WO1998015971A1

WO1998015971A1 - Wafer gripping device

Info

Publication number: WO1998015971A1
Application number: PCT/CH1997/000383
Authority: WO
Inventors: Christian Balg; Bernhard Strasser; Jakob Blattner
Original assignee: Stäubli Ag Pfäffikon
Priority date: 1996-10-09
Filing date: 1997-10-08
Publication date: 1998-04-16
Also published as: KR100521725B1; DE19781101D2; AU4449197A; KR20000048997A

Abstract

The present invention relates to a gripping device (1) for removing and transporting several separate parallel-lying wafers (3) that are stored in a container (4). Said device has a holder (10) and several gripping heads (6; 6') that are displaceable and rotatable with respect to the holder (10). Said heads (6; 6') can be transported from one swinging position between the wafer (3) to another swinging position. In this position, the gripping heads (6; 6') can be displaced against the borders of the wafer (3), where they come to a limiting stop and push in simultaneously the opposite borders of the wafer flanks (3) in the slot (11) of the holder (10). In this manner all wafers (3) inside the container (4) can be simultaneously grabbed safely, displaced from the container (4) and swung out. In swing position, the vertically-positioned wafers (3) can be placed on a processing support (5).

Description

Gripping device for wafers

The present invention relates to a gripping device for wafers according to the preamble of claim 1, and a

A method for gripping and transporting wafers according to claim 14.

For processing resp. Handling wafers (semiconductor plates) must go through these different process stages. Traditionally, raw wafers (unprocessed wafers) are produced and temporarily stored in containers. For the actual processing process, these unprocessed wafers must be removed from the container, a device for carrying out the

Machining process fed and then placed back in a container. A fundamental problem with all processing and intermediate storage is that the wafers must be kept away from contaminants and dirt. Even the smallest

Contamination by dust or other particles cause damage to the corresponding area of the wafer surface. This can lead to significant failure rates of the end products made from these wafers. Therefore, processing is usually carried out in a so-called

Clean room technology, i.e. the processing zones must have a certain, defined purity with regard to these dirt particles. The same naturally also applies to the intermediate storage, i.e. the storage containers.

The removal and feeding of the wafers is conventionally done either manually or automatically. There is always an increased risk with manual operation contamination, which is why an automatic process is sought.

Conventionally, such wafers with a diameter of up to 200 mm were produced and processed. These wafers are conventionally stored vertically in specially designed cassettes. For removal and feeding, they only have to be removed from the cassette in this vertical position. be moved back into this. Suitable are for this

Devices known which come to the edge of the wafer to stop. For this purpose, the wafers are held in rake-like holding devices, which can simply be removed from the cassettes. are retractable. The holding devices are designed in such a way that the edge zones of the wafers are partially exposed so that the removal devices can attack this edge zone. The wafers may only be touched by this device at their edge sections running perpendicular to the surface and in a narrowly limited area on the periphery of the rear side.

In particular, newer, larger wafers (up to 300 mm or more) are now mostly no longer stored vertically, but horizontally in containers. These wafers must now be removed from these containers and then pivoted into another position, often by 90 °, before they can be fed to the following processing device. No devices are previously known for this removal and pivoting movement.

The object of the present invention was to create a gripping device which is horizontal can remove stored wafers from their container and feed them to a processing carrier in a pivoted position.

According to the invention, this object is achieved by the features of claim 1. Due to the construction of the gripping device according to the invention, horizontally stored wafers can be removed from their storage container, pivoted and fed to a processing carrier and positioned thereon. The requirements regarding the area of the wafer that is not to be touched by any objects are fully met, since the gripping means come into contact with the wafer practically only at the edge and not on the wafer surface. Nevertheless, the wafers are kept stable and can therefore advantageously also be pivoted into practically any position. This can advantageously be done completely automatically. The device can therefore be installed and operated in a closed area of a processing machine.

Preferred embodiments of the invention result from claims 2 to 12. Furthermore, claim 13 shows a preferred use of the invention.

Due to the preferred swivel range of 90 °, the gripping heads can be advantageously pivoted into their insertion position for insertion between the stacked wafers. In this position, they can be easily moved into the space between the wafer plates without touching the surfaces of the wafer plates.

