JPH01150813A - Encoder - Google Patents

Abstract

PURPOSE:To obtain the resolution of an atomic order of about several Angstrom by constituting an encoder by using a tunnel current flowing between against a conductive probe, based on periodical unevenness by a regular atomic arrangement of the surface of a substance as a reference. CONSTITUTION:An object 101 and 102 are installed so that they can move relatively only in the horizontal direction, and on the objects 101, 102, a conductive reference scale 103 and a conductive probe 104 are provided, respectively. Between them, a bias voltage is applied by a bias power source 106, they are allowed to approach to the extent that a tunnel current 105 flows, and this tunnel current 105 is detected by a current detecting means 107. A tunnel current signal 118 which has been amplified 108 is binarized 110 and converted to a pulse in a horizontal direction relative position extracting means 109, brought to processing such as converted to a motion quantity signal 112 and a direction signal 113, etc., and a horizontal direction relative displacement quantity 117 from an initial position of the object 101 and 102 is derived. In this case, the resolution of this encoder is several Angstrom , if a periodical arrangement of a conductive substance surface atom. is used as a scale.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to position information measurement in micro-positioning, dimension measurement, distance measurement, speed and measurement, especially on the atomic order (several people).
This invention relates to an encoder used for measurement control that requires resolution of .

[Prior Art] Conventionally, this type of encoder has been composed of a reference scale having information regarding position or angle, and a detection means that moves relative to the reference scale to detect information regarding position or angle. They were classified into several types depending on this reference scale and detection means, such as optical encoders, magnetic encoders, and capacitance encoders.

Among these, the one that provides the highest resolution is, for example, an optical encoder that uses the principle of grating interference. 30th
The figure shows the configuration of a conventionally used optical encoder. This is the monochromatic light 3 emitted from the light source 3001.
002 is made incident on a diffraction grating 3003 as a reference scale, and the diffracted ±1st-order diffracted lights 3004 and 3005 are made incident on a semi-transparent mirror 300 via a reflecting mirror 3006. Then, this semi-transparent mirror 3007 synthesizes and interferes, and the resulting bright and dark interference light is photoelectrically converted by a photodetector 3008, and the amount of relative displacement between the optical system and the reference scale is detected from the brightness and darkness of the interference light. It is.

[Problems to be solved by the invention] However, the performance (resolution) of the grating interference optical encoder that has the highest resolution among the conventional examples listed above
is mainly determined by the grating pitch, and the important point is how to accurately carve this into minute intervals and detect it accurately. Current precision processing technology (e.g. electron beam lithography and ion beam curvature) is at most 0.01 μm (-1
oo people)! The limit is the preposition, and the limit of detection technology (eg, optical heterodyne method) is 0.01 μm resolution. Therefore, if an encoder with higher resolution is required for semiconductor manufacturing equipment, etc., it has not been possible to meet the demand.

The purpose of the present invention is to solve the above-mentioned problems in the conventional type.
The object of the present invention is to provide an encoder having a high resolution on the order of the interatomic distance.

[Means and effects for solving the problems] In order to achieve the above object, the present invention provides a conductive reference scale that serves as a reference for length, and a conductive probe whose tip is placed close to the reference scale surface. A voltage is applied between the needle and the needle, the value of the tunnel current flowing between the reference scale and the probe is detected, the tunnel current signal is subjected to waveform processing, and the processed signal is used to determine the horizontal direction between the reference scale and the probe. That is, the relative movement amount and relative movement direction in the scale in-plane direction are detected, and the lateral relative displacement amount of the reference scale and the probe is counted from the lateral relative movement amount signal and the relative movement direction signal, and finally The amount of relative movement in the lateral direction between the probe and the reference scale is detected.

The present invention will be explained in more detail below.

The present invention utilizes the fact that a tunnel current flows when a voltage is applied between a conductive substance and a conductive probe to bring them close to a distance of about inn ("Solid State Physics, I Vol. 22
No. 31987 PP176-186), ) Because the channel current depends on the work function at the surface, it is possible to read information about various surface states.

Let us now consider a metal sample as a representative example of a conductive substance. Distance @
It is known that when a voltage V (φ>eV, e is the electron charge) lower than the work-interval number φ is applied between two metal probes and a reference atomic array separated by 2, electrons tunnel through the potential barrier. It is being The tunnel current density JT is calculated using the free electron approximation as follows: JT = (βV / 2 rt input Z) exp (-2
2/λ)...(1) It can be expressed as follows.

