JPH0715367B2 - Displacement / rotation detection method and attitude control device - Google Patents

Description

The present invention relates to a highly accurate positioning stage device in a lithographic process of semiconductor manufacturing, a feed table device for an ultra-precision machine tool, a highly accurate stage for various measuring devices, and the like. The present invention relates to a displacement / rotation detection method and an attitude control device applicable to any high-precision motion stage device.

[Prior art]

In order to realize highly accurate linear motion with a conventional linear stage device, for example, a static pressure bearing guide mechanism or a magnetic bearing guide mechanism is combined with a laser interferometer and a control mechanism, the error is measured by the laser interferometer, and the bearing unit is measured. The method of controlling the error with a control mechanism to correct the error has been used. However, in order to measure an error direction component other than the traveling direction of the stage with a laser interferometer, a laser interferometer is required in the component direction, and a laser beam for measuring the error component perpendicular to the traveling direction is emitted. Since the point to be moved moves along with the movement of the stage, the reference plane must be filled to the full length of the stage, and there is a drawback in that the highly precise linear movement is limited to the length of the reference plane.

[Object of the Invention]

The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional example, and to measure all error direction components other than the traveling direction of the stage by using only a beam parallel to the traveling direction of the stage in which the irradiation point is not affected by the position of the stage, At the same time, another object of the present invention is to provide a displacement / rotation detecting method capable of easily identifying the error direction and an attitude control device using the same.

〔Example〕

FIG. 1 and FIG. 4 show an example which is a premise of the embodiment of the present invention. FIG. 1 is a perspective view of an error measuring unit. 1 is a laser oscillator which is a light source, 4 is a parallel prism for converting a laser beam into two parallel beams, and 5 is an optical for converting the cross-sectional shape of the laser beam into a ring shape. Elements (axicons), 6 and 7 are light receiving element substrates, 6a to 6d and 7a to 7d are optical array sensors arranged on the light receiving element substrates 6 and 7, respectively, and 10 is a sensor housing holding a sensor portion. Although not shown in the drawing, the housing 10 is installed on the stage, and the laser oscillator 1, the parallel prism 4, and the axicon 5 are installed on the fixed substrate. The stage can move in the direction of the arrow.

In the above configuration, the laser beam oscillated by the laser light source 1 is divided into two laser beams by the parallel prism 4, and further divided into two laser beams having a ring-shaped cross section by the axicon 5. The optical array sensors 6a to 6d and 7a to 7d, which have been converted and are incident on the light receiving element substrates 6 and 7 respectively in the sensor housing 10 and arranged in a cross, detect the positions of the respective ring members in the longitudinal direction. The beam position on the substrate is detected.

Generally, if the stage is set to the coordinates as shown in FIG. 2 and the stage is moved in the direction of the arrow in the figure, that is, in the x-axis direction, the motion has another five degrees of freedom, that is, translational motion in the y-axis and z-axis directions, Axis, y-axis, z
A rotational movement about the axis occurs. In FIG. 2, the rotation directions around the x-axis, y-axis, and z-axis are represented by ω _X , ω _Y , and ω _z , respectively.

FIG. 3 shows the change in the position of the ring-shaped laser light incident on the light receiving substrate when the stage moves in the above-mentioned five degrees of freedom in the configuration of FIG. In the figure, the broken line represents the ring position before the exercise, and the solid line represents the ring position after the exercise.
As can be seen from the figure, the change patterns of the ring positions on the light receiving element substrates 6 and 7 are different for each of the displacement ω _{Y and} ω _Z in the y direction and the z direction. Therefore, by detecting the change pattern at the same time as the change of the ring position with the optical array sensor, it is possible to measure the change in which motion component direction and how much.

FIG. 4 shows a block diagram of the control system of this example. 11 in the figure
Is the stage body, 13 is the guide, 14 is the actuator, A
Is an error signal detecting section B for converting and amplifying the signal sent from the sensor, and an operation section and an instruction section for processing the error signal in accordance with a constant instruction, and C is an actuator 14 based on the sent signal. It is an actuator driver section to be operated. When the stage moves and the posture changes, a deviation from the reference laser light is generated on the optical sensor, this signal is detected, appropriate arithmetic processing is performed, a command is issued to correct the posture, and it is sent via the driver. By moving the actuators that belong to the stage, the stage can move with high precision.