Due to the preferred design of the holding or. Slotted surfaces are advantageously only touched at their edge, the surface is practically not touched. This is due in particular to the inclination of the slot surface directed against the underside of the wafer.

The same effect is due to the preferred design of the holding rake, respectively. the design of its slots achieved. A stop area is deliberately provided here, which comes into contact with the underside of the wafer plate. However, this area is very small and lies within the tolerances permitted by the wafer manufacturers. Despite these small areas, a secure and stable fit of the wafer plates is achieved without their positions, in particular their spacing, changing.

Two gripping heads are preferably provided for each slice, which come together at a distance from each other to the edge region of a wafer. It is clear that for gripping a stack of, for example, 13 wafers, all gripping heads are advantageously moved together at the same time.

Such gripping devices according to the invention are preferably used in wafer processing plants.

Furthermore, the method according to claim 14 is proposed according to the invention to achieve the object. Preferred embodiments of the method result from claims 15 and 18.

Advantageously, according to the invention, the gripping device is raised slightly before the wafer stack is removed from its container, so that the wafers are released from their holders in the container. Damage to the wafer surfaces by the holders, which is avoided could arise if the wafers were simply pulled out and dragged over the holders.

Embodiments of the present invention are explained in more detail below with reference to drawings. Show it

Figure 1 schematically shows the view of a gripping device according to the invention before removing wafers from their container.

2 shows the view according to FIG. 1 when the wafers are fed onto the processing carrier;

3 shows the longitudinal section through a region of a gripping device according to the invention;

Fig. 4 is the supervision of the inventive

Gripping device according to Figure 3;

Fig. 5 shows the supervision of another according to the invention

Gripping device;

6 shows the longitudinal section through a region of a gripping device according to the invention for handling individual wafers;

7 shows the top view of the gripping device according to the invention according to FIG. 7.

In Figure 1, a gripping device 1 according to the invention is shown on a movable and pivotable carrier 2. The unprocessed wafers 3 are arranged horizontally, parallel to one another, in their container 4. The Wafers 3 are stored in this container 4 in such a way that only the wafer wafer edges and possibly a narrow edge area of the underside of the wafer wafer are in contact with the holding elements in the container 4.

After their production process, the wafer disks 3 are filled into these containers 4 and stored therein until they are fed to a further process step. The gripping device 1 shown here now serves to bring the wafers 3 out of their container 4 and one

To pass processing carrier 5. As shown, this processing carrier 5 is, for example, a construction of two rollers 5 ′ arranged parallel to one another, on which the round wafer plates 3, as will be explained below, can be placed vertically aligned.

The container 4 can now be moved to an emptying position, for example by means of a controlled means of transport. In this emptying position, the opening of the transport means is preferably in the

Clean room area. At this position, the front cover (not shown) of the container 4 is also removed, making the wafers 3 accessible to the gripping device 1. This position is shown schematically in FIG. 1.

The gripping device 1 is now moved by means of the carrier 2 in front of the opening of the container 4 and its gripping means grasp and fix the wafer plates 3 on the gripping device 1. Subsequently, the gripping device 1 together with the wafer plates 3 can be moved out of the container 4 and by the mobility of the carrier 2 can be pivoted into the desired vertical orientation. FIG. 2 shows schematically the positioning of the wafers 3 pivoted into the vertical position on the processing carrier 5. The rollers 5 'of the processing carrier 5 are preferably designed such that the wafers 3 can be pushed between the rollers 5' from below, and then by rotating the rollers 5 'about their own axis, the wafers 3 with their disc edges onto the rollers 5'. can be brought to rest. For this purpose, for example, the rollers 5 'have a circular cross section, which is flattened in a segment region, for example over 90 °.

By lowering the carrier 2, the gripping device 1 can now be moved out between the wafers 3 and the wafers 3 can be fed through the processing carrier 5 to a process stage.

Subsequent to the processing process carried out, the processed wafers 3 can be fed back into a container 4 by the gripping device 1 and then transported further.

Since this entire process can be automated and does not require any manual intervention, it can run completely in the clean room of the processing machine. This advantageously reduces the risk of contamination and thus also the rejection rate of the wafers 3 during the processing process in comparison to the manual feeding and removal of the wafers 3, and a higher processing rate can also be achieved.

