Positioning system for positioning an object in an XYZ coordinate system

Abstract

According to the present disclosure, there is provided a positioning system for positioning an object in an XYZ coordinate system, the system comprising: a support structure, an object table for supporting an object, and a positioning module for positioning the object table relative to the support structure in the XYZ coordinate system, the positioning module comprising a frame for supporting the object table and at least three actuator devices for positioning the frame in the Z direction of the XYZ coordinate system.

Description

[Technical Field]

[0001] The present disclosure relates to techniques for positioning an object within an XYZ coordinate system. In particular, the present disclosure relates to a Z-axis stage-type so-called wafer substrate positioning system. Z-axis stage-type positioning systems, also known as vertical stages, provide controlled positioning of an object along the Z-axis of the XYZ coordinate system. Such Z-axis stage-type positioning systems are used, for example, in product processing applications under high-vacuum or low-vacuum (or cleanroom) conditions. [Background technology]

[0002] In product processing applications under high or low vacuum (or clean room) conditions, or under atmospheric pressure conditions, such as, but not limited to, wafer handling applications in the semiconductor manufacturing industry, there is an increasing demand for improved process reliability and stability, and more precise positional handling combined with high product throughput.

[0003] These demands in a vacuum-operated product process environment set high standards for the positioning and orientation of products, such as wafers, during many subsequent process steps. In particular, vibrations induced in the process line by moving mechanical parts and electrical component circuits can adversely affect the positioning accuracy of products being processed within the process line.

[0004] Vibration reduction can be achieved by implementing air bearings or roller bearings, sometimes in combination with piezo actuators. In currently known Z-axis stage type positioning systems, the main challenge of applying air bearings in high-tech vacuum systems or under atmospheric conditions is their limitations in positioning performance, particularly their vulnerability to position errors, or "jitter." Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present disclosure to provide a Z-axis stage type positioning system with more refined setting capabilities in the Z direction and limited positional errors. [Means for solving the problem]

[0006] According to a first embodiment of the present disclosure, there is provided a positioning system for positioning an object in an XYZ coordinate system, the system comprising: a support structure, an object table for supporting an object, and a positioning module for positioning the object table relative to the support structure in the XYZ coordinate system, the positioning module comprising a frame for supporting the object table and at least three actuator devices for positioning the frame in a Z direction of the XYZ coordinate system.

[0007] The three actuator devices allow precise displacement and / or positioning of the object table in the Z direction through associated Rx, Ryz degrees of freedom (DOF). Furthermore, this structure is simple and can be actuated in complex ways compared to known Z stage applications.

[0008] Additionally, in a further embodiment, the positioning module may further comprise at least one actuator device configured to rotate said frame about the Z-axis of an XYZ coordinate system, thereby achieving an efficient setting mechanism and enabling accurate positioning of the object table in the XYZ coordinate system, in particular in the Z-direction thereof.

[0009] In a preferred embodiment, the frame is formed as a triangular frame; Each of the at least three actuator devices is attached to a vertex of the triangular frame. Additionally, in this particular embodiment, at least one further actuator device may be attached to a side of the triangular frame. This embodiment has the advantages of being lightweight, versatile, and capable of accurately positioning the object table with a relatively fast set-up time.

[0010] In particular embodiments, each actuator device is configured as a Lorentz-type actuator or as a variable reluctance magnetic bearing assembly. Such actuators and their associated sensors (encoders) are more or less standard components, resulting in relatively low non-repeatable engineering (NRE) effort and low bill of material costs relative to known complete six-degrees-of-freedom magnetic levitation solutions (alternative position technologies).

[0011] The use of such actuators and their mounting in Z stage positioning systems according to the present disclosure provides adequate vibration isolation from the "outside world," e.g., floor vibrations, as opposed to currently used solutions such as roller bearings, which have much less vibration isolation, resulting in superior positioning performance without requiring or reducing the need for any kind of active vibration isolation system or vibration compensation method.

[0012] Alternatively, the positioning module may include an XY setting mechanism for positioning the frame on the XY plane of an XYZ coordinate system, thereby creating a more advanced positioning system with two additional degrees of freedom in the X and Y directions of the XYZ coordinate system.

