JPH04347008A - Movable stage device - Google Patents

Abstract

PURPOSE:To improve productivity and precision of a movable stage device by locating a movable stage between the reference plane of a first base member and the surface of a second base located in opposition thereto while the movable stage is supported in a non-contact manner with the reference plane and the surface by means of respective guide means, and increasing the rigidity of the reference surface side of the guide means. CONSTITUTION:A second base 13 is located at a predetermined interval from a first base 11 having a reference plane 12 which has been finished by precision machining so that the plane 14 of the second base 13 is parallel to the reference plane 12. A movable stage is located between this reference plane 12 and the plane 14 by providing respective guide parts 17a, 17b. An air hole is provided for each guide part 17a, 17b. An air bearing function is provided by supplying air from the outside to form an air film and adjusting the pressure of the air film to set the rigidity of the guide part 17a higher than that of the guide part 17b. In addition, the plane 18 of the movable stage 16 is precisely finished while the precise flatness of plane 19 is not required.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable stage device, and more particularly to the structure of a movable stage device that can move an object with high precision in a one-dimensional direction or within a two-dimensional plane.

0002

[Prior Art] In movable stage devices used in semiconductor exposure equipment, ultra-precision processing equipment, etc., the accuracy of the guide section that guides and holds the stage when it moves and stands still greatly affects the movement accuracy and positioning accuracy of the stage. give. Therefore, a combination of a non-contact bearing device and a highly rigid guide structure is often used as a guide device.

[0003] For example, an exposure stage for next-generation VLSI manufacturing requires positioning accuracy of submicron or higher, and in order to realize such a movable stage device, it is necessary to provide driving force to move the stage. In addition to the accuracy of the actuator, the guidance accuracy of the guide device is also an important factor.

0004

FIG. 6 shows a cross-sectional structure of an example of a movable stage device according to the prior art. In FIG. 6, a first base 61 is a highly rigid surface plate having a flat surface 62 that has been precision-machined and has a high degree of flatness. Second
The base 63 is a highly rigid surface plate having a flat surface 64 that is precisely machined and has a high degree of flatness. planes 62 and 6
The support column 6
Combined with 5. A movable stage member 66 is placed between the flat surfaces 62 and 64 of the first and second bases 61 and 63. Stage member 66 facing planes 62 and 64
Both sides are precision machined and finished to have high flatness and parallelism. Guide portions 67a, 67b are provided in gaps between each surface of the stage member 66 and the flat surfaces 62, 64 of the bases 61, 63. Air is blown onto the guide portions 67a, 67b from an air supply device (not shown) through air holes (not shown) provided in the bases 61, 63 to form an air film. The air film of the guide portion functions as a sliding bearing for the stage 66, that is, an air bearing. Therefore, the stage member 66 is guided and supported by the first and second bases 61 and 63 and the guide portions 67a and 67b in a non-contact manner, and can move between the planes 62 and 64. As the moving device, electromagnetic drive means such as a linear motor is used.

In the conventional movable stage device as shown in FIG. is moved using both surfaces 62 and 64 as reference planes. Therefore, the surfaces 61 and 63 of the base 61 and the base 63 are important factors for determining movement and positioning accuracy.
2.64 flatness, flatness of the surface of the movable stage 66,
There are many factors involved, such as the parallelism between the surfaces 62 and 64 of the base 61 and the base 63, and the parallelism between the surfaces of the movable stage 66, which places a large burden on the processing and assembly of the device. If any of these elements is not accurate, not only the movement accuracy and positioning accuracy of the stage will decrease, but the movement itself may become unstable.

An object of the present invention is to reduce the number of elements that determine the accuracy of movement and positioning without reducing the accuracy, thereby achieving excellent mass productivity, and absorbing accuracy errors and variations in the above elements to achieve high accuracy. An object of the present invention is to provide a highly reliable movable stage device.

[0007]

[Means for Solving the Problems] A movable stage device according to the present invention that achieves the above object includes a first base member having a reference plane, and a movable stage device facing in parallel with the reference plane of the first base member at a predetermined distance. between the reference plane of the first base member and the surface of the second base member; A movable stage capable of relative movement without contact is disposed, and a first guide portion is disposed between the reference plane of the first base member and the movable stage to guide and support the movable stage with respect to the reference plane without contact. A second guide part for guiding and supporting the movable stage in a non-contact manner with respect to the surface of the second base member is disposed between the surface of the second base member and the movable stage, and the first guide part The rigidity of the guide portion was set to be higher than that of the second guide portion.

