DEVICE FOR EMPTYING A TRANSPORT CONTAINER

Description

Technical area

[0001] The invention relates to a device for emptying a transport container which has a stack of plate-shaped objects, comprising semiconductor wafers and / or packaging material, with at least one measuring device, with a holder which can be at least partially retracted into the transport container and which has a holding surface, a plurality of holding nozzles for holding at least one object of the stack and, in the region of the holding surface, at least one recess for the measuring device for recording measurement data from the object of the stack. State of the art

[0002] Devices with nozzles for picking up substrates and having measuring devices are known from the prior art (WO01 / 03893A1, WO2008 / 145085A1). WO2008 / 145085A1 describes a device with a holder, a holding surface with nozzles for generating the Bernoulli effect to pick up semiconductor wafers, and a measuring device. The measuring device is a capacitive sensor that protrudes through an area of ​​the holding surface to detect the correct pick-up of the sucked-in semiconductor wafer. A disadvantage of this device is that it is not capable of correctly picking up both semiconductor wafers and packaging material, such as foils, paper, or plastic foam. This is particularly problematic when the device must grip semiconductor wafers that are packaged in a stack for transport.This problem becomes increasingly serious when packaging material can adhere to the semiconductor wafer due to adhesive forces, making it difficult to empty the transport container piece by piece. Furthermore, damage to the semiconductor wafers cannot be ruled out during emptying, for example, if semiconductor wafers are pulled along during removal from the stack and then fall back onto the stack or fall off the holder elsewhere.

[0003] In addition, it is known (DE102012102239A1) to use a separating nozzle for separating stacked semiconductor wafers, which forms a directed gas flow onto one end face of the substrate stack. Alternatively to raising the stack in a stationary stack, the separating nozzle can be lowered to accommodate the reduced stack height resulting from a holder with suction nozzles lifting a substrate from the stack. Such a design with a movable separating nozzle or movable stack, in holders with suction nozzles, disadvantageously requires precise control and alignment of the separating nozzle to the stack in order to prevent the gas flow from the separating nozzle from disrupting the function of the holder's suction nozzles. US6345818 B1 discloses a device for emptying a transport container according to the preamble of claim 1. Description of the invention

[0004] The invention is therefore based on the object of creating, on the basis of the prior art described at the outset, a device of simple construction which is suitable for the safe emptying of a transport container with a semiconductor wafer.

[0005] The invention solves the problem by a device according to claim 1.

[0006] If the holder has at least one separating nozzle arranged on the holder outside the holding surface so that it can move from a rest position to a separating position in such a way that a gas flow directed towards the end of the stack is formed in the separating position of the separating nozzle, this can ensure, regardless of stack parameters, in particular its stack height, etc., that another object in the stack adhering to the object held by the holder is not carried along by the holder. The separating nozzle arranged so that it can move along with the holder towards the object in the stack to be picked up, whereby this separating nozzle, which is positioned together with the holder, can always assume the required separating position. Because the holder is positioned spatially relative to the object to be picked up, the position of the separating nozzle relative to the stack in space can be determined extremely precisely.This can be further improved because the measuring device provides data that can be taken into account when the holder is positioned relative to the object to more precisely adjust the separation position of the separation nozzle. The stability of the holder can thus be significantly improved. This ensures that an object picked up or held from the stack is free of any other objects adhering to it, regardless of the stack height and / or stack position. The precisely directed gas flow can always overcome adhesion forces between the objects in the stack and thus ensure that objects in the stack are lifted off piece by piece. The device according to the invention is therefore particularly suitable for safely emptying a transport container containing semiconductor wafers. Packaging material, for example foils, paper, plastic foam or the like, can thus be safely separated from the semiconductor wafer.In addition, this also protects the semiconductor wafers from damage that could occur if other removed items are taken along. This creates a device that is structurally simple, yet particularly robust and stable when emptying a transport container.

