wafer warpage in this way, the above-mentioned sloped section (alignment function) is stably effective even for wafers with thin walls and large diameters. Furthermore, if the positional deviation (eccentricity) of the wafer in the XY plane (horizontal plane) relative to the transfer arm during transfer is measured in advance (pre-alignment) and this eccentricity is reflected (corrected) in the transfer position to the chuck, variations in the measurement of the eccentricity can be suppressed. Therefore, the loading position accuracy of 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, it is possible to stably transport wafers of various thicknesses while suppressing misalignment by using Bernoulli's principle, to suppress the phenomenon of wafer warping during transport even for wafers with thin walls or large diameters, to stably ensure the accuracy of the loading position between the wafer and the chuck, and to stably unload the wafer even if the wafer sticks to the chuck. As a result, operation stoppages due to error judgments in the wafer testing device during loading and unloading processes are suppressed, and testing (inspection) can be performed efficiently and stably even on wafers that are prone to warping.

[0023] [Aspect 2 of the Present Invention] 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] [Aspect 3 of the Present Invention] The wafer transfer arm according to aspect 1 or 2, wherein the outer air outlets inject 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 The wafer transport arm according to Aspect 3, wherein the outer air discharge port and the inner air discharge port are arranged at different positions in the circumferential direction.

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

[0029] [Aspect 5 of the Present Invention] The wafer transfer arm according to Aspect 3 or 4, further comprising an exhaust port opening on the underside 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 radially inward along the underside of the arm top plate is exhausted from the exhaust ports opening 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 is the wafer transfer arm according to any one of Aspects 1 to 5, wherein six of the slope 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 advantageous effects are obtained. For example, even if the outer periphery of the wafer unintentionally sags during transport as shown in FIG. 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) of the X-Y plane directions (horizontal plane directions).

[0034] [Aspect 7 of the present invention] The minimum value of the cross-sectional area of ​​the flow path of the outer air discharge port and the piping member that sends air to the outer air discharge port 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] Aspect 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 to be 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 to be 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 discharge port 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 has a thin thickness of, for example, 100 μm or less, and the wafer is a type such as a power device having 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 outlet with 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 significantly shifting position during transport. Furthermore, the above-described function (action) of the outer air outlet also prevents the wafer from warping. In this way, the control device can automate transport using suction forces appropriate for various types and weights of wafers.

[0040] [Aspect 9 of the Present Invention] The wafer transport system according to Aspect 8, wherein the control device controls the air to be discharged from the inner air discharge port 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 ejection of air (strong air) from the inner air ejection port regardless of the type or weight of the wafer, which provides a strong suction force and allows 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] The wafer transport system according to aspect 8 or 9, wherein the control device stores measurement data of a shift amount 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] [Aspect 11 of the Present Invention] The wafer transport system according to aspect 10, wherein 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.

[0046] Probe cards used for functional testing of semiconductor chips mounted on wafers are attached to wafer testing equipment 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 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 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 center axis of the wafer to be 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 portion 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 (X-Y 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] The 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.), and the degree of alignment function obtained by the slope section varies 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 onto the chuck). This makes it possible to stably improve the loading position accuracy of the wafer and the chuck regardless of the type and weight of the wafer.

[0052] Aspect 13 of the present invention is a wafer transport system according to any one of Aspects 10 to 12, wherein 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 provided, and uses the measurement data as a correction value when another wafer is subsequently 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 among 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). This makes it possible to stably improve the load position accuracy between the wafer and the chuck in each wafer testing device, even when multiple wafer testing devices are used.

[0055] Aspect 14 of the Present Invention The 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, performs control such that the measurement data is used as a correction value when the wafer transport arm lifts the wafer off the chuck and places 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 X-Y plane (horizontal plane) (when the amount of misalignment exceeds a preset tolerance). During this retry, the previous misalignment amount of the same wafer is used as a correction value, so the misalignment amount (shift amount) of the reloaded wafer is significantly reduced. This not only reduces operational downtime due to an error judgment by the wafer testing device during the loading process, but also significantly improves the loading position accuracy between the wafer and the chuck.

[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.

