JP3349779B2 - Scanner system and scanning microscope using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a scanning probe microscope such as a scanning tunneling microscope (STM) and an atomic force microscope (AFM), and scans a sample with a scanning member such as a probe. related to, or
In addition, a scanning probe microscope using this scanner system
About the mirror.

[0002]

2. Description of the Related Art For example, a "method and apparatus for forming an image of a sample surface" in JP-A-62-130302.
As described above, a scanning probe microscope such as a scanning tunneling microscope (STM) and an atomic force microscope (AFM) having a simple structure and high vertical and horizontal resolution at the atomic size level has been proposed.

In order to realize high resolution with such a scanning probe microscope, a scanner system that can control the relative position between the probe and the sample with high accuracy is required. In general, a tripod-type or tube-type piezoelectric scanner using a piezoelectric material is used in a scanner system.

Such a tube-type piezoelectric scanner (tube scanner) is provided with a single common electrode on the inner peripheral surface of, for example, a tube-shaped piezoelectric body, and
The outer peripheral surface is provided with four drive electrodes in the circumferential direction.
Thus, by appropriately controlling the voltage application to the four drive electrodes, the free end of the piezoelectric body is bent by three times due to bending or expansion and contraction.
It can be displaced dimensionally. A stage is fixed to the free end of the piezoelectric body, and a probe or a sample is supported on the stage, so that the sample is scanned by the probe by displacement of the end of the piezoelectric body.

[0005]

However, it is well known that a piezoelectric body exhibits phenomena such as hysteresis and creep in displacement when voltage driving is performed. Therefore, when a probe or a sample is scanned using the above-described piezoelectric scanner, the movement characteristics of the stage (ie, the probe or the sample) exhibit non-linear characteristics (voltage-displacement nonlinear characteristics). Such non-linearity, in a scanning probe microscope,
There is a problem that it appears as distortion of the observed image and hinders quantitative measurement. As a scanning member, not only a probe but also another member having an opening, for example, which emits an electron beam, a light beam, and an ultrasonic beam, is known.

An object of the present invention is to eliminate the influence of hysteresis and creep like caused the displacement of the piezoelectric body, a scanner system capable of performing a good scan, this scan
It is an object of the present invention to provide a scanning probe microscope using a NAS system .

[0007]

SUMMARY OF THE INVENTION The present invention is a scanner system used in a scanning microscope and a scanning probe microscope using the scanner system, which scans a scanning member and a sample relatively. Scanner and
In order to detect the displacement of the free end with respect to the fixed end of the scanner, a mirror provided at the free end and light irradiating the mirror from the fixed end to detect a tilt angle of the mirror. And optical displacement detecting means for detecting the xy displacement of the scanner.

[0008]

By optically detecting the displacement of the free end of the scanner, a scanning microscope capable of compensating for the displacement peculiar to the scanner can be constituted by this detection signal.

[0009]

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a scanner system according to this embodiment, partially cut away. In the figure,
Reference numeral 1 denotes a tube-type piezoelectric scanner (hereinafter, referred to as a scanner). Although the detailed configuration of the scanner 1 is not shown, a single common electrode is provided on the inner peripheral surface of a tubular piezoelectric body, that is, a cylindrical body having both ends opened, The surface is provided with four drive electrodes in the circumferential direction. The scanner 1 has its lower end fixed on a fixed base 2. And this scanner 1
The stage 3 is fixed to the upper end, ie, the free end, of the opening so as to close the opening. The stage 3 is formed such that the upper surface and the lower surface are exactly parallel. A flat mirror 4 is fixed to the lower surface of the stage 3 with the reflecting surface facing downward. The fixed base 2 is formed with a through hole 2a coaxially with the scanner 1 so as to penetrate from the upper surface to the lower surface. A quarter-wave plate 5 and a collimator lens 6 are arranged in the through hole 2a so that the plane mirror 4 and the optical axis coincide with each other. The quarter-wave plate 5, the upper small-diameter portion of the through hole 2a, also, the collimator lens 6 is the solid so as to respectively positioned below the large diameter portion
It is fixed to the fixed base 2 . Below the collimator lens 6, a polarizing beam splitter 7 supported by support means (not shown) is disposed. Further, below the polarization beam splitter 7, a position detector 9 described later is provided. A light source 8 is disposed beside the polarization beam splitter 7, and the polarization beam splitter 7 reflects a light beam of a component having a specific vibration surface emitted from the light source 8 to the plane mirror 4 side. . The polarization beam splitter 7 transmits the light beam reflected by the plane mirror 4 and returned, and guides the light beam to the position detector 9.

The light source 8 comprises a semiconductor laser 8a and a lens 8b provided on the emission side of the semiconductor laser 8a.
And the spatial filter 8c. The light beam emitted from the semiconductor laser 8a is condensed on the opening of the spatial filter 8c by the lens 8b, and the light beam transmitted through the spatial filter 8c becomes divergent light and enters the polarization beam splitter 7. . Reference numeral 10 denotes an LD driver that is electrically connected to the semiconductor laser 8a and drives it to emit light.

The position detector 9 is arranged such that the light receiving surface is located at the focal plane of the lens 6, that is, at an optical distance from the lens equal to the spatial filter 8c, and transmitted through the polarizing beam splitter 7. The light beam forms a focused spot on the light receiving surface. Then, the position detector 9 detects the position of the condensed spot.

Reference numeral 11 denotes a non-linearity correcting means 1 to be described later.
1 shows a scan controller having 1a. The input side of the scan controller 11 is connected to the first and second waveform generators 12 and 13 and the output side of the arithmetic circuit 16 so that the reference in the X direction generated by the first waveform generator 12 can be referred to. Voltage and Y generated by the second waveform generator 13
A predetermined process (a process for feedback control described later, a process for rotating or shifting the movement of the scanner 1 from the XY directions, etc.) is performed on the reference voltage in the X direction and the X direction and the Y direction, respectively. Output a control signal. The respective control signals in the X and Y directions are supplied to a scanner driver 14 connected to the output side. A scanner drive / control unit 18 is configured by the scan controller 11, the first and second waveform generators 12 and 13, and the scanner driver 14.