[0013] In yet another embodiment, the XY setting mechanism does not serve to provide additional positioning in the X and Y directions of the XYZ coordinate system; instead, the XY setting mechanism constrains the frame, and thus the object table, in the XY plane of the XYZ coordinate system. This ensures that the Z-axis stage-type positioner is held stable in both the X and Y directions (i.e., in the XY plane parallel to the horizontal). In this example, the XY setting mechanism ensures rigidity and stability in both the X and Y directions. [Brief explanation of the drawings]

[0014] The present invention will now be described with reference to the drawings. [Figure 1] FIG. 1 is a front view of an example Z-axis stage positioning system according to the present disclosure. [Figure 2] FIG. 1 illustrates a side view of an example Z-axis stage positioning system according to the present disclosure. [Figure 3] FIG. 1 illustrates a top view of an example Z-axis stage positioning system in accordance with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] For a proper understanding of the present invention, in the following detailed description, corresponding elements or portions of the present invention are designated with the same reference numerals in the drawings.

[0016] 1-3 show front, side, and top views, respectively, of an example positioning system according to the present disclosure. In particular, the present disclosure relates to a so-called Z-axis stage type wafer substrate positioning system. Z-axis stage type positioning systems, also known as vertical stages, provide controlled positioning of an object along the Z axis of an XYZ coordinate system. Such Z-axis stage type positioning systems are used, for example, in product processing applications under high or low vacuum (or clean room) and even atmospheric conditions.

[0017] As outlined in the introduction to this specification, the main challenge with currently known Z-axis stage type positioning systems, applying air or roller bearings not only in high-tech in-vacuum systems but also under atmospheric conditions, is their limited positioning performance, and in particular their vulnerability to position errors or "jitter".

[0018] The present disclosure aims to provide a Z-axis stage-based positioning system with more refined setting capabilities in the Z direction and limited positional error.

[0019] An example of such a Z-axis stage-based positioning system according to the present disclosure is depicted in various views of Figures 1-3. The example positioning system for positioning an object in an XYZ coordinate system is designated 10 and comprises a support structure 11, which may function as a stable solid world. 12 denotes a positioning module or metrology unit mounted on support structure 11, which supports an object table or chuck 13.

[0020] The object table or chuck 13 serves to support a substrate wafer or similar product or object (not shown) that is subjected to, for example, a photolithography process step in a process chamber (also not shown), which process step requires extremely high precision in terms of movement and positioning under vacuum conditions. The object table 13 may be provided with a recess (not shown) for receiving the substrate wafer (object).

[0021] As shown, a positioning module or metrology unit 12 is mounted to a support structure 11 with an object table or chuck 13 mounted to the positioning module 12. The support structure 11 may further include additional mass or auxiliary means, for example, for cooling, supporting stability, and providing precision to the positioning module 12 and chuck 13 during operation.

[0022] The object table 13 can be positioned relative to the support structure 11 by the positioning module 12 in an XYZ coordinate system depicted by orthogonal axes XYZ in the figure. In particular, the Z-axis stage type positioning system according to the present disclosure is intended to accurately position the object table 13 in the Z direction of the XYZ coordinate system.

[0023] As shown in the figure, the positioning module 12 includes a frame 120 for supporting the object table 13, and at least three first actuator devices 130a-130b-130c. Each of the actuator devices 130a, 130b, and 130c is a structure for positioning the frame 120 relative to the support structure 11 in the Z direction, RX direction, and RY direction of the XYZ coordinate system.

[0024] In the illustrated example, frame 120 is formed as a triangular frame, consisting of three sides 120-1, 120-2, and 120-3 connected to each other at vertices 120a, 120b, and 120c. Each of the at least three actuator devices 130a, 130b, and 130c is attached to a vertex 120a, 120b, or 120c of triangular frame 120. Through their associated Rx, Ry, and z motions (degrees of freedom, DOF), the three actuator devices 130a, 130b, and 130c provide precise displacement and / or positioning of object table 13 in the Z direction. Furthermore, this structure has a simple configuration and can be actuated in a less complex manner compared to known Z-stage applications.

