JPH09218369A - Scanner system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide desired measuring data with high sensitivity by detecting the displacing state based on the change of light quantities of interference light beams having different phases and formed by optically processing the diffraction light beams and performing feedback control for a piezoelectric body so as to be a desired displacing state. SOLUTION: A reflection type scale 20 provided in a displacing part 16a generates diffraction light when a laser beam is projected from a semiconductor laser 18 to the displacing part and entrapping mirrors 22x, 24x, 26y, 28y entrap a prescribed diffracted light beam except a zero-order diffracted beam from among the diffracted light beams generated from the reflection type scale 20. An interference optical system 30 performs the prescribed optical processing to the diffracted beams entrapped by the entrapping mirrors, forms interference beams of different phases, the displacing state of the displacing part is detected based on the change of light quantity of interference beam formed by the interference optical system 30 and a control means performs feedback control of a tubular piezoelectric body 16 capable of displacing the displacing part 16a by a desired amount in a desired direction based on the displacing state so as to become a desired displacing state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner system incorporated in a scanning probe microscope such as a scanning tunneling microscope or an atomic force microscope.

[0002]

2. Description of the Related Art Conventionally, various scanner systems have been applied to a scanning probe microscope so that highly accurate measurement can be performed on a sample. As an example of this scanner system, as shown in FIG. 5D, a tube-type piezoelectric body 4 that moves a stage 2 on which a sample (not shown) can be mounted in a predetermined direction by a predetermined amount, and the tube-type piezoelectric body 4. There is known a scanner system including a reflecting mirror 6 attached to the back surface of the body 4.

In such a scanner system, the parallel light flux emitted from the beam splitter 8 to the reflecting mirror 6 via the λ / 4 plate 10 is reflected from the reflecting mirror 6 and then
The light is guided to the condenser lens 12 via the λ / 4 plate 10 and the beam splitter 8, and is condensed by, for example, a four-division photodiode 14 (hereinafter, referred to as 4PD). . At this time, when the tube-type piezoelectric body 4 is displaced, the spot position on the 4PD 14 changes. Since the 4PD 14 is configured to output an electric signal corresponding to the spot position, the signal output P from the 4PD 14 corresponds to the change in the spot position.
(See FIG. 5C) changes. Therefore, by detecting the change in the signal output P, the scanner displacement F (see FIG. 5C) of the tube-shaped piezoelectric body 4 is detected.

[0004]

By the way, FIG. 5 (C)
It is known that there is the following relationship between the scanner displacement F and the signal output P as shown in FIG. First, as shown in FIGS. 5A, 5C, and 5D, when the 4PD 14 is positioned at the focal position of the condenser lens 12, the spots S formed in the four light receiving regions 14a and 14b of the 4PD 14 are positioned. Has a very small diameter. When the tube-type piezoelectric body 4 is displaced in this state, 4PD14
Since the spot S is relatively deviated from the center of, the signal output P changes greatly. As a result, the detection sensitivity of the scanner displacement F increases.

On the other hand, since the spot S is displaced from the two light receiving regions 14a on the left side of the 4PD 14 in FIG. The measurement range, that is, the maximum signal allowable level D (dynamic range) is extremely limited (see the characteristic curve P1 in FIG. 5C).

Further, as shown in FIGS. 5B, 5C and 5D, when the 4PD 14 is positioned at the non-focus position of the condenser lens 12, the four light receiving regions 14 of the 4PD 14 are placed.
The spots S formed on a and 14b have a relatively large diameter. When the tube-type piezoelectric body 4 is displaced in this state, the signal output P does not change so much because the spot S is not relatively displaced from the center of the 4PD 14. As a result, the detection sensitivity of the scanner displacement F becomes small.

On the other hand, even if the spot S moves to some extent (for example, the minute amount d), the spot S does not deviate from the four light receiving regions 14a and 14b of the 4PD 14, and therefore the measurement range of the scanner displacement F is measured. That is, the maximum signal allowable level D (dynamic range) is expanded to some extent (see the characteristic curve P2 in FIG. 2C).

As described above, in the conventional scanner system, there is a reciprocal relationship between the detection sensitivity and the dynamic range corresponding to the size of the diameter of the spot S. Therefore, it is desired to develop a scanner system having a wide dynamic range D while maintaining high detection sensitivity. The present invention has been made to meet such a demand, and an object thereof is to provide a scanner system capable of obtaining desired measurement data with high sensitivity.

