Test structure for determining the shape and geometrical dimensions of the needle of a scanning probe microscope

 

(57) Abstract:

The test structure consists of a base and placed on its protruding microstructures geometric shapes, made in the form of needles. Needles can take the form of a many-sided pyramid or cone with the angle at the vertex of less than 20o. The radius of curvature of the tip may be less than 10 nm. Needles can be arranged regularly with a constant pitch. The test structure provides obtaining full three-dimensional image of the needle scanning microscope. 3 C.p. f-crystals, 1 Il.

The invention relates to nanotechnology equipment, and more particularly, to devices, providing surveillance and changing the geometrical shape of the needle of a scanning probe microscope (SPM), including atomic force microscopes (AFM).

Known test structure for a scanning probe microscope [1], representing the basis of the monocrystalline material is located on the microstructures in the form of strips of triangular shape in cross section. When scanning this structure in the image generated by the scanning probe microscope, describes the geometric shape of the bands. The radius of curvature of the upper ribs on polucen is Elitny edges of the test structures, we can determine the radius of curvature of the needle used for scanning. However, in this structure, it is possible to get only the radius of curvature of the tip in cross section perpendicular to the direction of the bands.

This disadvantage is not present in the test patterns [2], consisting of a base, which caused many gold particles in the form of balls with a characteristic size of from 5 to 50 nm. After scanning this structure, we get a distorted image of the hemispheres. The shape of the distortion is possible to mathematically calculate the form of three-dimensional image of the needle of the cantilever. However, this structure allows to determine the shape of a needle only within its tip no more than the diameter of the balls used. In addition, it requires complex mathematical calculations.

The purpose of the invention is the development of test structures to determine the shape and geometrical dimensions of the needle of a scanning probe microscope.

The technical result of the invention is to obtain a structure in order to obtain the full three-dimensional invention needle of a scanning probe microscope without additional mathematical operations in the altitude range from a few nanometers to tens of ICRI is strong geometric shapes.

Test structure for determining the shape and geometrical dimensions of the needle of a scanning probe microscope consists of a base and placed on its protruding microstructures of regular geometric shape. It differs in that the protruding microstructure in the form of needles of regular geometric shape. Needles can take the form of a many-sided pyramid or cone with the angle at the vertex of less than 20oand the radius of curvature of the tip is less than 10 nm. Needles can be located on the basis of regularly spaced.

For example, when scanning the sample surface the AFM tip moves in relief microstructure, causing the bending of the beam of the cantilever of the AFM. The amount of bending is measured by the amount of feedback that supports constant the amount of cantilever bending of the beam, which allows to obtain three-dimensional image of the surface. If the cantilever tip of the AFM has a larger angle at the vertex than needle test patterns, when scanning the cantilever tip rests against his side face in the top of the needle test patterns. This leads to bending of the beam of the cantilever, which is compensated by the feedback of the AFM, thus forming a three-dimensional image gr is EPA AFM. The radius of curvature obtained on the image of the needle is equal to the sum of the radii of needles cantilever and test patterns.

If the cantilever tip has an angle at the apex, less than the needle test patterns, when scanning is to be formed, the image is not needle cantilever and needle test patterns, although the radius of curvature of the needle on the received image is also equal to the sum of the radii of needles cantilever and test patterns.

Currently released cantilevers for AFM have needles with angle at the top of the 20oand more and nominal radius of curvature of from 10 to 40 nm. For example, the firm Park Scientific Instruments manufactures nitride cantilevers with needles, in which the angle at the vertex equal to 70o. If the test structure has a needle, in which the angle at the vertex of less than 20owhen the scanning needles above cantilevers will form a complete three-dimensional image of the needles of the cantilevers.

If the needle test patterns will have a radius of curvature less than 10 nm, the image of the needle, obtained by scanning the value of the radius of curvature will be determined by the radius of curvature of the tip of the cantilever. This significantly increases the accuracy of determining the radius krivis is when scanning the image, you can distinguish characteristic features, related to the AFM tip on the characteristics of the test structure. So, do not duplicate the image characteristic features apply only to the test structure. A recurring characteristic features may relate to the AFM tip, and to test the structure.

An example of execution of the test patterns. In Fig. 1 shows an image of the test patterns obtained on a scanning electron microscope in which the needles have the shape of a many-sided pyramid with an angle at the vertex of less than 20oand the radius of curvature of the tip is less than 10 nm. The height of the needle is 0.8 μm. This structure allows to obtain full three-dimensional image of the needles of cantilevers for scanning probe microscopes in the altitude range from a few nanometers up to 0.8 micron. It does not require additional mathematical operations. On the obtained image to determine the geometry parameters of the SPM needle, such as the angle of convergence of the edges in the range from 20 to 180oand the radius of curvature of 10 nm.

Needles of this structure are periodically with a pitch 2,12 μm. This allows to detect at least one needle of the lattice in a single scan using the scanner with a field of 3 μm.

Literature
scope imaging standard for assessing the compressibility of biomolecules." Byophysical J., 1993, v. 65, pp. 1 - 6.

1. Test structure for determining the shape and geometrical dimensions of the needle of a scanning probe microscope, consisting of a base and placed on its protruding microstructures of regular geometric shape, wherein the protruding microstructure in the form of needles.

2. The test structure under item 1, characterized in that the pins have the shape of a many-sided pyramid or cone with the angle at the vertex of less than 20o.

3. Test structure on p. 1, wherein the needles have a radius of curvature of the tip is less than 10 nm.

4. The test structure according to any one of paragraphs. 1-3, characterized in that the needles are regularly spaced.

 

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