JP3445787B2 - Physical quantity measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning force microscope, a high-resolution surface potential profile measuring device, and a physical quantity measuring device used for measuring a surface potential of a photosensitive drum, a toner profile, and a toner potential distribution. Regarding

[0002]

2. Description of the Related Art Conventionally, various types of physical quantity measuring devices for measuring the potential and shape of a sample surface have been proposed. First, a first conventional example (see Japanese Patent Application No. 5-93499) will be described with reference to FIG. When an electrostatic attraction acts due to a potential difference between the sample 2 installed on the conductive substrate 1 (sample table) and the probe 3 arranged opposite to the sample 2, the probe 3 has the probe 3 at its tip. The cantilever 5 whose part is supported by the base 4 vibrates. A reflection mirror 6 is attached to the surface (back surface) of the cantilever 5 opposite to the surface on which the probe 3 is attached. Thereby, the light emitted from the semiconductor laser 7 as the light source is reflected by the reflection mirror 6 and detected by the photodetector 8 as the light receiving element by the so-called optical lever method. The detected signal is output as the output Vo (AC signal) by the preamplifier 9, and the lock-in amplifier 1
At 0, it is converted into a DC voltage V ₁₁ in synchronization with the synchronization signal (ω ₀ ) of the sine wave AC power supply 11. This DC voltage V ₁₁
Is sent to the integrator 12. The integrator 12 varies the DC voltage V ₂₁ so that the amplitude of vibration of the cantilever 5 on which electrostatic attraction acts by the AC voltage V ₃₁ of the sine wave AC power supply 11 becomes 0 or a constant value. The integrator 12 has
A voltmeter 13 is connected to measure the changing potential of the DC voltage V ₂₁ . The voltage V ₂₁ which is the output value from the integrator 12 is the AC voltage V of the sine wave AC power supply 11.
₃₁ and the AC voltage V ₃₂ of the sine wave AC power supply 14 are input to the adder 15. The voltage V ₄₁ from the adder 15 is sent to the power amplifier 16, and the voltage V ₅₁ from the power amplifier 16 is applied to the probe 3 of the cantilever 5. On the other hand, the DC voltage V ₁₂ output from the lock-in amplifier 17 is sent to the comparator 18. The voltage V ₆ from the comparator 18 is sent to the integrator 19. The integrator 19 includes a voltmeter 2 for measuring the amount of displacement of the Z-axis actuator 21.
0 is connected. The voltage V ₂₂ of the integrator 19 is sent to the power amplifier 22, and the Z-axis actuator 21 is driven by the voltage V ₅₂ from the power amplifier 22.

As described above, the resonance frequency of the cantilever beam 5
ω₀ And its half frequency ω₀AC voltage V with / 2
a {= G (V₃₁+ V₃₂)} And the DC bias voltage Vb
(= GV_{twenty one}) And voltage V₅₁Mark cantilever 5
And the frequency ω₀ AC voltage V ₃₁Cantilever caused by
DC bias voltage Vb and sample 2
Detects the difference from the surface potential Vs (potential relative to ground potential) of
The DC bias voltage Vb is controlled so that this difference becomes zero.
The surface potential of Sample 2 is measured from the value of Vb.
On the other hand, the frequency ω₀AC voltage V of / 2₃₂Shaking caused by
The distance between the tip of the probe 3 and the surface of the sample 2 from the dynamic amplitude
d is measured and the Z-axis alignment is maintained so that the value of this distance d is kept constant.
By controlling the actuator 21 to drive the Z
The voltage V that is the control signal of the shaft actuator 21_{twenty two}Try from
The surface shape of Material 2 is measured. In this way the table of sample 2
Simultaneous and independent measurement of surface potential and surface shape
You can

Next, a second conventional example (Japanese Patent Laid-Open No. 6-1095).
61 reference) will be described with reference to FIG. Board 23
At one end thereof, three cantilever beams 24a, 24b, 24c are provided in a V-shaped structure. The tip of each of these three beams has a conductive probe 25 directed downward (Z direction).
Is installed. This probe 25 has a wiring pattern 2
6 (hereinafter referred to as wiring) are connected, and the wiring 26 is formed on the cantilever 24c and connected to the pad portion 27 on the substrate 23. In addition, strain detecting elements (piezoresistors) 27a and 27b are provided near the bases of the cantilevers 24a and 24b.
Are formed, and wirings 28a and 28b are connected to the piezoresistors 27a and 27b.
The pad portion 29b is connected to the pad portions 29a and 29b on the substrate 23.

