JPH05187865A - Regulation mechanism of displacement detection system - Google Patents

Abstract

PURPOSE:To obtain a regulation mechanism capable of easily performing the regulation of each element of a displacement detection system of a probe microscope without lowering the rigidity of a device. CONSTITUTION:A cantilever 18 is attached on the lower face of the case 12 of a scanning type probe microscope and a laser module 20 is fixed on the side face thereof. A direct viewing fiberscope 28 is attached to the cover 24 of the case 12 so that the shaft center of the fiberscope 28 crosses at right angles with the cantilever 18 and may be focused on the face thereof. A mirror attachment member 36 attaching a mirror 24 is supported on a ball receiver 40 of the lower face of the cover 24 through a ball 38. The mirror attachment member 36 has two arms 46 extending at right angles with each other. The intermediate part of these arms 46 is upward pulled with a spring 48 and the edge part thereof is held by the use of an adjust screw 50. The mirror 42 is stably supported in a specified direction and the adjust screw 50 is rotated to change the direction of the mirror 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adjusting mechanism for a displacement detecting system of a probe microscope such as an atomic force microscope.

[0002]

2. Description of the Related Art An atomic force microscope (AFM) is capable of observing the surface shape of a sample with atomic resolution by utilizing atomic force. The interatomic force acts between atoms that are very close to each other, and their magnitude changes depending on the interatomic distance. When a sharp probe supported by a flexible cantilever is brought close to the sample surface, an atomic force is generated between atoms at the tip of the probe and the sample surface, and the cantilever is displaced. In the AFM, the sample surface is scanned using a probe supported at a distance where an atomic force is generated. During scanning, the displacement of the cantilever that occurs according to the unevenness of the sample surface is constantly measured, and the atomic force acting on the probe at that time is detected to obtain the distance between the probe samples to obtain the uneven image of the sample. To get Alternatively, during scanning, feedback control is performed to keep the displacement of the cantilever constant, and an uneven image of the sample surface is obtained from the trajectory of the probe. In any case, the surface roughness image is obtained from the displacement of the cantilever by indirectly utilizing the atomic force.

The atomic force F (that is, the restoring force of the cantilever) is detected as the displacement δ of the cantilever. When the cantilever is a rectangular plate, this displacement δ can be expressed by the following equation, where L is length, a is thickness, b is width, and E is elastic modulus.

Δ = 4L ³ F / a ³ bE One of the methods for detecting this displacement δ is STM for the back surface of the cantilever (the surface opposite to the surface on which the probe is provided).
There is a method in which the displacement of the cantilever is detected as a change in tunnel current. However, this method
An atomic force is generated between the M probe and the cantilever, and this interferes with the atomic force generated between the AFM probe and the sample, so that the displacement of the cantilever cannot be accurately detected. As another method, the laser beam emitted from the light source is divided into two, and one of them is irradiated on the optical reflection surface provided on the back surface of the tip of the cantilever, and the reflected light interferes with the other beam. There is a method of detection using an interferometer. In this method, a high degree of stability is required for the laser light source and the optical path portion of the interferometer, and therefore the apparatus becomes large and expensive.

[0005]

According to another method, an optical position detector is used which irradiates a laser beam on an optical reflection surface provided on the rear surface of the tip of the cantilever to change a reflection angle which changes according to the displacement of the cantilever. There is a so-called optical lever method for detecting with. This optical lever system adjusts the positional relationship between the cantilever and the sample, the position of the beam spot irradiated on the surface of the cantilever, and the position of the beam spot on the optical position detector to detect the displacement of the cantilever before measurement. There is a need to. However, since the ordinary scanning probe microscope does not have a mechanism for optically observing, the above-mentioned adjustment cannot be performed, or even if it is possible, it is very difficult. Therefore, there is a scanning probe microscope in which an optical microscope is integrated, but this makes the configuration of the entire device much larger than that of the scanning probe microscope alone. The image resolution is reduced.
There is also a method in which a scanning probe microscope is provided with an observation hole for observing with an optical microscope in advance, and the optical microscope is installed when necessary for observation, but this is because the optical microscope is installed. It takes a lot of time.