[0007] In general, it is mentioned that the device is not limited to transport containers for semiconductor wafers and packaging material, but other items can also be provided in these stacks.

[0008] The invention can be simplified structurally if the holder has at least one pneumatic cylinder which is connected to the separating nozzle in order to displace it or to move it from its rest position into the separating position and back again.

[0009] If the separating nozzle and the pneumatic cylinder are connected to a common compressed air line, further design simplifications and thus cost savings can result. The working medium of the separating nozzles can also be used for the pneumatic cylinder, resulting in a more cost-effective device. If the back pressure at the separating nozzle is sufficiently high to keep the pneumatic cylinder in its working position—corresponding to the separating position of the nozzle—the separating nozzle and pneumatic cylinder can be easily controlled via a common valve. Furthermore, by appropriately dimensioning the nozzle and cylinder, pulsed gas flows with simultaneous movement of the cylinder and thus the separating nozzle can be realized.This can make it possible to achieve a particularly effective separation between the object held by the holder and the other object in the stack adhering to it.

[0010] If a first guide is provided between the holder and at least one separating nozzle, for moving the separating nozzle from the rest position to the separating position and back again, the separating nozzles can be moved with particular precision. A linear guide can be particularly well-suited for this.

[0011] Positioning the separating nozzle behind the holding surface in the rest position and in front of the holding surface in the separating position can significantly simplify the device's operation. For example, a retracted separating nozzle can facilitate the insertion and extension of the holder, or its positioning in the transport container. Furthermore, the risk of damage to stacked objects caused by the holder can be reduced by avoiding protruding parts on the holding surface.

[0012] For securely holding objects, it can be advantageous if the holding nozzles have several Bernoulli nozzles on the holding surface and several vacuum nozzles in the edge area of ​​the holding surface. Separate control or actuation of these Bernoulli nozzles and vacuum nozzles can be advantageous. This makes it possible to carry out different gripping and holding processes with one and the same device. For example, the Bernoulli nozzles can be used to grip the topmost object in the stack, and the vacuum nozzles are only activated once the object is lying on the holding surface. Of course, applications are also conceivable where the vacuum nozzles are switched on first, or where vacuum nozzles and Bernoulli nozzles are switched on simultaneously. A device having several separately controllable groups of nozzles, with the individual groups of nozzles arranged in a ring on the holding surface, can be particularly advantageous under certain circumstances.The separation process of the adhering object can be further promoted with the help of the differently controlled nozzle groups.

[0013] If a second guide is provided between the vacuum nozzles and the holder for moving the vacuum nozzles into a gripping position protruding from the holding surface, the device according to the invention can prove useful for holding a wide variety of objects. For example, the movably mounted vacuum nozzles can be moved towards the object to be gripped in order to hold it firmly. If the Bernoulli nozzles on the holding surface are subjected to a fluid to create a vacuum, the object to be gripped can simultaneously be attracted to the holding surface by the vacuum. As the object held in this way buckles, an underlying, adherent and stiffer object can be partially detached. This can be used in particular for detaching paper from a semiconductor wafer, whereby even delicate objects can be securely gripped from the stack and lifted off individually.In general, it is mentioned that even with guided vacuum nozzles, moving the vacuum nozzles back to a position that is at most flat with the holding surface can leave the handling of the device unaffected because this avoids projecting parts that would have to be taken into account when moving the device.

[0014] These advantages can be further improved by providing at least one Bernoulli nozzle in the center of the holding surface, as this allows the negative pressure for picking up the object to be more pronounced in the center of the holding surface and subsequently allows a particularly favorable curvature to form on the object to be picked up.

[0015] If the measuring device has a first device for measuring the distance, in particular a laser distance measurement, between the holding surface and the object to be picked up, the distance between them can be determined quickly and precisely by moving the distance measurement along with the holder. As a result, the holder can be brought into the optimal position for the picking process or for acquiring data from the object to be picked up. Furthermore, with the help of this precise position detection, the holder and thus the separation nozzles can be controlled so that the gas flow directed toward the front of the stack can develop at the correct height, namely between the object to be picked up and the object in the stack adhering to it.

