JPH07260801A - Scanning probe microscope - Google Patents

Abstract

PURPOSE:To enable high-speed and highly accurate observation of a specimen having a rough surface by providing a scattered-ray-filter means with an opening at the focusing point of the reflected ray which has passed through a condenser. CONSTITUTION:A ray 9 reflected on the surface of a cantilever 5 is collected with a condenser 6. A scattered-ray-filter means 7 has a small opening, at which the ray collected with the lens 6 focuses. Then, the ray focuses at the small opening and is projected on a ray detector 8. A ray 10 falling not on the cantilever 5 but on a specimen does not focus at the opening or is projected on the ray detector 8, because it is blocked with the scattered-ray-filter means 7. Thus, a ray that could be a noise is not projected the ray detector 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a scanning probe microscope.

[0002]

2. Description of the Related Art In the fields of medicine and biotechnology, the resolution is higher than that of a microscope using ordinary visible light (wavelength λ = about 400 nm to 800 nm), and a living sample (hereinafter referred to as biological sample) such as a cell, The demand for high-resolution microscopes that show bacteria, sperm, chromosomes, mitochondria, flagella, etc. is increasing day by day. Further, in the field of electronic industry, in developing and evaluating high-performance devices, there is an increasing demand for a high-resolution microscope capable of nondestructively observing a fine structure on the element surface.

In response to these requirements, the sample surface is scanned with a probe as a microscope satisfying the conditions of non-contact, non-destructive, high resolution, no restriction of resolution, etc. Attention has been paid to a scanning probe microscope for observing the surface. These microscopes include, for example, a scanning tunneling microscope (STM), an atomic force microscope (AFM), a magnetic force microscope (MFM), and a scanning capacitance microscope (SCaM). used. Among them, the atomic force microscope with less restrictions on observation samples will be used for various purposes in the future in product development and quality control in the optical industry, semiconductor industry, magnetic recording industry and the like. Some scanning probe microscopes use a cantilever as a probe. The cantilever is composed of a flexible plate material and a needle-shaped tip located at one end of the flexible plate material and projecting vertically from the plate surface.

In the atomic force microscope, when the tip of the needle-like tip at the tip of the cantilever and the sample surface come close to each other, a force acts between them and the flexible plate material of the cantilever bends in the Z direction. This amount of deflection is detected by a photodetector such as a light receiving element using optical means. For example, the laser beam emitted from the light source is obliquely incident on the flexible plate material, and the angle change of the reflected light is detected by the light receiving element. The change in angle is proportional to the change in the amount of bending. Deflection detected (Z
The surface of the sample is scanned by the cantilever in the XY directions while controlling the direction to be constant. The control amount in the Z direction corresponds to the uneven image on the sample surface, and the uneven image is obtained by scanning in the XY directions. The tip shape of the needle tip is an important factor that determines the resolution of the uneven image on the measurement principle. To improve the resolution, the tip of the needle tip may be made to have an acute angle. In the magnetic force microscope, the surface of the sample is scanned by the cantilever, so that the magnetic force depending on the difference in the direction of the magnetic moment in the sample influences the amount of bending of the cantilever. Thereby, the magnetization information of the sample can be observed as uneven information.

[0005]

When a sample is measured by using a compound microscope of an optical microscope and an atomic force microscope having a conventional structure, the atomic force microscope becomes unusable and its detection capability is low. There was a problem of decline. The laser beam emitted from the light source is focused on the flexible plate material, but the diameter of the spot of this laser beam is larger than the width of the cantilever, so the light protruding from the cantilever is incident on the sample. . It was found that the protruding light was reflected on the surface of the sample and a part of the light was incident on the photodetector of the atomic force microscope, which turned into noise. Therefore, for example, in Japanese Unexamined Patent Publication No. 5-71951, there has been proposed a structure in which a light reflecting flat plate having a diameter larger than the spot diameter of light is provided on a part of the cantilever so that incident light does not overflow from the conventional cantilever. However, when observed with a cantilever provided with such a light reflection plate, there was a problem that it was not suitable for high speed measurement. Furthermore,
There was also a problem that minute irregularities of the observation sample could not be measured.

[0006]

As a result of earnest research, the present inventor has found that a cantilever provided with a light-reflecting flat plate is formed at the tip of the cantilever in order to increase the size of the cantilever itself. It was found that the natural vibration of the existing probe was low. In addition, the reason why the minute unevenness of the observation sample cannot be measured is that the distance between the fulcrum of the probe and the point of action becomes long, and the angle change of the reflecting surface becomes smaller than the amount of change above and below the point of action It turned out that Therefore, the present inventor has tried to solve the problem by using the conventional cantilever from the viewpoint of improving the cantilever itself and solving the above problem.