The output side of the scanner driver 14 is connected to the scanner 1 and is connected to four drive electrodes of the scanner 1 so as to displace the scanner 1 to a state specified by a supplied control signal. Selective voltage application is performed.

A preamplifier 15 is connected between the output side of the position detector 9 and the input side of the arithmetic circuit 16 to amplify the output signal (signal indicating the position of the spot) of the position detector 9 and Supply to
The arithmetic circuit 16 includes the amplified position detector 9
The displacement state of the scanner 1 is obtained from the output signal of the scanner 1, and a displacement signal indicating the displacement state is supplied to the scan controller 11.

The non-linearity correcting means 11a of the scan controller 11 applies a predetermined correction to the generated control signal based on the displacement signal supplied from the arithmetic circuit 16. As shown in FIG. 2, the position detector 9 has four regions A, B, C,
D, which is a known four-division photodetector that can obtain an electric signal corresponding to the light amount of the light beam entering each area. The above position detector 9
, The preamplifier 15 and the arithmetic circuit 16 constitute a scanner displacement detector 19.

Next, the operation of the scanner system configured as described above will be described. First, the scanner driver 14
When no voltage is applied to any of the four drive electrodes of the scanner 1, the scanner 1 is not displaced and is in the reference state. When the scanner driver 14 selectively applies a voltage to the four drive electrodes of the scanner 1 based on a control signal output from the scan controller 11, a displacement occurs in the scanner 1 according to the state of the voltage application.

A divergent light beam having a linear polarization component in one direction, which has passed through the spatial filter 8c of the light source 8,
The light reflected by the polarizing beam splitter 7
Incident on. The incident divergent light beam is converted into parallel light by the lens 6 and is incident on the ４ wavelength plate 5. The 偏光 wavelength plate 5 converts the linearly polarized light component of the incident light beam into a circularly polarized light component. The light beam having a circularly polarized component transmitted through the quarter-wave plate 5 exits the through hole 2 a of the fixed base 2, enters the inside of the scanner 1, and enters the plane mirror 4. This incident light beam is reflected by the plane mirror 4 and enters the quarter-wave plate 5 again.
The light beam is a quarter-wave plate 5, and the beam splitter 7
The linearly polarized light component of the light beam reflected on the λ / 4 plate 5 and incident on the 波長 wavelength plate 5 is emitted as a light beam having a linearly polarized light component whose azimuth is rotated by 90 °. The emitted parallel light beam passes through the polarizing beam splitter 7 while being converged by the lens 6, enters the position detector 9, and forms a focused spot on the light receiving surface of the position detector 9.

Here, when the scanner 1 is not displaced, the focused spot is formed at the center of the light receiving surface of the position detector 9. That is, light beams having the same light amount are made to enter the four regions A, B, C, and D, respectively.

On the other hand, when the scanner 1 is displaced, for example, as shown in FIG. 2, the plane mirror 4 is inclined with respect to the optical axis of the light beam incident on the inside of the scanner 1 (for example, X
When the scanner 1 is displaced in the direction, the plane mirror 4 tilts around the Y axis.) Therefore, the light beam is transmitted to the plane mirror 4.
At an angle, and is reflected in the opposite direction. Specifically, when the tip of the scanner 1 has an inclination of θ with respect to the reference state, the light beam incident on the plane mirror 4 is
The incident light is reflected at an angle of 2θ.

The light beam reflected by the plane mirror 4 is １ ／
After being converted into linearly polarized light by the wave plate 5, the light is incident on the position detector 9 while being condensed through the lens 6 and the polarization beam splitter 7, and when forming a condensed spot on the light receiving surface of the position detector 9, the light beam Is reflected by the plane mirror 4 at an angle of 2θ with respect to the incident light beam, so that the position of the condensed spot is shifted from the center of the position detector 9 in accordance with the tilt direction of the plane mirror 4.

Here, between the displacement amount d of the spot forming position on the position detector 9 and the inclination angle θ of the plane mirror 4, d (θ) = ftan (2θ) = 2ffθ ... (1) There is a relationship as follows. In this equation, f is the focal length of the lens 6.

Similarly, when the scanner 1 is displaced in the Y direction, the plane mirror 4 is inclined about the X axis. If the inclination angle at this time is ψ, the displacement amount in the Y direction at this time is as follows: It is represented by

D (ψ) = f · tan (2φ) = 2 · f · ψ (2) Therefore, the displacement amount d of the spot formation position by the position detector 9 is transferred to each of the regions A, B, C, and D. By comparing the incident light amounts, the inclination angles θ and ψ of the plane mirror 4 can be obtained based on the expressions (1) and (2). In addition, the direction of displacement of the spot is the plane mirror 4.
Therefore, the arithmetic circuit 16 determines the tilt direction of the plane mirror 4 based on the output signal of the position detector 9. The arithmetic circuit 16 performs the above arithmetic based on the output signal of the position detector 9 to obtain
The inclination angle θ and / or ψ of the plane mirror 4 is obtained. Thus, the arithmetic circuit 16 specifies the tilt angle (θ, ψ) and tilt direction of the plane mirror 4, that is, the tilt angle and tilt direction of the stage 3, and detects the state of the stage 3.

The arithmetic circuit 16 converts the information thus obtained into monitor signals representing the displacements of the stage 3 in the X and Y directions, respectively,
Give to. Specifically, assuming that light receiving information in each of the four light receiving regions of the position detector 9 is A, B, C, and D, dx = (A + D)-(B + C) (3) dy = (A + B)-( C + D)... (4) The monitor signals dx and dy are obtained based on the following formula, and are supplied to the scan controller 11.

The scan controller 11 controls each of the control signals in the X and Y directions based on the reference waveforms output from the first and second waveform generators 12 and 13 to displace the stage 3 to a predetermined state. Is generated, and in this state, the non-linearity control means 11a monitors the monitor signal, and obtains a deviation between the currently desired state of the stage 3 and the actual state of the stage 3 indicated by the monitor signal. Since a deviation occurs between the desired state of the stage 3 and the actual state of the stage 3 due to hysteresis, creep, or the like occurring in the displacement of the piezoelectric body constituting the scanner 1, the nonlinearity control means 11a determines the deviation. Ask for. Then, the non-linearity control means 11a changes the control signal so as to compensate for this deviation. That is, the arithmetic circuit 16
The feedback control is performed so that the actual state of the stage 3 obtained by the above becomes the desired state.

