WO2008011970A2

WO2008011970A2 - Movable workpiece support for a machine, and machining system comprising a corresponding workpiece support

Info

Publication number: WO2008011970A2
Application number: PCT/EP2007/005992
Authority: WO
Inventors: Berthold Matzkovits; Kurt Brenner
Original assignee: Carl Zeiss Industrielle Messtechnik Gmbh
Priority date: 2006-07-26
Filing date: 2007-07-06
Publication date: 2008-01-31
Also published as: WO2008011970A3; DE102006034455A1

Abstract

The invention relates to a workpiece support (27) for a machine, comprising a work table (4) with a support area (28) for mounting a workpiece, and at least three bearing elements (7a, 7b, 7c) which rest upon a base (5) and are used for mounting the work table (4) on the base (5). At least one of said bearing elements is embodied in a longitudinally adjustable manner in order to be able to tilt the work table about at least one axis that extends parallel to the support area and/or modify the position of the work table perpendicular to the support area. In order to prevent hysteresis effects when the work table is adjusted, a guide, e.g. a leaf spring (8), is additionally provided which absorbs transversal forces parallel to the support area, thus preventing the work table from moving in directions that run parallel to the support area while allowing tilting about the at least one axis which extends parallel to the support area and/or allowing the entire work table to be moved perpendicular to the support area.

Description

Positionable workpiece base for a machine and processing system with a corresponding workpiece support

The invention relates to a workpiece support, comprising a workpiece table, which comprises a support surface for supporting a workpiece, and at least three bearing elements lying on a base for supporting the workpiece table, wherein at least one of these bearing elements is adjustable in length to the workpiece table by at least one parallel to the support surface tilted aligned axis and / or to change the position of the workpiece table perpendicular to the support surface can.

Such workpiece supports are already known from the prior art.

For example, US 4,731,934 shows such a workpiece support in the form of a turntable for a coordinate measuring machine, on which the workpiece to be measured can be stored. The turntable has a base that can be rotated about a vertical axis. The workpiece table, on which the workpiece to be measured can then be attached, is mounted on three balls, the workpiece table having cooperating with the balls inner spherical elements which rest on the balls. Two of the three balls are height adjustable via motor drives, so that the workpiece table can be rotated about each axis parallel to the support surface to thereby align the workpiece axis parallel to the axis of rotation of the turntable can. In addition, two more motor drives are available over which the workpiece table can be moved in any direction relative to the base in the plane parallel to the support surface horizontal plane.

DE-OS 2 248 535 also shows a workpiece support for a measuring device on which a workpiece to be measured can be stored. This includes, inter alia, three superimposed plates, of which the top plate serves to support the workpiece and thus this plate takes over the function of the workpiece table. This top plate is in this case supported by three balls on the middle plate, wherein both the top plate, as well as the middle plate for each of the balls have a V-guide, all V-guides have the same orientation, so that the top plate relative to the middle plate in a first horizontal direction can be moved. In exactly the same way, the middle plate is mounted on the lower plate via three balls, the guide direction of this V-guides this time is perpendicular to the guide direction of the above-mentioned V-guides, so that the middle plate relative to the lower plate in a direction perpendicular to the first direction of movement second horizontal direction of movement is movable. The lower plate thus assumes the function of the base. By corresponding manually operable Präzisionsverschiebungswerke the upper plate relative to the middle plate and the middle plate relative to the lower plate can be moved in the respective direction of displacement.

In addition, both in the storage of the upper plate on the middle plate, as well as in the storage of the middle plate on the lower plate one of the respective underlying V-guides mounted on a up and down movable lever whose height is in each case via a Another precision displacement work can be changed by a spherical end of the precision displacement movement pushes more or less far below a wedge-shaped end of the lever. In this way, the respective overlying plate can be raised or lowered at this point, whereby the respective plate above rotates about the two other balls acting as a pivot, so that the upper plate are rotated about two mutually perpendicular horizontal axes of rotation can.

DE 42 18 984 A1 shows a positioning system for optical testing equipment, in which a work table acting as a support plate on which an optical component to be tested can be arranged over six variable-length columns, relative to a base in all degrees of freedom can be moved. The variable-length supports are hinged to the support plate and attached to the base.