[0025] Furthermore, in this illustrated embodiment, the positioning module 12 may comprise at least one further actuator device, indicated by the reference numeral 140, which serves to rotate the frame 120 about the Z-axis z of the XYZ coordinate system, also denoted as the RZ direction, thereby enabling an efficient and accurate positioning of the object table 13 in the XYZ coordinate system, in particular in the RZ direction.

[0026] At least one further actuator device 140 can be attached to one of the edges 120-1, 120-2, 120-3 of the triangular frame 120, here on edge 120-3 between the first actuator devices 130a and 130c, in particular at the centre of edge 120-3. Such a structure is lightweight and offers versatile and precise positioning of the object table 13 relative to the support structure, with relatively fast settling times.

[0027] The concept illustrated in Figures 1-3 represents a relatively simple structure for a Z-axis stage-type positioning system 10 according to the present disclosure. The triangular frame 120 of the positioning module 12 can be effectively positioned with the aid of four Lorentz or reluctance actuators. Three of the actuators (labeled 130a, 130b, and 130c) actuate the triangular frame 120 in the vertical (z) direction, thus providing tilt Rx, Ry, and z motion within the XYZ coordinate system. A fourth additional actuator device 140 is positioned on one of the side edges 120-1, 120-2, or 120-3 of the triangular frame 120 and rotates the frame 120 about the Z axis (RZ direction).

[0028] The object table or chuck 13 can be positioned with its second, bottom object table surface 13b on the triangular frame 120. A substrate or wafer (not shown) can be placed on a first, upper surface of the object table surface 13a (opposite the second, lower surface 13b). This structure allows the object table 13 (and wafer) to be positioned with four degrees of freedom (4-DOF).

[0029] In particular embodiments, each of the first actuator devices 130a, 130b, 130c and the further actuator device 140 is configured as a Lorentz-type actuator or as a variable reluctance magnetic bearing assembly. Such actuators and their associated sensors (encoders) 160a-160b-160c-160d are more or less standard components, requiring relatively little non-repeatable engineering (NRE) effort and low cost of quality with respect to known complete six-degree-of-freedom magnetic levitation solutions (alternative position technologies).

[0030] The use of such actuators and their mounting in Z stage positioning systems according to the present disclosure provides adequate vibration isolation from the "outside world," e.g., floor vibrations, as opposed to currently used solutions such as roller bearings, which have much less vibration isolation. This isolation results in better positioning performance without or with a reduced need for any kind of active vibration isolation system or vibration compensation method.

[0031] Accordingly, each of the first actuator devices 130a, 130b, 130c and the further actuator device 140 may comprise a magnet coil 132a, 132b, 132c, and 142 mounted in the solid world formed by the support structure 11. For mounting purposes, the support structure 11 may include suitable mounting points or mounting cams 11a, 11b, and 11c to accommodate the mounting of the magnet coil 132a, 132b, and 132c of the corresponding first actuator device 130a, 130b, and 130c. The permanent magnets 131a-131b-131c are mounted at the vertices 120z-a, 120b, and 120c of the triangular frame 120. The permanent magnets 131a, 131b, and 131c are made of a ferromagnetic material for suitable interaction with the magnet coils 132a, 132b, and 132c mounted on the support structure 11.

[0032] Similarly, the further actuator device 140 may consist of a static bearing 141 of ferromagnetic material attached to one of the edges 120-1, 120-2, 120-3 of the triangular frame 120. The static bearing 141 interacts with a corresponding magnetic coil 142 connected to a mounting point or mounting cam 11d of the support structure 11. The four Lorentz or reluctance actuators 130a, 130b, 130c, and 140 enable effective positioning of the triangular frame 120 of the positioning module 12 relative to the support structure 11. The Z-axis stage-type positioning system 10 according to the present disclosure therefore enables efficient and accurate positioning of the object table 13 with four degrees of freedom (4-DOF).

[0033] Alternatively, the positioning module 12 may include an XY setting mechanism 150 for orienting the frame 120 in the XY plane of an XYZ coordinate system. This creates a more sophisticated positioning system with two additional degrees of freedom in the X and Y directions of the XYZ coordinate system. The XY setting mechanism 150 may be composed of a first setting spindle 151a and a second setting spindle 151b, the rods of which are flexible yet rigid in only a single degree of freedom (X or Y) and whose length dimensions can be changed in a known manner. In one embodiment, the flexible rod actuators may include piezo actuators that allow for small movements in the X and / or Y directions.