Thus, according to the present embodiment, the actual state of the stage 3 (the tilt angle θ and the tilt direction) is optically detected, and the detected actual state of the stage 3 becomes the desired state. Since feedback control is performed,
Even if hysteresis or creep occurs in the displacement of the piezoelectric body constituting the scanner 1, this does not affect the displacement of the stage 3, and the state of the stage 3 can be controlled well.

More specifically, a system is configured by using a tube scanner having a length of 15 mm having four divided electrodes as the scanner 1 and a 5 × objective lens (focal length of 35.9 mm) for a microscope as the lens 6. When the scanner 1 is driven at a voltage of 200 V, a comparison of the displacement results in the X direction using another displacement system and a displacement angle meter indicates that the displacement of the scanner 1 in the X direction at this time is 1.3 μm. Stage 3
Was 0.35 seconds. According to the equation (1), this is 0.12 μm as the displacement d of the spot formation position on the position detector 9. When the feedback control was performed on the basis of this, XY scanning without hysteresis was realized.

In STM and AFM, the stage 3 is also displaced in the Z direction (vertical direction in the figure). In this embodiment, since the parallel light beam is incident on the plane mirror 4, the expression (1) is obtained. Further, as can be seen from the equation (2), it is possible to detect the displacement only in the X and Y directions without being affected by the movement in the Z direction.

Further, according to the present embodiment, since the displacement of the stage 3 is optically detected, noise is not mixed due to the driving voltage of the scanner 1 and the like, and stable detection can be performed. When a magnetic sensor or a capacitance sensor is used, there is a concern that noise may be mixed due to the influence of the drive voltage of the scanner 1 which is a considerably high voltage.

In this embodiment, the interference of light is not used for detecting the displacement of the stage 3. When optical interference is used, the number of peaks of the sensor light intensity that changes like a sine wave is counted for a displacement exceeding one wavelength or a half wavelength, but the scanner 1 is used because of the increment method. If the displacement is rapid, a count error or the like is inevitable, causing an error. In the present embodiment, this can be avoided.

The present invention is not limited to the above embodiment. For example, in the above embodiment, feedback control is performed. For example, in the case of STM or AFM,
The XY coordinates are newly generated on the computer in accordance with the monitor signal from the arithmetic circuit 16, and the ST is displayed on the XY coordinates.
The object of the present invention can also be achieved by performing image processing such as rearranging the M signal or the AFM signal.

In the above embodiment, the semiconductor laser 8a is provided for the light source 8. However, other light emitting means such as an LED can be applied. When an LED is used, an adverse effect due to interference occurs. Therefore, the quarter-wave plate 5 can be omitted, a half mirror can be used instead of the polarization beam splitter 7, and the configuration can be simplified.

In the above embodiment, it is preferable that the XY operation direction of the scanner 1 and the XY direction of the position detector 9 coincide with each other. If they do not match, it is necessary to process the output signal of the position detector 9 to perform its configuration.

According to the system scanner of the first embodiment described above, a reflecting means such as a plane mirror provided on the stage and a parallel light beam incident on the reflecting means, for example, a light source, a beam splitter, A light source means comprising a 波長 wavelength plate; a light condensing means such as a lens for condensing a reflected light beam from the reflecting means to form a spot on a predetermined surface; Spot detecting means such as a position detector for detecting the position of the spot on a surface, and a tilt such as an arithmetic circuit for obtaining a tilt angle of the stage based on the position of the spot detected by the spot detecting means. Since it has angle calculation means, it eliminates the effects of hysteresis and creep, etc., that occur on the displacement of the piezoelectric body, and performs good scanning. It becomes capable scanner system.

Hereinafter, referring to FIG. 3, a scanner system according to a second embodiment of the present invention will be described with an atomic force microscope (AF).
M) will be described. In this embodiment and other embodiments to be described below, members that are substantially the same as those in the first embodiment and members that are substantially the same as those in the preceding embodiments are given the same reference numerals, and descriptions thereof are omitted.

FIG. 3 is a diagram showing a configuration of a piezoelectric displacement detecting device according to a second embodiment of the present invention. As shown in the drawing, the output side of the microcomputer 22 is connected to the host computer 21 and the input sides of the Z control unit 24, the X control unit 25, and the Y control unit 26, respectively. Are connected to corresponding electrodes of the scanner 1 which is constituted by a cylindrical piezoelectric body for driving XYZ. These members constitute a scanner drive / control unit. On a stage 3 supported on the scanner 1, a sample 30 as an object to be measured is placed. A cantilever 28 is provided above the sample 30. A scanning member, that is, a probe is supported at the free end of the cantilever 28 such that the tip has a very small distance from the upper surface of the sample 3. The cantilever 28 is connected to a cantilever displacement detection unit 27 that measures the displacement of the cantilever 28 in the Z direction, that is, the vertical direction, and outputs a displacement analog signal corresponding to the displacement. The output side of the cantilever displacement detector 27 is A /
The microcomputer 22 via the D conversion unit 23
Is connected to the input side.

The output side of the scanner displacement detecting section 19a provided below the scanner 1 is connected to the input side of the Z control section 24. In such a configuration, the cantilever displacement detecting unit 27 detects the displacement of the probe in the Z direction due to the atomic force generated between the sample and the probe, ie, the cantilever 28 corresponding to the unevenness on the upper surface of the sample. , And outputs a displacement signal S1 to the microcomputer 22 via the A / D converter 23. Based on this output signal, the host computer 21 stores the measurement data transferred from the microcomputer 22 and forms an image indicating the surface condition of the sample. In addition, the microcomputer 22 transmits an XYZ signal via the X control unit 25 and the Y control unit 26.
The measurement is performed while controlling the driving cylindrical piezoelectric body 1 to perform two-dimensional scanning, and the measurement data is transferred to the host computer 21 at the same time.

The microcomputer 22 has an A / D
The scanner 1 is expanded and contracted in the Z direction via the Z control unit 24 based on the information read from the conversion unit 23. At this time, Z control is performed to keep the displacement signal S1 at a constant value, and the Z control data is used as measurement data. However, Z control unit 2
4 is configured so that the Z displacement signal S5 detected from the scanner displacement detecting unit 19a is fed back, so that the relationship between the Z control data and the displacement of the scanner is linearly corrected by the microcomputer 22, and The formed Z-direction unevenness information is accurately reproduced.