The peculiarity of the workpiece supports shown is that forces acting parallel to the bearing surface of the workpiece table, so usually in the horizontal direction (hereinafter referred to as transverse forces) must be absorbed by the bearing elements. In the case of US Pat. No. 4,731,934, these are the spheres and the internally spherical elements interacting therewith. In the case of DE-OS 2 248 535, transverse forces which are present perpendicular to the guide direction of the V-guides, also taken up by the balls and the V-guides. In the case of DE 42 18 984 Al, the transverse forces are absorbed by the variable-length columns.

With relatively small workpiece supports, the absorption of the transverse forces by the bearing elements is not a problem. In workpiece supports for larger workpieces, however, considerable lateral forces can occur here, which can lead to undesirable hysteresis effects.

The object is therefore to propose a workpiece support of the type mentioned, with the hysteresis can be avoided.

The object is achieved by a workpiece support with the features of claim 1, wherein the workpiece support according to the invention contains a guide which receives transverse forces parallel to the support surface and thus prevents movement of the workpiece table in directions parallel to the support surface but tilted by at least one parallel to the support surface aligned Axis and / or movement of the entire workpiece table in a direction perpendicular to the support surface allows.

The basic idea of the invention can be seen in the fact that an independent of the bearing elements guide is provided which receives all lateral forces in directions parallel to the support surface. This ensures that the movable bearing elements are acted upon only in the direction of their length adjustment with forces and thus no hysteresis effects occur.

As guides a variety of solutions are conceivable. For an arrangement in which the workpiece table is to be moved only in a direction perpendicular to the support surface, for example, a linear guide (e.g., a ball rail guide or an air bearing guide) would be perfectly sufficient to movably support the work table in that direction.

Advantageously, however, the guide can also be designed as an elastic body which is stiff in directions parallel to the support surface and torsions about an axis perpendicular to the support surface and thus prevents movement of the workpiece table in directions parallel to the support surface, but at least by tilting a Axis aligned parallel to the bearing surface is designed to be elastic and / or is designed to be elastic with respect to a movement of the entire workpiece table in a direction perpendicular to the bearing surface. This has the advantage that such a guide is virtually completely hysteresis-free, since this guide has no mutually movable parts.

A particularly simple, and thus advantageous embodiment of such an elastic body, which acts as a guide, may be a leaf spring. Such a leaf spring advantageously has an area which is parallel to the bearing surface of the workpiece table. In this way, on the one hand, the lateral forces are received in directions parallel to the support surface, since the leaf spring in these directions is almost stiff, while the leaf spring is flexible with respect to movements of the workpiece table perpendicular to the support surface and also with respect to rotations of the workpiece table about axes parallel to the support surface.

The leaf spring may in principle be rigidly connected at one end to the workpiece table, while it is rigidly connected at its other end to the base.

In order to ensure improved mobility of the workpiece table in the movement direction perpendicular to the support surface, the leaf spring may have at least one of the ends of the region parallel to the support surface a second region angled at right angles to this region, which is perpendicular to the support surface. In such an embodiment, it is advantageous

Either both ends of the leaf spring rigidly connected to the base and the workpiece table centered between the two rigid connections of the leaf spring to the base rigidly connected to the leaf spring or both ends of the leaf spring rigidly connected to the workpiece table and the base centered between the two rigid connections of the leaf spring Workpiece table rigidly connected to the leaf spring.

Of course, instead of the leaf spring and other shaped elastic body can be used, which take over at least parts of the functions of the leaf spring just described. For example, a rigid frame could be used by itself corresponding milled areas become torsionally soft at defined locations. It could also be several leaf springs, for example, a plurality of elastic rods, which are arranged side by side, can be used.

As bearing elements, a variety of bearings may be used, as they were also called input in the prior art. For example, balls could be used which interact with internal spherical elements or V-guides or articulated, variable-length legs. However, it is particularly advantageous to be able to use bearing elements which can not absorb any transverse forces, ie forces parallel to the bearing surface. Such a bearing element comprises a running element with a flat surface and a ball which is movably mounted on the flat surface of the running element. It is clear that the running element with the flat surface can of course also be an integral part of the workpiece table or the base, for example by simply incorporating a flat surface in the workpiece table or in the base itself. Such a bearing element could, for example, comprise a ball roller with a ball bearing ball here, which is movably mounted on the flat surface. Alternatively, such a bearing element could also comprise a ball, which interacts with two running elements each having planar surfaces, wherein one of the running elements is connected to the workpiece table and the other running element is connected to the base.

