JP4416171B2 - Scanning probe microscope - Google Patents

Description

  The present invention relates to a scanning probe microscope.

  Atomic Force Microscope (AFM) has been devised by STM inventor G. Binnig et al. (See Non-Patent Document 1). It has been. The principle is that the atomic force acting between the detection tip with a sufficiently sharp tip and the sample is measured as the displacement of the cantilever to which the detection tip is attached, and the sample surface is scanned while keeping the displacement of the cantilever constant. The shape of the sample surface is measured using a control signal for keeping the displacement of the cantilever constant as shape information. In recent years, in addition to atomic force, applications for measuring various physical quantities such as magnetic force and surface potential force have spread and are collectively called scanning probe microscopes.

  The cantilever in the scanning probe microscope is manufactured by a semiconductor manufacturing process and has dimensions of a thickness of 0.3 to 0.5 mm, a width of 1.3 to 1.6 mm, and a length of about 3 mm. In the scanning probe microscopes that are currently commercialized, an intermediate part called a lever holder is provided for easy handling, and the cantilever is temporarily attached to the lever holder and then mounted on the probe microscope body. There are many type probe microscopes. However, since the presence of an intermediate part called a lever holder is disadvantageous in automation, there is also a system in which the cantilever is directly attached to the cantilever attaching portion at the tip of the fine movement mechanism without using the lever holder. In that case, the vacuum suction method is suitable for fixing the cantilever from the viewpoint of miniaturization and automation.

  4 is a side sectional view of a conventional cantilever supply mechanism, and FIG. 5 is a top view of the conventional cantilever supply mechanism. Conventionally, a cantilever supply mechanism that supplies a cantilever to a cantilever mounting portion has a metal block that has the same angle as the inclination angle of the cantilever mounting portion and that can mount a plurality of cantilevers side by side. Each cantilever 1 is installed in a groove for positioning with a tool such as tweezers.

  The position coordinates of each cantilever 1 are registered in the controller. Although the portion on which the cantilever 1 is mounted is inclined, the cantilever 1 is structured not to drop off by the stopper portion 40 for preventing slipping. If it is desired to fix the cantilever 1 more reliably, a vacuum suction source may be connected to the piping port 41 and suction fixed.

In order to attach the cantilever, first, the XY stage is moved to the registered coordinates and moved to a position just above the cantilever where the cantilever attaching portion is to be replaced. Next, the Z stage is moved, and the cantilever mounting part and the cantilever are brought close to a distance that allows vacuum suction. In the prototype device, it was approximately 0.5 mm or less. Finally, the vacuum suction source is operated to suck the cantilever onto the cantilever mounting portion, and the mounting operation is completed.
Physical Review Letters vol.56 p930 1986

However, the conventional cantilever mounting method using the cantilever supply mechanism has the following problems.
(1) Since the vacuum suction source is operated in a state where the cantilever mounting part and the cantilever are not in close contact, when the cantilever is attracted to the cantilever mounting part, dust floating around is also sucked, and the cantilever and the cantilever mounting part Operation may become unstable due to dust trapped between them.
(2) Since the cantilever mounting portion and the cantilever are not in close contact with each other, vacuum suction is performed, and when the cantilever is sucked and jumps to the cantilever mounting portion, the cantilever mounting portion is sucked in a state of translation or rotational displacement in the horizontal direction. The position reproducibility of cantilever mounting was poor.

  Accordingly, an object of the present invention is to obtain a novel cantilever supply mechanism and a cantilever mounting method which can solve the conventional problems.

  In order to solve the above-described problems, the present invention provides a scanning probe microscope in which a cantilever is fixed to an optical head portion by vacuum suction force, and the cantilever holding portion of the cantilever supply mechanism is formed by a cantilever fixing means and an elastic material. When the cantilever is attached to the cantilever attachment portion, the Z stage is operated until the cantilever attachment portion contacts the cantilever, and after the contact, the Z stage is further operated by a predetermined amount.

  In the cantilever supply mechanism configured as described above, when the cantilever is attached, the Z stage is operated until the cantilever attaching portion comes into contact with the cantilever, and the Z stage is further operated after the contact so that the cantilever attaching portion is moved to the cantilever. It is possible to make it adhere completely. Physical interference in the operation after contact is absorbed by elastic deformation of the elastic material. By vacuum-adsorbing the cantilever in a fully adhered state, the problem of sucking dust and the problem of positional displacement of the cantilever during adsorption are solved.

  As described above, according to the present invention, the cantilever holding portion of the cantilever supply mechanism is composed of the cantilever fixing means and the elastic material, so that the cantilever attaching portion is completely brought into close contact with the cantilever when attaching the cantilever. It became possible. Therefore, it has become possible to avoid the phenomenon of sucking dust floating around during vacuum suction as in the prior art.

In addition, the problem that the cantilever is displaced by suction when the cantilever mounting portion and the cantilever are completely in close contact with each other is solved.
Furthermore, if the cantilever supply mechanism incorporates a pressure-sensitive conductive elastomer, the electrical resistance value of the pressure-sensitive conductive elastomer is monitored, and the cantilever and fine movement mechanism are damaged due to erroneous operation of the stage or human error in operation. It is possible to reduce the possibility of the occurrence.