However, λ: λ=M/ f] "■ Attenuation distance m of the wave function in vacuum or in the atmosphere outside the metal
<φ is 1 to 5 eV, possibly 1 to 2 people) 1T: 1T=h/2π h is a blank constant m: electron mass β: β: e'/n In equation (1), the distance Il! ! ! If Z is set to a constant value of z=zc, the tunnel current density Ja changes depending on the work relationship φ of the reference atomic arrangement. In other words, when a relative positional shift occurs between the probe and the reference atomic arrangement while keeping the distance Z between the probe and the reference atomic arrangement constant, the tunneling current changes periodically according to the reference atomic arrangement. do. Therefore, the amount of positional deviation can be determined from the change in this tunnel current.

In addition, in equation (1), the tunnel current density JT is defined as JT
If ==Jc is a constant value, the distance llZ between the probe and the reference atomic array and the work function φ of the reference atomic array will change while maintaining a constant relationship. Therefore, if the distance Z is controlled so that the tunneling current density JT is constant, when a relative positional shift occurs between the tip and the reference atomic arrangement, the distance Z will change periodically according to the reference atomic arrangement. It will be controlled as follows. Therefore, the amount of positional deviation is determined from the amount of change in this distance rmZ.

Now, the in-plane resolution δ increases as the tip of the probe becomes thinner.
According to model calculation, it is expressed as follows.

δ=[2λ(R+Z)] l/where R is the radius of curvature of the tip of the metal probe.

If the number of atoms at the tip of the probe is R=1 person, the in-plane resolution δ will be about 3 people. A method using such a tunnel current has many advantages such as operating not only in the atmosphere but also in liquid and having high resolution.

The present invention applies the above-mentioned principle to construct an encoder using a tunnel current flowing between a conductive probe and a conductive probe based on the periodic unevenness caused by the regular atomic arrangement on the surface of a material. The present invention aims to provide an encoder having resolution on the atomic order of several people, which exceeds the resolution limit of encoders.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows the configuration of an encoder according to an embodiment of the present invention. FIG. 2 shows signals obtained in each component of this embodiment.

In FIG. 1, a target object 101 and a target object 102 are installed so that they can relatively move only in the horizontal direction (left and right directions in the drawing). The object 101 has a conductive reference scale 1.
03, a conductive probe 104 is provided on the object 102. A bias voltage is applied between the probe 104 and the reference scale 103 by a bias power supply 106.

The tip of the probe 104 and the reference scale 103 are brought close to each other to the extent that a tunnel current 105 flows between them. Here, the tunnel current 105 is determined by the current detection means 10
7 and amplified by current amplification means 108.

Tunnel current signal 118 after amplification (its waveform is shown in Fig. 2)
(a) shows binarization by cutting at a certain threshold level by the waveform processing means 110, waveform processing of detecting the edges of the obtained binarized signal and converting it into pulses, and later horizontal relative processing. A direction detection process as described in the explanation of the means for detecting the direction of displacement is performed, and the motion amount/direction conversion means 111 generates a motion amount signal 112 (FIG. 2(b)).
and a direction signal 113 (FIG. 2(C)), which are respectively input to a counter 114. The counter 11
4, the input motion amount signal 112 and direction signal 113 are converted into a lateral relative displacement amount. Furthermore, using the initial position data stored in the memory 115 in advance, the subtraction means 116 calculates the distance between the object 101 and the object 10.
The relative displacement amount 117 in the lateral direction from the initial position with respect to 2 (FIG. 2(d)) is determined. The resolution of the encoder is approximately the pitch of the reference scale 103 (several angstroms if a periodic arrangement of atoms on the surface of a conductive material is used as the reference scale), but by further dividing the detected position signal, the resolution can be reduced to less than angstroms. It is also possible to do so (FIG. 2(e)).

Next, the probe material used in the present invention will be explained.

The probe material may be any material as long as it has conductivity, such as Au, Pt, Ag, or Pd.

A11. Metals such as In, Sn, Pb, and W, and alloys thereof can be used. Furthermore, conductive oxides such as graphite, silicide, and ITO (In-3n oxide) can also be used.

The tip of the probe needs to be as sharp as possible, down to the atomic order, in order to increase the resolution of the encoder.

In this example, a 1 mmφ tungsten wire is
Although the probe 104 is mechanically ground to about mmφ and has a sharpened tip by electrolytic polishing, the processing method is not limited thereto.

Next, the reference scale will be explained. FIG. 3 is a schematic diagram showing the probe 104 and the conductive reference scale 103 of this embodiment. This is an example using In this way, by using a periodic arrangement of minute structures such as atoms and molecules as the reference scale 103, an encoder with a resolution on the order of interatomic distances, that is, on the order of angstroms can be realized. Examples of such conductive materials include:
For example, metals such as Au, Pt, TaS, CuAu
, alloys such as PtIr, metalloids such as graphite, St, MoS2. GaAs.

Semiconductors such as SiC, conductive LB (Langmuir-Prodgett) films, and conductive organic materials such as TCNQ (tetracyanoquinodimethane) can be considered for application to the present invention.