Next, the optical system of the Z-direction displacement detecting mechanism will be described with reference to FIG. As shown in the figure, the scanner 1 has a lower end fixed to a fixed base 2 constituting a lower part of a mirror body 33, and a stage 3 disposed at an upper end thereof. The photodetector 32a is fixed to the lower surface of the stage 3 with the light receiving surface facing downward. A fixing hole is formed on the upper surface of the fixing table 2 coaxially with the scanner 1, and a laser diode 32e is provided inside the fixing hole.
And the collimator lens 32d
The optical axis is equal to a and fixed. The two light beams emitted from the laser diode 32e are arranged so as to become parallel light beams by the collimator lens 32d and head inside the scanner 1 upward.

An optical system support 32c is provided coaxially with the scanner 1, and a condenser lens 32b is mounted on the upper end thereof so as to face the photodetector 32a. This condenser lens 32b is
Although the parallel light beam from the collimator lens 32d is aligned so as to be focused toward the photodetector 32a, the focusing lens 32b and the photodetector 32a are shorter than the focal length of the focusing lens 32b, As shown in FIG. 5, the light-converging spots 42 are arranged at predetermined intervals so that the light-collecting spot 42 is larger than the light-receiving surface 41.

As described above, in the system of the second embodiment, the photodetector 32a, which is a light receiving element, is added to the upper end, ie, the free end, of the scanner 1, which is the sample fine movement mechanism of the conventional scanning probe microscope. A laser diode 32e as a light source and a light beam emitted from the laser diode 32e
and a collimator lens 32b for condensing the light to a. The light receiving surface of the photodetector 32a is shifted inward from the focal position of the condenser lens 32b, so that the focused spot is adjusted to be larger than the light receiving surface.

Then, as in the conventional case, the scanner 1 is expanded and contracted by the Z-direction control (Z servo) unit 24 so that the sample 30 is moved in the Z direction so as to keep the sample surface and the tip of the probe at a constant distance. When XY scanning is performed in the two-dimensional direction, the change in the amount of light detected by the photodetector 32a is
By forming an image of the light amount detected by the photodetector 32a as an unevenness signal on the sample surface, unevenness information can be obtained with high accuracy.

FIGS. 5A to 5C are diagrams showing the relationship between the light receiving surface 41 and the converging spot 42 when the scanner 1 expands and contracts in the Z direction. 5A shows the state when the scanner 1 contracts in the Z direction, FIG. 5B shows the state when the scanner 1 has the standard length, and FIG. 5C shows the state when the scanner 1 extends in the Z direction. Are respectively shown. As can be understood from this figure, the diameter of the focused spot 42 changes as the scanner 1 expands and contracts in the Z direction. As a result, the light receiving surface 4
The light amount P received at 1 also changes according to the expansion and contraction of the scanner. If the received light amounts in the states of FIGS. 5A, 5B, and 5C are Pa, Pb, and Pc, respectively, Pa <Pb <Pc. The relationship holds. Therefore, the displacement of the scanner 1 in the Z direction can be detected from a change in the amount of light received by the photodetector 32a.

Next, a third embodiment will be described with reference to FIG. In the case of this embodiment, as compared with the configuration of the second embodiment, the output side of the scanner displacement detector 19a is
4, the output side is connected, A / D
The difference is that it is connected to the microcomputer 22 via the conversion unit 51.

The microcomputer 22 controls the cantilever displacement detecting section 2 while controlling the scanner 1 to perform two-dimensional scanning via the X control section 25 and the Y control section 26.
7 and the displacement measurement data sent via the A / D converter 23 are transferred to the host computer 21.

The microcomputer 22 has a Z controller 24 based on the information read from the A / D converter 23.
The scanner 1 is expanded and contracted in the Z direction via. That is, Z control is performed so that the displacement signal S1 is maintained at a constant value, and the Z control data is used as measurement data. The Z displacement signal S5 measured by the scanner displacement detector 19a is output to the A / D converter 51, and the Z displacement data read out from the A / D converter 51 forms an image as measurement data. In the example, the same effect as in the second embodiment can be obtained.

Next, a fourth embodiment will be described with reference to FIGS.
Description will be made with reference to FIG. In this embodiment, FIG.
3, the signal from the scanner displacement detection unit 19b is not supplied only to the Z control unit 24, as compared with the embodiment shown in FIG. 3, but the Z control unit 24, the X control unit 25, and the Y control The control unit and the scanner displacement detecting unit 1 are fed back to the unit 26 as signals S5 to S7, respectively.
9b. In this embodiment, the Z control unit 24
Is configured so that the Z displacement signal S5 detected from the scanner displacement detecting unit 19b is fed back, and the X control unit and the Y control unit 26 perform the X displacement signal S6 detected by the scanner displacement detecting unit 19b and the Y displacement signal. Since the configuration is such that S7 is fed back, the relationship between the X, Y, Z control data and the scanner displacement is linearly corrected, and the three-dimensionally formed unevenness information is accurately reproduced. I have. Note that each displacement signal S5, S6, S7 is directly A
The same effect can be obtained by outputting the data to the / D conversion unit and forming the image using the A / D converted data as the measurement data.

In this embodiment, as shown in FIG. 7, the optical displacement detecting means comprises a light receiving element, a central light receiving area 41a having a light receiving surface located at the center, and a light receiving element located at the periphery thereof.
Four peripheral light receiving areas 4 symmetrical in the X and Y directions, respectively.
Photodetector 32 divided into five parts 1b to 41e
a, the photodetector 32a is connected to the scanner 1
In any Z-direction displacement state, the light spot 42 is set to be smaller than the entire light receiving surface and larger than the central light receiving surface 41a.

In the XYZ scanning, the central light receiving area 4
The change in the light amount detected in 1a becomes a change in the expansion and contraction of the scanner 1 in the Z direction, and the change in the difference in the light amount detected in the peripheral light receiving areas 41b to 41e becomes the X displacement and the Y displacement. Is the unevenness signal of the sample surface, and the light amount difference between the X symmetric light receiving area and the Y symmetric light receiving area is an X signal,
By forming an image as a Y signal, three-dimensional information can be obtained with high accuracy.