[0009]

In order to achieve such an object, a scanner system according to the present invention includes a scanner configured to be capable of displacing a displacement portion in a desired direction by a desired amount and a displacement portion of the scanner. Of the diffracted light generated by this diffracting means, a light source that irradiates light toward the light source At least an capturing optical element that captures a predetermined diffracted light other than the secondary diffracted light and an interference optical system that forms a predetermined phase of interference light on the diffracted light captured by the capturing optical element are formed. It is possible to obtain desired measurement data with high sensitivity by detecting the displacement state of the displacement portion of the scanner based on the change in the amount of interference light formed by this interference optical system. And it is configured to kill.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A scanner system according to a first embodiment of the present invention will be described below with reference to FIGS. As shown in FIGS. 1 and 2, the scanner system according to the present embodiment is a scanner or a tube-type piezoelectric body 16 configured to be able to displace the displacement portion 16 a in a desired direction by a desired amount, and the tube-type piezoelectric body 16. Displacement part 16
a light source that emits light toward a, that is, a semiconductor laser 18,
Diffraction means or reflection type scale 20 provided on the displacement portion 16a of the tube-type piezoelectric body 16 and generating diffracted light when irradiated with laser light from the semiconductor laser 18, and diffracted light generated from this reflection type scale 20. Of the first to fourth capturing mirrors 22x, 24x, 26y, which capture the predetermined diffracted light other than the 0th-order diffracted light.
28y and the first to fourth capturing mirrors 22x,
Based on the interference optical system 30 that forms interference light having different phases by performing predetermined optical processing on the diffracted light captured by 24x, 26y, and 28y, and based on the change in the amount of interference light formed by the interference optical system 30. Detecting means 32 for detecting the displacement state of the displacement portion 16a of the tube-type piezoelectric body 16.
And a control means 34 for feedback-controlling the tube-shaped piezoelectric body 16 to a desired displacement state based on the displacement state detected by the detection means 32.

In the present embodiment, a stage 36 on which a sample (not shown) can be placed is attached to the displacement portion 16a of the tube-type piezoelectric body 16, and the reflective scale 20 is mounted on the back surface of the stage 36. It is installed.

The reflective scale 20 is provided with a diffraction grating 20a formed in a two-dimensional direction (arrow XY direction in the figure), and when the reflective scale 20 is irradiated with laser light, diffracted light is generated. Is configured.

First through fourth capture mirrors 22x, 24
x, 26 y, and 28 y are other than the tube-type piezoelectric body 16 so that a predetermined diffracted light other than the 0th-order diffracted light in the diffracted light generated from the reflective scale 20 can be reflected toward the interference optical system 30. It is located at the site. Specifically, the first to fourth capturing mirrors 22x, 24x, 26y, 28y applied to the present embodiment are placed at positions where the ± first-order diffracted light can be constantly reflected in the interference optical system 30 direction. is set up.

Next, the operation of this embodiment will be described. The laser light emitted from the semiconductor laser 18 is regulated into a parallel light flux by the collimator lens 38, and then λ
The reflection mirror 42 is irradiated with the circularly polarized light through the / 4 plate 40, and the reflection scale 20 is irradiated with the reflection mirror 42.

Of the diffracted light generated from the reflection type scale 20 at this time, the ± first-order diffracted light generated in the direction of the arrow X in the figure is reflected by the first and second taking-in mirrors 22x and 24x, and The ± first-order diffracted lights generated in the direction of the middle arrow Y are reflected in the direction of the interference optical system 30 by the third and fourth capturing mirrors 26y and 28y, respectively. In addition,
In the present embodiment, as an example, the + 1st-order diffracted light is reflected by the first capture mirror 22x, and the -1st-order diffracted light is reflected by the second capture mirror 24x toward the interference optical system 30. It is assumed that the + 1st-order diffracted light is reflected by the third capturing mirror 26y and the -1st-order diffracted light is reflected by the fourth capturing mirror 28y toward the interference optical system 30.

In the interference optical system 30, the ± 1st-order diffracted light reflected from the first and second taking-in mirrors 22x and 24x is selected by the first and second polarizing plates 44x and 46x only for a specific polarization component. After that, the first and second interference mirrors 48x and 50x are used to form the x-direction half mirror 52.
x is irradiated. Also, the third and fourth capture mirrors 26
The ± 1st-order diffracted lights reflected from y and 28y are the third and fourth
After only the specific polarization component is selected by the polarizing plates 54y and 56y of the third, the third and fourth interference mirrors 58y and 6y.
The y direction half mirror 62y is irradiated with 0y.