In addition to the arrangement of atoms and molecules of the above-mentioned substances, there are also
A scale 4 made by processing using a focused ion beam, an electron beam, etc. on a conductive material surface 401 as shown in a)
02 or a coating 40 of a conductive material on an object surface 403 having a diffraction grating shape as shown in FIG. 4(b).
4 can also be used as a reference scale.

Next, an example will be shown in which a periodic arrangement of atoms, molecules, etc. and a manufactured scale are combined and used as a reference scale (hereinafter referred to as a composite scale).

FIG. 5 is a sectional view showing an example of a composite scale. As shown in the figure, a reference origin 501 is placed on the reference scale 103.
If the initial set point is when the probe 104 comes to the position of this origin 501, the amount of movement from this reference origin 501 can always be determined, and the absolute heart motion of the object 102 with respect to the object 101 can be determined. You can find the quantity. The rest can be handled in the same way as described above for relative amount detection.

FIG. 6 is a sectional view showing another embodiment of the composite scale. In the same figure (a), a part of the surface of the atomic arrangement of the reference scale 103 is replaced with another substance, and the reference origin 601a, ~6
This is an example of 01a3. In addition, the figure (b) shows the reference scale 1.
A reference origin 601b is created by attaching another substance to a part of the surface of the atomic arrangement of 03.

~601b, is an example. The figure (C) is reference scale 1
This is an example in which reference origins 601c and 601C3 are formed by etching and scraping a part of the atomic arrangement of 03 near the surface.

These have multiple reference origins (3 in each of these figures).
(Illustrated)

The operation of the probe 104 will be explained with reference to FIG.
A coarse movement signal is output every time the reference origin 601a I (i = 1 to n) passes, and the reference origin 601a
1 to the next reference origin 601al*1, a slight movement signal is output. The operation is similar in the examples of composite scales shown in FIGS. When the amount of relative movement of the objects 101 and 102 is large, by obtaining such a coarse movement signal, it is possible to simplify the detection process and shorten the time.

FIG. 7 is a sectional view showing another embodiment of the composite scale. The reference origins 701d and 701d4 shown in the same figure have different widths and intervals between the reference origins, but the widths and intervals are known from the measurements of the sweet potatoes, and their values are It is stored on memory 115 (FIG. 1). In the same figure, the width of the reference origin of 701d is
−,,701d2 width of the reference origin is L−,701(13
The width of the reference origin of is Lllll, 1.701d1 and 701d
The reference origin interval of 2 is indicated by W, 701d, and the reference origin interval of 701d3 is indicated by W, . These values are stored in advance in the memory 115 (FIG. 1). And the probe 104
The stored width and spacing values can be counted each time the object passes through each reference origin. That is, each time the reference origin is passed, a coarse movement signal (the interval W, , W, between each reference point) is output, while the width t, m of each reference origin is output.
-1+Lm, L@+1, etc., as shown in Figure 6.
Similar to the previous method, the detection process can be simplified and the time can be shortened.

FIG. 8 is a cross-sectional view showing yet another embodiment of the composite scale. In the same figure (a), i, ~i are placed on the reference origin 801.
The absolute position information of the reference origin of up to n bits is recorded. When the probe 104 passes this reference origin 801, the absolute position information of the reference origin is output in the same way as the coarse movement signal, so it is possible to specify which position of the reference origin the probe 104 has passed through, and the position information can be obtained in a short time. can get.

Similarly, in FIG. 4B, absolute position information is recorded on reference origins 802, 803, and 804. Reference origin 802
, 803, 804 as 802', 803, respectively.
', 804'-shaped unevenness is formed.

This unevenness serves as absolute position information, and each reference origin can be specified using this information. That is, the unevenness 802
Addresses i-1, i, and i+1 of the reference origin are recorded in ', 803', and 804', respectively. In this case, the position of each reference origin is determined in advance, for example, on the left side of the protrusion in the figure. 805° and 806 are atomic scales. Note that in this embodiment, bits of absolute position information are arranged in the direction of movement of the probe 104, but are not limited to this.
They can also be arranged in a direction perpendicular to the direction of relative movement between 1 and the object 102.

FIG. 9 is a sectional view showing an embodiment using an aperiodic scale as a reference scale. This is done by measuring the intervals between the aperiodic scales 901 using known scales, storing the interval information on the memory 115 (FIG. 1), and
The probe 104 scans the aperiodic scale 901 due to the relative movement of the object 102 and the object 102, and the distance information stored in advance in the memory 115 is used to detect the object 101 and the object 102. This is to detect the amount of effort relative to 102.

Next, means for detecting the direction of relative lateral displacement between the object 101 and the object 102 will be explained using FIGS. 10 to 18.

FIG. 10 shows a configuration diagram of an embodiment using a reference scale 10o1 having an asymmetric shape (electron cloud distribution) in the direction of relative displacement.