[0008]

[Operation] By setting the first guide part so that the rigidity of the guide medium is higher than that of the second guide part, the movable stage moves only with reference to the reference plane of the first guide part, and Errors and variations in the flatness of the surfaces of the first and second base members, the flatness of the surface of the movable stage, the parallelism between the surfaces of the first and second bases, the parallelism of the surfaces of the movable stages, etc. The resulting motion error of the stage is absorbed by the second guide portion with lower rigidity.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of an embodiment of a movable stage apparatus according to the present invention will be described in detail below with reference to the drawings.

First, the structure will be explained with reference to FIG. FIG. 1 shows a cross-sectional structure of an embodiment of a movable stage device according to the present invention. The embodiment shown in FIG. 1 is a movable stage device in which the movable stage is vertically movable. Note that the movable stage device of this embodiment is not limited to vertical movement, but may be horizontal movement or diagonal movement in between, and is assumed to be movable within a two-dimensional plane.

In FIG. 1, a first base 11 is a highly rigid surface plate having a reference plane 12 that has been precision-machined and has a high degree of flatness. The second base 13 is a surface plate having a surface 14 parallel to the reference plane 12 of the first base 11 . The flat surface 14 is not required to have a flatness as compared to the reference surface 12, and may be relatively rough. The planes 12 and 14 are fixed to the floor 15 so as to be parallel to each other with a predetermined distance between them, or they are fixed together by a holding column (not shown). However, the parallelism of the reference plane 12 and the plane 14 may be relatively low compared to the conventional device shown in FIG. The material for the bases 11 and 13 is selected from a material with high rigidity, but is not limited to a magnetic material such as iron. For example, ceramics are preferable because they have high specific rigidity and high processing accuracy.

Flat surfaces 12 of the first and second bases 11 and 13
, 14, a movable stage 16 is arranged. A surface 18 of the stage 16 facing the reference surface 12 is precision-machined and has a high flatness similar to the reference surface 12. The surface 19 of the stage 16 facing the second base 13 is not required to be as flat as the surface 18, and may be relatively rough.

A first guide portion 17a and a second guide portion 17b are provided in the gaps between each surface of the stage 16 and the flat surfaces 12 and 14 of the first and second bases 11 and 13, respectively. Air is blown onto the first and second guide portions 17a, 17b from an air supply device (not shown) through air holes (not shown) provided in the stage 16 or the bases 11, 13 to form an air film. The air film of the guide parts 17a and 17b is
It functions as a sliding bearing for the stage 16, that is, an air bearing. Therefore, the stage 16 includes the first and second bases 11, 13, the first and second guide portions 17a,
17b and can move between the planes 12 and 14 while being guided and supported in a non-contact manner. As the moving device, it is preferable to use electromagnetic drive means such as a linear motor. First and second guide parts 17
The distance between a and 17b is determined in consideration of the magnitude of the stage load, the required stiffness of the air film, etc., which will be explained later.

As the guide portions 17a and 17b, in addition to an air bearing means using an air film, it is possible to use one that utilizes the repulsive force of a magnet. In this case, bases 11, 13
The flat surfaces 12 and 14 of and the surface of the stage 16 are made of magnetic material. Magnets are attached to each of the planes 12 and 14 and the surface of the stage 16 so that magnetic poles of the same polarity face each other. This magnet may be a permanent magnet or an electromagnet. Also,
One of the guide parts 17a and 17b may use an air bearing, and the other may use the repulsive force of a magnet.

Next, the operation of the movable stage device of this embodiment will be explained with reference to FIGS. 2, 3 and 4. Figure 2 shows
This is an enlarged view of the main parts of the movable stage device shown in FIG. 1, showing how the stage 16 vertically moves downward as 16'.