At this time, two interference lights having phases different from each other by 90 ° are emitted from the x-direction half mirror 52x, and these two interference lights respectively correspond to the first and second corresponding lights.
After being converted into an X-direction electric signal by the photo detectors 64x and 66x, it is output to the detecting means 32 through the preamplifier 68. On the other hand, two interference lights having a phase difference of 90 ° from each other are emitted from the y-direction half mirror 62y, and these two interference lights correspond to the corresponding third and fourth beams, respectively.
After being converted into a Y-direction electric signal by the photo detectors 70y and 72y of FIG.

In the detecting means 32, the X-direction dividing circuit 74 divides the X-direction electric signal into a desired resolution to discriminate the X-direction. Next, the X-direction counter 76 counts the X-direction displacement amount (that is, the X-direction movement amount of the reflective scale 20) based on the X-direction discrimination data. on the other hand,
The Y direction division circuit 78 divides the Y direction electric signal into a desired resolution to discriminate the Y directionality. Next, the Y-direction counter 80 counts the Y-direction displacement amount (that is, the Y-direction movement amount of the reflective scale 20) based on the Y-direction discrimination data.

At this time, the X-direction and Y-direction count data counted by the X-direction and Y-direction counters 76 and 80 (that is, the X-direction and Y-direction corresponding to the X-direction and Y-direction movement amount of the reflective scale 20). The direction count data) is output to the control means 34.

The scanner controller 82 provided in the control means 34 controls the scanner driver 88 based on the reference waveform signals from the X-direction waveform generator 84 and the Y-direction waveform generator 86, so that the tube type The piezoelectric body 16 is displaced in the XY directions. As a result, the detection means 3
The X-direction and Y-direction count data output from 2 changes according to the X-direction and Y-direction movement amounts of the reflective scale 20.

In this case, the movement amount of the reflection type scale 20 in the X and Y directions counted by the detecting means 32, that is, the displacement amount of the tube type piezoelectric body 16 is determined by the tube type piezoelectric body 16.
When there is a deviation from the desired value due to the hysteresis, creep, or the like (when a deviation occurs), the non-linearity correction unit 90 provided in the scanner controller 82 calculates the deviation and compensates for the deviation. That is, the scanner driver 88 is controlled so as to be eliminated (so that the displacement amount of the tube-shaped piezoelectric body 16 becomes a desired value).

As a result, since the tube-shaped piezoelectric body 16 is controlled to a desired displacement amount, it becomes possible to move the stage 36 by a predetermined amount in a predetermined direction with high accuracy. According to the present embodiment, the tube-type piezoelectric body 16 is feedback-controlled based on the change in the optical characteristics of the ± 1 diffracted light from the reflective scale 20, so that the tube-type piezoelectric body 16 is not affected by hysteresis and creep. Piezoelectric 16
Since the displacement can be controlled, it is possible to provide a scanner system capable of obtaining desired measurement data with high sensitivity.

Next, a scanner system according to the second embodiment of the present invention will be described with reference to FIG. In the description of the present embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 3, the scanner system according to the present embodiment includes a sample 92 mounted on the stage 36.
Sensor 94 capable of detecting sample data at a desired position of
And sample display means for taking in sample data at a preset position and displaying it on the monitor 96 based on the X-direction and Y-direction count data output from the detection means 32. The measurement data of a desired position of the placed sample 92 can be obtained with high sensitivity.

Further, in the control circuit 98 provided in the sample display means, the amount of movement of the reflective scale 20 in the X and Y directions (hereinafter, referred to as a set value) is measured on the XY coordinates (for each measurement range and each measurement point). (Not shown) is preset.

At the time of measurement, measurement is performed by the control circuit 98 based on the X-direction and Y-direction count data (that is, the actual X-direction and Y-direction movement amount of the reflective scale 20) from the detecting means 32 and the set value. The timing signal is output to the A / D converter 100.

At this time, the A / D converter 100 sequentially digital-converts the sensor signal (the signal corresponding to the sample image) output from the sensor 94 based on the measurement timing signal, and is set in the control circuit 98. Captured on the XY coordinates.

The control circuit 98 subjects the digital signal taken in on the XY coordinates by the A / D converter 100 to predetermined image processing to display a sample image of the sample 92 on the monitor 96.

As described above, according to the present embodiment, the measurement timing of the sample 92 is determined based on the actual movement amounts of the reflective scale 20 in the X and Y directions (absolute movement amount of the entire measurement range of the sample 92). Since it is controlled, it is possible to provide a scanner system capable of obtaining desired measurement data with high sensitivity without being affected by hysteresis or creep.