As a result, when a voltage is applied from the pad portion 27 to the probe 25 via the wiring 26, an electrostatic attractive force acts between the surface of the sample (not shown) and the probe 25, and the probe 25 The beams 24a and 24b are deformed. This mechanical deformation is detected by the piezoresistors 27a and 27b, and the wiring 28a and 2
The force applied to the probe 25 can be measured by converting the electric signal from 8b through the pad portions 29a and 29b and outputting the electric signal. In this case, since the probe potential is about 1 KV, discharge is likely to occur, but discharge can be prevented by separating the distance D between the cantilever 24c and the cantilevers 24a, 24b sufficiently. .

Next, a third conventional example (OPTRONICS, 1992, N
o.9, p.97) will be described with reference to FIGS. As shown in FIG. 8, a cantilever 31 is provided in the center of the substrate 30, and an optical waveguide 32 is formed on the cantilever 31 along the extending direction thereof. This cantilever 31
The end face 34 facing the end face 32 a of the optical waveguide 32 is provided on the fixed portion 33 of the substrate 30 with the gap between the ends of the optical waveguide 32 interposed therebetween.
An optical waveguide 34 having a is formed. In the substrate 30 having such a structure, the light propagating through the optical waveguide 32 is radiated from the end face 32a located at the tip of the cantilever 31, and the radiated light is faced with the end face 3 facing the end face 32a.
The light enters from 4a, recombines, and propagates in the optical waveguide 34. In this case, as shown in FIG. 9A, the cantilever 31
In the state in which is not deformed, the optical axis shift does not occur between the optical waveguides 32 and 34, so that the amount of propagated light does not decrease. However, as shown in FIG.
When 1 is deformed, an optical axis shift occurs and the amount of light incident on the optical waveguide 34 side decreases. Therefore, since the amount of light propagated changes according to the amount of deformation (bending amount) of the cantilever 31, the amount of deformation of the cantilever 31 can be easily measured by detecting the amount of light on the optical waveguide 34 side. can do. Examples of this application include pressure sensors, acceleration sensors,
A flow sensor or the like can be considered.

Next, a fourth conventional example (Japanese Journal o
f Applied Physics, Vol.28, No.2, Feb., 1989, p.287
Will be described with reference to FIG. A cantilever beam 36 is provided on the substrate 35. An optical waveguide 37 is formed near the root of the cantilever beam 36 so as to be orthogonal to the extending direction of the beam. Further, on the fixed portion 38 of the substrate 35,
The optical waveguide 39 is formed in parallel with the optical waveguide 37. In this case, the optical waveguide 37 is used as a signal detection waveguide for detecting the amount of deformation of the cantilever 36, and the optical waveguide 39 is used as a reference waveguide. It is connected to 40. In the substrate 35 having such a structure, the optical waveguide 37 is deformed along with the deformation of the cantilever 36, whereby the refractive index is changed and the phase of light propagating in the waveguide is changed. The amount of deformation of the cantilever beam 36 can be measured by such a phase change.

Here, the principle of operation for detecting a signal by such a phase change will be described using a Mach-Zehnder interferometer having a basic structure shown in FIGS. The deformation area corresponding to the cantilever beam 36 of FIG. 10 described above is shown in FIG.
Corresponds to area A (diaphragm portion having a fine structure).
The light whose phase has changed through the optical waveguide 37 on the deformed area A and the light whose phase has not changed through the optical waveguide 39 on the fixed portion 38 merge at the Y-shaped branching portion and are combined at the optical waveguide 40. The light intensity of the light output from the optical waveguide 40 changes due to the phases of both lights when the light beams interfere with each other. in this case,
As shown in FIG. 12A, when both lights are in phase,
The 0th-order mode is excited by being combined, and the amount of light output from the optical waveguide 40 is maximized. Also, FIG.
As shown in FIG. 2 (b), when both lights are in opposite phases, the first-order mode is excited, so that a light wave is radiated to the outside of the waveguide (in the case of a single mode waveguide), and the light from the optical waveguide 40 Is not output. By measuring the amount of light output from the optical waveguide 40 in this way, the amount of deformation of the area A, that is, the cantilever 36 can be measured.