FIG. 7A shows a case where the sample is scanned in the “+ X direction” in the figure, FIG. 7B shows a case where the sample is at the scanning center position, and FIG. It is a figure which shows a mode when scanning in the "-X direction", respectively.

As shown in FIGS. 7A to 7C,
The condensing spot 42 is formed by the photodetector 32 according to the scanning.
The light amount P received on each of the peripheral light receiving areas 41b to 41e moves on the light receiving surface of a. At this time, the light receiving amounts in the respective light receiving areas 41a to 41e are Pa to Pe, respectively, and Px = (Pb + Pc)-(Pd-Pe) (5) If Px = Px in FIGS. The size of Px1
Assuming that Px3, the following relationship is established.

Px1 <Px2 <Px3 (6) At this time, the displacement in the X direction can be represented by the above Px. The displacement in the Y direction can be similarly determined. As a result, the displacement in the two-dimensional direction can be detected from the change in the calculated value of the amount of light on the peripheral light receiving area surfaces 41b to 41e received by the photodetector 32a of the scanner 1. Further, similarly to the second embodiment, the displacement of the scanner 1 in the Z direction can be detected by detecting a change in the amount of light in the central light receiving area 41a.

Next, as in the first embodiment, the scanner system according to the fifth embodiment using an optical displacement sensor of the type in which a plane mirror is provided on the stage is shown in FIG. Please refer to FIG.

First, as shown in FIG. 9, in the optical displacement sensor of this embodiment, a cylindrical lens holding mechanism 60 is provided on the fixed base 2 so as to protrude into the scanner 1. A collimator lens 6 is mounted on the upper end so as to face the plane mirror 4 at a predetermined interval. The lens holding mechanism 60 is provided with a lens position adjusting mechanism 61 so as to adjust the movement of the scanner 1 in the vertical direction coaxially with the scanner 1. By this mechanism 61, the distance between the collimator lens 6 and the collimator lens 6 is adjusted so that the focal point is on the plane mirror 4.

A beam splitter 7 is disposed below the lens holding mechanism 60. Beside the beam splitter 7, a semiconductor laser 8a driven by an LD driver 10 and a light beam emitted from the laser are provided. And a collimator lens 8b for shaping the light into a parallel light beam.

The beam splitter 7 receives the parallel light beam from the collimator lens 8b, and vertically deforms the parallel light beam.
A first half mirror 62 that transmits the reflected light beam and reflects the reflected light beam from the plane mirror 4 at right angles.
And a second half mirror 63 that separates the reflected light beam from the first half mirror 62 into a transmitted light beam and a reflected light beam.

On the transmission side of the second half mirror 63, a critical angle prism 65 having a reflection surface set so as to be substantially at a critical angle with respect to a reflected light beam from the second half mirror 63 is provided.
Is arranged. On the reflection side of the second half mirror 63 and the critical angle prism, first and second position detectors 9a and 9b formed of photodiodes are provided.
Are arranged respectively. These position detectors 9
The light receiving surfaces a and 9b are separated into four light receiving regions b1 to b4 and a1 to a4, respectively, as shown in FIG.

Next, the operation of the scanner system having the above configuration will be described below. The scanner 1 is driven by selectively applying voltages to the four electrodes of the scanner 1. At this time,
An elliptical beam composed of a parallel light beam emitted from the light source 8 is shaped by the irregular prism 64 to be a perfect circular beam.
Reflected upward. This reflected parallel light beam passes through the first half mirror 62 and enters the collimator lens 6 through the inside of the lens holding mechanism 60. The incident light beam is condensed and reflected by the collimator lens 6 on the surface of the plane mirror 4 attached to the lower surface of the stage 3. The reflected light beam is converted into a parallel light beam by the collimator lens 6 and is incident on the first half mirror 62, where it is reflected and is incident on the second half mirror 63. This incident light beam is reflected by the second half mirror 63 to the first position detector 9a, and the first light beam that forms the first condensed spot A1 on the light receiving surface and the second light beam that is transmitted therethrough. And two light beams.
This second light beam is reflected by the critical angle prism 65 to the second position detector 9b, and the second light beam
Is formed.

In this embodiment, the displacement of the scanner 1 in the X and Y directions is detected as the displacement of the condensed spot on the position detector by the same principle as in the first embodiment. In this case, the first position detector 9a and the second position detector 9b have the same condensing spots A1 and A2 with the same displacement d (ψ) and the same light amount.
Is formed, but when displaced in the Z direction, the light amount of the condensed spot A2 of the second position detector 9b changes accordingly. The reason will be described below.

Since the position of the plane mirror 4 is deviated from the focal position of the collimator lens 6, the light amount of the light beam reflected by the critical angle prism 65 changes according to the displacement of the plane mirror 4 in the Z direction. As a result, the second position detector 9b
Since the amount of light of the condensing spot A2 incident on the light source changes, the displacement in the Z direction can be known by calculating the amount of change. A method for detecting the displacement in the optical axis direction using the critical angle in this way is known, for example, from Japanese Patent Application Laid-Open No. Sho 56-7246.

For example, when the scanner 1 is displaced in the + Z direction, the condensed spot A2 of the incident light beam on the second position detector 9b reflected by the critical angle prism 65 is located on the light receiving area a1, a2 side from the center. Is reduced, and the light amount in the portion on the light receiving area a3, a4 side becomes a true circle in which the light quantity does not change. As described above, the difference d between the light amount distributions of the perfect circular condensed spots on the second position detector 9b
By measuring (Z), the amount of displacement of the scanner 1 in the + Z direction can be detected.

According to the above principle, each displacement in the XYZ directions can be detected in this embodiment, but the effect of the displacement in each direction on the displacement detection in the other direction is neglected as described below. Can be.

