KR100428051B1 - 6-axis positioning system - Google Patents

Abstract

The present invention relates to a six-axis positioning mechanism, the vertical linear actuator and the horizontal linear actuator is symmetrically arranged at the vertices of the polygon to obtain thermal stability to precisely control the positioning, the vertical linear actuator has an operating interval A permanent magnet and a coil receiving current are arranged around the movable shaft, and the movable shaft is driven by a magnetic flux density difference formed at an operating interval, and the horizontal actuator is disposed between a pair of permanent magnets arranged horizontally opposite each other. The repulsive force generated by applying a current to the coil is used.

Description

6-axis positioning system

The present invention relates to a six-axis ultra-precision positioning mechanism, in particular three degrees of freedom of yaw operation with the X-axis, Y-axis, rotation angle (θ) in the plane direction, Z-axis, pitch in the vertical direction It can be applied to transfer and align wafers in lithography during semiconductor process by freely adjusting three degrees of freedom of operation and roll operation. The present invention relates to a six-axis ultra-precision mechanism used for a drive device requiring sub-micron precision position control such as a high density magnetic recording device.

The six-axis positioning mechanism can be used in high force drive systems, ultra-precision drive systems that require small forces, and in both cases.

Conventionally, in the case of the vertical linear actuator, the piezoelectric element (PZT) has sufficient force for movement. However, when it is about to move about ± 0.1 mm to 10 nm, it is driven by the limitation of the driving distance and driving voltage of the piezoelectric element. In order to increase the interval, it is necessary to configure the whole system using the amplifier.

The use of these amplifiers complicates the overall system and makes it difficult to implement. And in the case of non-symmetrical structures, environmental control is needed to overcome the thermal problem, which is a big problem in ultra-precision systems, which involves much more effort than making the system symmetrical.

In addition, in the case of a horizontal linear driver, a piezoelectric element or the like has a stroke distance of about 100 μm even if a complicated amplifier is used, and a stroke length of 10 mm cannot be made.

As a result, a six-axis stage having a long motion section, enabling a positive and negative bidirectional motion with respect to the reference plane, and having the entire structure symmetrical is required.

As a use example, it can be applied to the 6-axis stage and ultra-precision 6-axis stage required in the lithography equipment.

The present invention was conceived in view of the above circumstances, and can have a long movement section without using an amplifier, and is capable of precise positioning control, simple configuration, and symmetrically arranged to solve thermal instability. Its purpose is to provide a decision-making body.

Specific means of the present invention for achieving the above object,

A six-axis positioning mechanism configured to move a moving table disposed on a base plate in a three-dimensional direction,

An upper fixing plate disposed below the moving table;

At least three or more disposed between the base plate and the upper fixing plate in a regular polygonal shape to support the moving table and installed at each vertex of the regular polygonal to induce a linear movement of the Z axis and a tilting movement about the X and Y axes. A vertical linear driver;

The vertical linear driver,

A lower yoke disposed close to the base plate;

An upper yoke supported and arranged above the lower yoke;

It is disposed between the lower yoke and the upper yoke and at the same time the magnetic flux generated in the upper and lower gaps by the strength of the current or the direction of the current or voltage applied to the upper and lower yokes and the predetermined upper and lower gaps, respectively, An electromagnet coil unit for vertically raising and lowering by the attraction force generated by the difference in density;

A movable shaft penetrating and fixed to the electromagnet coil unit through the upper and lower yokes, and transmitting an operation of the electromagnet coil unit to the moving table;

An elastic membrane supported on the movable shaft or the electromagnetic coil part to maintain the upper and lower gaps on the electromagnetic coil part side and to prevent rotation of the moving table;

At least three horizontal actuators arranged in a regular polygonal shape below the moving table and arranged one at each vertex of the regular polygon to induce X, Y axis horizontal movement and Z axis rotation angle (θ) movement of the movement table. Wow;

The horizontal driver,

A first member disposed in a regular polygonal shape between the fixing plate and the base plate and positioned at each vertex of the regular polygon;

A second member fixed to either one of the upper fixing plate or the base plate;

The first member and the second member are both magnetic members, at least one of which is an electromagnet, and the second member can move relative to the first member according to the direction of the current supplied to the electromagnet. And a linear actuator fixing plate disposed between the fixing plate and the base plate to fix the first member.

The electromagnet coil unit according to the present invention,

Cylindrical inner and outer yokes;

First and second coils symmetrically disposed between these inner and outer yokes;

It is composed of a permanent magnet interposed between the first coil and the second coil to form a magnetic flux closed loop facing each other including the upper and lower yokes.