In addition, the flat surface of the running element can also be inclined relative to the support surface by the running element is for example wedge-shaped. This has the particular advantage that a relative movement of the ball relative to the flat surface in a direction parallel to the support surface is converted into a movement perpendicular to the support surface, thereby achieving the change in length of the bearing element. To achieve this, for example on the basis of a running element may be provided, for example in the form of a wedge, which is movably mounted in a direction parallel to the support surface and the flat surface is inclined in the direction of displacement relative to the support surface, so that upon displacement of the running element in the direction of displacement, the ball is moved perpendicular to the support surface and the workpiece table is thereby moved perpendicular to the support surface, that is raised or lowered at a horizontal support surface. There are many variants possible. Alternatively, for example, a wedge-shaped element with a flat surface, which is inclined against the support surface, while the ball on the base in the direction of the support surface on the workpiece table is slidably mounted. By displacement parallel to the support surface of the workpiece table can be raised or lowered in an analogous manner.

As far as flat surfaces are used, which are inclined against the support surface, resulting from the force acting on the bearing element weight of the workpiece table, which acts on the displaceably mounted running element with the inclined flat surface, according to the principle of the downgrade force in the direction of displacement of the running element, So in a direction parallel to the support surface. In a particularly advantageous embodiment of the invention, therefore, at least one spring is provided which at least partially compensates for this force in the direction of displacement. The spring can, depending on the arrangement, be designed either as a tension spring or as a compression spring.

The workpiece table has a bearing surface on which a workpiece can be stored. The workpiece can either be stored directly on the workpiece table by the workpiece is attached directly thereto. Alternatively, however, can be mounted on the workpiece table, a further device, such as a turntable or a jig on which in turn the workpiece is attached.

Also, the workpieces can be a variety of variants. For example, it may be a wafer that is being machined to make an integrated circuit or a substrate, such as a glass sheet, that is coated on one side with a semiconductor layer. But it can also be a workpiece that is measured by a measuring device or a workpiece that is processed by a workpiece processing machine.

The base can also be designed differently. In the simplest case, this may be the hall floor on which the workpiece table is mounted via the bearing elements. Alternatively, this may be a component of the machine, which is possibly even movably mounted in one or more directions.

A further improvement results when the workpiece table is additionally mounted on at least one resilient element relative to the base, which receives at least parts of the weight of the workpiece table. This has the particular advantage that the Bearing elements only need to absorb low weight forces, and thereby can move the possibly heavy workpiece table with relatively small forces.

As already stated above, the workpiece support described above can be used in a wide variety of machines. Advantageously, however, the workpiece support can be used in a processing system with a machining tool for machining a workpiece comprising a semiconductor material to be processed, for example in a system with which the surface of a wafer or of a carrier substrate coated with a semiconductor material is melted by a laser beam Crystal structure of the semiconductor material to change. The processing tool may then be a laser device which fans out a laser beam so that the laser beam impinging on the semiconductor material of the workpiece results in a line. In such a case, it is particularly important to tilt the workpiece table with high precision in the above-mentioned manner about an arbitrary axis parallel to the support surface or to move it perpendicular to the support surface in order to move the surface of the semiconductor material to be processed in the best possible way in the focus line. In addition, since movement of the laser beam is difficult in such an arrangement, the base of the workpiece support should also be slidably mounted in at least one direction perpendicular to the plane defined by the fanned-out laser beam.

Thus, the respective position of the support surface of the workpiece table can be accurately determined, at least one bearing element, a distance measuring system is assigned, via which the distance between the base and the workpiece table can be determined. If the workpiece table is mounted on three variable-length bearing elements and each bearing element is associated with a distance measuring system, then the position of the bearing surface in the direction perpendicular to the support surface direction, as well as tilt angle about axes of rotation, which are aligned parallel to the support surface determined from the signals of the Wegmessysteme and be set. For measurement, the displacement measuring systems can be configured differently, for example with incremental scales, or with an inductive measuring system.