Regarding the influence of the XY displacement on the Z displacement detection; the critical angle with respect to the light beam incident on the critical angle prism 65 is an angle in a plane parallel to the plane of the paper, so that the angular change in the plane of the scanner 1 ψ , But is not affected by the angle change θ in a plane perpendicular to the paper surface of the scanner 1.
Therefore, only the influence of the former angle change ψ needs to be considered.
That is, when the scanner 1 is simultaneously displaced in the XYZ directions,
Focused spot A on the second position detector 9b
2 is the displacement amount in the Z direction of the scanner 1 and the displacement amount in the Y direction.
Includes both directional displacement and information. On the other hand, the displacement amount of the condensed spot A1 in the Y direction on the first position detector 9a detects only information on the displacement of the scanner 1 in the Y direction. Accordingly, only the displacement of the scanner 1 in the Z direction can be detected by subtracting the output information of the first position detector 9a from the output information of the second position detector 9b as follows. Here, the light receiving amounts of the four light receiving regions b1 to b4 of the first position detector 9a are B1 to B4, and the light receiving amounts of the four light receiving regions a1 to a4 of the second position detector 9b are A1 to A4.
Then, the displacement amount dZ in the Z direction is represented by the following equation.

DZ = (A3 + A4)-(A1 + A2) -k [(B3 + B4)-(B1 + B2)] (7) where k is an appropriate constant.

Influence of Z displacement on XY displacement detection; according to the principle described above, when scanner 1 is displaced in the X direction only, it involves an angle change θ, and the light is condensed on first position detector 9a at that time. The displacement d (θ) of the spot A1 is as shown in the equation (1) described in the first embodiment. Here, when the scanner 1 is simultaneously displaced in the X direction and the Z direction, the expression (1) becomes as follows.

D (θ) = 2 · (f + Z) · θ (8) Specifically, since f = 4 mm and Z = 0.005 mm, d (θ) has a displacement in the Z direction. It changes only about 0.1% compared to when there is no display. Therefore, X
The effect of the displacement in the Z direction on the detection of the displacement in the direction is negligible. The same can be said for the influence of the displacement in the Z direction on the detection of the displacement in the Y direction. Therefore, scanner 1
Are simultaneously displaced in the X direction, the Y direction, and the Z direction, and the displacements in the X direction and the Y direction can be obtained by performing the following calculations, respectively.

X = (B1 + B3)-(B2 + B4) (9) Y = (B3 + B4)-(B1 + B2) (10) Thus, in the system of this embodiment, the scanner 1, that is, the stage 3 in the XYZ directions 3 The dimensional position can always be monitored optically.

Next, a scanner system using the optical displacement sensor will be described with reference to FIG. In the figure,
Reference numeral 71 denotes an optical system unit, which includes the beam splitter 7, a light source 8, and first and second position detectors 9a and 9b. The measurement signals from the first and second position detectors 9a and 9b are amplified by the preamplifier 15 and input to the arithmetic circuit 16. In this arithmetic circuit 16, the above equation (7) is obtained.
According to the expressions (9) and (10), the input signal is calculated, and the displacement of the scanner 1 in the XYZ directions is obtained.
This calculation processing information is input to the scan controller 11. On the input side of the scan controller 11,
A third waveform generator 70 that generates a reference voltage in the Z direction
They are connected in the same manner as the first and second waveform generators 12 and 13. The scan controller 11 performs a predetermined process (a process for feedback control, a process for a scanner, or the like) on reference voltages in the X, Y, and Z directions generated by the first to third waveform generators 12, 13, and 70. 1 is performed on the XY plane, or a process for shifting or shifting the motion is performed, and control signals in the X, Y, and Z directions are output. These control signals are input to the scanner driver 14, and the scanner driver 14 selectively applies voltages to the electrodes of the scanner 1 so as to displace the scanner 1 in a state instructed by the supplied control signals.

In this embodiment, as in the first embodiment, the scan controller 11 applies a predetermined correction to the control signal to be generated based on the displacement signal supplied from the arithmetic circuit 16. It has means 11a.

The operation of the AMF of the fifth embodiment is the same as that of the first embodiment, except that the correction of the displacement in the Z direction is added. The state of the stage 3 is controlled three-dimensionally. can do.

When the scanner system shown in FIG. 9 is used, the position of the object fixed on the stage 3 can be controlled so as to be three-dimensionally in a desired state. For example, stage 3
This scanner system is versatile, for example, if a mirror is fixed on the upper surface of the scanner, the angular displacement of the mirror in the θ and ψ directions and the displacement in the Z direction can be controlled to a desired state. Further, it is obvious that this embodiment has the effects described in the first embodiment.

Next, a scanning prode microscope (STM) to which the scanner system shown in FIG. 10 is applied will be described with reference to FIG. In FIG. 11, reference numeral 80 denotes a probe, which can be varied in the Z direction by an interaction between the probe and the sample 30, such as a tunnel current, a frictional force, a magnetic force, and an atomic force. Has become. The displacement is detected by the probe displacement sensor 81. The output side of the probe displacement sensor 81 is connected to the input side of the scan controller 11.
The output of the arithmetic circuit 16 is the SPM of the sample 30.
It is connected to an SPM display device 82 for displaying an image.

At the time of actual SPM measurement, the scanner 1
The feedback control is performed only for the displacement in the X and Y directions according to the detection signal from the optical displacement sensor, and the displacement in the Z direction of the scanner 1 is feedback controlled according to the detection signal from the probe displacement sensor 81.

The scan controller 11 controls each of the control signals in the X and Y directions so as to displace the stage 3 to a predetermined state based on the reference waveforms output from the first and second waveform generators 12 and 13, respectively. In this state, the non-linearity control means 11a monitors the displacement signal obtained from the arithmetic circuit 16, and determines the state of the stage 3 currently desired and the actual state of the stage 3 indicated by the XY displacement signal. Is determined. And the non-linearity control means 11a
As a result, the control signal in the XY directions is changed so as to compensate for this deviation. That is, feedback control in the XY directions is performed so that the actual scanning of the stage 3 obtained by the arithmetic circuit 16 becomes a desired scanning.