Since the beam is parallel to the traveling direction of the stage, the beam is incident on the same position on the substrates 6 and 7 regardless of where the stage moves unless the movement of the stage of 5 degrees of freedom occurs.
Therefore, it is possible to perform a long stroke highly precise linear movement of the stage. Further, since the direction of the beam may be one direction, the error measuring device is simple. Since the array-shaped sensor in which the axicon-shaped beam is arranged in a cross is detected, the beam position can be detected with a smaller number of photoelectric elements than when the emitted laser beam is directly incident on the photoelectric plate, etc. Since the thickness of the ring that substantially coincides with the arrangement direction can be made sufficiently small, the position detection accuracy by the optical array sensor can be sufficiently improved.

With the configuration of the error measuring device in the example of FIG. 1, it is difficult to detect a change in the rotation direction ω _X about the x-axis, and similar to other motion component change patterns depending on the position of the detector and the rotation center position. It is possible that a pattern appears. This problem can be solved in the first embodiment shown in FIG.

In FIG. 5, the same members as those in FIG. 1 have the same reference symbols. Reference numeral 2 is a beam splitter for splitting the laser light into two directions. Reference numeral 3 is a beam bender for bending the traveling direction of the laser light. The beam splitter 2 and the beam bender 3 are arranged so as to produce two parallel laser lights. 4'is 4
Same parallel prism, 5'is the same axicon as 5, 8a ~
8d and 9a to 9d are optical array sensors corresponding to 6a to 6d and 7a to 7d, respectively, and 10 'is the same sensor housing as 10. Housing 10,10 'is a static pressure guide type linear stage body 11
It is installed in. Reference numeral 12 is a stage driving linear motor.

In the above configuration, the laser light oscillated from the laser light source 1 is split into two directions by the beam splitter 2, and the transmitted light enters the axicon 5 through the parallel prism 4 and the cross section is converted into a ring shape, so that the sensor housing 10 The light is incident on the light receiving element substrates 6 and 7 inside and is detected by the optical array sensors 6a to 6d and 7a to 7d. Similarly, the reflected light is also reflected by the beam bender 3, passes through the parallel prism 4'and the axicon 5 ', and is detected by the optical array sensors 8a to 8d, 9a, 9d.

The sensor housings 10 and 10 'are installed on the stage main body so that they are symmetrically located in the driving direction of the linear stage. FIG. 6 shows an example of changes in the rings on the substrates 6, 7, 8 and 9 associated with movements in five degrees of freedom other than the driving direction in this case.
As you can see from this figure, the displacements in the y and z directions, x, y,
The pattern of changes in the ring positions on the four substrates is different for each rotation around the z-axis. Therefore, it is possible to detect the amount of change and the change pattern at the same time, and measure in one direction how much and how much the change has occurred.

FIG. 7 shows a second embodiment. In FIG. 1, FIG.
The same symbols are given to the same members as those in FIG. The sensor housings 10 and 10 'are installed in a bearing body 11' of a direct acting magnetic bearing guide. 15 is an electromagnet, 13
a is a guide.

The sensor housings 10 and 10 'are installed at vertically symmetrical positions on the bearing main body 11', and the ring changes on the four substrates due to the movement of five degrees of freedom are the same as those in the first embodiment.
The pattern is as shown. Therefore, the change direction change amount simultaneous measurement can be similarly performed. Since it is a direct-acting type magnetic bearing, correction operation without an actuator is possible by controlling the current of the electromagnet.

FIG. 8 shows a third embodiment. In FIG. 1, FIG.
The same symbols are given to the same members as those in FIGS. 5 and 7. 7'and 9'are optoelectronic element substrates made of transparent material, and 6a 'to 6d' and 8a 'to 8d' form an angle of 45 ° with the optical array sensors 7a 'to 7d' and 9a 'to 9d', respectively. The optical array sensors are arranged on the substrates 6'and 8 '.

The beam emitted from the laser oscillator 1 is split into two beams by the beam splitter 2, the transmitted light is unchanged, and the reflected light is made parallel to the transmitted light by the beam bender 3 and passes through the axicons 5 and 5 ', and the cross section is ringed. It is converted into a shape and enters the substrates 7'and 9 ', respectively. The part of the incident beam ring which hits the optical array sensors 7a'-7d ', 9a'-9d' is blocked, while the other parts pass through the transparent substrates 7 ', 9',
It is incident on the substrates 6'and 8 ', respectively.