Further, according to the present embodiment, the control means 34 applied to the first embodiment is unnecessary, so that the measurement data at the desired position can be obtained with high sensitivity with a simple structure. .

Next, a scanner system according to the third embodiment of the present invention will be described with reference to FIG. In the description of this embodiment, the same components as those in the above-described embodiments are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 4, the scanner system according to the present embodiment has a control circuit 102 capable of outputting measured distance data in the X and Y directions defined based on the measurement range and the number of measurement points, and the X direction. And the X-direction and Y-direction measurement by performing a predetermined calculation on each electric signal output from the photodetector means, that is, the first to fourth photodetectors 64x, 66x, 70y, 72y based on the Y-direction measurement distance data. A measurement timing signal generation circuit 104 that outputs a timing signal, and a control circuit 102 that sequentially digital-converts a sensor signal (a signal corresponding to a sample image) output from the sensor 94 based on the X-direction and Y-direction measurement timing signals. And an A / D converter 106 to be loaded into.

Further, the measurement timing signal generation circuit 104
Based on the electric signal whose X directionality is discriminated by the X direction division circuit 74 and the X direction measurement distance data output from the control circuit 102, the X direction measurement timing signal is converted into the control circuit 102 and A / D converted. X output to the container 106
Direction small bit counter 108 and Y direction division circuit 7
Based on the electric signal whose Y direction is discriminated by 8 and the Y direction measurement distance data output from the control circuit 102, the Y direction measurement timing signal is output to the control circuits 102 and A.
A Y direction small bit counter 110 for outputting to the / D converter 106 is provided.

The operation of the characteristic part of this embodiment will be described below. Similar to each of the above embodiments, the first and second photodetectors 64x and 66x are connected to the preamplifier 6
When an electric signal in the X direction is output to the measurement timing signal generating circuit 104 via 8, the dividing circuit for the X direction 74
The directional electric signal is divided into desired resolutions to discriminate X directionality. Next, based on this X-direction discrimination data, the X-direction small bit counter 108 counts the X-direction displacement amount (that is, the X-direction movement amount of the reflective scale 20), and
An X-direction measurement timing signal is generated based on the X-direction displacement amount and the X-direction measurement distance data from the control circuit 102. On the other hand, the third and fourth photo detectors 70
When an electric signal in the Y direction is output from y, 72y to the measurement timing signal generation circuit 104 via the preamplifier 68,
The Y-direction dividing circuit 78 divides the Y-direction electric signal into a desired resolution to discriminate the Y-direction. Next, based on this Y-direction discrimination data, the Y-direction small bit counter 110
Counts the Y-direction displacement amount (that is, the Y-direction movement amount of the reflective scale 20), and based on this Y-direction displacement amount and the Y-direction measured distance data from the control circuit 102, Y
Generate a direction measurement timing signal.

The X-direction and Y-direction measurement timing signals generated at this time are supplied to the control circuit 102 and the A / D converter 1.
06 is output. The control circuit 102 sets the XY coordinates on the basis of the X-direction and Y-direction measurement timing signals, and also sets the X-direction and Y-direction small bit counters 108,
Initialize 110.

The A / D converter 106 sequentially digital-converts the sensor signal output from the sensor 94 based on the X-direction and Y-direction measurement timing signals, and the control circuit 10
It is taken in on the XY coordinate set to 2.

The control circuit 102 subjects the digital signal captured on the XY coordinates by the A / D converter 106 to predetermined image processing, and displays a sample image of the sample 92 on the monitor 96.

As described above, according to the present embodiment, the measurement timing of the sample 92 is not controlled based on the absolute movement amount of the entire measurement range of the sample 92 as in the second embodiment, but the reflection is performed. Mold scale 20 (Stage 3
6) controls the measurement timing each time it moves by the desired measurement distance, that is, based on the relative movement amount between the measurement points, and therefore the total number of counts for generating the X-direction and Y-direction measurement timing signals. (That is, the count data of the X-direction and Y-direction small bit counters 108 and 110) can be reduced. As a result, desired measurement data can be obtained with high sensitivity without being affected by hysteresis and creep, and the X direction and Y are inexpensive.
It is possible to provide a scanner system including the small bit counters 108 and 110 for directions.

For example, the absolute movement amount is for A, X direction and Y
Assuming that the resolution of the direction division circuits 74 and 78 is B and the number of measurement points is C, the total count number M of the second embodiment is M = A / B, and the total count number N of the present embodiment is N = A / B / C = M
/ C. Specifically, if the number of measurement points C is 256, it is 8 bits, or if it is 1024, only 10 bits are used for the X direction and Y direction small bit counters 108, 1.
The number of bits of 10 can be reduced.