Further embodiments and developments of the invention will become apparent from the figures. Herein show: Figure 1: A processing plant 1 with a workpiece support 27 according to the invention;

Figure 2: Perspective view of the workpiece table 4 in the demounted state seen from the side below;

Figure 3: A bearing element 7a of Figure 2 in side view;

Figure 4: The bearing element 7a of Figure 3 in plan view;

Figure 5 + 6: schematic representation of the interaction between the carriage 17a and the ball 16a of the ball roller 15a;

Figure 7: Perspective view of the ball roller 15a with a cut

Housing 33a; and

FIG. 8: Perspective view of the path measuring system 29a from FIG

Assigned bearing element 7a.

FIG. 1 shows a processing installation 1 with a workpiece support 27 according to the invention. As can be seen from this, the processing installation 1 has a laser 2 with which the laser beam required for processing the workpiece, which is not closer here (a glass plate which is coated with a semiconductor layer), is produced. The laser beam is reflected by mirrors into an optical system 3, by means of which the laser beam is fanned out in such a way that the laser beam incident on the semiconductor material gives a line transversely to the direction of movement (see arrow y) of the workpiece support 27. The optical system 3 is in this case mounted on a base frame 6 via a steel construction 23, which in turn is supported by dampers 26 on the underlying floor. The workpiece support 27, on which the workpiece to be machined rests, can only be roughly recognized here in FIG. This workpiece support 27 comprises a base 5 which are movably guided via air bearings 25 in the direction of the arrow y. In addition, a channel 24 is incorporated in the base frame 6, via which the workpiece support 27 also guided laterally. The workpiece support 27 is driven by a friction wheel drive, not shown here in detail, wherein the exact position of the workpiece support is determined via a likewise not closer to scale. In addition, the workpiece support also includes a workpiece table 4, on the workpiece (a glass plate with a semiconductor layer) rests. The workpiece table 4 has a support surface 28, which is horizontally aligned in the present case.

In order to position the workpiece as accurately as possible relative to the laser beam in the focus, which is designed here as a focus line, the position of the workpiece table 4 can be moved in the direction indicated by the arrow z perpendicular to its horizontal support surface 28 on which the workpiece rests so that the workpiece so in the vertical direction can be moved up and down a total of the laser beam. In addition, the workpiece table 4 can also be tilted about an arbitrary axis parallel to the bearing surface 28, that is to say both about an axis of rotation which is parallel to the arrow designated x, and about an axis of rotation parallel to the arrow y. In this way, the support surface 28 and consequently the surface of the workpiece resting thereon can also be tilted with respect to the laser beam.

The control of the laser 2, the optical system 3, the movement of the workpiece support 27 in the direction shown by the arrow y and the movement of the workpiece table 4 relative to the base 5 takes place here, as usual, by a controller that can not be seen here is. The concrete mechanism by means of which the workpiece table 4 is moved in the direction z perpendicular to the bearing surface 28 and is rotated about the axes parallel to the bearing surface (axes parallel to the x and y axes) will be described in more detail with reference to FIGS. 2 to 8 which follow explained.

FIG. 2 shows parts of the workpiece table 4 together with the elements which are necessary for the movement of the workpiece table 4, in the disassembled state in a perspective view from the side below. As can be seen here initially, three bearing elements 7a, 7b, 7c are provided on the workpiece table 4 for mounting the workpiece table 4 on the base 5, which is not visible here. The bearing elements 7a, 7b, 7c are on the one hand on its upper side connected to the workpiece table 4, while its bottom, in the present case, the plates 13a, 13b and 13c rest on the not visible in Figure 2 base 5 and are fixed here. In the present case, all three bearing elements 7a, 7b, 7c are designed to be adjustable in length in the direction shown by the arrow z, as will be described in more detail below with reference to FIGS. 3 to 8. In this way, the workpiece table 4 on the one hand be moved so that the position of the workpiece table 4 is changed perpendicular to the support surface 28. For this purpose, only in all bearing elements 7a, 7b, 7c the respective length La (length of the bearing element 7a, see Figure 3), Lb (length of the bearing element 7b) and Lc (length of the bearing element 7c) are extended or shortened by the same amount. In addition, the support surface 28 of the workpiece table can also be tilted about a substantially any axis parallel to the bearing surface 28, ie an axis which is parallel to the arrows x or y, by the lengths La, Lb and Lc of the bearing elements 7a, 7b and 7c are changed so that the length differences La-Lb and / or La-Lc and / or La-Lb change.