Another example of detecting a signal based on a phase change will be described with reference to FIGS. 13 and 14. As shown in FIG. 13, two optical waveguides 41, 42 are provided on the substrate 35.
Are formed, and these optical waveguides 41 and 42 intersect the optical waveguides 37 and 39 at the X-shaped branching portion. In this case, the optical waveguide 42 is formed so that the width of the optical waveguide is narrower than that of the optical waveguide 41. The reflection mirror 4 is provided on the end face of the substrate 35.
3 is provided. Such a structure functions as a mode divider. First, the light incident from the wide optical waveguide 41 on the left side is split into 1: 1 at the branching portion, propagates in the optical waveguides 37 and 39, is reflected by the reflection mirror 43, and is branched again. Come back to. At this time, if both lights are in phase as shown in FIG. 14A, the 0th-order mode is excited, and the lights propagate toward the optical waveguide 41 having a wide width. If both lights have opposite phases as shown in FIG. 14B, the primary mode is excited and the lights propagate toward the optical waveguide 42 having a narrow width. As described above, whether or not the lights are in phase is determined by the amount of deformation of the region A, that is, the cantilever 36. Therefore, the amount of deformation of the cantilever 36 is measured by checking the amount of light returning to the optical waveguides 41 and 42. can do.

[0010]

Consider a case where the sample 2 described in the first conventional example (see FIG. 6) is a photosensitive drum used in an electrophotographic apparatus. Now, when the drum is rotated in order to measure the surface potential of the photosensitive drum, the eccentric structure causes the rotational axis and the central axis of the drum to be misaligned. Move. At this time, the distance d between the surface of the drum and the probe 3 is initially set to the order of μm or less in order to obtain sufficient resolution. In the apparatus of Figure 6, in order to keep always constant the distance d, the Z-axis actuator 21 to measure the distance d at the time of actual operation from the amplitude of the resonant vibration of the cantilever 5 caused by the frequency omega _0/2 I am returning. However, while the distance d is, for example, 2 μm, the vertical movement of the drum surface is as large as 100 μm, which is an order of magnitude larger. Therefore, the return operation cannot be performed in time, and as a result, the drum surface collides with the probe 3. In the worst case, the probe 3 may be damaged.

The vibration state of the cantilever 5 is detected by a so-called optical lever method using an optical system composed of the semiconductor laser 7, the reflection mirror 6 and the photodetector 8. In this case, not all the light emitted from the semiconductor laser 7 is guided to the photodetector 8, but a part of the light is scattered and applied to the drum surface of the photosensitive drum. As a result, the leaked light exposes the surface of the drum to discharge the surface charge, which disturbs the normal state (electrostatic latent image).

Further, electrostatic attraction acts between the probe 3 and the drum surface. The potential difference is V ₁ and the distance is d.
₁ , the equivalent area of the tip of the probe 3 facing the drum surface is S ₁ , the force F ₁ acting between the probe 3 and the drum surface is F ₁ = S ₁ ε ₀ (V ₁ ² / d ₁ ² ) (1) However, ε ₀ can be expressed as the permittivity of air. On the other hand, the cantilever 5 having the same potential as the probe 3 is supported by the base 4, and a support mechanism (peripheral device) for supporting these parts is provided around the base 4. Such a support mechanism is at ground potential for noise shielding. Therefore, the electrostatic attractive force acts between the cantilever 5 and the supporting mechanism around the cantilever 5. Assuming that the potential difference between the _two is V ₂ , the equivalent distance is d ₂ , and the equivalent area is S ₂ , the force F ₂ in this case is F ₂ = S ₂ ε ₀ (V ₂ ² / d ₂ ² ) It can be expressed as (2). Here, comparing F ₁ and F ₂ in the equations (1) and (2), d ₁ << d ₂ , but the area S ₂ is the cantilever beam 5.
It is the back side of, and S ₂ >> S ₁ . Further, since the potential of the probe 3 and the potential of the drum surface are substantially equal to each other in structure, the potential of the supporting mechanism in the periphery is always the ground potential, so that the value of V ₂ is high when the potential of the drum surface is high. Becomes larger, which results in V ₁ << V ₂ . Therefore, from such a fact, the force F ₂ may be the force F ₁ depending on the environmental conditions of the peripheral devices.
However, this value causes a measurement error.

Further, in the measurement initial stage bringing the probe 3 on the drum surface, since the distant and the probe 3 and the sample 2 is far several mm or more, (1) a force F ₁ is the formula (2) It becomes a rather small value for the force F ₂ , which causes the cantilever 5
The voltage V ₁₁ detected from the erroneous value shows an erroneous value, and the integrated value V ₂₁ becomes larger and larger. As a result, the probe 3
The potential difference V ₁ between the drum surface and the drum surface is also KV order,
A discharge is generated between the two, disturbing the potential of the surface of the drum to be measured. Even if such a discharge is not generated, a discharge is generated between the support mechanism in the peripheral portion and the cantilever 5. As a result, the probe 3 is damaged, or a cutoff circuit (not shown) of the adder 15 that is grounded for safety is activated to make measurement impossible.