The structure of the gripping device 1 according to the invention can now be seen exactly from the example in FIG. 3, partly in longitudinal section. In order to pull the wafers 3 out of their container 4, gripping heads 6 are provided, which are arranged at one end of rods 7 which can be displaced longitudinally and rotated about their axis.

The gripping heads 6 have a slot 8, the slot width of which is slightly greater than the thickness of the wafer plates 3, and the lower cheek 8 ', which comes to lie against the underside of the wafer plate 3, is aligned at a flat angle with respect to the wafer plate surface. In the position shown in FIG. 3, a gripping head 6 can be pulled against the side edge of the corresponding wafer 3 by pulling back its rod 7 in the direction of the arrow. This movement can be generated by a corresponding movement of the entire gripping device 1. As a result, the side edge of the wafer 3 comes into contact with the bottom of the slot 8. Due to the design of the slot 8 with the lower cheek arranged at an angle, the surface of the wafer 3 does not come into contact with the gripping means.

In Figure 4, two different configurations of the gripping head 6 are shown as an example. The upper gripping head 6 is designed for gripping a single wafer 3 and has a single slot 8. This gripping head is advantageously used as a start or end gripper in the gripping device 1. The gripping head 6 'shown below is designed for the simultaneous gripping of two wafers 3 and, in addition to the lower slot 8, has a second cutout 9. This cutout 9 also has a cheek surface 9 ′ aligned at a flat angle with respect to the wafer surface and a vertical stop surface 9 ″. A holding rake 10 is provided as a counterpart to the gripping heads 6, 6 '. This now also has slots 11 for receiving the wafer 3. These slits are essentially wedge-shaped, the lower slit surface preferably each having a short region 11 ′ aligned parallel to the surface of the pane. The depth of this area is not greater than the width of the area on the underside of the wafer 3 which is permitted for such means. However, the slots 11 could in principle also be designed in accordance with the slots of the gripping heads 6, 6 '. Due to the relative displacement of the rods 7 with respect to the holding rake 10, the wafer disks 3 are clamped reliably without a large force being applied. The clamping nevertheless ensures a secure hold of the wafers 3, which also allow these wafers 3 to be pivoted from the horizontal to the vertical position. The pivoting is preferably carried out in such a way that the wafers for this purpose each lie with their lower side against the holding rake 10. Thus, in the vertical position, the gripping heads 6, 6 'can be removed from the stop on the wafer edges by moving and rotating the rods 7, the wafers 3 maintaining their position through the design of the holding rake 10.

In Figure 4, the supervision of a gripping device 1 according to Figure 3 is shown schematically. 4, a gripping head 6 is shown in the holding position, as described above. By moving the rod 7 in the direction of the arrow, the wafer 3 is clamped between the gripping head 6 and the holding rake 10. It is clear that, instead of using a adhesive with force, the gripping head 6 can also preferably be positioned in a predetermined position resulting from the exact diameter of the wafer 3. This prevents the wafer 3 due to the

Contact pressure is damaged or deformed. Due to the shape of the gripping head 6 and the holding rake 10, precise positioning with a small clearance nevertheless allows the entire arrangement to be pivoted.

The movement of the gripping heads 6 respectively. the rods 7 can be made by means of hydraulic, pneumatic or electrical drive means.

In the lower area of FIG. 4, a gripping head 6 'is also shown in a pivoted position. For this purpose, the rod 7 is displaced away from the holding rake 10 in the direction of the arrow and then rotated by 90 °. It is now possible to move the holding head 6 'between two adjacent disks 3. This will be when the

Gripping device 1 is required in the container 4 for the removal of the wafers 3 and later also when the gripping device 1 is withdrawn from the processing carrier 5 or. when moving out of the container 4 at the end of the machining process.

Furthermore, this FIG. 4 also schematically shows two different possibilities for arranging the holding rake 10. In the upper area of FIG. 4, for example, there is a one on the side of rod 7

Holding rake 10 shown. However, this can also be arranged between the rods 7, as shown as 10 '. Of course, the holding rake 10 can be in one or more parts, and the rods 7 can next to the Holding rake 10 or be arranged in recesses through the holding rake 10.