[0016] This creates the opportunity to make the separation process even more effective and safer.

[0017] If the measuring device has a second device with an image sensor for capturing image data from the object to be picked up, the object to be picked up from the stack can be precisely identified based on the obtained image data, which can provide greater reliability in determining the type of object to be picked up than is possible with capacitive sensors. For example, it is almost impossible for a capacitive sensor to distinguish between a semiconductor wafer and a semiconductor wafer on which an 80µm thin layer of paper, a packaging material known as interleave, is placed. Only by capturing image data can the precise distinction between different packaging materials and semiconductor wafers be made.In addition, the interaction with the first distance measurement device can result in advantages for the second device for acquiring image data, as precise distance measurement enables improved focus on the object. Image data acquisition can therefore be carried out with considerably greater precision. In general, it is noted that the image data can be evaluated both in the device for acquiring image data and in an external control device that controls the entire apparatus. For example, the color of the object can be deduced from a simple evaluation of the average RGB value of the image data. Depending on the objects in the stack to be distinguished, this alone may be a sufficient distinguishing feature.Furthermore, with sufficiently high image data resolution, the surface structure of the object can also be inferred, thus providing another distinguishing feature. Another conceivable option is the use of an image data acquisition device with a learning mode for recognizing and programming specific materials. During operation, the device can then report the inserted object, identified based on its surface and color, to a controller, for example, via digital outputs. This allows the various objects in the stack (semiconductor wafers, paper, foil, plastic foam, etc.) to be correctly recognized and, accordingly, correctly picked, separated, and held.

[0018] If the first and second devices acquire measurement and image data through the shared opening in the holder, this can have a beneficial effect on the gripping and holding properties of the device due to a reduced cutout on the holding surface. The object to be held can then be held more securely and thus more firmly on the device thanks to the holding nozzles. In general, it should be noted that the measurements of the various sensors can be taken through an opening sequentially or in parallel. The choice of the more suitable method may depend on potential mutual influences between the sensors as well as the performance of the device's control system.

[0019] If at least one of the measuring devices records the measurement and / or image data via a deflecting mirror, the respective measuring device can be installed parallel to the alignment of the mounting surface, which can allow for a more compact design of the device. It is generally mentioned that, with appropriate miniaturization of the measuring devices, direct installation of the measuring device into the holder is also conceivable.

[0020] If the measuring device has a capacitive sensor provided in an opening, the successful picking up and holding of an object can be monitored.

[0021] If the separation position of the separation nozzle can be adjusted based on the measurement data acquired by the measuring device from the object in the stack, the separation of adhered objects can be further improved. For example, by detecting the wafer, its thickness can be determined and the separation position of the separation nozzle can be adjusted accordingly. Short description of the drawing

[0022] The figures show, for example, the subject matter of the invention in more detail using an embodiment variant. Fig. 1a front view of the device with the transport container partially opened Fig. 2a view of the device from below Fig. 3a partially opened front view of the device with the nozzles in the separating and gripping position and with the transport container partially opened and Fig. 4an enlarged section of the nozzles in the separating and gripping position of the Fig. 3 . Way to implement the invention

[0023] According to Fig. 1 a front view of an exemplary device 1 with a partially opened transport container 2 is shown. In the transport container 2 there is a cylindrical stack 3 of round and plate-shaped objects 4. The objects 4 are packaged semiconductor wafers 5 and packaging material 6 which are alternately stacked in a transport container 2. In addition, the device 1 has a holder 7, on whose holding surface 8 several holding nozzles 9 - as in Fig. 2 can be seen. In the area of ​​the holding surface 8, a recess 10 is provided for receiving a measuring device 11, which is responsible for recording measurement data of an object 4 of the stack 3.