As already stated above, a guide is further provided which receives transverse forces parallel to the support surface 28, ie in the directions indicated by the arrows x and y directions and thus prevents movement of the workpiece table 4 in directions parallel to the support surface 28, but a tilt by at least an aligned parallel to the support surface axis and / or movement of the entire workpiece table 4 perpendicular to the support surface 28 permits.

The guide is advantageously designed as an elastic body which is rigid in directions parallel to the support surface 28, ie in directions of the arrows x and y and torsions about an axis perpendicular to the support surface, ie torsions about an axis parallel to the axis z. As a result, movements of the workpiece table in directions parallel to the support surface 28 are prevented, so movements in directions x and y and also rotations about a parallel axis z axis of rotation. With respect to tilting about an aligned parallel to the support surface 28 axis of the elastic body, however, is designed to be elastic and with respect to a movement of the entire workpiece table 4 in a direction z perpendicular to the support surface 28th

In the present case, this elastic body, through which the guide is realized, realized by a leaf spring 8, which, inter alia, a region 8a which is parallel to the support surface 28 of the workpiece table and at one end of the bearing surface 28 parallel to the area 8a opposite This region has an angularly angled second region 8b, which is perpendicular to the support surface 28. As can be seen, in this case both ends of the leaf spring 8 are rigidly connected to the workpiece table 4, namely once via a terminal block 1 1, and the other via a terminal block 12. The base 5, not shown in Figure 2, however, is centered between the two rigid connections the leaf spring 8 to the workpiece table 4 rigidly connected to the leaf spring by a Clamping strip 9 is attached thereto, to which in turn one side of an angle piece 10 is fixed, wherein the other side of the angle piece 10 is fixed to the base 5. Due to the leaf spring 8 of the workpiece table 4 and the base 5 is therefore rigidly coupled together in the direction indicated by the arrows y and x directions, which are parallel to the support surface 28 and also with respect to torsions about perpendicular to the support surface 28 axes parallel to Z axis are, so that transverse forces are received parallel to the support surface 28. Movements of the workpiece table 4 perpendicular to the support surface, ie in the direction indicated by the arrow z leaves the leaf spring 8, however, after the leaf spring can deform elastically in the relevant direction. Similarly, leaves the leaf spring 8 and tilting about parallel to the support surface 28 aligned axes, ie about tilting axes, which are parallel to the axes x and y, since the leaf spring 8 can deform correspondingly elastic.

So that the bearing elements 7a, 7b, 7c have to absorb as few forces as possible, the workpiece table 4 is additionally mounted on resilient elements 22a, 22b, 22c which respectively receive parts of the weight force of the workpiece table 4. As a result, practically the entire weight force of the workpiece table 4 is received by the resilient elements 22a, 22b and 22c, so that the bearing elements 7a, 7b, 7c can move the workpiece table 4 with very small forces.

Reference numeral 29c denotes a displacement measuring system with which the respective set length Lc (cf., the length La for the bearing element 7a in FIG. 3) of the associated bearing element 7c can be determined, here the distance between the base 5 and the workpiece table 4 corresponds. The other bearing elements 7a and 7b have corresponding displacement measuring systems, with which the respective set length Lb and Lc can be detected, so that via a corresponding control loop by the control highly accurately a desired position of the workpiece table 4 in the direction of support surface 28 perpendicular direction (see Arrow z) and / or a tilt about an axis parallel to the support surface 28 can be adjusted.

The function of one of these three bearing elements 7a, 7b, 7c will now be explained with reference to FIGS. 3 to 8, namely for the bearing element 7a. FIG. 3 shows the bearing element 7a in the side view and FIG. 4 in the plan view. As can be seen from FIG. 3, the bearing element 7a is only partially cut away via a plate 13 at the in FIG attached base 5 attached. To change the length La of the bearing element 7a, this has a linear drive, which is designed for example in the form of a spindle drive. The spindle drive in this case comprises an electromotive drive 20a and a threaded spindle 19a, which is driven via the electromotive drive 20a.

