JP3764816B2 - Flamingo optical probe, flamingo optical probe manufacturing method, and scanning probe microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention performs an optical physical property measurement or processing by irradiating or exciting a surface of an object to be measured with an atomic force microscope (AFM) for the purpose of observing the shape of the surface to be measured in the nanometer region. The present invention relates to an optical probe used in a target near-field effect microscope, an optical probe manufacturing method, and a scanning probe microscope.
[0002]
[Prior art]
Aperture-type optical probes that are made by sharpening glass capillaries and optical fibers have been reported, and with the development of micromachining technology, probes with extremely sharp tips can be produced, which reduces the resolution of conventional optical microscopes. An optical image over it can be realized with a scanning probe microscope. In addition, by reducing the outer diameter of the optical probe by the chemical etching method, the spring elasticity of the optical probe is reduced, enabling operation in the contact mode used in AFM without damaging soft samples. An optical probe is used.
[0003]
[Problems to be solved by the invention]
However, in the optical probe that has been thinned to reduce the spring elasticity, the size of the reflecting mirror for the optical lever used to control the distance between the optical probe and the target sample has become smaller as the probe becomes thinner. And there is a problem that the mirror cannot be produced because the spring constant of the probe is small.
[0004]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a method of manufacturing an optical probe, in which an optical fiber is first bent into a saddle shape, and then made ultrafine, thereby making use of the difference in wet chemical etching rate depending on the shape to make the bent portion a flamingo. The part functioning as the elastic element part can be made extremely fine while keeping the mold relatively thick.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1A is a cross-sectional view of a flamingo type optical probe according to the first embodiment of the present invention as seen from the side. The optical fiber 1 includes a core part 2 that propagates light and a clad part 3 having a different refractive index. The tip portion 4 of the portion that functions as an elastic element of the optical probe is bent into a bowl shape, and is processed to be thin relative to the support portion 5 in a step shape. The outside is covered with a metal film 7 except for the opening 8. The metal film 7 is made of a material that reflects light, such as gold, platinum, aluminum, chromium, and nickel.
[0006]
FIG. 1B is a view of the optical probe as seen from above. Of the distal end portion 4 of the elastic element portion that is thinly processed, the portion that is just bent is relatively thick. A flat mirror surface 9 is formed on the back of the bent portion by mechanical polishing.
FIG. 2 is a diagram showing a part of the manufacturing process of the flamingo type optical probe according to the second embodiment of the present invention. The synthetic resin coating is removed about 1 cm to 10 cm at the end of the optical fiber 1 to clean the surface. FIG. 2A shows a process of processing the tip portion 4 into a bowl shape by a local heating means such as a CO2 laser. The heated fiber creates a difference in stress between the inside and outside and is bent in the direction of the heat source.
[0007]
FIG. 2B shows an optical probe etching process, and shows a state where the fiber is immersed in an etching solution. A tip portion 4 of 0.5 mm to 50 mm from the end of the optical fiber 1 is inserted into the first solution layer 10 of the etching solution. The etching solution includes a first solution layer 11 mainly composed of hydrofluoric acid and a second solution layer 10 having a specific gravity smaller than that of the first solution layer and not reacting with and mixing with the first solution layer 10. Consists of layers. As the second solution layer 10, an organic solvent such as hexane, heptane, and octane, and fats and oils such as mineral oil, vegetable oil, and chemically synthesized oil are used, but the specific gravity is smaller than that of the first solution layer 11. Other solutions that do not react and mix with each other in solution layer 11 can also be used.
[0008]
This state is maintained until the supporting portion 5 is immersed vertically in an etching solution and becomes a desired thinness. By reducing the outer diameter of the optical probe, the spring elasticity of the optical probe can be reduced, and a flamingo optical probe suitable for observing a soft sample surface is obtained. The bent portion of the tip 4 has a concentration gradient in ion diffusion due to the effect of this shape, and the etching rate is not uniform, so the etching rate of the side portion from the inside becomes slower than the bending. The state, that is, it remains thick and is etched. This makes it possible to enlarge the part for producing the mirror surface for the light lever, and it is possible to prevent the mirror surface from being produced even in the optical probe having the elastic function part made extremely thin.