  The scanning probe microscope of the present invention measures the force acting between the probe and the sample as the displacement of the cantilever to which the probe is attached, and the surface of the sample is maintained while keeping the displacement of the cantilever constant by a fine movement mechanism. Using a control signal for scanning and maintaining a constant displacement of the cantilever as physical property information, the physical property of the sample surface is measured, the Z stage for bringing the cantilever closer to the sample, and the cantilever in the sample surface The cantilever and the sample are observed in a scanning probe microscope having an XY stage for positioning at an arbitrary position of the lens and a cantilever mounting portion that is attached to the end of the fine movement mechanism and holds the cantilever by a vacuum suction force. Holding an optical microscope, a plurality of cantilevers, positioning by the XY stage and the And a cantilever supply mechanism for supplying the cantilever to the mounting portion by the approaching operation of the stage, the cantilever holding portion of the cantilever supply mechanism, the cantilever is held via an elastic member.

  More specifically, the scanning probe microscope of the present invention includes a probe at the tip, a cantilever that is displaced by a force acting on the probe and the sample surface, a semiconductor laser, a lens, and a light detection element. , An optical lever type displacement detecting means for irradiating the semiconductor laser light to the cantilever and detecting the positional deviation of the reflected light as a displacement of the cantilever by a light detecting element, a cantilever mounting portion for holding the cantilever by a vacuum adsorption force, A cantilever mounting part is attached to the tip, a fine movement mechanism for scanning the sample surface while controlling the cantilever at a constant distance from the sample, a Z stage for bringing the cantilever closer to the sample, and the cantilever as the sample XY stage for positioning at an arbitrary position in the plane, and light for observing the cantilever and sample Holding a microscope, and a controller for controlling the entire apparatus, a plurality of cantilevers, wherein is positioned by the XY stage, and a cantilever supply mechanism for supplying the cantilever to the cantilever attaching portion.

The cantilever holding part of the cantilever supply mechanism is composed of a cantilever fixing means and an elastic material.
The fixing means may be an adhesive material or a vacuum suction mechanism.
As the material having elasticity, for example, a polymer material or metal material having elasticity is used. If a pressure-sensitive conductive elastomer is used as the polymer material having elasticity, when the cantilever of the holding portion of the cantilever supply mechanism is pressed against the cantilever mounting portion, the elastic deformation amount of the pressure-sensitive conductive elastomer can be checked by the resistance value. . This prevents it from being pushed more than necessary.

  The cantilever holding part of the cantilever supply mechanism may be made of an elastic material having adhesiveness. For example, silicon gel is used as the elastic material having adhesiveness, and the adhesiveness and elasticity are utilized. Further, an elastomer having both adhesiveness and pressure-sensitive conductivity may be used as the elastic material having adhesiveness.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a first embodiment of a scanning probe microscope according to the present invention.
In FIG. 1, the displacement detection system and the cantilever mounting portion 2 are integrated to constitute an optical head 3. The displacement detection system includes a semiconductor laser 4, a lens 5, and a light detection element 6. The cantilever mounting portion 2 is disposed at the tip of the optical head 3. The cantilever 1 is attached to the cantilever attachment portion 2 by vacuum suction. A tube (not shown) is connected to the piping port 2a of the cantilever mounting portion and is connected to a vacuum pump. The laser light emitted from the semiconductor laser 4 is condensed at the tip of the cantilever 1 by the lens 5, and the reflected light is irradiated to the light detection element 6. The optical head 3 is attached to the tip of the fine movement mechanism 7. The fine movement mechanism 7 scans the cantilever 1 with respect to the sample 8 in the in-plane direction of the sample while controlling the position in the height direction. An optical microscope 11 is provided for the state of the surface of the sample 8 and the alignment of the cantilever 1 and the sample 8. The fine movement mechanism 7 is attached to the Z stage 9, and the cantilever 1 is sent to the position where it contacts the sample 8 by the Z stage 9. The sample 8 is mounted on the XY stage 10. While observing the positional relationship between the cantilever 1 and the sample 8 with the optical microscope 11, the XY stage 10 can be operated to measure any location on the sample 8.

The cantilever supply mechanism 20 is disposed at one corner of the XY stage 10. An elastic material 20a having adhesiveness and an elastomer layer 20b having pressure-sensitive conductivity are formed on the cantilever supply mechanism 20 to constitute a cantilever holding portion. The cantilever 1 is held on the adhesive elastic material 20a by an adhesive force.
FIG. 2 shows the flow of cantilever mounting work. A series of operations are performed under monitoring by an optical microscope. First, the cantilever supply mechanism 20 is moved directly below the cantilever attachment portion 2 by the XY stage, and the cantilever attachment portion 2 is brought close to the vicinity of the cantilever holding portion of the cantilever supply mechanism 20 by the Z stage (FIG. 2a). The cantilever holding part of the cantilever supply mechanism 20 is made at the same angle as the inclination angle of the cantilever mounting part 2. Next, the Z stage is lowered to bring the cantilever mounting portion 2 into contact with the cantilever 1 (FIG. 2b). Judgment of contact can be made by observation with an optical microscope. Further, the Z stage is lowered by a predetermined amount, and the cantilever mounting portion 2 and the cantilever 1 are completely brought into close contact (FIG. 2c). The amount of displacement pushed in after contact is absorbed as elastic deformation of the adhesive elastic material 20a and the pressure-sensitive conductive elastomer 20b. After the cantilever mounting portion 2 and the cantilever 1 are completely in contact, the vacuum suction source is operated and fixed by suction. Finally, the Z stage is raised to complete the cantilever mounting operation.