5 to 7 show two further exemplary embodiments of gripping devices according to the invention, some of which correspond to the gripping device shown in FIGS. 1 to 4. In order to avoid repetitions, only the differences between the exemplary embodiments are discussed in the following.

The gripping device shown in FIG. 5 is a multiple gripper in which the structural design of its two-part holding rake 10 and 10 ', the rods 7 and the gripping heads 6, 6' is essentially that shown in FIGS. 3 and 4 Components corresponds. In contrast to this, a gripping device 16 is arranged between the two rods 7 in this gripping device, which is longitudinally displaceable in a direction parallel to the longitudinal axes of the rods 7. The counterholder 16 is also located on a side opposite the gripper heads 6, 6 ^' with respect to the wafer 3. Furthermore, the counter holder 16 each has a slot for receiving the wafers 3 (not shown, the width of the individual slots being greater than the thickness of the wafers 3, so that the wafer surfaces do not come into contact with the counter holder 16.

In order to remove wafers 3 from the container, the rods 7 are also moved between the wafers by a feed movement of the gripping device 1 along their longitudinal axes and parallel to the wafer surfaces in such a way that the gripping heads are located behind the wafers 3. The gripping heads are then rotated through 90 ° and the gripping device is retracted until the wafers rest in the slots 8, 9 on the gripping heads 6, 6 '. Then the counter-holder 16 is advanced in the direction of the gripping heads 6, 6 'until the wafers 3 also lie in their slots with their circumference. The appropriately designed profile of the slots in the counter-holder 16 ensures that the wafer surfaces are not damaged.

The wafers 3 fixed in this way in a kind of “three-point support” between the counter-holder 16 and the gripping heads 6, 6 ′ can now be moved by a corresponding movement of the

Gripping device 1 can be raised slightly so that they no longer lie in the container. The wafers are then moved out of the container by a removal movement in the direction of arrow 17.

For the subsequent pivoting of the wafers by 90 ° into a vertical orientation, the holding rakes 10, 10 'are used, which are moved towards the wafers 3 with a feed movement parallel to the rods 7. As a result, the wafers 3 lie in the slots 11 of the holding rakes 10, 10 'in the manner already described above. After the counter-holder 16 has been moved back from the wafer with a movement opposite to the feed movement of the holding rakes 10, 10 ′, the wafers 3 are pivoted into the vertical position and in the manner already described in connection with FIGS. 1 to 4 Machining carrier 5 positioned.

Here, too, the processed wafers with the gripping device can be arranged in a container again in the reverse order of the method steps. In principle, the present invention can also be used for the handling of individual wafers, as is required when processing individual wafers 3. 5 and 6, a corresponding exemplary embodiment is shown in which a slot 11 of the holding rake 10 is provided with inclined surfaces 12, 13. The gripping head 6 provided for a single disk likewise has inclined slot surfaces 14, 15.

When a wafer is gripped, its edges come to rest against a counter-holder 16, aside from two gripping heads 6 (only one of which is shown), as is shown schematically in FIG. 6. As a result, the wafer 3 can be moved in the gripping device 1 without significant relative movements between the gripping device and the wafer 3 being possible. For this purpose, the counter holder has an elastomeric stop surface 16 ′, which is oriented essentially at right angles to the surface of the wafer 3. This measure contributes to the fact that the wafer 3 can be removed from the container and inserted into the holding rake 10 without the gripping heads 6 starting to oscillate. The counter-holder 16 preferably remains in abutment against the wafer even during the pivoting movement of the gripping device, as a result of which rapid pivoting movements while at the same time avoiding undesired ones

Vibration movements of the wafer can be achieved. Finally, in connection with the handling of individual wafers, it is preferred if the gripping device has no holding rakes for a construction which is as complex as possible. The entire handling of the

Wafers - from gripping the wafer in a container to positioning it on a processing carrier - are then only carried out with the two gripping heads 6 and the counter-holder 16.

Claims

claims

1. Gripping device (1) for wafers (3) which are stacked at a distance from one another in a container (4), characterized in that they have a holding rake (10) with slots (11) suitable for receiving the wafers (3) and with respect to the Holding rake (10) has displaceable and pivotable gripping heads (6; 6 '), which have stop surfaces (9 ^,! ) For the stop on the wafer edges.