[0058] FIG. 1 is a side view (side cross-sectional view) schematically showing a wafer transfer arm and a wafer transfer system according to this embodiment. FIG. 2 is a side view (side cross-sectional view) schematically showing the function of the sloped portion of the wafer transfer arm, with some of the components of the wafer transfer arm omitted. FIG. 3 is a bottom view of the wafer transfer arm, schematically showing the flow direction of air discharged from the outer air outlet and the inner air outlet. FIG. 4 is a bottom view of the wafer transfer arm, showing a state in which the wafer is suction-held by the transfer arm. FIG. 5 is a bottom view of an enlarged V-section of FIG. 3. FIG. 6 is a flowchart showing an example of a loading process performed by the wafer transfer system. FIG. 7 is a side view (side cross-sectional view) schematically showing a chuck and a wafer provided in a wafer transfer system according to a modified embodiment of this embodiment. FIG. 8 is a perspective view schematically showing a state in which a wafer that is prone to warping is deformed by its own weight (a state in which a sagging portion occurs).

[0059] A wafer transfer arm 10, a wafer transfer 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 generally 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. Within the radial direction, 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. Furthermore, the direction going around the central axis C is called the circumferential direction.

[0063] First, we will explain the components other than the transfer system 20 included in the wafer testing apparatus 1. Although not particularly shown, a 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. The chuck moving means also fine-tunes 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 component of the transfer system 20 will be described. The transfer arm 10 holds the wafer W by suction from above using Bernoulli's principle. 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 a lower surface 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 lower surface 12 of the arm top plate 11, and a slope portion 15 provided on the lower surface 12 of the arm top plate 11 and sloping radially outward as it extends downward.

[0070] The arm top plate 11 is plate-shaped and extends in a direction perpendicular to the up-down direction (horizontal direction). In this embodiment, the arm top plate 11 is disk-shaped and centered on a central axis C. The underside 12 of the arm top plate 11 is flat and 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 plurality of air discharge ports 13, 14 include an outer air discharge port 13 arranged opposite 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 to be 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 to be higher than the pressure of the air discharged from the outer air outlet 13. The pressure of the air discharged from the outer air outlet 13 (weak air) is, for example, in the range of 80 to 250 kPa, and the pressure of the air discharged from the inner air outlet 14 (strong air) is, for example, in the range of 180 to 500 kPa.

[0074] 3, a plurality of outer air discharge ports 13 are provided. The plurality of 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] 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] 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 discharge ports 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] The inner air outlet 14 also discharges swirling air (swirl air) toward the entire periphery (all directions) of the opening of the inner air outlet 14. The opening of the inner air outlet 14 is shaped like a circular hole.

[0082] 1, the plurality of air pipes 16, 17 include an outer air pipe 16 connected to the outer air outlet 13 and supplying air to the outer air outlet 13, and an inner air pipe 17 connected to the inner air outlet 14 and supplying air to the inner air outlet 14. The outer air pipe 16 and the inner air pipe 17 form air flow paths that are independent of each other. The minimum value of the flow path cross-sectional area of ​​the outer air outlet 13 and the piping member (outer air pipe 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 the air discharge ports 13 and 14, air pipes 16 and 17, and switching valve 18 are not shown in FIG. 2.

[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 has an arc-shaped plate shape 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 the radially opposite 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 Figure 5, in this embodiment, the opening of the outer air discharge port 13 is a semicircular hole that convex radially inward. The outer air discharge port 13 is disposed radially inward of 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 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 performs control to discharge high-pressure air from the inner air discharge port 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 ejection of low-pressure air from the outer air outlet 13 through the outer air piping 16.

[0095] In addition, 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 ejection of air from the inner air ejection 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 with 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 (X-Y coordinates) of the chuck 21 by adding the correction value and reflects it in the load process.

[0097] The control device 25 also 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 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.

[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 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 same specified wafer testing device 1.

[0100] The control device 25 also stores measurement data on 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 transfer arm 10 lifts the wafer W from the chuck 21 and places the wafer W back 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] 6 is a flowchart showing an example of a loading process performed by the wafer transfer system 20 of this embodiment. In FIG. 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 sloped portion 15 guides the wafer W in the XY plane direction (horizontal direction). This causes the wafer W to be 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 (X-Y 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 and 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 and 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 apparatus 1 of the present embodiment described above, the following excellent 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 according to 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, thereby aligning the wafer W. In other words, the sloped portion 15 provides a wafer W centering function.