[0024] According to the invention, two diametrically arranged, movably mounted separating nozzles 12, 13 are provided, which are arranged outside the holding surface 8 on the holder 7 in order to ensure a piece-by-piece emptying of the transport container 2. Advantageously, a linearly movable mounting of the separating nozzles 12, 13 is provided, the rest position 14, 15 of which is in Fig. 1 is shown.

[0025] According to the Fig. 3 or Fig. 4 The separating nozzles 12, 13 can be seen in the separating layers 16, 17, forming gas flows 18, 19 toward the end face 20 of the stack 3. The gas flows 18, 19 toward the end face 20 of the stack 3 can penetrate between the object 21 held by the holder 7 and the other object 22 of the stack 3 adhering to it. Accordingly, the adhesion forces between the objects 21, 22 of the stack 3 are overcome with the help of these gas flows 18, 19 in the separating layers 16, 17 of the separating nozzles 12, 13. By this effected detachment of the two objects 21, 22 from each other, the device 1 can carry out the inventive picking up and holding of an object 21 from the stack 3 of the transport box 2, without inadvertently holding an adhering object 22 or thereby subsequently possibly pulling along and thus damaging semiconductor wafers 5.In addition, assuming the separation positions 16, 17 of the separation nozzles 12, 13 is simple and therefore stable because the holder 7, which is positioned spatially opposite the object 21 to be picked up, determines the position of the separation nozzles 12, 13 relative to the stack 3 with extreme precision. The measurement data acquisition of the measuring device 11 from the uppermost object 21 of the stack 3 is also used to adjust the separation positions 16, 17 of the separation nozzles 12, 13 even more precisely, for example, via a control unit (not shown in detail) on the holder 7, which is data-linked to the measuring device 11.

[0026] According to Fig. 3 or Fig. 4 The device has pneumatic cylinders 23, 24 for moving the separating nozzles 12, 13 from the rest position 14, 15 to the separating position 16, 17. Since the separating nozzles 12, 13 already form a gas flow 18, 19 to achieve the inventive task, they must be supplied with a gas via the compressed air connections 49, 50. This gas can also be used as the working medium for the pneumatic cylinders 23, 24. Such synergy effects usually result in savings and thus a more cost-effective device 1.

[0027] As in Fig 4 As shown, further synergy effects are achieved when the separating nozzle 12 and the pneumatic cylinder 23 are connected to a common compressed air line 51. The pneumatic cylinder 23 is open at the bottom and simultaneously feeds the nozzle orifice 25. The prerequisite for this is that the back pressure at the nozzle orifice 25 is so great that the pneumatic cylinder 23 is still held in its working position - corresponding to the separating position 16 of the separating nozzle 12. The separating nozzle 12 and the pneumatic cylinder 23 are thus controlled in a structurally simplified manner by a common valve 54. In addition to the cost-reducing effects on the device 1, this arrangement, with suitable dimensioning of the nozzle orifice 25 and cylinder 23, enables pulsed gas flows with simultaneous movement of the separating nozzle 12 to be realized in a simple and elegant manner.In this way, a particularly effective detachment between the object 21 held by the holder 7 and the other adhering object 22 of the stack 3 can be achieved.

[0028] The linear guides 27, 53 serve to move the separating nozzles 12, 13 from the rest position 14, 15 to the separating position 16, 17 and back again. Accordingly, the separating nozzles 12, 13 can retract into a position concealed by the holder 7 in the rest position 14, 15. This facilitates or enables the partial insertion and removal of the holder 7 into the transport box 2 and also the picking up of the objects 4 of the stack 3 that are close to the floor, because projections from the holding surface 8 are avoided.