2. Gripping device (1) for wafers (3), which are stacked spaced apart in a container (4), in particular according to claim 1, characterized in that they have a counter-holder (16) for contacting the wafer edges and with respect to the counter-holder (16) has displaceable and pivotable gripping heads (6; 6 '), which have stop surfaces (9' ') for the stop on the wafer edges, so that a wafer can be fixed by contacting the counter-holder (16) and the two gripping heads is manageable.

3. Gripping device according to one or both of the preceding claims, characterized in that the gripping heads (6; 6 ') are pivotable by 90 °.

Gripping device according to one or more of the preceding claims, characterized in that the gripping heads (6; 6 ') are attached to the end of rods (7).

5. Gripping device according to one or more of the preceding claims, characterized in that the gripping heads (6; 6 ') have at least one slotted surface (8', 9 ') which is inclined with respect to the wafer surfaces.

6. Gripping device according to one or more of the preceding claims, characterized in that the stop surfaces (9 '') are aligned perpendicular to the wafer surfaces.

7. Gripping device according to one or more of the preceding claims, characterized in that the thickness of the gripping heads (6, 6 ') is smaller than the distance of the wafers (3) from one another in the container (4).

Gripping device according to one or more of the preceding claims, characterized in that the holding rake (10; 11) is constructed in several parts.

9. Gripping device according to one or more of the preceding claims, characterized in that for each slot (11) in each case at least one slot surface has a region (11 ') which runs parallel to the wafer surface, preferably at the slot base.

10. Gripping device according to one or more of the preceding claims, characterized in that hydraulic, pneumatic or electrical drive means for the pivoting and sliding movement of the gripping heads (6; 6 ') are operatively connected to them.

11. Gripping device according to one or more of the preceding claims, characterized in that in each case two gripping heads (6; 6 ') are displaced parallel to one another and moved with one another, and are arranged such that they each stop at the edge of the same wafer disc (3) are feasible.

12. Gripping device according to one or more of the preceding claims, characterized in that the holding rake is a multi-part, in particular two-part, component.

13. Use of a gripping device according to one or more of claims 1 to 12 for the removal, pivoting and transporting of wafer slices (3) m wafer processing plants.

14. A method for gripping and transporting wafers (3) stacked at a distance from one another by means of gripping means (6; 6 ') and holding means (10, 16) having gripping devices (1), characterized in that when the container (4 ) the

Gripping means (6; 6 ') are moved from the container opening between the wafers (3) to the edge regions of the wafers (3) opposite the container opening, there by a pulling movement in the direction of the respective wafer (3) with its edge region m Be brought in contact by a relative movement - In ¬

Between the respective wafer (3) and a holding means (10, 16), which has a slot (11) for each wafer (3), the holding means also comes into contact with the edge region of the wafer (3), so that the corresponding one Wafer is held between the holding means (10, 16) and the gripping means (6; 6 '), and that the gripping device (1) is then raised such that the wafers (3) are lifted off their support means arranged in the container (4) , and that the gripping device (1) together with the wafers (3) held therein are then removed from the container.

15. The method according to claim 14, characterized in that the gripping device (1) is pivoted after removing the wafers from the container, preferably by 90 °, so that the wafers (3) are aligned vertically with respect to the container (3).

16. The method according to one or both of claims 14 or 15, characterized in that the gripping means (6; 6 ') are in a retracted position before entering between the wafers (3) and before contacting the edges of the wafers (3rd ) are pivoted into a holding position, the pivoting angle preferably being 90 °.

17. The method according to one or more of the preceding claims 14 to 16, characterized in that after the gripping means (6; 6 ') have been brought into contact with the edge region of the wafers (3) Counterholder (16) of the holding means is fed in the direction of the gripping means, so that the wafers (3) are each held in a three-point support between the gripping means and the counterholder (16).

18. The method according to both claims 15 and 17, characterized in that after removal and before pivoting the gripping device, a holding rake (10) approach the edges of the wafers (3) and the counter-holder (16) from the wafers (3) is removed again.