The threaded spindle 19a cooperates with an internal thread of a guided on a ball rail guide 35 slide 17a and moves it in the direction indicated by the arrow x direction. The carriage 17a is partially covered by a spring 18a, the exact function will be explained later. The carriage 17a in this case has a plane 32a, which is inclined relative to the horizontal and thus relative to the bearing surface 28, wherein the ball 16a of a ball roller 15a runs on this plane 32a. The ball roller 15a, in turn, is mounted slightly inclined in a holder 14a, which in turn is fastened to the workpiece table 4, which is shown only partially in section in FIG.

The cooperation between the carriage 17a and the ball 16a of the ball roller 15a will now be illustrated in more detail with reference to FIGS. FIG. 6 shows purely schematically the carriage 17a from FIG. 3, which is moved by the spindle drive in the direction indicated by the arrow x. Due to the inclined plane 32a of the carriage 17a, the ball 16a of the ball roller 15a is raised in the direction indicated by the arrow z. The hub 14a is transferred to the workpiece table 4 via the holder 14a to be seen in FIG.

FIG. 7 shows exactly the reverse process to FIG. Herein, the carriage 17a is displaced in the direction indicated by the arrow -x. Due to the inclined plane 32a of the carriage 17a, the ball 16a of the ball roller 15a is lowered in the direction indicated by the arrow -z. By way of the holder 14a to be seen in FIG. 3, the lowering is transmitted to the workpiece table 4.

The construction of a ball roller 15a with the ball 16a will be explained briefly with reference to FIG. As can be seen in Figure 7, the ball 16a is movably supported in a cage by a plurality of small balls 21a. The cage is formed by a housing, of which only the cut half 33a can be seen and formed by a core 34a. Thus, the bearing element 7a shown here comprises a wedge-shaped running element (carriage 17a) which is mounted displaceably parallel to the support surface 28 and which has a flat surface 32a, which is inclined in the displacement direction relative to the support surface 28. The bearing element 7a also comprises a ball-mounted ball 16a in a ball roller 15a, which is movably mounted on the flat surface 32a of the running element (carriage 17a). By a displacement of the running element (slide 17a) in the direction of displacement, therefore, a movement of the ball 16a perpendicular to the support surface 28 can be generated.

Due to the force acting on the relevant bearing element 17a weight of the workpiece table 4 on the displaceably mounted running element (carriage 17a) with the inclined flat surface (32a) is generated according to the principle of "downgrade force" a force in the direction of displacement of the wedge-shaped running element (carriage 17a) acting in the direction indicated by the arrow-x of Figure 6. To accommodate this force, springs 18a and 34a are provided on the side of the carriage 17a to compensate for this force in the direction of displacement 4 shows a plan view of the bearing element 7a.

FIG. 8 shows a perspective view of a displacement measuring system 29a, which is constructed in the same way as the displacement measuring system 29c according to FIG. 2, but which is associated with the bearing element 7a. This is a displacement measuring system in which the distance of a plate 30a from the encapsulated measuring device 31a is measured by means of a corresponding measuring device. The encapsulated measuring device 31 a is in this case attached to the base 5, while the plate 30 a is fixed to the workpiece table 4. In this case, the plate 30 is connected via a rod to a reading head located in the interior of the measuring device 31a, which determines the respective position with respect to an incremental scale also located in the interior of the measuring device 31a. By way of this, the respective position of the plate 30a relative to the measuring device 31a can be determined. The signal of the measuring device 31a, as well as for the signals of the other measuring devices, which are assigned to the bearing elements 7b and 7c, supplied to the controller, and here incorporated into a control loop, in which the drives 20a, 20b and 20c are integrated, so that the corresponding length La, Lb and Lc can be set with high precision for each bearing element 7a, 7b and 7c. Finally, it should be noted that the invention is of course in no way limited to the described embodiment and can vary widely, as already stated above. For example, the support surface 28 need not be horizontally aligned, but may also include an angle with the horizontal.

Claims

claims:

A workpiece support (27) for a machine, comprising:

- A workpiece table (4) with a support surface (28) for supporting a workpiece

- At least three on a base (5) resting bearing elements (7a, 7b, 7c) for supporting the workpiece table (4) on the base (5), wherein at least one of these bearing elements is adjustable in length to the workpiece table by at least one parallel to the support surface tilted aligned axis and / or to be able to change the position of the workpiece table perpendicular to the support surface,

- A guide that receives transverse forces parallel to the support surface and thus movement of the workpiece table in directions (x, y) parallel to the support surface (28) but prevents tilting about the at least one aligned parallel to the support surface axis and / or movement of the entire workpiece table in a direction (z) perpendicular to the support surface (28).