[0108] This makes it possible to minimize the amount of misalignment (eccentricity) of the wafer W in the XY plane direction (horizontal plane direction) 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 wafer W to be transported by the transport arm 10 has a thickness of, 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 suction-hold and transport the wafer W by 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 discharge ports 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 above-described effect (alignment function) of the slope portion 15 is stably achieved even for wafers W that have been thinned and increased in diameter. Furthermore, if the positional deviation (eccentricity) of the wafer W in the XY plane direction (horizontal plane direction) relative to the transfer arm 10 during transfer is measured in advance (pre-alignment) and this eccentricity is reflected (corrected) in the transfer position to the chuck 21, variation in the measurement of the eccentricity can be suppressed. Therefore, the load position accuracy of 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 stuck to the lower surface of the wafer W, the wafer W can be stably separated from the chuck upper surface 22 and transferred by the transfer arm 10.

[0115] As described above, according to this embodiment, wafers W of various thicknesses can be stably transported using Bernoulli's principle while suppressing misalignment of the wafer W, and even for wafers W that have been thinned or have a large diameter, the phenomenon of the wafer W warping during transport can be suppressed, the accuracy of the loading position between the wafer W and the chuck 21 can be stably ensured, and the wafer W can be stably unloaded even if it sticks to the chuck 21. Therefore, operation stoppages due to error determinations of the wafer testing apparatus 1 during the loading process or unloading process can be suppressed, and testing (inspection) can be performed efficiently and stably even on 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 amount of misalignment (shift) of the load position was measured, and it was found that the variation in the amount of shift in the X direction was kept to within 30 μm and the variation in the amount of shift in the Y direction was kept to within 42 μm after 180 load processes. Also, when a thin wafer W that is prone to warping was placed on the chuck upper surface 22, the amount of misalignment (shift) of the load position was measured, and it was found that the variation in the amount of shift in the X direction was kept to within 148 μm and the variation in the amount of shift in the Y direction was kept to within 155 μm after 180 load processes.

[0117] Furthermore, in this embodiment, the outer air discharge port 13 is disposed radially inward of 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 portion We) of the outer periphery of the wafer W. This makes the above-described effects of the outer air discharge port 13 more stable and particularly remarkable.

[0118] In this embodiment, the outer air outlets 13 discharge air radially inward along the lower surface 12 of the arm top plate 11. In this case, the air discharged from the outer air outlets 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] Furthermore, in this embodiment, the outer air outlet 13 and the inner air outlet 14 are arranged at different positions in the circumferential direction. In this case, the air discharged radially inward from the outer air outlet 13 does not pass over the inner air outlet 14 (over the opening hole). This prevents turbulence from occurring in the air discharged from the outer air outlet 13, making the suction force by the outer air outlet 13 more stable.

[0120] Furthermore, in this embodiment, an exhaust port 30 is provided that opens on the underside 12 of the arm top plate 11, and the exhaust port 30 is disposed radially inward relative to the outer air outlet 13. In this case, air discharged from the outer air outlet 13 radially inward along the underside 12 of the arm top plate 11 is exhausted from the exhaust port 30 that opens on the underside 12. This makes it possible to appropriately maintain the negative pressure (suction force) that brings the wafer W close to the arm top plate 11. Furthermore, part of the air discharged from the inner air outlet 14 may be exhausted from the exhaust port 30. In this case as well, the effect of appropriately maintaining the negative pressure can be obtained.

[0121] In this embodiment, six slope portions 15 are provided at equal intervals in the circumferential direction. Compared to forming the slope portions 15 in a circular ring shape extending around the entire circumference of the underside 12 of the arm top plate 11, the above configuration allows each slope portion 15 to be formed in an arc shape using small, easy-to-handle members (in this embodiment, using guide members 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 (portions where no slope portions 15 are 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) of the X-Y 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 ２According 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, so that the sagging phenomenon of the outer periphery of the wafer W is stably suppressed. 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 depending on the type (device type, etc.) and weight (thickness, etc.) of the wafer W to be loaded onto the chuck 21. For example, depending on 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 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 performs control to eject air from the inner air ejection 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 having a metal film on its underside, which is light 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 being significantly displaced 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 transport using suction forces suitable for various types and weights of wafers W.

[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 controls the use of 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). The degree of the alignment function obtained by the slope portion 15 also differs depending on the amount of warping of each wafer W.

[0132] Therefore, in the above-described 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 onto the chuck 21). As a result, regardless of, for example, the production lot, the loading position accuracy of the wafer W and the chuck 21 can be stably improved at least for the second (second wafer) or subsequent wafers W transferred.

[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 center axis WC, and uses the measurement data as a correction value depending on the transport angle of the wafer W around the wafer center axis WC.