The sample 30 is scanned by the probe 80 by performing the XY scanning as described above. At this time, the probe 80 is displaced by the interaction between the sample 30 and the probe 80, and this displacement is detected by the probe displacement sensor 81, and a displacement signal corresponding to this displacement is supplied to the scan controller 11. . At the same time, a reference signal is supplied from the third waveform generator 70 to the scan controller 11 so that the position of the probe 80 becomes a desired state. As a result, a deviation between the probe displacement signal from the probe displacement sensor 81 and the reference signal from the waveform generator 70 is obtained by the scan controller 11, and a Z signal for compensating for this deviation is transmitted via the scanner driver 14. It is supplied to the scanner 1. Thus, the interaction between the probe 80 and the sample 30 is
The scanner 1 is displaced in the Z direction so as to have a constant value in accordance with the reference signal output from the third waveform generator 70. Since the amount of displacement in the Z direction is proportional to the interaction acting between the probe 80 and the sample 30, the distribution of the interaction, that is, an SPM image is obtained by setting the amount of displacement in the Z direction to MIQ ≧. Can be

Next, a method of displaying an SPM image will be described. As described above, during the SPM measurement, the X signal and the Y signal obtained from the arithmetic circuit 16 indicate the position of the sample 30 with respect to the probe 80 during scanning, and the Z signal indicates the position between the probe 80 and the sample 30. These signals are applied to the SPM image display device 82 and displayed, whereby an SPM image is obtained.

The SPM image obtained at this time is obtained by directly monitoring the displacement of the scanner 1 in the XYZ directions by this optical displacement sensor, and thus becomes an image without three-dimensional distortion. Also, at this time, since the XY signals supplied to the SPM image display device 82 are not the signals from the arithmetic circuit 16, the same results can be obtained even when the signals from the waveform shapers 12 and 13 are supplied. The input of device 82 may be connected to the output of a waveform generator.

Next, a scanning probe microscope (STM) using the scanner system according to the seventh embodiment is shown in FIG.
This will be described with reference to FIG. In this embodiment, the upper end of the scanner 1 is fixed to a fixed base (not shown), and the lower end is a free end. An optical unit 71 is provided above the scanner 1, and a stage 3 is provided at the lower end.
Is attached. A plane mirror 4 is fixed on the upper surface of the stage 3, and a light beam incident from the optical system unit 71 via the collimator lens 6 is reflected by the plane mirror 4 to the optical system unit 71. The optical system unit 71 detects the displacement of the scanner 1 from the reflected light beam and outputs the same to the preamplifier 15 as in the above-described embodiment.

The lower surface of the stage 3 has a probe 80
Is attached downwards at its proximal end. Below the tip of the probe 80, a sample table 83 is provided. The sample 30 is supported on the upper surface of the sample table 83 so as to have a small distance from the tip of the probe 80.

Also in the apparatus of this embodiment, an SPM image without distortion can be obtained by performing the same SPM measurement as in the fifth embodiment. Further, in the device of this embodiment,
Probe scan type SP as in the fifth embodiment
There is an effect that SPM measurement can be performed on a large sample that cannot be measured even by using M. Therefore, three-dimensional distortion of an SPM image when a large sample is measured by SPM can be corrected.

Next, an SPM device according to an eighth embodiment will be described with reference to FIG. The device of this embodiment is
11 and the XY of the scanner 1
Substantially the same except that the scanning is not feedback controlled. That is, the first and second waveform shaping devices 1
The scanner 1 is open-controlled by the X reference signal and the Y reference signal output from the scanners 2 and 13, respectively. However,
As in the case of the fifth embodiment, the displacement of the scanner 1 in the Z direction is feedback-controlled based on a signal from the probe displacement sensor 81. At this time, the arithmetic circuit 16 sends the probe 80 X of sample 30 with respect to
An XY signal corresponding to the Y coordinate and a Z displacement signal of the scanner 1 at the XY coordinate are given to the SPM image display device 82. This Z displacement signal is a signal proportional to the interaction between the sample 30 and the probe 80, as in the case of the fifth embodiment.

In the device of the eighth embodiment, the SP
The X position and the Y position of the probe 80 are supplied to the M image display device 82 with interaction information that acts on the probe 80 at that position. If the interaction information acting on the probe 80 is mapped by the SPM image display device 82 according to the information on the XY position of the probe 80, a distortion-free SPM image can be obtained as in the above embodiment.

In the apparatus according to the eighth embodiment, since it is not necessary to provide the scanner controller 11 with non-linear control means for the scanner 1 in the X and Y directions, the configuration is simplified.

Next, the device according to the ninth embodiment is shown in FIG.
This will be described with reference to FIG. The device of this embodiment is different from that of the fourth embodiment shown in FIG. 8 in that a critical angle prism 90 is added between the second half mirror 63 and the first position detector 9a in the optical displacement sensor. Except that they are substantially the same. With such a configuration, the light beams split by the half mirror 63 pass through the critical angle prisms 65 and 90, respectively, so that the condensed spot A1 on the first position detector 9a and the second position The amount of light and the amount of change in position are the same as those of the converging spot A2 on the detector 9b. . For this reason, in this embodiment, the respective position detectors 9a and 9b
There is an effect that the error of the result of the calculation of the output signal from is zero in principle.

Next, a method of detecting the displacement of the scanner 1 in the XYZ directions will be described. When the scanner 1 is rotationally displaced in the ψ and θ directions, the displacement of the second converging spot A2 on the second position detector 9b and the scanner 1
The second focused spot A2 when is displaced in the Z direction
Is the same as that of the fourth embodiment.
Therefore, when the scanner 1 is displaced in the ψ and θ directions, the displacement amount of the second converged spot is represented by d (ψ), d
(Θ), the second when the scanner 1 is displaced in the Z direction.
Let d (z) be the difference between the left and right light quantity distributions of d and (d), d (θ), d
(Z) can be obtained.

D (ψ) = (A3 + A4) − (A1 + A2) (11) d (θ) = (A1 + A3) − (A2 + A4) (12) d (z) = (A3 + A4) − (A1 + A2) (13) According to the above equations (11) and (13), d (ψ) + d (z) = 2 {(A3 + A4) − (A1 + A2)} (14) Further, the condensed spot on the first position detector 9a And the light amount distribution change in the same manner with respect to the displacement of the scanner 1 in the ψ, θ, and Z directions, and d (ψ), d
(Θ) and d (z) are as follows.