[0009]
FIG. 2C shows a step of sharpening the tip of the flamingo type optical probe. The tip part 4 is immersed in the etching solution so that the front part is perpendicular to the bending of the tip part 4 so that the tip is just a meniscus part at the liquid interface of the two-layer etching solution. Etching at the meniscus portion creates a tapered shape and sharpens the tip. This sharpening process is described in Dennis R. et al. Turner et al. (US 4,469,554). Since the hydrofluoric acid solution is highly volatile, there are problems that the concentration gradually changes and that the influence on the human body and the environment is great. The two-layer structure of the hydrofluoric acid solution and the organic solution layer has an effect of preventing volatilization and suppressing hydrofluoric acid released to the atmosphere.
[0010]
In FIG. 2, the sharpening process by chemical etching is shown, but the sharpening of the tip can also be performed by a heating and stretching method.
FIG. 3 shows a process for producing a flamingo probe by subjecting the present optical probe according to the third embodiment of the present invention to a heat extraction method. As shown in FIG. 3A, the portion that becomes the tip of the flamingo type optical probe is heated while pulling both ends of the optical fiber 1. The optical fiber 1 is stretched in a taper shape and finally broken. As a heating means, a method of condensing and applying CO2 laser light or a method of passing an optical fiber through the center of a platinum wire wound in a coil shape and supplying a current to the platinum wire to heat can be used.
[0011]
In the following, the outer shape of the optical probe is produced using the process shown in FIG. Although the structure in which the core portion is tapered and cut by tapering by the heat-drawing method is structurally different, the following steps are not different from those shown in FIG.
FIG. 4 shows a step of performing metal coating on the optical probe according to the fourth embodiment of the present invention. It is sectional drawing showing the process of depositing the metal film 7 in the part except the opening 8 of the optical fiber shape | molded by the front process. As a method for depositing the metal film 7, an anisotropic thin film deposition method such as vacuum evaporation or sputtering is used, and the film thickness is selected in the range of 20 nm to 1000 nm. The deposition direction is behind the tip as shown by the arrow in FIG. 6, and the angle A is selected in the range of 20 degrees to 90 degrees.
[0012]
FIG. 5 shows an example of an optical probe microscope equipped with the optical probe according to the fifth embodiment of the present invention. The saddle-shaped flamingo type optical probe 12 shown in the second embodiment of FIG. 1B is installed on the bimorph 13 that is a vibrating means by the support unit 5, and the tip of the flamingo type optical probe 12 is vibrated perpendicularly to the sample 14. Then, the displacement detecting means 15 detects an atomic force acting between the tip of the flamingo type optical probe 12 and the surface of the sample 14 or a force related to other interaction as a change in vibration characteristics of the flamingo type optical probe 12, The configuration is such that the surface shape is measured by scanning the sample with the XYZ moving mechanism 17 while being controlled by the control means 16 so as to keep the distance between the tip of the flamingo type optical probe 12 and the surface of the sample 14 constant. At the same time, light from the optical property measurement light source 18 is introduced into the flamingo type optical probe 12, the sample 14 is irradiated with light from the opening 8 of the flamingo type optical probe 12, and detected by the optical property measurement light detection means 19. Measure the optical properties of the area.
[0013]
FIG. 5 shows a transmissive configuration for detecting the measurement light on the back surface of the sample 14, but a reflective configuration for detecting the measurement light on the sample surface and a configuration for detecting light with the flamingo optical probe 12 are also possible. is there.
Further, FIG. 5 shows an apparatus configuration that vibrates the flamingo type optical probe 12, but it is also possible to perform measurement as a contact mode AFM with an apparatus configuration that does not vibrate the bimorph 13 or does not use the bimorph 13.
[0014]
Furthermore, the measurement in the liquid can be performed by providing a cover for the reservoir so that the probe and the sample are held in the liquid.
The flamingo type optical probe 12 has been described above, but this probe can be used as a probe dedicated to AFM. In this case, the metal film 7 is unnecessary, and the tip can be made sharper. As the probe material, optical fiber, glass fiber, fine metal wire, or the like can be used. As a feature when used as an AFM probe, especially in a mode in which the atomic force is detected by vibrating the probe in the liquid, since the conventional AFM probe has a plate structure, the influence of the viscosity of the liquid and the disturbance vibration transmitted through the liquid Although it is affected, it exhibits extremely stable resonance characteristics and can be measured stably.
[0015]
【The invention's effect】
As described above, according to the flamingo type optical probe and the method of manufacturing the flamingo type optical probe according to the present invention, the spring constant of the elastic function part can be made smaller than that of the conventional slim type optical probe, and the bending part is relatively Therefore, it is possible to avoid that the mirror required for the optical lever is small and the operability is deteriorated, and that the mirror cannot be manufactured because the spring constant is small.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a flamingo type optical probe of the present invention.