Assume that the tunnel current signal 118 shows a change as shown in FIG. 11(a) with the relative displacement between the object 101 and the object 102. At this time, the lateral relative position information extraction means 1
09, the motion distortion signal 112 and the direction signal 113
are as shown in FIG. 11(b) and FIG. 11(C), respectively, and from these, the lateral relative displacement amount shown in FIG. 11(d) is determined. Therefore, in this case, it can be seen that the object 102 in FIG. 10 is displaced rightward in the plane of the paper with respect to the object 101 by the amount shown in FIG. 11(d).

Similarly, the tunnel current associated with relative displacement is shown in Figure 11(e).
If such a change is shown, the motion distortion signal 112 and the direction signal 113 will be changed as shown in Fig. 11 (
f) and as shown in (g) of the same figure. From these, it can be seen that the object 102 is displaced leftward in the plane of the paper by the amount shown in FIG. 11(h) with respect to the object 101.

Furthermore, if the tunnel current shows a change as shown in FIG. 11(i), for example, it means that the direction of the relative displacement of the object 102 with respect to the object 101 at point T has changed from right to left in the plane of the paper. I understand.

Examples of reference scales with such an asymmetrical shape (electron cloud distribution) include the (111) plane of a face-centered cubic lattice as shown in Figure 12, and conductive LB films that exhibit asymmetry in the pulling direction. etc.

FIG. 13 shows another embodiment in which the direction of the relative lateral displacement between the object 101 and the object 102 is detected. This figure shows an example in which the probe 104 is slightly vibrated in the direction of relative displacement using the probe lateral vibration means 13o1. If the probe 104 is vibrated sufficiently fast compared to the relative movement speed between the object 101 and the object 102, the position differential coefficient with respect to the lateral relative displacement of the tunnel current signal can be obtained, and from this the direction of the lateral relative displacement can be obtained. can be detected.

Let me explain this. When imaging in the direction of relative displacement, the obtained signal is a tunnel current signal corresponding to the scale position,
The signal is shaped like a minute vibration signal component due to probe vibration, which has a smaller amplitude and higher frequency than the tunnel current signal corresponding to this scale position. This signal is divided and input to a low-pass filter and a bypass filter, respectively, and the output from the low-pass filter becomes an almost pure tunnel current signal corresponding to the scale position, excluding minute vibration signal components, so it can be used to measure relative displacement. use The output from the bypass filter is only a minute vibration signal due to probe vibration, excluding the tunnel current signal component. This minute vibration signal is considered positive when the probe moves in one direction, and negative when it moves in the opposite direction.If the probe moves in the positive direction with respect to the scale, when the tunnel current signal increases, the tip A minute vibration signal having the same phase as the vibration of the probe is generated with an amplitude corresponding to the amount of increase, and when the tunnel signal decreases, a signal having the opposite phase to the vibration of the probe is generated with an amplitude corresponding to the amount of decrease. Therefore, this obtained signal is input to a lock-in amplifier using the probe vibration signal as a reference signal, and from the obtained amplitude and phase, a signal corresponding to the position differential coefficient regarding the positive direction relative displacement of the tunnel current, that is, the 14th figure(
The signal shown in c) is obtained. If the probe moves in the negative direction relative to the scale, the minute vibration signals when the tunnel current signal increases and decreases will be in opposite phase and in phase with the probe vibration, respectively, and can be similarly input to the lock-in amplifier and obtained. The signal received is
This results in a signal corresponding to the position differential coefficient regarding the relative displacement of the tunnel current in the negative direction, that is, the signal shown in FIG. 14(g). In this way, the position differential coefficient signals regarding relative displacement obtained for the same tunnel current signal have completely opposite phases depending on the direction of travel, so the direction of travel can be determined by looking at this phase.

For example, the tunnel current signal and its position differential coefficient due to the lateral relative displacement between the object 101 and the object 102 are the first
4(a) and 4(c), the object 102 in FIG. 13 is moved to the right in the plane of the paper with respect to the object 101 by the amount shown in FIG. 14(d). It can be seen that there is a displacement of

Similarly, the tunnel current accompanying relative displacement is shown in Fig. 14(e).
If a change such as that shown in Fig. 14 (f) is shown below,
After the signal waveform processing shown in FIG.
), it can be seen that it has been displaced by the amount shown in ).

Furthermore, for example, if the tunnel current is
When the change shown in Figure (Ill) is shown, it can be seen that the direction of the relative displacement of the object 102 with respect to the object 101 at point T has changed from right to left.

FIG. 15 shows yet another embodiment in which the direction of the relative lateral displacement between the object 101 and the object 102 is detected. In the figure, a probe lateral vibration means 1501 vibrates the probe 104 in the direction of relative displacement of the object. Then, tunnel current signals are obtained at two different points A and H. In this embodiment, it is necessary to vibrate the probe 104 sufficiently faster than the relative movement speed between the target object 101 and the target object 102. If the width of the vibration of the probe 104 is d, this method uses two probes separated by a distance d to measure the reference scale 1.
This is equivalent to the method of detecting direction from two tunnel current signals having a phase difference with respect to 03.