According to the present invention, the adjustment mechanism of the displacement detection system of the probe microscope which can easily adjust each element of the displacement detection system without lowering the rigidity of the apparatus, that is, without lowering the resolution of the observed image. For the purpose of providing.

[0007]

The present invention relates to a displacement detection system adjusting mechanism provided in a probe microscope, which supports an optical element of the displacement detection system, a means for changing the direction of the optical element, and an optical element. And a fiberscope for confirming the orientation of the element.

[0008]

The adjusting mechanism of the displacement detecting system of the present invention includes a fiberscope. When adjusting the orientation of the optical elements of the displacement detection system, such as the mirror that deflects the laser beam,
The orientation of the optical element is visually confirmed using a fiberscope. Since the fiberscope is small, even if the adjusting mechanism of the present invention is incorporated into the scanning probe microscope, the rigidity is not significantly reduced.

[0009]

An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a partial sectional view of the front of a scanning probe microscope incorporating the adjusting mechanism of the displacement detection system of the present embodiment, FIG. 2 is a partial sectional view of the left side surface thereof, and FIG. 4 is a partial sectional view of the upper surface thereof. ..

On the lower surface of the housing 12 of the scanning probe microscope, a cantilever 18 is arranged at an angle of 15 degrees with respect to the horizontal plane by a leaf spring 16 fixed by a screw 14. A laser module 20 containing a semiconductor laser and a lens is attached to the side surface of the housing 12. A lens position adjusting screw 22 is provided at the end of the laser module 20 so that the beam spot on the cantilever can be adjusted to a suitable diameter.

A lid 24 is fixed on the housing 12 by screws 26. A direct-view type fiberscope 28 is attached to the lid 24 so that its axis is orthogonal to the cantilever 18 and its surface is in focus, and is fixed by a scope fixing screw 34. This direct-view type fiberscope 28 is provided with an objective lens 30 and a light guide 32 on its end face, as shown in FIG. 3, so that an object on the extension of its axis can be observed while being enlarged. ..

A mirror mounting member 36 is provided on the lower surface of the lid 24.
There is provided a ball receiver 40 for accommodating the ball 38 fixed to and supporting it by magnetic force. The mirror 42 attached to the mirror attachment member 36 is fixed by a fixing spring 44. The mirror mounting member 36 has a ball 38
Two arms 46 extending from each other at an angle of 90 degrees are provided. These arms 46
Although it is pulled upward by a spring 48 extending from the lid 24 attached in the middle thereof, the tip end of the spring 48 abuts on an adjusting screw 50 extending from the lid 24, so that it is stably stopped at a predetermined position. Therefore, by turning the adjusting screw 50 to move it back and forth, the mirror 42
Can be directed in any desired direction.

A photodetector 52 for vertically receiving the laser beam from the cantilever 18 is provided inside the housing 12. Photo detector 5
2 is fixed to the detector stage 54. The detector stage 54 is attached by using three D screws 56 so that the detector stage 54 is pressed against a plane provided in the housing orthogonal to the laser beam from the cantilever 18.

The housing 12 is placed on the scanner support 60 supported by the three legs 62, and is supported by the three coarse movement screws 64 evenly arranged on the same circumference. . The scanner support 60 is moved by three position adjusting screws 66 and is fixed so as to be pressed against a base plate 68.
It has 0. The scanner base 70 is made of a magnetic material and does not easily move even when the position adjusting screw 66 is loosened by the magnetic force of the magnet 72 embedded in the central portion of the base plate 68. A tube scanner 7 is mounted on the scanner base 70.
4 is attached by adhesion. A sample stand 76 is attached to the upper end of the tube scanner 74, and a sample 78 is placed thereon.