Next, in the case of the second conventional example (see FIG. 7),
In order to prevent discharge between the wiring 26 for applying a voltage to the probe 25 and the piezoresistors 27a, 27b or the wirings 28a, 28b, the two are separated by a distance D. However, since the voltage applied to the wiring 26 is as large as about 1 KV, when this voltage fluctuates, noise due to the voltage fluctuation is generated via the parasitic capacitance generated between the two.
It is mixed with the signal detected by a and 27b and causes a measurement error. Also, the cantilever beam 5 is bent by Joule heat caused by the current flowing through the piezoresistors 27a and 27b, which causes a measurement error.

Next, in the case of the third conventional example (see FIG. 8) and the fourth conventional example (see FIG. 10), the optical waveguides 32, 34, 3 are provided.
The basic operating principle of detecting the amount of deformation of the cantilevers 31, 36 from the difference in the amount of light using 7, 39 is described. However, there is no example in which such optical waveguides 32, 34, 37, 39 are used to measure the surface potential of the photoconductor drum, the toner potential distribution, and the like.

[0016]

According to the invention of a physical quantity measuring device as set forth in claim 1, a probe to which a voltage in which an alternating current component and a direct current component are superposed is applied, and a surface of a sample which is arranged so as to face the probe. In the physical quantity measuring device for measuring the physical quantity of the sample from the displacement or vibration of the probe caused by the electrostatic attraction acting in between, at the stage where the probe is separated from the sample surface.
Is the direct current component of the voltage applied to the probe of the sample surface potential.
It can be set to an approximate value and the probe approaches the sample surface.
In the step, DC component feedback amount control means for controlling the amount of feedback from the displacement or vibration of the probe to the DC component of the applied voltage applied to the probe was provided.

Therefore, by using the DC component feedback amount control means, first, before the actual measurement when the probe is separated from the sample surface, the DC component of the applied voltage applied to the probe is roughly calculated as the sample surface potential. After that, at the actual measurement stage when the probe approaches the sample surface, the amount of feedback of the DC component of the applied voltage applied to the probe due to displacement or vibration of the probe due to electrostatic attraction. Was controlled to measure the physical quantity.

According to a second aspect of the invention, in the physical quantity measuring device according to the first aspect, the scanning means for scanning the surface of the sample with the probe, and at least one of the surface of the sample and the probe are displaced. Before the actual measurement, the inter-sample-probe distance varying means including a coarse actuator that greatly varies the distance between the two and a fine actuator that finely adjusts the distance.
The probe is moved away from the surface of the sample to cause the scanning means to scan the surface of the sample, and the coarse movement actuator and the fine movement actuator are not driven in synchronization with the scanning of the surface of the specimen by the scanning means. A correction distance calculating means for calculating a correction distance for keeping the distance between the tip of the probe and the surface of the sample constant, and a correction distance storing means for storing the calculated correction distance in comparison with the scanning position. , And at the time of actual measurement, the probe is brought close to the surface of the sample to scan the surface of the sample by the scanning means, and based on the correction distance stored in comparison with the scanning position. The distance between the surface of the sample and the probe is varied by driving the coarse actuator, and the fine actuator is driven according to the interaction between the surface of the sample and the probe. The distance between the surface and the probe of the sample was kept constant.

Therefore, the sample surface is scanned in advance before the actual measurement by using the scanning means, and the distance between the sample surface and the tip of the probe is kept constant by using the correction distance calculating means in synchronization with this scanning. The calculated correction distance is calculated, and the calculated correction distance is compared with the scanning position and temporarily stored in the correction distance storage means. Then, during the actual measurement, the stored correction distance is compared with the scanning position. The physical quantity can be measured while always keeping the distance between the surface of the sample and the probe constant by using the variable distance between sample probes.