Here, for example, suppose that the pitch of the reference scale 103 is p, and the width d of the vibration of the probe 104 is set so that d=-+N-L<N=o, s, 2...) . At this time, the tunnel current accompanying the lateral relative displacement between the object 101 and the object 102 is the 16th
When the change shown in figure (a) is shown, it can be seen that the object 102 in Fig. 15 is displaced to the right in the plane of the paper with respect to the object 101, and the tunnel current changes as shown in Fig. 16 (e). If it shows a change like this, it can be seen that it is displaced to the left. Furthermore, the tunnel current is shown in Fig. 16(i).
Or, when a change as shown in (m) is shown, it means that the direction of the relative displacement of the object 102 with respect to the object 101 has changed from right to left at point T.

FIG. 17 shows yet another embodiment in which the direction of the relative lateral displacement between the object 101 and the object 102 is detected. The figure shows an example using two probes. By detecting tunneling current signals 1705A and 1705B at two probes 170'lA and 1701B separated by a distance d, the direction of the relative lateral displacement can be detected. For example, if the pitch of the reference scale 103 is p,
The width d of the probe 1701A and the probe 1701B is set as follows. At this time, the two probes 1701A and 1701 due to the relative displacement in the lateral direction between the target object 101 and the target object 102
If the tunnel currents 1705A and 1705B at B show changes as shown in FIG. 18(a), it can be seen that the object 102 in FIG. 17 is displaced to the right in the plane of the paper with respect to the object 101. On the other hand, when the tunnel current shows a change as shown in FIG. 18(e), it can be seen that the tunnel current is displaced to the right.

Furthermore, the tunnel current is shown in Figure 18 (i) and (m).
If the change shown in is shown, it can be seen that at point T, the direction of the relative displacement of the object 102 with respect to the object 101 has changed from right to left.

[Other Examples] Next, regarding an example in which the relative g-movement in the lateral direction is calculated while controlling the vertical position of the probe by the probe longitudinal position control means so that the tunneling current value becomes a predetermined value. explain.

FIG. 19 shows the configuration of an encoder according to another embodiment of the present invention. FIG. 20 is a block diagram for explaining the operation of this embodiment.

In FIG. 19, in order to detect the relative lateral displacement between the object 101 and the object 102, the set tunnel current value I0 is first determined (block B1 in FIG. 20), and the probe longitudinal position control means 1901 is set. is used to control the vertical position of the probe 104. This control first detects the tunnel current value I (block B2), then detects the detected current value I and sets the tunnel current value (2). (block B4). ■When ≠ 10, the feedback control means 1902 feeds back to the probe longitudinal position control means 1901 (block B
3). When the detected current value I becomes equal to the set current value I0 (block B4), the vertical absolute position signal of the probe 104 is output to the horizontal relative position information extraction means 109 (block B5). Thereafter, the probe longitudinal position control means 1901 and the feedback control means 1902 are used so that the detected current value I is always equal to the set current value IO even when the target object 101 and the target object 102 are relatively displaced in the horizontal direction. feedback control of the vertical position of the probe 104 is performed, and an absolute vertical position signal of the probe 104 is output to the horizontal relative position information extraction means 109. At this time, the object 101 and the object 102 are on the reference scale 10.
The time required for the above-mentioned feedback control must be sufficiently small compared to the time required to relatively displace one pitch in the lateral direction.

Now, in the lateral relative position information extraction means 109,
The manually inputted vertical absolute position signal 1903 of the probe 104 and information about the reference scale 103 and the probe 104 (
From block B6), the horizontal relative movement amount and the BwJ direction are detected (block B7), that is, the vertical absolute position signal 1903 (the waveform of which is shown in FIG. 21(a)) is subjected to waveform processing by the waveform processing means 110. is added, and the total motion signal 112 (second
1 (b)) and the direction signal 113 (Fig. 21 (C))
, and is manually input to the counter 114. counter 1
The total motion signal 112 and the direction signal 113 input in step 14 are converted into lateral relative displacement amounts, and further, the subtraction means 116 uses the initial position data stored in the memory 115 to calculate the difference between the object 101 and the object 102. The lateral relative displacement amount 117 (FIG. 21(d)) is determined (block B8).

The resolution of the encoder is approximately the pitch of the reference scale 103 (several angstroms if a periodic arrangement of atoms on the surface of a conductive material is used as the reference scale), but a motion amount pulse signal is generated from the tip longitudinal change amount signal. If a multivalued pulse signal (Fig. 21 (f)) is obtained by setting multiple threshold values (Fig. 21 (e)), then the relative displacement direction signal shown in Fig. 21 (g) ) It is possible to obtain a signal by further dividing the detected position signal, and it is also possible to obtain a signal with a resolution of angstrom or less (FIG. 21(h)).