According to the present invention, the first member of the horizontal actuator is a coil, the second member is a pair of permanent magnets facing each other at a predetermined interval, so that the magnetic flux flow is formed from one permanent magnet to the other permanent magnet, The coil is positioned in the magnetic flux region.

According to the present invention, the three vertical linear drivers and the three horizontal linear drivers are characterized by being arranged symmetrically with each other in two equilateral triangles.

According to the present invention, the bottom surface of the base plate includes an air bearing portion at a suitable location so that the base plate can move in the horizontal direction in a state where a predetermined amount is lifted from the measurement floor.

1 is a front view of a six-axis positioning mechanism according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating an arrangement of a vertical linear driver and a horizontal horizontal driver disposed on a fixed plate in a state in which a moving table is removed from FIG. 1; FIG.

3 is an assembled cross-sectional view of the vertical linear driver included in FIG.

Figure 4 is a perspective view showing a triangular arrangement of the vertical linear driver in Figure 1;

5 is a perspective view of a horizontal driver included in FIG.

FIG. 6 is a perspective view of an air bearing part included in FIG. 1 upside down. FIG.

<Explanation of symbols for the main parts of the drawings>

10: moving table 12: base plate

14 vertical linear driver 16 top plate

18: lower plate 20: upper yoke

22: lower yoke 24: cylindrical case

26: inner yoke 28: outer yoke

30: permanent magnet 32, 34: coil

36: upper elastic film 38: lower elastic film

40: movable shaft 50: horizontal actuator

52,54: permanent magnet 56: coil

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows an overall assembled front view of a six-axis positioning mechanism according to the present invention.

In FIG. 1, reference numeral 10 denotes a moving table, and the moving table 10 supports an apparatus for chucking a wafer, for example, an object to be positioned.

The movable table 10 is supported by three vertical linear actuators 14 as shown in FIG. 2, and the upper fixing plate 11 and the base plate 12 are disposed below the movable table 10. The vertical linear actuator 14 is arranged between these upper fixing plates 11 and the base plate 12.

The three linear linear actuators 14 are arranged in the form of an equilateral triangle and are installed corresponding to each vertex one by one to support the moving table 10.

The structure of the vertical linear actuator 14 is shown in the assembled cross section of FIG.

As shown in FIG. 3, the upper plate 16 and the lower plate 18 and the upper yoke 20 fixed to the upper plate 16 side and the lower yoke 22 fixed to the lower plate 18 side are provided. The yokes 20 and 22 are connected by a cylindrical case 24. An inner yoke 26 and an outer yoke 28 are disposed coaxially in the inside of the cylindrical case 24, and the inner yoke 26 is provided. Between the outer yoke 28 and the permanent magnet 30, the first coil 32 and the second coil 34 is disposed, the first coil 32 and the second coil 34 is permanent The magnet 30 is placed in the upper and lower portions, respectively, in the middle.

Therefore, as shown in FIG. 3, when the N poles of the permanent magnets 30 are disposed on the outside and the S poles are disposed on the inside, the flow of magnetic flux 27 is divided up and down on the basis of the center of the permanent magnets 30 to N poles. The magnetic flux flows in the direction of the arrow, i.e., enters the S pole. That is, the flow of one of the upper magnetic flux forms a closed loop that passes through the permanent magnet 30, the outer yoke 28, the upper yoke 20, and the inner yoke 26 back to the permanent magnet 30, The other lower magnetic flux flows through the permanent magnet 30, the outer yoke 28, the lower yoke 22, and the inner yoke 26 to form a closed loop that proceeds to the permanent magnet 30 again.

Further, a minute gap g1 is provided between the upper surfaces of the inner and outer yokes 26 and 28 and the lower surface of the upper yoke 20, and the lower and lower yokes of the inner and outer yokes 26 and 28 are also provided. The fine space | interval g2 is provided also with the upper surface of (22).

This gap g1 and g2 can be maintained by the upper elastic film 36 and the lower elastic film 38. The upper and lower elastic membranes 36 and 38 are thin thin plates having elasticity of resilience and enable vertical movement and tilting movement of the moving table 10, and serve as a guide to eliminate unnecessary movement such as rotation during movement of the moving table. do.