According to a third aspect of the present invention, in the physical quantity measuring device according to the first aspect, a scanning means for scanning the surface of the sample with the probe, and a distance sensor for measuring a distance between the sample and Sample inter-probe distance varying means including a coarse movement actuator that displaces at least one of the surface of the sample and the probe to greatly change the distance between the two and a fine movement actuator, and before actual measurement Driving the coarse actuator and the fine actuator based on a distance signal detected by the distance sensor by causing the scanning unit to scan the surface of the sample by separating the probe from the surface of the sample. Instead, a correction distance calculating means for calculating a correction distance for keeping the distance between the tip of the probe and the surface of the sample constant, and the calculated correction distance as a scanning position. Compensation distance storage means for storing in comparison with each other, and at the time of actual measurement, the probe is brought close to the surface of the sample to cause the scanning means to scan the surface of the sample, and to compare with the scanning position. Based on the stored correction distance, the distance between the surface of the sample and the probe is changed by driving the coarse movement actuator, and the interaction between the surface of the sample and the probe is changed. Accordingly, the fine movement actuator is driven to keep the distance between the surface of the sample and the probe constant.

Therefore, the sample surface is scanned in advance before the actual measurement by using the scanning means, and the distance between the sample surface and the tip of the probe is kept constant by using the correction distance calculating means in synchronization with this scanning. The calculated correction distance is calculated, and the calculated correction distance is compared with the scanning position and temporarily stored in the correction distance storage means. Then, during the actual measurement, the stored correction distance is compared with the scanning position. The physical quantity can be measured while always keeping the distance between the surface of the sample and the probe constant by using the variable distance between sample probes.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION First, an embodiment of the present invention will be described with reference to FIGS. The description of the same parts as those of the above-described first conventional example (see FIG. 6) is omitted,
The same reference numerals are used for the same portions.

[Overall Structure] The sample is a photosensitive drum 44 used in an electrophotographic apparatus. A rotation motor 45 for rotating the photosensitive drum 44 is provided on the photosensitive drum 44.
And the encoder 46 are connected. Of these, the rotary motor 45 is connected to a motor drive power source 47, and the encoder 46 is connected to a control device 48 (computer). In addition, the surface of the photosensitive drum 44 has a cantilever beam 5.
The probe 3 attached to the tip of is opposed to the probe with a distance d. The base 4 that supports the cantilever 5 to which the probe 3 is attached, and the optical lever optical system 49 (physical quantity detection optical system) including the reflection mirror 6, the semiconductor laser 7, and the photodetector 8 are driven. It is fixed to the device 50. The drive unit 50 includes a Y-axis actuator 51, a Z-axis coarse movement actuator 52, and a Z-axis fine movement actuator 53. These three actuators 51, 52, 5
3 is driven and controlled by the control device 48. In this case, the Y-axis actuator 51 causes the probe 3 to scan the drum surface in the sub-scanning direction (rotational axis direction). Further, the rotation motor 45 rotates the photoconductor drum 44, which causes the probe 3 to scan the drum surface in the main scanning direction (drum rotation direction).

Further, the control device 48 includes a voltmeter 56 for measuring the voltage V ₆ and a voltmeter 13 for measuring the voltage V _21.
And a voltmeter 20 for measuring the voltage V ₂₂ are connected. In addition, the voltage V output from the power amplifier 22
₅₂ is connected to the a terminal of the switch circuit 57 composed of a, b, and c terminals. The b terminal is a ground terminal. The c terminal connected to the a or b terminal is connected to the Z-axis fine movement actuator 53. As a result, ac
By connecting the terminals, the Z-axis fine movement actuator 53 is driven and controlled by the feedback loop.

In this case, the Y-axis actuator 51 for sub-scanning, the rotary motor 45 for main scanning and the motor drive power source 47 constitute a scanning means 54. Further, the Z-axis coarse movement actuator 52 and the Z-axis fine movement actuator 53
Is the distance d between the surface of the photosensitive drum 44 and the probe 3.
The inter-sample probe distance varying means 55 for varying Further, the control device 48 that performs overall control synchronizes with the scanning position by the scanning means 54 and corrects the distance d ₀ for keeping the distance d between the tip of the probe 3 and the drum surface constant.
And a memory (not shown) as a correction distance storage means for storing the calculated correction distance d ₀ in comparison with the scanning position. .