FIG. 2 is a view showing an etching process of a flamingo type optical probe of the present invention.
FIG. 3 is a view showing a heat-drawing process of the flamingo type optical probe of the present invention.
FIG. 4 is a diagram showing a process of coating a flamingo type optical probe of the present invention with a metal film.
FIG. 5 is a diagram showing an example in which the flamingo optical probe of the present invention is mounted on a scanning probe microscope.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical fiber 2 ... Core part 3 ... Cladding part 4 ... Tip part 5 ... Support part 6 ... Tapered part 7 ... Metal film 8 ... Opening 9 ... Mirror surface 10 ... first solution layer 11 ... second solution layer 12 ... flamingo type optical probe 13 ... bimorph 14 ... sample 15 ... displacement detecting means 16 ... control Means 17 ... XYZ moving mechanism 18 ... Optical characteristic measuring light source 19 ... Optical characteristic measuring light detecting means

Claims (8)

The tip consists of an optical fiber with a tapered tip, and has an opening that transmits light at the end of the elastic element. The other part is covered with a metal film, and the shape near the tip is saddle-shaped. A flamingo optical probe characterized in that the diameter of the saddle-shaped bent portion is relatively larger than the diameter of the elastic element portion. 2. The flamingo optical probe according to claim 1, wherein the outer diameter of the optical probe elastic element is processed to be thin in a step shape with respect to the substrate. The method of manufacturing a flamingo optical probe, characterized in that the optical probe comprises a step of processing the shape near the tip of the fiber into a saddle shape, a step of processing the outer diameter thinly, and a step of sharpening the tip portion in a tapered shape. A method of manufacturing a flamingo type optical probe, comprising: a step of heating and heat-breaking the optical probe; a step of processing the shape near the tip of the fiber into a saddle shape; and a step of processing the outer diameter of the optical probe. A state in which the distance between the probe tip and the sample or medium surface to be measured is close to an operating distance in which an atomic force or other interaction force acts between the probe tip and the surface. In the scanning probe microscope that scans the sample surface by a two-dimensional scanning unit and controls the probe along the shape of the surface by a control unit to measure the sample shape, the tip of the probe and the surface Vibration means for relatively vibrating the probe, displacement detection means for detecting the displacement of the probe, and the distance between the probe tip and the surface is kept constant based on a detection signal output from the detection means. A scanning probe microscope characterized by having a control means for controlling and at least the probe according to claim 1. A state in which the distance between the probe tip and the sample or medium surface to be measured is close to an operating distance in which an atomic force or other interaction force acts between the probe tip and the surface. Then, the sample surface is scanned by a two-dimensional scanning means, the probe is controlled along the shape of the surface by a control means, and light irradiation or light detection is performed on a minute region of the surface, In a scanning probe microscope for simultaneously measuring a sample shape and two-dimensional optical information, vibration means for vibrating the probe tip and the surface in a relatively vertical direction, displacement detection means for detecting displacement of the probe, and Based on the detection signal output by the detection means, the control means for keeping the distance between the tip of the probe and the surface constant, and at least Scanning probe microscope characterized by having a probe according to claim 1 and 2 wherein. A state in which the distance between the probe tip and the sample or medium surface to be measured is close to an operating distance in which an atomic force or other interaction force acts between the probe tip and the surface. In the scanning probe microscope that scans the sample surface by a two-dimensional scanning unit, controls the probe along the shape of the surface by a control unit, and measures the sample shape, the displacement of the probe is measured. 3. A displacement detecting means for detecting, and a control means for keeping the distance between the tip of the probe and the surface constant based on a detection signal output from the detecting means, and at least the probe according to claim 1 and 2. A scanning probe microscope characterized by comprising: A state in which the distance between the probe tip and the sample or medium surface to be measured is close to an operating distance in which an atomic force or other interaction force acts between the probe tip and the surface. Then, the sample surface is scanned by a two-dimensional scanning means, the probe is controlled along the shape of the surface by a control means, and light irradiation or light detection is performed on a minute region of the surface, In a scanning probe microscope for simultaneously measuring a sample shape and two-dimensional optical information, a displacement detection means for detecting the displacement of the probe, and a distance between the probe tip and the surface based on a detection signal output from the detection means 3. Control means for keeping the constant and a twist detection means for detecting twist of the probe, and at least Scanning probe microscope characterized by having a probe.

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