  When the adhesive strength of the adhesive elastic material 20a is stronger than the vacuum suction force of the cantilever mounting portion 2, the cantilever 1 remains in the cantilever holding portion when the Z stage is finally raised in the above procedure. The size of the vacuum suction hole is limited by the size of the cantilever, and therefore the suction force is also limited. In the case of a cantilever having a width of 1.3 mm and a length of 3 mm, the limit of the adsorption force is about 10 g, and the adhesive force of the adhesive elastic material 20 a must be 10 g or less. As a result of trial manufacture, silicone gel showed a suitable adhesive strength. Moreover, it is not deviated from this patent even if it uses the raw material which apply | coated the adhesive instead of the material which has adhesiveness as an adhesive material.

  The pressure-sensitive conductive elastomer 20b is wired and the electrical resistance value is monitored by the controller. When the elastic deformation amount increases and the resistance value falls below a predetermined resistance value, the Z stage is automatically stopped to operate as a safety mechanism against crash destruction.

  FIG. 3 shows a second embodiment of this patent. The cantilever holding part is composed of a leaf spring 30 and a pipe fitting 31, and a tube 32 is piped to the pipe fitting 31. The tube 32 is made of a flexible material such as silicon. A vacuum pump (not shown) is connected to the end of the tube 32, and the cantilever 1 is fixed by a vacuum suction force. When the Z stage is pushed in a predetermined amount, the leaf spring 30 is deformed, thereby realizing an elastic deformation function. By attaching a sensor such as a strain gauge to the leaf spring 30 or measuring the deflection of the leaf spring 30 with an optical displacement meter, it is possible to provide a safety mechanism against crash destruction. The leaf spring is made of a material usually used as a spring, such as metal or resin. Further, the form of the spring need not be plate-like, and can be easily realized by a form such as a coil spring.

It is a block diagram of the scanning probe microscope of this invention. It is explanatory drawing which shows the procedure of the cantilever attachment operation | work concerning this invention. It is a block diagram of the 2nd Example of the cantilever supply mechanism of this invention. It is a sectional side view of the conventional cantilever supply mechanism. It is a top view of the conventional cantilever supply mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cantilever 2 Cantilever attachment part 2a Piping port 3 Optical head part 4 Semiconductor laser 5 Lens 6 Photodetection element 7 Fine movement mechanism 8 Sample 9 Z stage 10 XY stage 11 Optical microscope 12 Frame 20 Cantilever supply mechanism 20a Adhesive elastic material 20b Pressure sensitive Conductive elastomer 30 Leaf spring 31 Piping bracket 32 Tube 40 Stopper 41 Piping port

Claims (6)

A cantilever with a probe,
A cantilever supply mechanism having a holding portion of the cantilever;
A cantilever mounting portion for mounting the cantilever supplied from the cantilever supply mechanism;
In a scanning probe microscope equipped with
The cantilever holding part has a fixing means for the cantilever and an elastic member that elastically deforms,
The elastic member is connected to monitoring means for monitoring its deformation;
The cantilever is held by the cantilever holding portion via the elastic member;
The elastic member is prevented from being displaced by elastically deforming when the cantilever is attached to the cantilever mounting portion by pressing,
The scanning probe microscope characterized in that the monitoring means monitors the end point of the pressing . The elastic member is a pressure-sensitive conductive elastomer , and the monitoring means includes the pressure-sensitive conductive elastomer and wiring applied therefrom , and an electrical resistance value is monitored;
The scanning probe microscope according to claim 1, wherein when the cantilever is attached to the cantilever mounting portion, the cantilever is determined to be in close contact when the electrical resistance value is equal to or lower than a predetermined value. The elastic member is a spring , and the monitoring means is composed of a sensor that detects the amount of deformation of the spring,
The scanning probe microscope according to claim 1, wherein it is determined that the sensor is in close contact with the cantilever from a value detected by the sensor. Deformation amount of the spring is constituted by deflection measuring means for measuring the deflection of the spring,
The scanning probe microscope according to claim 3 , wherein it is determined that the cantilever is in close contact with the measured value obtained by the measuring means. The fixing means is either an adhesive material or a vacuum suction mechanism
The scanning probe microscope according to claim 1 . A portion for tightly fixed cantilever in the cantilever attaching portion, the portion to be adsorbed and fixed in a cantilever held by the cantilever holder, both being adapted to be substantially parallel when in physical contact, wherein Item 6. A scanning probe microscope according to any one of Items 1 to 5 .

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