The operation of the present apparatus having such a configuration will be described. First, before the actual measurement, the rotary motor 45 is driven by the motor drive power source 47 to drive the photosensitive drum 4
By rotating 4 the main scan for measuring the surface potential distribution is performed. At the same time, the Y-axis actuator 51 is used to move the probe 3 in the direction of the rotation axis of the photosensitive drum 44 to perform sub-scanning. In this case, the rotation speed of the photosensitive drum 44 is slower than that at the time of actual measurement. At this time, in order to prevent the Z-axis fine movement actuator 53 from operating, the c terminal of the switch circuit 57 is connected to the b terminal. Then, while rotating the photosensitive drum 44 in this way, the rotation angle θ is read by the encoder 46 and sent to the control device 48. At the same time when the rotation angle θ is read, the voltage V ₆ is read by the voltmeter 56.
Is read and sent to the controller 48. As a result, in the control device 48, the correction distance calculating means is used to calculate the control amount for driving and controlling the Z-axis coarse motion actuator 52 such that the value of V ₆ becomes 0, that is, the correction distance d _0. A table showing the relationship between the correction distance d ₀ and the rotation angle θ of the encoder 46 is created and stored in the memory.

At the time of actual measurement, the photosensitive drum 44 is rotated by the rotation motor 45, and the rotation angle θ
Is read by the encoder 46, and the read rotation angle θ
The correction distance d ₀ corresponding to is read from the memory table. By moving the Z-axis coarse movement actuator 52 by the read correction distance d ₀ , the vertical movement of the drum surface due to the eccentricity of the photosensitive drum 44 is eliminated, and the distance d is always maintained at a constant state. be able to. At this time, the c terminal in the switch circuit 57 is connected to the a terminal, so that the Z-axis coarse actuator 52 is connected.
It is possible to eliminate the fluctuation of the distance d due to the unevenness of the drum surface which is less than the minimum resolution of. Further, when eliminating the vertical movement of the drum surface due to the eccentricity of the photosensitive drum 44,
A low-pass filter (not shown) that removes vertical movement due to such high frequency components so that vertical movement due to dust, toner, etc. attached to the drum surface other than the eccentricity is not recorded in the table obtained by the correction distance calculation means. May be disposed on the output side of the voltmeter 56, or the high frequency component may be removed by calculation in the control device 48, whereby the feedback control operation can be further stabilized. Therefore, because of this, the device
Even when the photosensitive drum 44 whose vertical movement is very large during rotation is measured as a sample, the probability that the probe 3 collides with the drum surface becomes very small, which results in the displacement of the probe 3. Alternatively, since the physical quantity of vibration can be accurately measured, the potential distribution on the drum surface can be accurately measured.

Next, a modified example of the apparatus shown in FIG. 1 will be described with reference to FIGS.

First, the apparatus shown in FIG. 2 will be described. A pulse rotation motor 58 is attached to the photosensitive drum 44, and the pulse rotation motor 58 is connected to the control device 48. As a result, by controlling the drive of the pulse rotation motor 58 by the control device 48, the photosensitive drum 44 can be rotated and the rotation angle θ can be measured. In this case, the rotary motor 45, the encoder 46, and the motor drive power source 47 are unnecessary, and the number of parts can be reduced, so that the device can be simplified.

Next, the apparatus shown in FIG. 3 will be described. At a position close to the drum surface of the photosensitive drum 44, a distance sensor 59 for measuring the distance between the photosensitive drum 44 and the drum surface is arranged. The distance sensor 59 is connected to the control device 48. Accordingly, by sending a signal of the distance detected by the distance sensor 59 to the control device 48, the corrected distance d ₀ for creating the table can be calculated. In this case, the voltmeter 56 is unnecessary, and the wiring state of the circuit can be simplified.

[DC Component Feedback Amount Control Means] Next, as shown in FIG. 4, a DC voltage is provided between the output stage of the lock-in amplifier 10 that outputs the DC voltage V ₁₁ and the input stage of the adder 15. A DC bias voltage control circuit 60 as a component feedback amount control means is connected. The DC bias voltage control circuit 60 controls the feedback amount of the DC component of the applied voltage V ₅₁ applied to the probe 3 from the displacement or vibration of the probe 3. Figure 5
Shows the configuration of the internal circuit of the DC bias voltage control circuit 60. This DC bias voltage control circuit 60
Is a first voltage adjusting unit 61 connected to the constant voltage power supply Vcc and capable of varying the voltage Vr ₁ , a comparator 62, a second voltage adjusting unit 63 capable of varying the voltage Vr ₂ to which the DC voltage V ₁₁ is input, and an addition. And an integrator 64 that outputs a voltage V ₂₁ to the device 15. In addition, here, the probe 3 is similar to FIG.
It is arranged to face the sample 2 installed on the sample table 1 on the Z-axis actuator 21.

