JP2883952B2 - Micro probe access 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 probe microscope (SPM) and a microprobe approaching device for approaching the surface of a sample without damaging a microprobe serving as a sensor and a processing needle of a microregion processing device. Things.

[0002]

2. Description of the Related Art An SPM probe is brought close to a sample surface, and the shape and various physical quantities (electric potential, magnetism, friction, capacitance,
), The distance between the sample surface and the probe must be
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 sample replacement 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 large, the probe should be approached at high speed, and when the distance between them is short, switch to low speed and approach the sample surface nearest. Let it. The detection of the switching point from the high speed to the low speed is performed by, for example,
As disclosed in the patent of 74754, the speed may be switched by detecting a long-range force acting between the sample and the probe (the vibration amplitude of the cantilever attenuates as it approaches the sample surface due to air resistance). In the case of an apparatus having an optical microscope as disclosed in Japanese Patent Application Laid-Open No. 03-040355, measurement may be performed using the focal length of the objective lens to determine the speed switching point. But any z
The coarse movement system also uses a motor and a reduction system such as a screw or lever for the drive system, and the movement amount per step is 5 nm.
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, and to prevent collision between the sample and the probe, z Activate the servo system 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 needs to be faster than the start of one step of the motor. Also z
The end point detection of the coarse drive system is performed by detecting the amount of attenuation of the vibration amplitude of the cantilever or the amount of warpage of the cantilever when the probe contacts the sample.

[0003]

SUMMARY OF THE INVENTION The present invention relates to z-coarse movement of a scanning probe microscope. 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 reduced from several mm to several mm without breaking the probe.

[0004]

In order to solve the above-mentioned problems, the present invention has a small probe, and has a small number of probes.
A scanning probe microscope that measures the shape and various physical quantities (electric potential, magnetism, friction, capacitance, etc.) of the sample surface by approaching a distance of several mm from the mm, or a microprobe close to the sample surface to process the sample surface In the micro-probe approaching device of the micro-area processing machine, an electromagnetic direct-acting force generating mechanism (for example, a voice coil motor or the like) for moving an axis supporting the sample or the probe to bring the sample and the micro-probe close to each other is provided. The force transmitting portion has a damper mechanism and a bearing for linear motion.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of a microprobe access device according to the present invention. Move the sample in the z direction,
z In the coarse motion system, the cantilever (2), which is a displacement sensor having a force generation unit (101), a force transmission unit (61), a damper unit (81) as a driving element, and a probe (micro probe) at the end, and a displacement Detection mechanism (1) and displacement detector controller (131
) Detects the switching point and the end point of the feed speed of the drive mechanism, and controls the force generator controller (111).

[0006]

FIG. 2 shows a specific example of the z-coarse motion system. The configuration is
Below the sample (4), there is an xyz fine movement mechanism (5) for scanning the sample (4) in xyz, for example, a three-dimensional scanner using a piezo scanner. A damper is constituted by a spindle (6) for raising and lowering the sample, a damper housing (7), and a viscoelastic body (8) thereunder. The spindle (6) is restricted to movement only in the z-direction (for example, using a bearing or a spindle as shown in FIG. 4) by direct-acting spindle bearings (16) arranged at two positions above and below the damper housing. (9) is wound and forms 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 where the spindle 6 meshes with a spindle bearing 16 provided on the upper and lower portions of the damper housing 7 and a concave portion provided on the spindle. FIG. 4 (b) shows the spindle 6
FIG. 4 is a perspective view showing a prism-shaped portion of the spindle 6 at a portion where the spindle 6 meshes with the bearing 16. A constant current source (11) is attached to the coil (9) and is controlled by a coil current controller (12). On the sample (4), there are a cantilever (2) as a displacement sensor and a piezo (3) for cantilever excitation, and a micro probe (probe) is provided at the end of the cantilever. The displacement of the lever is detected by the cantilever displacement detector (1) and the end point detector (13) which is a displacement detector controller.

Next, the operation of the z coarse movement system will be described. At first, when the distance between the sample surface and the probe is large, a current I0 flows 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 direction in which the spindle (6) moves up and down. The magnitude of the force F0 is set so as to exceed the elastic limit stress (σS) of the viscoelastic body (8), and the strain εI0 = ε0−εs remains even after removing this force. (See FIG. 3) By this force F0, the spindle (6) receives the viscous resistance of the viscoelastic body (8) in the damper housing (7),
It moves by a very 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 slight vibration, so that the probe does not collide with the sample surface. Conventional drive system pulse motors and the like have no damping mechanism such as a damper and tend to generate minute vibrations when driven. Next, when the distance between the sample surface and the probe approaches a certain distance (this detection is based on the methods described in JP-A-6-74754 and JP-A-03-040355). The current is changed to I1 to generate a force F1.
The strain amount at this time is εI1 = ε1-εs. Therefore, the amount of distortion can be continuously varied by continuously changing the current from I0 to I1. In this point, the increment of the feed amount can be set finely unlike the z-coarse movement system driven by the pulse motor.

[0008] The end point detection signal of the coarse movement is detected by the end point detector (13).
When the generated force F1 is removed, the spindle (6)
Is pulled back by about εs, and moves in a direction in which the distance between the sample surface and the probe increases, that is, in a direction in which the probe 20 does not contact the sample surface. When the movement amount 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 movement amount εs.

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

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

[0011]

According to the above mechanism, the feed amount of the z-coarse movement can be set small only by adjusting the current flowing through the coil, and at the same time, the moving axis does not vibrate due to the large viscous resistance of the viscoelastic body. Therefore, the probe can be prevented from colliding with the sample surface. Further, the viscous resistance of the viscoelastic body can be varied by the temperature variable mechanism attached to the damper portion, and the moving speed per unit force during the movement of the z-axis can be varied, so that the time of z coarse movement can be reduced.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a z-coarse motion system.

FIG. 2 is an embodiment 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 view showing a linear motion spindle bearing.

[Explanation of symbols]

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

Claims (4)

(57) [Claims] Claims 1. A micro probe having a small number of probes
A scanning probe microscope that measures the shape and various physical quantities (electric potential, magnetism, friction, capacitance, etc.) of the sample surface by approaching a distance of several mm from the mm, or a microprobe close to the sample surface to process the sample surface In the micro-probe approaching device of the micro-area processing machine, an electromagnetic direct-acting force generating mechanism (for example, a voice coil motor or the like) for moving an axis supporting the sample or the probe to bring the sample and the micro-probe close to each other is provided. A micro-probe access device, characterized in that the force transmitting section has a damper mechanism and a bearing for direct movement. 2. The microprobe access device according to claim 1, wherein the damper portion is filled with a viscoelastic body (for example, silicone rubber). 3. The microprobe access device according to claim 2, wherein a mechanism (for example, a heater and a temperature controller) for changing the temperature is added to the damper unit to change or stabilize the viscoelasticity of the viscoelastic body. . 4. The microprobe access device according to claim 2, wherein the damper portion is filled with an 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. .