Optical array sensors 6a'-6d ', 8a'-9 on substrates 6', 8 '
d ′ are the optical array sensors 7a ′ to 7d ′, 9a ′ to 9d ′, respectively.
They are arranged at a 45 ° offset. The ring portions shaded by the optical array sensors on the substrates 7'and 9'do not come on the optical array sensors 6a 'to 6d', 8a 'to 8d' within the range of possible movement of the stage 11 and always The optical array sensors facing each other are sufficiently spaced so that the ring portion passing through the substrates 7'and 9'can be detected. Therefore, one ring-shaped beam can be detected by the two sets of cross-shaped optical array sensors, and the structure is simple and compact as compared with the first to third embodiments. Again 2-3
In the second embodiment, two boards are placed in one housing.
If they are rotated in the ω _X direction because they are displaced from each other in the z-direction or in the z-direction, the amount of change in the rings on the two substrates will be different from each other, and if the motion in the other direction is added to this. The change pattern of was complicated. In the third embodiment, the two substrates in one housing are not displaced in the y direction and the z direction, and even if they are rotated in the ω _X direction, the change amounts of the rings on the two substrates are equal, The change pattern when a motion in another direction is added is not complicated. FIG. 9 shows an example of changes in the rings on the substrates 6 ', 7', 8 ', 9'according to the movement of five degrees of freedom other than the driving direction in the third embodiment. The positions of the optical array sensors on the substrates 6'and 8'are different, but the change pattern of the ring is the same as in FIG.

FIG. 10 shows a fourth embodiment. In FIG. 1, FIG.
The same symbols are given to the same members as those in FIGS. 5, 7, and 8. 17, 19 are light receiving element substrates installed in the housing with a tendency of 45 ° in the traveling direction of the stage 11, 16 and 18 are received at positions where the beams incident on the light receiving element substrates 17 and 19 in the figure are substantially reflected. Element boards 17, 19 and 4
It is a light receiving element substrate installed in the housing to form an angle of 5 °.

Half mirrors are installed on the surfaces of the substrates 17 and 19 in close contact with the substrates. The thickness of the half mirror is made small enough to prevent refraction when incident light is transmitted. Boards 17, 19
The beams respectively incident on the upper half mirrors are divided into two beams, and the transmitted light is detected as it is by the optical array sensors 17a to 17d and 19a to 19d on the substrate which are in close contact with each other. On the other hand, the reflected light is incident on the substrates 16 and 18 which are inclined by 45 ° on the half mirror, and is received by the optical array sensors 16a to 16d and 18a to 18d. Substrates 16,17,18,1 associated with movement in five degrees of freedom other than the driving direction in this case
Fig. 11 shows an example of changes in the upper ring. Unlike FIG. 6, the positions of the rings on the substrates 17 and 19 do not change during rotation in the ω _Y and ω _Z directions. However, since the change patterns of the positions of the rings on the four plates are different for each movement, the change direction change amounts can be simultaneously measured as in the first to third embodiments. Also, there is no pattern complication when rotating in the ω _X direction,
The apparatus can be made smaller than in the third embodiment, and the displacement and angle can be measured only in a small area on the stage.

In the first and second embodiments, in the drawing, the two substrates in the housing may be displaced in the z direction or may be displaced in the y direction. In the third embodiment, the deviation between the optical array sensor on the front substrate and the optical array sensor on the rear substrate as seen from the laser oscillator side is within the range of stage movement in which the shadow of the front optical array sensor can be considered. Any shape may be used as long as it does not come on the optical array sensor in the back. In the fourth embodiment, the substrate for receiving the reflected light of the half mirror inclined by 45 ° with respect to the traveling direction may be on the side surface side or the bottom surface side of the housing. Further, the inclined substrate is formed by a total reflection mirror without attaching a half mirror, and the arrangement of the optical array sensors on the substrate that receives the reflected light is shifted from the arrangement of the optical array sensors on the inclined substrate as in the third embodiment. I don't care. In all the examples, the cross-sectional shape of the beam is ring-shaped using an axicon, but any cross-sectional shape of the beam may be used within the scope of the present invention. For example, since the cross-sectional intensity distribution of the laser light has a Gaussian distribution as shown in FIG. 12, if the optical array sensor is used to detect a certain intensity point, the same effect as that of the described embodiment can be considered. The arrangement of the photoelectric elements on the substrate can be any shape other than the cross shape as long as the effect of the embodiment is not impaired. You may install a laser oscillator etc. and a light-receiving part in reverse.