The operation of the DC bias voltage control circuit 60 having such a configuration will be described. First, when the distance between the probe 3 and the surface of the sample 2 is large and the electrostatic attraction between the two is weak, and the potential of the probe 3 deviates more and more from the surface potential of the sample 2. think about. In such a case, the R point located at the middle point of Vr ₂ of the second voltage adjusting unit 63 is moved to the upper side (in the figure), and the R point is connected to the P point to be short-circuited. As a result, the value of the voltage V ₂₁ is determined by the voltage Vr from the first voltage adjuster 61, so that the value of the voltage V ₂₁ can be varied by manually adjusting the voltage Vr ₁ . By manually varying the value of the voltage V _{21 in} this way, the DC component of the applied voltage V ₅₁ applied to the probe 3 can be controlled and the potential of the probe 3 can be brought close to the surface potential of the sample 2. .

After manually adjusting the voltage Vr _{1 so} that the value of the voltage V ₂₁ substantially matches the surface potential of the sample 2, the distance between the probe 3 and the surface of the sample 2 is reduced. ,
The R point, which was connected to the P point of Vr ₂ of the second voltage adjusting unit 63, is gradually moved to the lower side (in the figure) and connected at the Q point side. As a result, the value of the voltage V ₂₁ can be shifted from the manual control state of the voltage Vr by the first voltage adjusting section 61 to the automatic feedback control state by the DC voltage V ₁₁ . And
By starting the actual measurement in such a state, it is possible to prevent discharge from the probe 3 to the surface of the sample 2 or its peripheral devices, and to disturb the state of the surface of the sample 2. Moreover, since the electric circuit is not interrupted, the surface potential and the like can be measured smoothly.

[0034]

According to the invention of the physical quantity measuring device described in claim 1, the direct current component feedback quantity control means is used, and the voltage applied to the probe is measured before the actual measurement when the probe is separated from the sample surface. The DC component is set to the approximate value of the sample surface potential, and at the actual measurement stage when the probe approaches the sample surface, the DC component of the voltage applied to the probe due to the displacement or vibration of the probe due to electrostatic attraction. Since the amount of feedback of is controlled to measure,
By changing the feedback amount of the DC component according to the state of the sample placed in this way, it is possible to make discharge from the probe to the sample surface or its peripheral equipment less likely to occur, thereby disturbing the state of the sample surface. It is possible to provide a physical quantity measuring device having high measurement accuracy, which enables smooth measurement of a physical quantity without interruption of an electric circuit.

According to the second aspect of the invention, the sample surface is scanned in advance before the actual measurement by using the scanning means, and the correction distance calculating means synchronizes with the scanning to correct the distance between the sample surface and the tip of the probe. The distance is calculated, the calculated correction distance is stored in the correction distance storage means in comparison with the scanning position, and at the time of actual measurement, the correction distance is read in comparison with the scanning position. Since the electric potential and shape of the sample surface are measured while always keeping the distance between the sample surface and the probe constant by using, the vertical movement becomes extremely large when rotating like a photoconductor drum. Even when measuring a sample, the probability that the probe will collide with the sample surface is extremely small, which allows the physical quantity of displacement or vibration of the probe to be measured accurately, and the physical quantity measurement with high measurement accuracy. Providing equipment Can.

According to the third aspect of the invention, the sample surface is scanned in advance before the actual measurement by using the scanning means, and the correction distance calculation means synchronizes with the scanning to correct between the sample surface and the tip of the probe. The distance is calculated, the calculated correction distance is stored in the correction distance storage means in comparison with the scanning position, and at the time of actual measurement, the correction distance is read in comparison with the scanning position. Since the electric potential and shape of the sample surface are measured while always keeping the distance between the sample surface and the probe constant by using, the vertical movement becomes extremely large when rotating like a photoconductor drum. Even when measuring a sample, the probability that the probe will collide with the sample surface is extremely small, which allows the physical quantity of displacement or vibration of the probe to be measured accurately, and the physical quantity measurement with high measurement accuracy. Providing equipment Can.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a physical quantity measuring device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a modified example.

FIG. 3 is a circuit diagram showing another modification.

FIG. 4 is a circuit diagram.

5 is a circuit diagram showing a configuration of a DC bias control circuit of FIG.

FIG. 6 is a circuit diagram showing a first conventional example.

7A and 7B show a second conventional example, in which FIG. 7A is a sectional view and FIG. 7B is a top view.

FIG. 8 is a perspective view showing a third conventional example.