D (ψ) = (B2 + B4) − (B1 + B3) (15) d (θ) = (B1 + B2) − (B3 + B4) (16) d (z) = (B1 + B3) − (B2 + B4) (17) From the above equations (15) and (16), d (ψ) −d (z) = 2 {(B2 + B4) − (B1 + B3)} (18) Also, the above equations (14) and (18) By the formula, 2 · d (ψ) = 2 ｛(A3 + A4) − (A1 + A2) +
(B2 + B4) − (B1 + B3)｝ (19) Then, according to the above equations (14) and (18), 2 · d (z) = 2 [(A3 + A4) − (A1 + A2) −
{B2 + B4)-(B1 + B3)}] (20) Further, according to the above equations (8) and (12), 2 · d (θ) = (A1 + A3) − (A2 + A4) + (B
1 + B2)-(B3 + B4) (21)

Here, d (θ), d (ψ), d (z)
Is proportional to the displacement of the scanner 1 in the X, Y, and Z directions, so that X = (A1 + A3)-(A2 + A4) + (B1 + B2)
− (B3 + B4) (22) Y = (A3 + A4) − (A1 + A2) + (B2 + B4)
− (B1 + B3) (23) Z = 2 [(A3 + A4) − (A1 + A2) − ｛(B2
+ B4)-(B1 + B3)}] (24). The displacements of the scanner 1 in the X direction, the Y direction, and the Z direction can be detected from the expressions (22), (23), and (24).

As described above, in this embodiment, the critical prism 90 is added between the half mirror 63 of the optical displacement sensor and the first position detector 9a. The amount of light and the amount of change in the position of each focused spot at
For this reason, the error of the result of calculating the output from each of the position detectors also becomes zero in principle, and there is an effect that more precise measurement can be performed.

As in the apparatus of the ninth embodiment, the technique of adding a critical angle prism 90 between the second half mirror 63 and the first position detector 9a in the optical displacement sensor is described in the fifth to fifth embodiments. Of course, it can be applied to the device of the eighth embodiment.

In each of the above embodiments, the measuring light beam for measuring the displacement of the scanner 1 is passed through the cylindrical scanner 1 in order to reduce the size of the entire apparatus. The technique of the present invention is not limited to the configuration, and the plane mirror 4 may be mounted on the lower surface of the stage 3 outside the scanner 1 as shown in FIG. In this case, by arranging the collimator lens 6 and the optical system unit 71 outside the scanner 1, there is an effect that the arrangement of parts and the maintenance and inspection are facilitated. Also in this case, the plane mirror 4
Is not limited to the lower side of the stage 3. For example, the optical system unit 71 may be fixed above the stage 3 and disposed above the stage 3.

FIG. 16 shows the relationship between the voltage applied to the piezoelectric body and the displacement of the piezoelectric body when the displacement of the piezoelectric body constituting the scanner, which is the basic idea of the present invention, is not corrected. As can be understood from this figure, the piezoelectric body does not deform linearly as the applied voltage increases or decreases.

In the above embodiment, a probe is used as a scanning member. However, other types are used depending on the type of microscope, and an electron beam, a light beam, and an ultrasonic beam are emitted therefrom. Other members may be used.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a scanner system according to a first embodiment, partially cut away;

FIG. 2 is a diagram showing an optical system unit of the scanner system shown in FIG. 1 in a state where the scanner is deformed.

FIG. 3 is a diagram showing a scanning probe microscope using a scanner system according to a second embodiment of the present invention.

4 is a diagram showing a Z-direction displacement detection mechanism of the device shown in FIG.

5 (a) to 5 (c) are diagrams for explaining the operation of the Z-direction displacement detecting mechanism shown in FIG. 4, and show different positional relationships between a light receiving surface and a condensing spot.

FIG. 6 is a diagram for explaining a scanning probe microscope according to a third embodiment.

FIGS. 7A to 7C are diagrams for explaining the operation of a displacement detection mechanism of a scanning probe microscope according to a fourth embodiment, and show different positional relationships between a light receiving surface and a converging spot; Is shown.

FIG. 8 is a diagram schematically showing an entire scanning probe microscope according to a fourth embodiment, based on the operation principle shown in FIG. 7;

FIG. 9 is a diagram illustrating a scanner system according to a fifth embodiment.

FIG. 10 is a view schematically showing a scanning probe microscope using the scanner system shown in FIG. 9;

FIG. 11 is a diagram schematically showing a sixth atomic force microscope.

FIG. 12 is a diagram schematically showing a seventh atomic force microscope.

FIG. 13 is a diagram schematically showing an eighth atomic force microscope.

14A and 14B are diagrams for explaining a ninth atomic force microscope, wherein FIG. 14A schematically shows the whole, FIG. 14B is a plan view of a first position detector, and FIG. FIG. 3 is a plan view of the position detector of FIG.

FIG. 15 is a diagram illustrating a modified example of the scanner system according to the present invention.

FIG. 16 is a diagram showing a relationship between a voltage applied to a piezoelectric body and a displacement of the piezoelectric body in a conventional device.

[Explanation of symbols]

1. Piezoelectric scanner, 3. Stage, 4. Planar mirror, 6.
... Collimator lens, 8 ... Light source, 9 ... Position detector, 11 ... Scan controller, 12 ... First waveform generator, 13 ... Second waveform generator, 14 ... Scanner driver, 16 ... Operation circuit, 19 ... Scanner displacement Detection unit, 3
0: sample, 80: probe.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Akira Yagi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (56) References JP-A-3-6405 (JP, A) Hei 4-1517 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 21/30 G01B 11/26 H01J 37/28

Claims (7)

(57) [Claims] A scanner for relatively scanning a scanning member and a sample; a mirror provided at the free end for detecting displacement of the free end with respect to a fixed end of the scanner; A scanner system comprising: an optical displacement detection unit that irradiates light from the fixed end to a mirror and detects an inclination angle of the mirror to detect an xy displacement of the scanner. 2. The scanner system according to claim 1, wherein said mirror and said optical displacement detecting means have an optical path inside said scanner. 3. The scanner system according to claim 1, wherein the mirror and the optical displacement detecting means have an optical path outside the scanner. 4. The scanner system according to claim 1, wherein the light emitted from the fixed end to the mirror is a parallel light. 5. The scanner system according to claim 4, wherein the light emitted from the fixed end to the mirror is obtained by a collimator lens. 6. The scanner system according to claim 1, wherein said optical displacement detecting means has a four-division photodetector. 7. A scanning microscope using the scanner system according to claim 1.