〔The invention's effect〕

According to the present invention, even if the detection target is located at any position along a plurality of reference beams, displacements in two directions perpendicular to the emission direction of the plurality of beams and two directions perpendicular to the emission direction of the plurality of beams are performed.
With a simple configuration, it is possible to accurately detect all the rotations about one axis parallel to the axis by distinguishing them from each other.

[Brief description of drawings]

FIG. 1 is a perspective view of an error measuring device as an example which is a premise of an embodiment of the present invention, FIG. 2 is a coordinate diagram showing a directional relationship of other 5 degrees of freedom with respect to a moving direction of a moving body, and FIG. In the example which is a premise of the example, a pattern diagram of the position change of the ring-shaped laser light incident on the light receiving element substrate when the movement of 5 degrees of freedom is performed, and FIG. 4 is a premise example of the embodiment FIG. 5 is a block diagram of the control system of FIG. 5, FIG. 5 is a perspective view of the first embodiment of the present invention, and FIG. 6 is a light receiving element substrate in the case where the movement of 5 degrees of freedom is performed in the first embodiment. FIG. 7 is a perspective view of the second embodiment of the present invention, FIG. 8 is a perspective view of the third embodiment of the present invention, and FIG. 9 is a perspective view of the third embodiment of the present invention. The figure shows that the light is incident on the light receiving element substrate in the case where the movement of 5 degrees of freedom is performed in the third embodiment. Position pattern diagram of changes of the ring-shaped laser beam, FIG. 10 is a perspective view of a fourth embodiment of the present invention, the
FIG. 11 is a pattern diagram of the position change of the ring-shaped laser light incident on the light-receiving element substrate when the movement of 5 degrees of freedom is performed in the fourth embodiment, and FIG. 12 is the sectional intensity of the laser beam. It is an explanatory view of an example of distribution. In the figure; 1: laser oscillator, 2: beam splitter 3: beam bender, 4: parallel prism 5: axicon 6,7,8,9,6 ', 7', 8 ', 9': light receiving element substrate 6a ~ 6d, 7a to 7d, 8a to 8d, 9a to 9d, 6a 'to 6d', 7a 'to 7d',
8a 'to 8d', 9a 'to 9d': Optical array sensor 10,10 ': Sensor housing 11: Linear stage body 12: Linear motor 13,13': Hydrostatic bearing guide 13a: Magnetic bearing guide 14,14 ': Micro-actuator, 15: electromagnet 16,17,18,19: light-receiving element substrate 16a to 16d, 17a to 17d, 18a to 18d, 19a to 19d: optical array sensor.

Claims (5)

[Claims] 1. A beam reference type displacement / rotation detection method, wherein a plurality of parallel reference beams are formed, and a plurality of light receiving means for receiving corresponding ones of the plurality of beams at different positions are arranged. However, due to the combination of the outputs of the plurality of light receiving means, at least two displacements perpendicular to the emission direction of the plurality of beams and two axes perpendicular to the emission direction of the plurality of beams and one axis parallel to the emission direction are generated. Displacement / rotation detection method characterized by detecting rotations separately. 2. The displacement / rotation detecting method according to claim 1, wherein the light receiving means is a two-dimensional light receiving means in which light receiving elements are arranged two-dimensionally. 3. A plurality of the plurality of beams are present, and the plurality of light receiving means are respectively fixedly arranged so as to receive the respective four beams apart from each other in a direction parallel to a direction perpendicular to a traveling direction of light. The displacement / rotation detection method according to claim 1, wherein the displacement / rotation detection method is performed. 4. The plurality of beams are present, and the plurality of light receiving means are arranged so that the respective light beams are separated by the two light receiving means. The displacement / rotation detection method according to item 1. 5. An apparatus for controlling an attitude of an object using a beam reference type displacement / rotation detection method, and light source means for forming a plurality of parallel reference beams, and any one of the plurality of beams. A plurality of light receiving means for receiving light at different positions, one of the plurality of light receiving means and the light source means is arranged on the object, and a combination of outputs from the plurality of light receiving means irradiated with the beam Means for detecting at least two displacements perpendicular to the emission direction of the plurality of beams, rotation about two axes perpendicular to the emission direction of the plurality of beams, and rotation about one axis parallel to the emission direction, respectively. A posture control device, comprising means for controlling the posture of the object based on the result of the detection.