Therefore, the first aspect of the present invention is that it has a flexible plate-like shape, has a needle-like probe at one end of the plate, and has a reflective film on at least the back surface of the probe forming region. The formed cantilever, the driving means of the cantilever, the light source for measuring the deflection amount of the cantilever installed at a position where the light can be obliquely incident on the reflection film, the condenser lens that collects the reflected light of the light from the light source, In a scanning probe microscope having at least a light receiving means for receiving the reflected light passing through the condenser lens, a scattered light removing means having an opening portion formed at the focal position of the reflected light passing through the lens is installed. And a scanning probe microscope (claim 1) ".

Preferably, the "scanning probe microscope according to claim 1 (claim 2)" is provided in which the means for removing scattered light is made of a material coated with black alumite.

[0009]

The atomic force microscope of the present invention has a scattered light removing means 7 as shown in FIG. The reflected light 9 reflected by the reflecting surface of the cantilever is condensed by the lens 6, and the scattered light removing means 7 is provided with a very small opening 11, and the lens 6 collects the light at the position of this opening. The emitted light is configured to focus. The light reflected by the surface of the cantilever is focused on the photodetector 8 by focusing on the very small opening 11 of the scattered light removing means 7, but is separated from the cantilever and directly reflected on the sample surface.
The aperture 10 does not focus at the opening 11 and is blocked by the scattered light removing means 7, so that the reflected light does not enter the light detecting means 8. Therefore, the light that becomes noise is not incident on the light detecting means 8.

The present invention can be applied to a scanning probe microscope, and particularly AFM (atomic force microscope), LF
It is effective for M (friction force microscope), MFM (magnetic force microscope), electrostatic force microscope, potential microscope, and intermolecular force microscope.

[0011]

Embodiment 1 FIG. 1 is a schematic diagram of an atomic force microscope according to this embodiment. The cantilever 5 includes a needle-shaped portion, a flexible plate having the needle-shaped portion formed at one end, and a support portion that cantilevers the other end of the plate. The support portion supports the tip end portion of the needle-shaped portion at a position where an atomic force is received from the sample, and the plate is bent by the atomic force received by the needle-shaped portion. This deflection amount is detected by the detection optical system.

For observation, the sample 4 is set on the sample table 3. The light emitted from the light source 1 passes through the lens 2 and enters the cantilever 5 installed on the sample. Then, the light reflected on the cantilever passes through the lens 6 of 1000 times and is focused on the scattered light removing means 7 made of black alumite having a rectangular opening of 1.2 mm in length and 15 mm in width. The light that has passed through the opening enters the photodetector 8. The amount of displacement of the cantilever due to the unevenness of the sample surface is measured from the difference between the upper and lower light receiving elements.

As the scattered light removing means, black one whose surface is coated with black alumite, for example, is preferable. In the case of black, when scattered light hits the scattered light removing means, reflection does not occur and noise is generated. It can be further reduced. Further, the size and shape of the opening of the scattered light removing means are changed depending on the shape of the laser beam emitting section and the magnification of the lens.

[0014]

As the atomic force microscope of the present invention, the same one as the conventional cantilever can be used, and therefore high speed measurement and observation of a sample having minute irregularities can be performed with high accuracy. Further, the cantilever is easily damaged and is frequently replaced, but since a special cantilever is not manufactured, running cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view of a scanning probe microscope of the present invention.

FIG. 2 is a schematic view showing an optical path of the scanning probe microscope of the present invention.

[Explanation of symbols]

 1 ... Light source for measuring cantilever deflection amount 2 ... Lens 3 ... Sample stage 4 ... Sample 5 ... Cantilever 6 ... Condensing lens 7 ... Scattered light removing means 8 ....・ Light receiving means 9 ・ ・ ・ Normal reflected light 10 ・ ・ Abnormal reflected light 11 ・ ・ Aperture

Claims (2)

[Claims] 1. A flexible plate-like shape,
A cantilever having a needle-like probe at one end of the plate and a reflective film formed on the back surface of at least the probe forming region, a driving means for the cantilever, and a position where light can be obliquely incident on the reflective film. A scanning probe microscope having at least a light source for measuring the bending amount of the cantilever, a condensing lens that condenses the reflected light of the light from the light source, and a light receiving unit that receives the reflected light that has passed through the condensing lens, A scanning probe microscope, characterized in that a scattered light removing means having an opening is provided at a focal position of reflected light passing through a lens. 2. The scanning probe microscope according to claim 1, wherein the scattered light removing means is made of a material coated with black alumite.