[0034] The first setting spindle 151a and the second setting spindle 151b each include a first spindle end 151a-1 and 151b-1 that are attached to a central cam 11z of the support structure 11. The connection point between the first spindle ends 151a-1 and 151b-1 is in the z-AS direction of the XYZ coordinate system.

[0035] Each of the first and second setting spindles 151a and 151b has its second end 151a-2, 151b-2 mounted at a distance from an end 120-3 of the triangular frame 120. Lengthening or shortening of the first and second setting spindles 151a and 151b relative to the central Z-axis z causes a corresponding displacement of the triangular frame 120 in the X and / or Y directions of the XYZ coordinate system.

[0036] However, in other embodiments, it may be preferable for the Z-axis stage-based positioning system 10 of the present disclosure, and in particular the object table or chuck 13, to be maintained in a stable position in these other two degrees of freedom, namely the X and Y directions (horizontal plane).

[0037] Thus, in that particular example, XY setting mechanism 150 does not serve to provide additional positioning in the X and Y directions of the XYZ coordinate system. Rather, XY setting mechanism 150 is structured to constrain or restrain (triangular) frame 120, and thus object table or chuck 13, in the XY plane of the XYZ coordinate system. This keeps Z-axis stage-type positioning apparatus 10 stable in both the X and Y directions (in other words, in the XY plane parallel to the horizontal), and XY setting mechanism 150 provides rigidity / stability in the X and Y directions. [Explanation of symbols]

[0038] 10 Positioning system according to the present disclosure 11 Support structure 11a to 11c Mounting cam of support structure Support structure of 11z center cam 12 Positioning module 13 Object table or chuck 13a: First upper surface of object table or chuck 13b Second lower surface of object table or chuck 120 frames 120-1~120-3 Triangular frame sides 120a~120c Apex of triangular frame 130a to 130c Actuator devices at each vertex of the triangular frame 131a to 131c Permanent magnet of actuator device (Lorentz actuator) 132a to 132c Coil of actuator device (Lorentz actuator) 140 Further actuator devices at the ends of the triangular frame 141 Permanent magnets in further actuator devices (Lorentz actuators) 142 Coil of further actuator device (Lorentz actuator) 150 XY setting mechanism 151a First setting spindle / flexible rod 151b Second Setting Spindle / Flexible Rod 151a-1, 151b-1 First / Second Setting Spindle / First End of Flexible Rod 151a-2, 151b-2: First / Second Setting Spindle / Second End of Flexible Rod 160a-160d encoder x X-axis y Y-axis z Z axis

Claims

1. 1. A positioning system for positioning an object in an XYZ coordinate system, comprising: a support structure; an object table for supporting an object; a positioning module for positioning the object table relative to the support structure in an XYZ coordinate system; Equipped with The positioning module includes: a frame for supporting the object table; at least three actuator devices for positioning the frame in the Z direction of an XYZ coordinate system; A positioning system comprising:

2. The positioning system of claim 1 , wherein the positioning module further comprises at least one actuator device configured to rotate the frame about a Z-axis of an XYZ coordinate system.

3. The frame is formed as a triangular frame, 3. The positioning system according to claim 1, wherein each of said at least three actuator devices is attached to a vertex of said triangular frame.

4. 4. A positioning system according to any one of claims 1 to 3, wherein the at least one further actuator device is attached to a side of the triangular frame.

5. 5. The positioning system according to claim 1, wherein each actuator device is a Lorentz type actuator.

6. 6. A positioning system according to any preceding claim, wherein each actuator device is a variable reluctance magnetic bearing assembly.

7. 7. The positioning system according to claim 1, wherein the positioning module includes an XY setting mechanism for positioning the frame on an XY plane of an XYZ coordinate system.

8. The positioning system according to claim 7 , wherein the XY setting mechanism constrains the frame within an XY plane of an XYZ coordinate system.

9. The positioning system of claim 7 , wherein the XY setting mechanism includes a spindle actuator.

10. 9. The positioning system according to claim 7, wherein the XY setting mechanism includes a flexible rod actuator.

11. The positioning system of claim 10 , wherein the flexible rod actuator comprises a piezoelectric actuator.

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