Next, procedures for adjusting various optical elements will be described. The laser beam emitted from the laser module 20 is reflected by the mirror 42. Turn the two adjusting screws 50 while magnifying and observing the cantilever 18 with the direct-view type fiberscope 28 so that the beam spot formed by the laser beam reflected by the mirror 42 comes to the tip (free end) of the cantilever 18. Adjust the orientation of the mirror 42. Next, the position of the photodetector 52 is adjusted by turning the three D screws 56 while watching the output of the photodetector 52 so that the laser beam reflected by the cantilever 18 irradiates the center of the photodetector 52. The position of the tip of the cantilever 18 with respect to the sample 78 is adjusted by rotating the three position adjusting screws 66 while simultaneously observing the cantilever 18 and the sample 78 using the direct-viewing type fiberscope 28. The probe approach to the sample 78 is performed by using the three coarse movement screws 64 while observing the output from the photodetector 52.

After the various adjustments are completed, the applied voltage of the tube scanner 74 is controlled to scan the probe along the surface of the sample 78, and the beam spot on the photodetector which moves according to the displacement of the cantilever 18 is moved. By monitoring the position of, the uneven image of the sample 78 can be obtained with atomic resolution.

As described above, since the adjusting mechanism of the displacement detecting system of this embodiment has the direct-viewing type fiberscope,
Various optical elements can be easily adjusted. Moreover, since the fiberscope is small, even if it is incorporated into a scanning probe microscope, the rigidity of the device is not deteriorated, so that high-resolution sample observation can be performed.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows a partial sectional view of the front of a scanning probe microscope incorporating the adjustment mechanism of the displacement detection system of the present embodiment, and FIG. 7 shows a partial sectional view of the upper surface thereof. In this embodiment, the same members as those in the above-mentioned embodiments are designated by the same reference numerals, and the description thereof will be omitted.

The basic structure of this embodiment is the same as the above-mentioned embodiment except for the following points. That is, in this embodiment, the side-view type fiberscope 80 is attached to the side surface of the housing 12 instead of the direct-view type fiberscope. This side-view type fiberscope 80 can be magnified and observed while illuminating an object in the vicinity of its side surface,
As shown in FIG. 5, a light guide 82 and an objective lens 84 are provided on the side surface thereof.

The side-view type fiberscope 80 is attached at a position equidistant from the cantilever 18 and the photodetector 52. Therefore, if the objective lens 84 of the side-view fiberscope 80 is directed toward the cantilever 18 and fixed by the fiber fixing screw 86, the cantilever 18 can be obtained.
And the objective lens 84 is used as the photodetector 52.
The photodetector 52 can be observed if it is fixed toward.

According to this embodiment, similarly to the above-mentioned embodiment, not only the position of the beam spot on the cantilever and the position of the probe of the cantilever on the sample can be confirmed without lowering the rigidity of the apparatus. , You can visually check the position of the beam spot on the photo detector. Therefore, in addition to the effects of the above-described embodiment, there is an advantage that the photodetector can be roughly adjusted.

[0022]

According to the present invention, the adjustment of the displacement detection system of the probe microscope that can easily adjust each optical element without lowering the rigidity of the apparatus, that is, without lowering the resolution of the observed image. A mechanism is provided.

[Brief description of drawings]

FIG. 1 is a partial front sectional view of a scanning probe microscope incorporating an adjustment mechanism of a displacement detection system according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the left side surface of the scanning probe microscope shown in FIG.

FIG. 3 shows a direct-view type fiberscope attached to the scanning probe microscope of FIG.

4 is a partial cross-sectional view of the scanning probe microscope of FIG. 1 seen from above.

FIG. 5 shows a side-view fiberscope attached to the scanning probe microscope shown in FIG.

FIG. 6 is a partial front sectional view of a scanning probe microscope incorporating an adjustment mechanism of a displacement detection system according to another embodiment of the present invention.

7 is a partial cross-sectional view of the scanning probe microscope of FIG. 6 seen from above.

[Explanation of symbols]

28 ... Direct-view type fiberscope, 36 ... Mirror mounting member, 38 ... Ball, 40 ... Ball receiver, 42 ... Mirror,
46 ... Arm, 48 ... Spring, 50 ... Adjustment screw.

Claims (1)

[Claims] 1. A displacement detection system adjusting mechanism provided in a probe microscope, comprising means for supporting an optical element of the displacement detection system, means for changing the direction of the optical element, and means for confirming the direction of the optical element. Displacement detection system adjustment mechanism equipped with a fiberscope.