Next, using FIGS. 22 to 29, the object 101 and the object 1 in the above embodiment for detecting the longitudinal position of the probe will be explained.
02 will be described below.

FIG. 22 shows an example in which a shape (electron cloud distribution) asymmetrical in the direction of relative displacement of the object as shown in FIG. 12 is used as a reference scale in the example shown in FIG. 19. When the vertical displacement of the probe due to the relative displacement between the target object 101 and the target object 102 shows a change as shown in FIG. and the direction signal 113 are as shown in FIGS. 23(b) and (C), respectively, and from these, the amount of lateral relative displacement shown in FIG. 23(d) is determined. Therefore, in this case, it can be seen that the object 102 in FIG. 22 is displaced rightward in the plane of the paper with respect to the object 101 by the amount shown in FIG. 23(d).

Similarly, if the vertical displacement of the probe 104 due to the relative displacement of the object shows a change as shown in FIG.
After the signal waveform processing shown in FIGS. 3(f) and 3(g), the object 102 is displaced to the left in the plane of the paper with respect to the object 101 by the amount shown in FIG. 23(h). I understand.

Furthermore, for example, the vertical displacement of the probe 104 is shown in FIG.
), the object 10 at point T
It can be seen that the direction of relative displacement of the object 102 with respect to 1 has changed from right to left.

FIG. 24 shows another embodiment in which the direction of the relative displacement in the lateral direction between the object 101 and the object 102 can be detected in the above embodiment in which the vertical position of the probe is detected. In the figure, the probe 104 is caused to minutely vibrate in the direction of relative displacement of the object by a probe lateral vibration means 1301. Object 1
01 and the object 102, the probe 10
4 is vibrated fast enough, the position differential coefficient of the vertical absolute position signal of the probe 104 with respect to the relative lateral displacement can be obtained, and the direction of the relative lateral displacement can be detected from this.

For example, the longitudinal displacement of the probe 104 and its position differential coefficient due to the relative displacement of the objects 101 and 102 in the lateral direction are
5(a) and 5(C), the object 102 in FIG. 24 moves to the right in the plane of the paper with respect to the object 101 by the amount shown in FIG. 25(d). It can be seen that there is a displacement of

Similarly, if the vertical displacement of the probe 104 due to the relative displacement of the object shows a change as shown in FIG.
After the processing shown in Figures 5(f) and (g), the object 10
1 as a reference, the object 102 is placed to the left in the plane of the paper,
It can be seen that it is displaced by the amount shown in Figure 5 (h).

Furthermore, when the change shown in FIG. 25(i) or FIG. 25(m) is shown, the direction of the relative displacement of the object 102 with respect to the object 101 at point T changes from right to left. I know what you did.

FIG. 26 shows still another embodiment in which the direction of the relative horizontal displacement between the object 101 and the object 102 can be detected in the above-described embodiment in which the longitudinal position of the probe is detected. This uses a probe transverse vibration means 1501 to vibrate the probe 104 in the direction of relative displacement of the object, and obtains vertical absolute position signals of the probe 104 at two different points A and B. be. The probe 104 detects the object 101 and the object 102.
The longitudinal position control means 1901 is used to control the longitudinal position of the probe 104 (the tunnel It is necessary to perform feedback such that the current 105 is constant. If the width of the vibration of the probe 104 is d, this method is equivalent to the method of detecting direction from two signals having a phase difference with respect to the reference scale using two probes separated by a distance d. .

Here, for example, let the pitch of the reference scale be p, and the probe 104
Let us assume that the width d of the vibration is set so that d=-+N-L (N=o, 1.2...). At this time, if the vertical displacement of the probe 104 due to the horizontal relative displacement between the target object 101 and the target object 102 shows a change as shown in FIG. 27(a), the target object 102 in FIG. It can be seen that the probe 10 is displaced to the right in the plane of the paper with reference to 101.
When the vertical displacement of 4 is as shown in FIG. 27(e), it can be seen that the displacement is to the left.

Furthermore, when the longitudinal displacement of the probe 104 shows changes as shown in FIGS. 27(i) and 27(m), T
It can be seen that the direction of the relative displacement of the object 102 with respect to the object 101 at the point has changed from right to left.

FIG. 28 shows still another embodiment in which the direction of the relative horizontal displacement between the object 101 and the object 102 can be detected in the above embodiment of detecting the longitudinal position of the probes, in which two probes are used. This is an example.

In the same figure, probe longitudinal position control means 2801A and 2801B control two probes 17 separated by a distance d.
The vertical position control (feedback to keep the tunnel current constant) of 01A and 1701B is performed independently. Then, two probe longitudinal displacement signals 2803A
By detecting 2803B and 2803B, the direction of the relative lateral displacement can be detected.