[0134] The probe card used for functional testing of semiconductor chips mounted on a wafer W is attached to the wafer testing device 1 at an optimal attachment angle, taking into consideration the layout area (layout) of the electrical circuits and electronic elements on the card substrate, shortening of the circuit length, etc. 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 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 transport angle about the wafer central axis WC determined in accordance with the attachment angle of the probe card. That is, the transport 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 transporting 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 transport angle. Therefore, the alignment function provided by the slope portion 15 also changes depending on the transport angle.

[0136] Therefore, in the above-described 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 center 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 transfer position onto the chuck 21). Because an optimal offset value can be added to the transfer position (X-Y 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 wafer W is affected by the type (device type, etc.) and weight (thickness, etc.) of the wafer 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-described 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 onto 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 the 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 (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 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 (horizontal plane) (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. This not only reduces operation stoppages due to error determinations of the wafer testing device 1 during the loading process, but also significantly improves the loading position accuracy of the wafer W and the chuck 21.

[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 to within 60 μm, and the variation in the shift amount in the Y direction was kept to 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 denoted by the same reference numerals, and the following mainly describes the differences.

[0147] In the above-described embodiment, the loading and unloading processes of a disk-shaped wafer W having a certain thickness and a flat bottom surface are described, but this is not limiting. Fig. 7 is a side view (side cross-sectional view) schematically showing a chuck 21 and a wafer W provided in a wafer transport system 20 according to a modified example of the above-described embodiment. Note that components of the transport system 20 other than those described above are not shown in the figure.

[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 a circular plate-like shape, and a thin portion 102 that is arranged radially inward of the thick portion 101 and has a circular plate-like shape that is thinner than the thick portion 101. The thin portion 102 has an effective chip formation 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 above the step portion 22a, and 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 upper surface 22 of the chuck, 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, to ensure a large effective chip formation area 103 and increase the number of effective chips (gross number) (i.e., to increase the profit margin per wafer), the diameter of the convex surface 22b must be closer to the diameter 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.

[0153] 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.

[0154] REFERENCE SIGNS LIST 1...wafer testing device, 10...wafer transport arm, 11...arm top plate, 12...underside, 13...outside air outlet (air outlet), 14...inside air outlet (air outlet), 15...slope portion, 20...wafer transport system, 21...chuck, 22...upper 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 created by ejecting air, comprising: a plurality of air ejection ports opening on the underside of the arm top plate; and a sloped section provided on the underside that slopes radially outward as it goes downward, wherein when the wafer is sucked by the negative pressure and moves close to the underside, the sloped section is able to come into contact with the outer periphery of the wafer, and the plurality of air ejection ports include: an outer air ejection port arranged to face the outer periphery of the wafer from above, and an inner air ejection port arranged radially inward from the outer air ejection port, and wherein the pressure of the air ejected from the outer air ejection port is smaller than the pressure of the air ejected from the inner air ejection port.

2. The wafer transfer arm according to claim 1, wherein the outer air outlet is disposed radially inside the sloped portion and adjacent to the sloped portion.

3. The wafer transfer arm according to claim 1, wherein the outer air outlets discharge air radially inward along the underside of the arm top plate.

4. The wafer transport arm according to claim 3, wherein the outer air outlet and the inner air outlet are arranged at different positions in the circumferential direction.

5. The wafer transfer arm according to claim 3, further comprising an exhaust port opening on the underside of the arm top plate, the exhaust port being positioned radially inward of the outer air outlet.

6. The wafer transfer arm according to claim 1, wherein six of the sloped sections are provided at equal intervals in the circumferential direction.

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 The wafer transfer arm according to claim 1 , wherein:

8. A wafer transport system comprising: a wafer transport arm as defined in claim 1; a chuck on whose upper surface a wafer transported by said wafer transport arm is placed; and a control device, wherein said control device controls the discharge of air from either said outer air outlet or said inner air outlet depending on the type and weight of the wafer transported to said chuck.

9. The wafer transport system according to claim 8, wherein the control device controls the air to be discharged from the inner air outlet when the wafer transport arm lifts the wafer from the upper surface of the chuck.

10. The wafer transport system according to claim 8, 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.

11. The wafer transport system according to claim 10, wherein the control device stores measurement data of the shift amount in association with the 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.

12. The wafer transport system according to claim 10, 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 according to the type and weight of the wafer.

13. The wafer transport system of claim 10, wherein 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 uses the measurement data as a correction value when another wafer is subsequently placed on the upper surface of the chuck in the predetermined wafer testing device.

14. The wafer transport system of claim 8, 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, when placing the wafer on the upper surface of the chuck again, uses the measurement data as a correction value.

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