JPH09113519A - Very small probe approaching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bring the distance between the surface of the sample and a probe close to the distance of several mm to several Å without breaking the probe by continuously adjusting the feeding amount of a Z-driving mechanism in a scanning probe microscope and a very small probe machine. SOLUTION: A small probe approaching device is provided with a magnetic directly-driven force generating part 101 (e.g. a voice coil motor) to drive a canti-lever 2 or a shaft to support the sample, and a damper part 81 is provided on a force transmitting part 61. In the damper part 81, a heater is fitted, the visco-elastic body (e.g. silicone rubber) is filled internally, the electromagnetic fluid is filled, an electrode is fitted, and the electric field is applied from the outside to vary or stabilize the visco-elasticity of the visco-elastic body or the electromagnetic fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe microscope (SPM) and a microprobe approaching device for approaching the outermost surface of a sample without damaging a microprobe which is a sensor and a working needle of a fine area working device. It is a thing.

[0002]

2. Description of the Related Art The probe of SPM is brought close to the sample surface, and the shape and various physical quantities of the sample (electric potential, magnetism, friction, capacitance,
Etc.), the distance between the sample surface and the probe should be Å
It is necessary to control with a degree of accuracy. On the other hand, it is desirable that the distance between the sample and the probe is several mm or more for operations such as replacement of the sample and alignment between the sample and the probe. Therefore, in order to put the probe into the measurement area in a short time, when the distance between the sample surface and the probe is distant, the probe approaches at high speed, and when the distance between them decreases, it switches to low speed and approaches to the nearest sample surface Let This switching point from high speed to low speed is detected, for example, by Japanese Patent Laid-Open No.
As in the patent of 74754, the long range force acting between the sample and the probe (the vibration amplitude of the cantilever is attenuated as it approaches the sample surface due to air resistance) may be used to switch the speed. In the case of a device equipped with an optical microscope as disclosed in Japanese Patent Laid-Open No. 03-040355, the focal length of the objective lens may be used for measurement to obtain the speed switching point. But any z
The coarse motion system also uses a motor and a reduction system such as a screw or lever for the drive system, and the amount of movement per step is 5 nm.
It is about. Even in this case, the last step is large to control the distance between the sample surface and the probe with an accuracy of about Å.To prevent the sample from colliding with the probe, the piezo element under the sample stage is included. Keep the servo system active z
The sample stage is moved by a distance of several nm until the coarse drive system stops. At this time, the moving speed of the z servo system must be faster than the one step rise of the motor. Also z
The detection of the end point of the coarse motion drive system is performed by detecting the amount of attenuation of the vibration amplitude of the cantilever or the amount of warp of the cantilever when the probe contacts the sample.

[0003]

The present invention relates to z coarse motion of scanning probe microscopes. In particular, the feed amount of the z drive mechanism can be adjusted steplessly, and the distance between the sample surface and the probe can be approached from several mm to several Å without breaking the probe.

[0004]

In order to solve the above-mentioned problems, the present invention has a minute probe,
The sample surface is processed by bringing a scanning probe microscope that measures the shape and various physical quantities (electric potential, magnetism, friction, capacitance, etc.) of the sample surface close to the sample surface from mm to a few Å or close the sample surface to the sample surface. In a microprobe approaching device of a microregion processing machine, an electromagnetic direct-acting force generating mechanism (for example, a voice coil motor) that moves an axis that supports the sample or the probe to bring the sample and the microprobe into close proximity is provided. The force transmitting portion has a damper mechanism and a linear motion bearing.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of a microprobe approaching device according to the present invention. Move the sample in the z direction,
z In the coarse movement system, the force generating part (101), the force transmitting part (61) and the damper part (81) are the driving elements, and the displacement cantilever (2) which is a displacement sensor having a probe (micro probe) at the end is displaced. Detection mechanism (1) and displacement detector controller (131
) Detects the switching point and the end point of the feed rate of the drive mechanism, and controls the force generator controller (111).

[0006]

[Example] Fig. 2 shows a specific example of the z coarse movement system. The configuration is
Below the sample (4) is the xyz fine movement mechanism (5) that scans the sample (4) in xyz, for example a three-dimensional scanner using a piezo scanner. Below that, a damper is composed of a spindle (6) for moving the sample up and down, a damper housing (7) and a viscoelastic body (8). The spindle (6) is restricted to move in the z direction only (for example, by using a bearing or spindle as shown in Fig. 4) by the direct-acting spindle bearings (16) arranged at the upper and lower parts of the damper housing, and the coil is placed at the bottom. (9) is wound to form a voice coil motor used in speakers etc. together with the magnet (10). FIG. 4A is a sectional view taken along the line AA ′ in FIG. 2 and shows a situation in which the spindle 6 meshes with the spindle bearings 16 provided in the upper and lower portions of the damper housing 7 and the recesses provided in the spindle. FIG. 4B shows the spindle 6
FIG. 6 is a perspective view showing a prismatic portion of the spindle 6 in a portion that meshes with the bearing 16. A constant current source (11) is attached to the coil (9) and controlled by a coil current controller (12). A cantilever (2) and a cantilever excitation piezo (3) are provided as displacement sensors on the sample (4), and a microprobe (probe) is provided at the end of the cantilever. The displacement of the lever is detected by the displacement detector (1) of the cantilever and the end point detector (13) which is the displacement detector controller.