9 shows a mode state of the guided light of FIG.
(A) is a schematic diagram showing the operation when there is no optical axis deviation,
(B) is a schematic diagram showing an operation when there is an optical axis shift.

FIG. 10 shows a fourth conventional example, in which (a) is a perspective view and (b) is a sectional view taken along line a ₅ -a ₅ .

FIG. 11 is a perspective view showing a basic configuration of a Mach-Zehnder interferometer.

12A and 12B are diagrams showing the operation of the Mach-Zehnder interferometer, in which FIG. 12A is a schematic diagram showing the operation in the in-phase, and FIG. 12B is a schematic diagram showing the operation in the anti-phase.

FIG. 13 is a perspective view showing a basic configuration of a Michelson interferometer.

14A and 14B are diagrams showing the operation of the Michelson interferometer, in which FIG. 14A is a schematic diagram showing an operation in the same phase, and FIG. 14B is a schematic diagram showing an operation in a reverse phase.

[Explanation of symbols]

2 sample 3 probe 52 coarse motion actuator (Z-axis coarse motion actuator) 53 fine motion actuator (Z-axis fine motion actuator) 54 scanning means 55 sample probe distance varying means 59 distance sensor 60 DC component feedback amount control means (DC bias voltage Control circuit)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G03G 21/00 G03G 21/00 (56) References JP-A-5-273276 (JP, A) JP-A-6-174461 (JP , A) JP 1-206202 (JP, A) JP 5-312873 (JP, A) JP 6-26855 (JP, A) JP 6-308180 (JP, A) JP 6-201373 (JP, A) JP-A-8-86792 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 13/10-13/24 G01B 7/00-7 / 34 G01B 21/00-21/32 G12B 21/00-21/24 G03G 5/00 101 G03G 9/08 G03G 21/00

Claims (3)

(57) [Claims] 1. Displacement or vibration of the probe caused by electrostatic attraction acting between a probe to which a voltage in which an alternating current component and a direct current component are superimposed and a voltage applied to the probe and a surface of a sample arranged opposite to the probe are generated. In the physical quantity measuring device for measuring the physical quantity of the sample from the
Set the DC component of the applied voltage to the rough value of the sample surface potential
When the probe approaches the sample surface, a DC component feedback amount control means for controlling the feedback amount from the displacement or vibration of the probe to the DC component of the applied voltage applied to the probe is provided. A physical quantity measuring device characterized by the following. 2. A scanning means for scanning the surface of the sample with the probe, and a coarse movement actuator for displacing at least one of the surface of the sample and the probe to greatly change the distance therebetween. A sample inter-probe distance varying means including a variable fine movement actuator, and before actual measurement, the probe is separated from the surface of the sample to cause the scanning means to scan the surface of the sample, and the sample by the scanning means. Correction distance calculation means for calculating a correction distance for keeping the distance between the tip of the probe and the surface of the sample constant without driving the coarse movement actuator and the fine movement actuator in synchronization with surface scanning. Correction distance storage means for storing the calculated correction distance in comparison with the scanning position, and at the time of actual measurement, the probe is brought close to the surface of the sample. The surface is scanned in the scanning means,
Based on the correction distance stored in comparison with the scanning position, the distance between the surface of the sample and the probe is changed by driving the coarse movement actuator, and the surface of the sample and the probe are changed. The physical quantity measuring device according to claim 1, wherein a fine actuator is driven according to an interaction between the probe and the probe to keep a distance between the surface of the sample and the probe constant. 3. A scanning means for scanning the surface of the sample with the probe, a distance sensor for measuring a distance between the sample, and at least one of the surface of the sample and the probe being displaced. A sample inter-probe distance varying means including a coarse movement actuator that greatly changes the distance between the two and a fine movement actuator that finely changes the distance, and the surface of the sample separated from the surface of the sample before actual measurement. The scanning means, and based on the signal of the distance detected by the distance sensor, the distance between the tip of the probe and the surface of the sample can be determined without driving the coarse actuator and the fine actuator. A correction distance calculating means for calculating a correction distance for keeping constant and a correction distance storing means for storing the calculated correction distance in comparison with the scanning position are provided. The surface of the sample is scanned in the scanning means the probe is brought close to the surface of the sample,
Based on the correction distance stored in comparison with the scanning position, the distance between the surface of the sample and the probe is changed by driving the coarse movement actuator, and the surface of the sample and the probe are changed. The physical quantity measuring device according to claim 1, wherein a fine actuator is driven according to an interaction between the probe and the probe to keep a distance between the surface of the sample and the probe constant.