Further, in the second embodiment, it is necessary to set and store the XY coordinates together with all the movement amounts of the reflective scale 20 in the X and Y directions for each measurement range and each measurement point. Therefore, a large memory capacity is required, but in the present embodiment, the XY coordinates are set based on the X-direction and Y-direction measurement timing signals, and the small bit counters 108 and 110 for the X and Y directions are set. Initializing. Therefore, the memory capacity can be significantly reduced.

The present invention is not limited to the above-mentioned respective embodiments, and can be variously modified without adding new matter. For example, instead of separately attaching the reflective scale to the stage, even if a diffraction grating is formed on the back surface of the stage, the same operation and effect as in the respective embodiments can be obtained.

[0042]

According to the present invention, it is possible to provide a scanner system capable of obtaining desired measurement data with high sensitivity.

[Brief description of drawings]

FIG. 1 is a perspective view showing a peripheral configuration of a tube-type piezoelectric body provided in a scanner system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the overall configuration of a scanner system according to the first embodiment of the invention.

FIG. 3 is a diagram showing an overall configuration of a scanner system according to a second embodiment of the invention.

FIG. 4 is a diagram showing an overall configuration of a scanner system according to a third embodiment of the invention.

5A is a diagram showing a detection sensitivity characteristic of a scanner displacement, FIG. 5B is a diagram showing a positional relationship between a four-division photodiode positioned at a focal position and a spot, and FIG.
FIG. 3D is a diagram showing a positional relationship between a four-divided photodiode positioned at a non-focus position and a spot, and FIG.

[Explanation of symbols]

 16 Tube-type piezoelectric body 16a Displacement part 18 Semiconductor laser 20 Reflective scale 22x First capturing mirror 24x Second capturing mirror 26y Third capturing mirror 28y Fourth capturing mirror 30 Interference optical system

Claims (3)

[Claims] 1. A scanner configured to displace a displacement portion in a desired direction by a desired amount, a light source for irradiating light toward the displacement portion of the scanner, and a scanner provided on the displacement portion of the scanner and from the light source. Diffracting means for generating diffracted light when the above-mentioned light is irradiated, a capturing optical element for capturing a predetermined diffracted light other than the zero-order diffracted light among the diffracted light generated by the diffracting means, and this capturing optical element The diffracted light captured by the interferometer is subjected to predetermined optical processing to form interference light having different phases, and the displacement unit of the scanner is based on the change in the amount of the interference light formed by the interference optical system. Detecting means for detecting the displacement state of, and based on the displacement state detected by this detecting means,
A scanner system comprising: a control unit that feedback-controls the scanner to a desired displacement state. 2. A scanner configured so that a displacement part capable of setting a sample can be displaced in a desired direction by a desired amount, a light source for irradiating light toward the displacement part of the scanner, and a displacement part of the scanner. A diffracting means for generating diffracted light when irradiated with light from the light source, and a taking-in optical element for taking in predetermined diffracted light other than the 0th-order diffracted light among the diffracted light generated by the diffracting means, Based on the interference optical system that performs predetermined optical processing on the diffracted light captured by this capturing optical element to form interference light with different phases, and the change in the amount of interference light formed by this interference optical system, Based on the displacement state detected by the detection unit that detects the displacement state of the displacement unit of the scanner, the sensor that can detect the sample data of the desired position of the sample, and the detection unit.
A scanner system comprising: sample display means for taking in the sample data at a preset position and displaying it on a monitor. 3. A scanner configured to displace a displacement portion capable of setting a sample in a desired direction by a desired amount, a light source for irradiating the displacement portion of the scanner with light, and a displacement portion of the scanner. A diffracting means for generating diffracted light when irradiated with light from the light source, and a taking-in optical element for taking in predetermined diffracted light other than the 0th-order diffracted light among the diffracted light generated by the diffracting means, Based on the interference optical system that performs predetermined optical processing on the diffracted light captured by this capturing optical element to form interference light with different phases, and the change in the amount of interference light formed by this interference optical system, A photodetector that outputs a predetermined electric signal, a sensor that can detect sample data at a desired position of the sample, and measurement distance data defined based on the measurement range and the number of measurement points. A force capable of control circuit, on the basis of the measured distance data, by performing a predetermined operation on each electric signal output from said light detecting means,
A measurement timing signal generating circuit for outputting a measurement timing signal, and A for converting the sample data into a digital signal based on the measurement timing signal and outputting the digital signal to the control circuit.
A scanner system comprising a / D converter.