Next, the operation of the z coarse movement system will be described. First, when the distance between the sample surface and the probe is long, a current I0 is made to flow from the constant current source (11) to the coil (9). Due to the magnetic field of the permanent magnet (10) and the current I0, a force F0 is generated in the vertical direction of the spindle (6). The magnitude of this force F0 is set so as to exceed the elastic limit stress (σ S) of the viscoelastic body (8) and the strain amount εI0 = ε0-εs remains even after this force is removed. (See Fig. 3) This force F0 causes the spindle (6) to move while receiving the viscous resistance of the viscoelastic body (8) in the damper housing (7).
It moves only a small amount εI0 without vibrating. Here, it is important to increase the viscous resistance of the viscoelastic body (8) and move the spindle (6) without causing microvibration so that the probe does not collide with the sample surface. Until now, pulse motors and the like in drive systems have had no damping mechanism such as dampers, and were susceptible to minute vibrations when driven. Next, when the distance between the sample surface and the probe approaches within a certain distance (this detection is performed by the method of the above-mentioned JP-A-6-74754 and JP-A-03-040355), the constant current source (11) The current is changed to I1 and the force F1 is generated.
The strain amount at this time is εI1 = ε1-εs. Therefore, the amount of strain can be continuously changed by continuously changing the current from I0 to I1. In this respect, unlike the z coarse movement system driven by a pulse motor, the increment of the feed amount can be set finely.

Z The coarse end point detection signal is the end point detector (13).
When the more generated force F1 is removed, the spindle (6)
Is pulled back by about ε s and moves in a direction in which the distance between the sample surface and the probe is increased, that is, the probe 20 does not contact the sample surface. When the amount of movement is large and the distance between the sample surface and the probe is too large, the z servo system is activated and the piezo scanner of the x, y, z fine movement mechanism 5 is extended to cancel the amount of movement εs.

Further, the elastic limit of the viscoelastic body (8) is lowered (3
Heater for temperature change (14) on the outside of the damper housing to reduce εs in the figure) and to reduce viscous resistance.
Can be installed to change the moving speed of z coarse motion per unit force. Further, the viscoelasticity of the viscoelastic body (8) can be stabilized by controlling the heater temperature.

Further, the same effect as that of the damper by the combination of the viscoelastic body and the heater can be realized by a structure in which the damper portion is filled with the electromagnetic fluid and the electrode is arranged inside the damper. The elasticity and viscosity of the electromagnetic fluid can be changed by applying a voltage to the electrodes from the outside.

[0011]

With the above mechanism, the feed amount of z coarse movement can be set to a small value by simply adjusting the current flowing through the coil, and the viscoelastic body's large viscous resistance can also prevent the moving axis from vibrating. Since it can be moved to, it is possible to avoid the probe from colliding with the sample surface. In addition, the temperature variable mechanism attached to the damper section can change the viscous resistance of the viscoelastic body and the moving speed per unit force during the movement of the z-axis, thus shortening the z coarse movement time.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a z coarse movement system.

FIG. 2 is an example of a z coarse movement system using a viscoelastic body.

FIG. 3 is a schematic diagram showing a stress-strain relationship of a viscoelastic body.

FIG. 4 is a diagram showing a direct-acting spindle bearing.

[Explanation of symbols]

 1 Displacement detector 2 Cantilever 6 Spindle 8 Viscoelastic body 9 Coil 10 Magnet

Claims (4)

[Claims] 1. A micro probe, which has a number of probes
The sample surface is processed by bringing a scanning probe microscope that measures the shape and various physical quantities (electric potential, magnetism, friction, capacitance, etc.) of the sample surface close to the sample surface from mm to a few Å or close the sample surface to the sample surface. In a microprobe approaching device of a microregion processing machine, an electromagnetic direct-acting force generating mechanism (for example, a voice coil motor) that moves an axis that supports the sample or the probe to bring the sample and the microprobe into close proximity is provided. A microprobe approaching device having a damper mechanism and a linear motion bearing in the force transmitting portion. 2. The microprobe approaching device according to claim 1, wherein the damper portion is filled with a viscoelastic body (for example, silicone rubber). 3. The microprobe approaching device according to claim 2, wherein a mechanism for changing the temperature (for example, a heater and a temperature controller) is added to the damper part to change or stabilize the viscoelasticity of the viscoelastic body. . 4. A microprobe approaching device according to claim 2, wherein the damper part is filled with the electromagnetic fluid, and an electrode is attached to apply an electric field from the outside to change or stabilize the viscoelasticity of the electromagnetic fluid. .