As described above, the reference surface 12 of the first base 11 has a high degree of flatness, and the surface 14 of the second base 13 has a rougher degree of flatness as shown. Furthermore, the first
The rigidity of the second guide portion 17a is set to be considerably higher than the rigidity of the second guide portion 17b. In the case of an air film, the rigidity can be adjusted by changing the pressure of the air film, the aperture, and the shape of the aperture. For example, high rigidity of the guide section can be obtained by making the pressure rise rapidly when approaching. Furthermore, when using the repulsive force of a magnet, the rigidity can be adjusted by changing the magnetic force. For example, if the repulsive force of the magnet increases rapidly as it approaches, the rigidity of the guide section will increase.

Now, when the stage 16 is in the upper position in FIG. 2, the interval between the first guide parts 17a is h1, the width of the stage 16 is ht, and the interval between the second guide parts 17b is h2.
, the distance between the first and second bases 11 and 13 is h0. Assume that the stage moves downward from this upper position to the position of stage 16'. stage 16
At the position ', the distance between the first guide parts 17a is h1
+Δh1, the width of the stage 16' is ht (no change), the interval between the second guide portions 17b is h2 +Δh2,
The distance between the first and second bases 11 and 13 is h0 +Δh0
Suppose that

FIG. 3 is a characteristic curve in which the horizontal axis represents the distance h between the first and second guide portions 17a and 17b, and the vertical axis represents the load capacity w of the air film. The left side of the graph from the vertical axis shows the characteristics of the first guide part 17a, and the right side shows the characteristics of the second guide part 17b. The stiffness of the guide portion is expressed by the slope of this characteristic curve. In other words, the steeper the slope of the curve, the higher the rigidity. That is, the load (stage 16
The more the spacing of the guide portions does not change with respect to changes in the reaction force (reactions from), the higher the rigidity is. As shown,
The curve of the first guide portion 17a has a steeper slope, indicating that the first guide portion 17a has higher rigidity than the second guide portion 17b.

In the position of the stage 16 in FIG.
and the load capacities of the second guide portions 17a and 17b are balanced at points x1 and x2 where they become equal. The spacing between the guide portions 17a and 17b at this time is as shown in FIG. At a position where the stage moves downward from this position and becomes stage 16' in FIG. 2, the load capacities w of both guide portions are balanced at points x1' and x2' in FIG. The spacing between the guide portions 17a and 17b at this time is as shown in FIG.

FIG. 4 shows a model of the states shown in FIGS. 2 and 3 using spring and mass elements. Mass (stage) 16
and 16' are supported from both sides to the bases 11 and 13 by spring constants k1 and k2. Here, the spring constant (
It is assumed that k1 ≫ k2 (corresponding to stiffness) is selected.

When the mass (stage) 16 moves to the position 16', the interval h0 increases by Δh0, and the guide part 1
The equilibrium points of 7a and 17b are x1' and x2' in Figure 3.
Move to. The distance between the first guide portion 17a and the second guide portion 17b increases by Δh1 and Δh2, respectively. (Δh1 +Δh2 =Δh0) As can be seen from FIG. 3, since k1≫k2, Δh1≪Δh2, and the roughness of the flatness of the surface 14 of the second base 13, the reference surface 12 and the surface 14 of the base 13 The second guide part 17b absorbs the error in parallelism between the stage 16 and the reference plane 1.
2 in the direction of the distance h with almost no change (within tolerance).

Next, FIG. 5 shows an example in which the movable stage device of FIG. 1 is applied to an aligner stage device of a semiconductor exposure apparatus.
Explain with reference to. The first base 51 is a highly rigid ceramic surface plate whose reference plane 52 is precisely machined and has a high degree of flatness. The second base 53 is a ceramic surface plate whose flat surface 54 is rougher than the reference surface 52 in flatness. The planes 52 and 54 are fixed to the floor 55 so as to be parallel to each other and facing each other with a predetermined distance therebetween. A movable wafer stage 56 is arranged so as to be sandwiched between flat surfaces 52 and 54 of the first and second bases 51 and 53. Reference plane 5
One surface 58 of the wafer stage 56 facing the wafer stage 2 is precision machined and has a high degree of flatness. Each surface 58, 59 of the wafer stage 56 and the surfaces 52, 5 of the base 52, 53
4, air is supplied from an air supply device (not shown) to form an air film between the non-contact guide portions 57a and 57b.
is placed. Both guide portions function as air bearings for the wafer stage 56. Therefore, the wafer stage 56 is guided and supported by the first and second bases 51 and 53 and the guide portions 57a and 57b in a non-contact manner, and can move along the reference plane 52. As the moving device, electromagnetic driving means is used that includes a planar motor 20 comprising a permanent magnet 21 provided on the base 53 and a coil 22 provided on the wafer stage 56 side.