2. workpiece support according to claim 1, wherein the support surface (28) is aligned horizontally.

3. workpiece support according to claim 1 or 2, wherein the workpiece table can be moved both perpendicular to its support surface, as well as about an arbitrary axis parallel to the support surface can be tilted.

4. workpiece support according to one of the preceding claims, wherein the workpiece table is mounted on exactly three bearing elements (7a, 7b, 7c).

5. workpiece support according to claim 4, wherein all three bearing elements are adjustable in length

6. workpiece support according to one of the preceding claims, wherein at least one of the bearing elements comprises:

a running element (17a) having a flat surface (32a) a ball (16a) movable on the flat surface (32a) of the running element. is stored

7. workpiece support according to claim 6, wherein the flat surface (32 a) of the running element (17 a) relative to the support surface (28) is inclined.

8. workpiece support according to claim 7, wherein the running element (17 a) is wedge-shaped.

9. workpiece support according to one of claims 6 to 8, wherein the ball (16 a) is guided ball-bearing in a ball roller (15 a).

10. workpiece support according to one of claims 7 to 9, wherein the running element (17a) is mounted displaceably parallel to the support surface, and the flat surface (32a) is inclined in the displacement direction relative to the support surface, so that by a displacement of the running element in the direction of displacement movement the ball is perpendicular to the support surface generated.

11. workpiece support according to claim 10, wherein the force acting on the respective bearing element weight of the workpiece table on the displaceably mounted running element (17 a) with the inclined planar surface (32 a) generates a force in the displacement direction of the running element, and wherein a spring (18 a) is provided that at least partially compensates for this force in the direction of displacement.

12. Workpiece support according to one of claims 8 to 11, wherein the displaceably mounted running element in the displacement direction by a linear drive, in particular by a spindle drive (19a, 20a), is drivable.

13. workpiece support according to one of the preceding claims, wherein the workpiece table is additionally mounted on at least one resilient element (22a, 22b, 22c) which receives at least parts of the weight of the workpiece table.

14. Workpiece support according to one of the preceding claims, wherein the guide is an elastic body which is rigid in directions (x and y) parallel to the support surface and with respect to torsion about an axis perpendicular to the support surface axis (z) and thus movement of the workpiece table in Direction (x and y) parallel to the support surface (28) prevents, but at a tilt about the at least one aligned parallel to the support surface axis is elastically and / or with respect to a movement of the entire workpiece table in a direction (z) perpendicular to the support surface (28 ) is elastic.

15. workpiece support according to claim 14, wherein the elastic body is a leaf spring (8).

16. Workpiece support according to claim 15, wherein the leaf spring (8) has a region (8a) which is parallel to the bearing surface (28) of the workpiece table.

17. workpiece support according to claim 16, wherein one end of the leaf spring (8) is rigidly connected to the base (5) and the other end is rigidly connected to the workpiece table (4).

18. Workpiece support according to claim 16, wherein the leaf spring at least at one end of the support surface (28) parallel region (8a) has a relative to this region at right angles angled second region (8b) which is perpendicular to the support surface.

19. workpiece support according to claim 18, wherein either both ends of the leaf spring (8) are rigidly connected to the base (5) and the workpiece table (4) centrally between the two rigid connections of the leaf spring to the base (5) rigidly with the leaf spring (8 ) is connected or both ends of the leaf spring (8) rigidly connected to the workpiece table (4) and the base (5) is connected centrally between the two rigid connections of the leaf spring to the workpiece table rigidly connected to the leaf spring

20. Workpiece support according to one of the preceding claims, wherein at least one bearing element (7a) is associated with a Wegmesssystem (29a), via which the Distance (La) between the base (5) and the workpiece table (4) can be determined.

21. A processing plant for processing a workpiece, which comprises a semiconductor material to be processed, with a processing tool for processing the semiconductor material and a workpiece support (27) according to one of claims 1 to 20.

22. Processing plant according to claim 21, wherein the base (5) of the workpiece support is displaceably mounted in at least one direction (y).

23. Processing plant according to one of claims 21 to 22, wherein the machining tool is a laser device (2, 3) which fanned a laser beam so that the incident on the semiconductor material of the workpiece laser beam gives a line.