For example, if the pitch of the reference scale 103 is p, the probe 170
The width d between 1A and probe 1701B is a=L+N-! j(N
= o, 1.2...). At this time, if the vertical displacement of the two probes 170IA and 1701B due to the relative horizontal displacement of the target object 101 and the target object 102 shows a change as shown in FIG. It can be seen that the object 101 is displaced to the right in the plane of the paper as a reference, and if the vertical displacement of the two probes shows a change as shown in FIG. I understand.

Furthermore, if the vertical displacement of the two probes 1701A and 1701B due to the relative horizontal displacement of the target object 101 and the target object 102 shows a change as shown in FIGS. 29(i) and (m), then T At the point, it can be seen that the direction of the relative displacement of the object 102 with respect to the object 101 changes from right to left.

[Effects of the Invention] As explained above, according to the present invention, the tunnel current flowing between the probe and the reference scale is detected using an atomic arrangement or the like as the reference scale, and the relative positional deviation between the probe and the reference scale is detected. , it is possible to realize an encoder with high resolution on the order of interatomic distance (Angstrom order).

Further, if the tunnel current value is detected while keeping the interval between the probe and the reference scale constant, high-speed position detection becomes possible. If the longitudinal position of the probe is detected while keeping the tunnel current value constant, more accurate position detection becomes possible.

Further, by using the atomic arrangement and the fabricated scale in combination as a reference scale, absolute position detection, a wide position detection range, and high-speed position detection become possible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an encoder using tunnel current detection according to an embodiment of the present invention, Fig. 2 is a waveform diagram showing signals obtained in each component of Fig. 1, and Fig. 3 is a reference scale. A schematic diagram (Fig. 4(a)) showing an example using a periodic arrangement of atoms and molecules on the surface of a conductive material is shown as
A cross-sectional view showing an example of using a scale fabricated by processing a focused ion beam, electron beam, etc. on the surface of a conductive material as a reference scale, and FIG. 4(b) shows a material having a diffraction grating shape as a reference scale. 5 is a sectional view showing an example using a scale whose surface is coated with a conductive substance, FIG. 5 is a sectional view showing an example using a composite scale with one reference origin on the reference scale, and FIG. FIG. 7 is a sectional view showing an example of using a composite scale in which multiple reference origins are periodically provided on the reference scale, and FIG. Fig. 8 is a cross-sectional view showing an example using a compound scale; is a sectional view showing an example in which an aperiodic scale is used as a reference scale, FIG. 10 is a configuration diagram showing an example in which an asymmetric reference scale is used as a reference scale, and FIG. A waveform diagram representing the obtained signal; Figure 12 is a schematic diagram showing the (1,1,1) plane of a face-centered cubic lattice as a specific example of an asymmetric reference scale; FIG. 14 is a waveform diagram showing the signal obtained in the embodiment of FIG. 13. FIG. 15 is a cross-sectional view showing an embodiment in which direction is detected by vibrating the tip. FIG. 16 is a sectional view showing an embodiment in which direction is detected by
5 is a waveform diagram showing the signal obtained in the embodiment of FIG. 17. FIG. 17 is a configuration diagram showing an embodiment of direction detection using a plurality of probes. Figure 19 is a diagram showing the configuration of an encoder that detects the longitudinal position of the probe, and Figure 20 shows the relative lateral displacement that is detected by detecting the longitudinal position of the probe under a constant tunnel current. FIG. 21 is a block diagram for explaining the procedure for performing detection; FIG. 21 is a waveform diagram showing signals obtained at each component in the configuration of FIG. 19; FIG. 23 is a waveform diagram showing a signal obtained in the embodiment shown in FIG. 22, and FIG. 24 is a cross-sectional view showing an example in which an asymmetric scale is used as a reference scale. 25 is a waveform diagram showing the signal obtained in the embodiment of FIG. 24; FIG. 26 is the waveform diagram shown in FIG. 19. A cross-sectional view showing an example in which direction detection is performed by vibrating the probe in the transverse direction in the embodiment, FIG. 27 is a waveform diagram representing the signal obtained in the embodiment of FIG. 26, and FIG. FIG. 29 is a waveform diagram showing the signal obtained in the embodiment of FIG. 28. FIG. 30 is a diagram showing the principle of grating interference, which is a conventional example. It is a block diagram of the optical encoder used. 101.102: Object, 103: Reference scale, 104: Probe, 105: Tunnel current, 106: Bias power supply, 107: Current detection means, 108: Current amplification means, 109: Lateral relative position information extraction means, 110 : waveform processing means, 111: motion amount/direction conversion means, 112: motion amount signal, 113: direction signal, 114: counter, 115: memory, 116 subtraction means, 117: lateral relative displacement amount, 118:)- channel current signal, 301: Periodic arrangement of atoms and molecules on the surface of the conductive material, 302: Electron cloud on the surface of the conductive material, 401: Surface of the conductive material, 402: Fabrication scale, 403: Diffraction grating shape Material surface with, 404:
Coating with conductive material, 501: Reference origin, 601alxa3: Reference origin created by replacing part of the surface of the reference scale atomic array with another substance, 601b1-b3: Part of the surface of the reference scale atomic array with other material. Reference origin created by attaching a substance, 601 C1-c: Reference origin created by scraping a part of the surface of the reference scale atomic array, 701d+-d4: Multiple reference origins with known widths and intervals. , 801: Reference origin where absolute position information is recorded, 802.8
04: Reference origin, 803.805: Absolute position information bit, 901: Aperiodic scale, 1001: Asymmetric reference scale, 1301.1501: Lateral probe vibration means, 1701A
, 1701B: Probe, 1702A, 1702B: Bias power supply, 1703A,
1703B: Current detection means 1704A, 1704B: Current amplification means, 1705A, 1705B: Tunnel current signal, 1901: Probe longitudinal position control means, 1902: Feedback control means, 1903: Vertical absolute position signal, 2801A, 2801B: Detection Needle vertical position control means, 2802A, 2802B: Feedback control means, 2803A, 2803B: Vertical absolute position signal, 300, light source, 3002:, 41 color light, 3003: diffraction grating, 3004.3005: ±1st order diffracted light, 3006 : Reflector, 3007 : Semi-transparent mirror, 3008 : Photodetector. Fig. 3 Fig. 4 Fig. 9 Fig. 12 Fig. 11 to Kili Ran 11 Ka1 et al. -12, ~1. -2-1~ 1,2-
m-,,2-1〜〜〜〜,2-5,N-Kyo+
~, + -1 +/ \ Cross section Figure 21 Figure 21 Figure 22 Figure 24