An opening 23 is provided in the center of the first base 51 to allow exposure light to pass therethrough. Opening part 2
A mask stage 24 is provided at 3. A mask 25 on which a pattern is drawn is placed on the mask stage 24. The wafer stage 56 is provided with a recess 26 . Recess 2
A wafer chuck 27 is arranged approximately at the center of the wafer 6, and a wafer 28 is fixed thereon. The wafer stage 56 is moved vertically or horizontally by the planar motor 20 to achieve alignment with the mask 25. In addition,
The guide portions 57a and 57b may be formed using magnetic repulsion instead of air bearings.

The present invention has been described above with reference to examples, but
The present invention is not limited to these. for example,
It will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

[0025]

Effects of the Invention By setting the first guide portion to have higher guide rigidity than the second guide portion, the movable stage moves only with reference to the reference plane of the first guide portion. By using a non-contact guide as a guide and using a guide configuration in which the two guide parts have different rigidities, the flatness of the surfaces of the first and second base members, the flatness of the surface of the movable stage, and the first The stage motion error caused by errors or variations in the parallelism between the surfaces of the movable stage and the surfaces of the movable stage is absorbed by the second guide portion with low rigidity, resulting in high precision. Movement and positioning are possible.

Furthermore, the accuracy of the movable stage device is as follows:
Only the flatness of the reference surface and the flatness of the stage facing the reference surface need to be manufactured with high precision, and the accuracy of other elements can be reduced compared to conventional ones, improving mass production and eventually Manufacturing costs are reduced and reliability is improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a cross-sectional structure of an embodiment of a movable stage device according to the present invention.

FIG. 2 is a diagram illustrating the operation of the movable stage device in FIG. 1.

FIG. 3 is a graph showing the rigidity characteristics of the guide portion of the movable stage device in FIG. 1;

4 is an equivalent mechanical diagram illustrating the operation of the movable stage device of FIG. 1. FIG.

FIG. 5 is a diagram when the movable stage device of FIG. 1 is applied to an aligner device of a semiconductor manufacturing device.

FIG. 6 is a diagram showing a cross-sectional structure of an example of a movable stage device according to a conventional technique.

[Explanation of symbols]

11, 51, 61...first base 12, 52, 6
2...Surfaces 13, 23, 63... of the first base
- Second base 14, 24, 64... Second base surface 15, 55... Floor surface 16, 56, 66... Movable stage 17a, 57a
, 67a...first guide portion 17b, 57b, 67b
... Second guide part 20 ... Planar motor 21 ... Permanent magnet 22 ... Coil 23 ... Opening 24 ... Mask stage 25 ... ... Mask 26 ... Concavity 27 ... Wafer chuck 28 ... Wafer

Claims (4)

[Claims] 1. A first base member having a reference plane; and a second base member having a surface facing parallel to the reference plane at a predetermined distance from the first base member;
The base member is disposed between the reference plane of the first base member and the surface of the second base member, and is capable of relative movement along the reference plane without contacting the first and second base members. a first guide means disposed between the reference plane of the first base member and the movable stage and guiding and supporting the movable stage in a non-contact manner with respect to the reference plane; a second guide means disposed between the surface of the second base member and the movable stage to guide and support the movable stage in a non-contact manner with respect to the surface; A movable stage device whose rigidity is set to be higher than that of the second guide means. 2. The movable stage device according to claim 1, wherein the flatness of the surface of the second base member is rougher than the flatness of the reference surface of the first base member. 3. At least one of the first and second guide means is arranged on a predetermined plane formed between the reference plane of the first base member or the surface of the second base member and the movable stage. 3. The movable stage device according to claim 1, further comprising an air film having a rigidity of . 4. At least one of the first and second guide means has a predetermined magnetic field between the reference plane of the first base member or the surface of the second base member and the movable stage. 3. The movable stage device according to claim 1, further comprising magnet means for generating force.