[0029] According to Fig. 2 The view of the device 1 is shown from below. On the holding surface 8, the holding nozzles 9 are divided into separately controllable groups of nozzles 28, 29, 31, 32, wherein the individual groups of nozzles 28, 29, 31, 32 are arranged in a ring shape. In the embodiment shown, several Bernoulli nozzles 28, 29 are arranged in groups in the inner region of the holding surface 8, and vacuum nozzles 31, 32 are arranged in groups in the edge region 30. Using this nozzle configuration, different gripping and holding processes can be carried out. Depending on the uppermost object 21 of the stack 3, for example, the Bernoulli nozzles 28, 29 can be used for gripping, and the vacuum nozzles 31, 32 for holding the object. The separation according to the invention is further improved by controlling nozzle groups at different times depending on the uppermost object 4 of the stack 3. As the Figuren 1 and 3can be removed, the vacuum nozzles 32 are supplied via the connections 52.

[0030] According to Fig. 4 It can be seen that the vacuum nozzles 32 are movably mounted on guides 33. With the aid of these, the vacuum nozzles 32 can be moved into a gripping position 34 protruding from the holding surface 8. This gripping position 34 is particularly suitable for picking up a thin object 21, for example paper, from the stack 3, since this object is in the edge area according to Fig. 3 can be held at a distance from the holder 7 by the vacuum nozzles 32. If the Bernoulli nozzles 28, 29 on the holding surface 8 are activated to generate a negative pressure, the object 21 to be gripped is simultaneously attracted to the holding surface 8 by the negative pressure and is held at a distance from the holding surface 8 in the gripping position 34 by the movably mounted vacuum nozzles 32. Due to these pressure conditions, a bulge 35 occurs on a thin object 21 to be gripped, which causes a partial detachment of the object 22 underneath, which may also be adhering. If the movably mounted separating nozzles 12, 13 are now in their separating position 16, 17 and they form a gas flow 18, 19 in the direction of the front side 20 of the stack 3, the object 21 to be picked up and the object 22 adhering to it and lying underneath are simply separated from each other - the movably mounted vacuum nozzles 32 are returned to their starting position 36 accordingly Fig. 1 relocated back.

[0031] According to Fig. 2 A further circle of Bernoulli nozzles 37 is provided centrally on the holding surface 8. With their help, the curvature 35 can be more clearly defined toward the center of the object 21 to be picked up, further simplifying or improving the separation.

[0032] According to Fig. 1 The measuring device 11 has a laser distance measurement 38. This determines the distance 39 between the holder 7 and the object 21 to be picked up. This ensures precise positioning of the device 1 for the picking process or for the acquisition of data from the object 21 to be picked up. The precise distance measurement 38 is particularly important for the exact positioning of the holder 7 in interaction with the separation nozzles 12, 13 in the separation position 16, 17. This ensures that the gas flows 18, 19 hit the end face 20 of the stack 3 at the correct height, i.e., between the object 21 to be picked up and the object 22 of the stack 3 adhering to it.

[0033] In addition, Fig. 1 on the measuring device 11, a second device 40, namely one with an image sensor for capturing image data 41 of the object 21 to be picked up, can be recognized. With the captured image data 41, the uppermost object 21 of the stack 3 is identified, and this information is used for the gripping and holding process. Thus, the device can be operated automatically, depending on the uppermost object 21 of the stack 3, with the best possible control of the separating nozzles 12, 13 and holding nozzles 9. Furthermore, the capture of image data 41 works particularly advantageously in conjunction with the laser distance measurement 38, because the precise distance measurement 38 allows the device 40 for capturing image data 41 to optimally focus on the object 21 and thus capture more meaningful image data 41.

[0034] As in Fig. 1 As shown, the laser distance measurement 38 and image sensor 40 record measurement 39 and image data 41 via a common opening 42 in the holder 7. As a result, the remaining holding surface 8 is larger, thus achieving a more stable holding of the object 21. In the event that the measuring devices 11 should adversely affect each other, the measurement can of course also be carried out via a further optional opening 43, as shown in Fig. 2 shown in dashed lines, conceivable.

[0035] The Fig. 1 The deflecting mirror 44 shown, which is mounted on a mirror holder 45, allows the arrangement of the measuring devices 11 parallel to the orientation of the holding surface 8. Thus, a more compact design of the device 1 can be achieved.