The movable shaft 40 is fixedly installed in the center of the said inner yoke 26, The movable shaft 40 is installed through the upper and lower yokes 20 and 22, and the upper end part of the movable shaft 40 is provided. The lower and lower ends of the fixing nuts 42 and 44 are respectively screwed together to connect the upper elastic film 36 and the lower elastic film 38 to the movable shaft 40.

At this time, all the yoke (20, 22, 26, 28) is preferably a material that forms a smooth flow of the magnetic flux, the cylindrical case 24 is an example of the magnetic flux does not occur, preferably aluminum material.

In the vertical linear actuator 14 configured as shown in FIG. 2, a predetermined magnetic flux density is formed at intervals g1 and g2 by a predetermined magnetic force of the permanent magnet 30, thereby attracting an attractive force. At this time, the magnitudes of the magnetic flux densities acting in the intervals g1 and g2 are equal to each other, so that the sum of external forces applied to the movable shaft 40 is zero. Thus, the movable shaft 40 maintains a stationary state.

In this state, the magnetic flux densities generated at intervals g1 and g2 vary depending on the magnitude of the current applied to the coils 32 and 34 and the direction of the applied current. For example, if the amount of current applied to the second coil 34 is relatively larger than that of the first coil 32, the magnetic flux density of the lower side gap g2 becomes larger than the magnetic flux density of the upper side gap g1. The axis 40 moves downward. The current applied to the coils 32 and 34 is made by a controller not shown. In addition, when a current is applied to the first coil 32 and the second coil 34 in the counterclockwise direction, the magnetic flux density of the lower side gap g2 becomes larger than the magnetic flux density of the upper side gap g1 and the movable shaft 40. Moves downwards.

Therefore, in FIG. 4, the three vertical linear actuators 14 are driven or controlled by the control unit simultaneously or selectively, respectively, so that the movement table 10 is perpendicular to the X and Y axis planes of the movement table 10. Both positioning and tilting of the X and Y axes ({R} _ {X}, {R} _ {Y}) can be performed.

The upper and lower elastic membranes 36 and 38 have a disc shape of a thin plate and perform a guide function for suppressing unnecessary movement during driving, such as rotation of a spring support and a moving table. If such a guide function is not required greatly, it can be replaced by a coil spring.

On the other hand, the present invention includes a plurality of horizontal actuator 50 to induce a horizontal movement about the X, Y axis and a rotational movement about the Z axis perpendicular to the X, Y axis.

The horizontal actuator 50 of the present invention utilizes a Lorentz force (F). That is, F = nBil, where n = coil winding number, B = magnetic flux density, I = current, and l = effect length. In this embodiment, the magnitude of the force is adjusted by controlling the current.

In the present embodiment, the horizontal actuator 50 is arranged in a regular polygonal shape as shown in FIG. 2 below the moving table 10, and one at each vertex of the regular polygonal angle. In the present embodiment, three horizontal actuators 50 arranged in the form of equilateral triangles are provided.

In this case, the three vertical linear drivers 14 and the three horizontal linear drivers 50 are arranged in an equilateral triangle and symmetrically with each other.

The horizontal actuator 50 includes an upper permanent magnet 52 mounted on the bottom of the upper fixing plate 11 and a lower permanent magnet 54 mounted on an upper surface of the base plate 12 and these permanent magnets. And a coil 56 disposed with a predetermined gap between the 52 and 54, respectively.

The upper and lower permanent magnets 52 and 54 are coupled to the yokes 57 and 58, respectively, and the yokes 57 and 58 are fixedly mounted to the upper fixing plate 11 and the base plate 12, respectively. The permanent magnets 52 and 54 are restrained and supported.

A magnetic field acts in one direction in a space facing the permanent magnets 52 and 54, and the coil 56 is disposed in the region of the magnetic field. Therefore, when a current is applied to the coil 56, the current flowing through the coil 56 is subjected to a force in the magnetic field by Fleming's left hand law. Therefore, by controlling the direction of the current flowing through the coil 56, it is possible to control the direction of the operating force of the coil 56, the coil 56 is a force (F = corresponding to the amount of current of the control signal of the circuit control unit not shown) nBil). At this time, the moving direction of the coil 56 is changed by controlling the direction of the current flowing in the coil 56.

In the present embodiment, the coil 56 is fixed, and the permanent magnets 52 and 54 are fixed to the upper fixing plate 11 to allow relatively free movement with respect to the coil 56. To this end, the three horizontal actuator 50 side coils 56 are mounted on a fixed plate 60 disposed between the upper fixing plate 11 and the base plate 12.