Claims (14)

[Claims] (1) A conductive reference scale that serves as a reference for length, a conductive probe whose tip is placed close to the reference scale surface, and means for applying a voltage between the reference scale and the probe. , means for detecting a tunnel current value flowing between the reference scale and the probe and outputting a signal corresponding to the amount of relative movement in the lateral direction between the reference scale and the probe based on the tunnel current value; means for detecting the relative movement amount and relative movement direction in the lateral direction between the reference scale and the probe based on the output signal of the signal output means; An encoder comprising a scale and means for counting the amount of relative displacement of the probe in the lateral direction. (2) The encoder according to claim 1, wherein the counting means is an up/down counting means. (3) The scope of the present invention is to provide means for keeping the vertical relative position of the reference scale and the probe constant, and to detect the relative displacement of the reference scale and the probe in the lateral direction from a change in the tunnel current value. The encoder according to item 1 or 2. (4) A means for controlling the vertical relative position of the reference scale and the probe is provided, and the vertical relative position is controlled so that the tunnel current is constant, and the amount of displacement of the vertical relative position is provided. 3. The encoder according to claim 1, wherein the encoder detects a lateral relative displacement between the reference scale and the probe. (5) The encoder according to any one of claims 1 to 4, wherein the reference scale is an arrangement of atoms or molecules on the surface of a conductive material. (6) The encoder according to any one of claims 1 to 4, wherein a conductive object having a periodic surface shape is used as the reference scale. (7) Any one of claims 1 to 6, wherein a reference origin is provided on the reference scale having a periodic arrangement.
The encoder described in . (8) The encoder according to claim 7, wherein a plurality of reference origins are provided periodically on the reference scale having a periodic arrangement. (9) The encoder according to claim 7 or 8, wherein the memory stores information regarding the widths of a plurality of reference origins provided on the reference scale having a periodic arrangement and the intervals between the reference origins. (10) The encoder according to any one of claims 7 to 9, wherein absolute position information is recorded at or near a reference origin provided on the reference scale having a periodic arrangement. . (11) The encoder according to any one of claims 1 to 5, which uses, as a reference scale, an aperiodic scale in which information regarding intervals between scales is stored in a memory in advance. (12) Using an arrangement as the reference scale in which the change in tunneling current obtained by relatively scanning the reference scale and the probe in the lateral direction is asymmetric within one cycle, the reference scale and the probe are An encoder according to any one of claims 1 to 11, which detects the direction of relative movement of the hands. (13) A probe lateral position control means is provided, and the relative movement direction of the reference scale and the probe is detected by vibrating the probe in a relative displacement detection direction. Encoder according to any one of clause 12. (14) In the periodic arrangement of the reference scale, a plurality of probes each corresponding to a different phase is provided, and the reference scale and the probe An encoder according to any one of claims 1 to 12, which detects the direction of relative movement of the hands.