[0036] According to Fig 1. The measuring device 11 additionally has a capacitive sensor 46 in an opening 47. The capacitive sensor 46 determines measurement data 48, which indicate the successful picking up and holding of an object 21, and serves to monitor the gripping and holding process.

Claims

1. Apparatus for emptying a transport container (2), which is provided with a stack (3) of plate-shaped objects (4) comprising semiconductor wafers (5) and / or packaging material (6), with at least one measuring device (11) for acquisition of measured data from the object (4) of the stack (3) for acquisition of measured data from the object (4) of the stack (3), and with a holder (7), which can be inserted at least partly into the transport container (2) and which is provided with a holding surface (8), several holding nozzles (9) for at least holding an object (4) of the stack (3) and, in the region of the holding surface (8), at least one recess (10) for the measuring device (11) for acquisition of measured data from the object (4) of the stack (3), wherein the holder (7) is provided with at least one separating nozzle (12, 13), disposed on the holder (7) outside the holding surface (8) so as to be movable from a resting position (14, 15) into a separating position (16, 17), wherein in the separating position (16, 17), the separating nozzle (12, 13) generates a gas stream (18, 19) directed onto the end face (20) of the stack (3), in order to loosen at least one other object (22) of the stack (3) adhering to the object (21) held by the holder (7), characterized in that the separating nozzle (12, 13) is arranged behind the holding surface (8) in the resting position (14, 15) and in front of the holding surface (8) in the separating position (16, 17).

2. Apparatus according to claim 1, characterized in that the holder (7) is provided with at least one pneumatic cylinder (23, 24), which is connected to the separating nozzle (12, 13) in order to displace it.

3. Apparatus according to claim 2, characterized in that the separating nozzle (12, 13) and the pneumatic cylinder (23, 24) are connected to a common compressed-air line (51, 55).

4. Apparatus according to claim 1, 2, or 3, characterized in that a first guide (27, 53), more particularly linear guide, for displacement of the separating nozzle (12, 13) from the resting position (14, 15) into the separating position (16, 17) and back is provided between holder (7) and at least one separating nozzle (12, 13).

5. Apparatus according to one of claims 1 to 4, characterized in that the holding nozzles (9) are provided with several Bernoulli nozzles (28, 29) on the holding surface (8) and several vacuum nozzles (31, 32) in the rim region (30) of the holding surface (8).

6. Apparatus according to claim 5, characterized in that a second guide (33) for displacement of the vacuum nozzles (32) is provided between the vacuum nozzles (32) and the holder (7) in a gripping position (34) protruding from the holding surface (8).

7. Apparatus according to claim 5 or 6, characterized in that at least one Bernoulli nozzle (37) is provided centrally on the holding surface (8).

8. Apparatus according to one of claims 1 to 7, characterized in that the measuring device (11) is provided with a first device for measurement of the distance (38), more particularly laser measurement of the distance, between holding surface (8) and object (21) to be picked up.

9. Apparatus according to one of claims 1 to 8, characterized in that the measuring device (11) is provided with a second device (40) having an image sensor for acquisition of image data (41) from the object (21) to be picked up.

10. Apparatus according to claim 8 and 9, characterized in that the first and second devices (38, 40) record measured and image data (39, 41) via the common opening (42) in the holder (7).

11. Apparatus according to one of claims 8 to 10, characterized in that at least one of the measuring devices (38, 40) records the measured and / or image data (39, 41) via a deflection mirror (44).

12. Apparatus according to one of claims 1 to 11, characterized in that the measuring device (11) is equipped with a capacitive sensor (46) provided in an opening (47).

13. Apparatus according to one of claims 1 to 12, characterized in that the separating position (16, 17) of the separating nozzle (12, 13) is adjusted as a function of the measured-data acquisition of the measuring device (11) from the object (21) of the stack (3).