When the three horizontal actuators 50 configured as described above are used to move the vertical linear actuator 14 fixed to the upper fixing plate 11 and the base plate 12, the fixing nut 42 of the vertical linear actuator 14 is moved. ) Can move both the horizontal movement with respect to the X, Y axis and the rotational movement about the Z axis perpendicular to the X, Y axis.

That is, the horizontal motion about the X and Y axes and the rotational motion about the Z axis can be induced by using the vector component motions of the three horizontal drivers 50.

In the above embodiment, the permanent magnets 52 and 54 are installed in a movable type, but the present invention permanently mounts the permanent magnets 52 and 54 to the fixing plate 11 and the base plate 12, respectively, and moves the coil 56. The coil 56 may be relatively moved by the fixed mounting on the table 10 or the base plate 12 to induce positioning of the moving table 10.

On the other hand, the present invention is the air bearing 13 in a plurality of places on the bottom surface of the base plate 12 mediated in the moving table 10 so that the rotation and horizontal plane motion of the moving table 10 occurs in a state of floating a predetermined amount from the ground. ) Can be installed more. At least three locations of the air bearings 13 are arranged so that the base plate 12 can be held in a horizontal state.

When the air bearing 13 is installed in this way, the base plate 12 floats a predetermined amount together with the moving table 10 on the ground by the air pressure from the air bearing 13. Therefore, when the movable table 10 performs horizontal movement or rotational movement, the movable table 10 is operated with almost no friction loss with the ground.

As described above, according to the six-axis positioning mechanism of the present invention, since the vertical linear actuator has a symmetrical structure, it is possible to precisely and stably control the position of the three-axis movement by reducing the structural disadvantages caused by the thermal state.

In addition, an air levitation system can be applied to induce movement to precise positioning without friction.

Claims (5)

A six-axis positioning mechanism configured to move a moving table disposed on a base plate in a three-dimensional direction, (A) an upper fixing plate disposed below the moving table; (B) is arranged in a regular polygonal shape between the base plate and the upper fixed plate to support the moving table, and installed at each vertex of the regular polygon to at least induce a linear movement of the Z axis and a tilting motion of the X and Y axes. Three or more vertical linear drivers; The vertical linear driver, A lower yoke disposed close to the base plate; An upper yoke supported and arranged above the lower yoke; It is disposed between the lower yoke and the upper yoke and at the same time the magnetic flux generated in the upper and lower gaps by the strength of the current or the direction of the current or voltage applied to the upper and lower yokes and the predetermined upper and lower gaps, respectively, An electromagnet coil unit for vertically raising and lowering by the attraction force generated by the difference in density; A movable shaft penetrating and fixed to the electromagnet coil unit through the upper and lower yokes, and transmitting an operation of the electromagnet coil unit to the moving table; An elastic membrane supported on the movable shaft or the electromagnetic coil part to maintain the upper and lower gaps on the electromagnetic coil part side and to prevent rotation of the moving table; (C) at least three or more arranged in a regular polygonal shape below the moving table, one at each vertex of the regular polygon to induce X, Y axis horizontal movement and Z axis rotation angle (θ) movement of the moving table. Horizontal driver; The horizontal driver, A first member disposed in a regular polygonal shape between the fixing plate and the base plate and positioned at each vertex of the regular polygon; A second member fixed to either one of the upper fixing plate or the base plate; The first member and the second member are both magnetic members, at least one of which is an electromagnet, and the second member can move relative to the first member according to the direction of the current supplied to the electromagnet. A six-axis positioning mechanism comprising a linear actuator fixing plate disposed between the fixing plate and the base plate to fix the first member. The method of claim 1, The electromagnet coil portion, Cylindrical inner and outer yokes; First and second coils symmetrically disposed between these inner and outer yokes; And a permanent magnet interposed between the first coil and the second coil to form a magnetic flux closed loop facing each other including the upper and lower yokes. The method of claim 1, The first member of the horizontal actuator is a coil, the second member is a pair of permanent magnets opposed to each other at a predetermined interval, the magnetic flux flow is formed from one permanent magnet to the other permanent magnet, the coil in the magnetic flux region 6-axis positioning mechanism, characterized in that configured to be positioned. The method of claim 1, And the three vertical linear drivers and the three horizontal linear drivers are symmetrically arranged in two equilateral triangles. The method of claim 1, The bottom surface of the base plate is a six-axis positioning mechanism, characterized in that the air bearing portion is included in a suitable place so that the base plate can move in the horizontal direction in a state in which the base plate floats a predetermined amount from the measurement floor.