JP2870431B2 - Surface morphology analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface morphology analyzer for a sample surface, and more particularly to a surface morphology analyzer using a scanning probe microscope (SPM) for a sample surface where friction and wear are problematic. .

[0002]

2. Description of the Related Art Heretofore, the shape of a sample surface has been evaluated only based on the magnitude relationship of the surface roughness. For example, the center plane average roughness Ra corresponds thereto. Here, Ra is defined as the average value of the distance from the integration center plane to the surface profile, and is an index indicating the amplitude of the undulation of the sample surface.

On the other hand, regarding an apparatus for measuring a sample surface morphology, an SPM represented by an atomic force microscope (AFM) is used.
With the development of the (Scanning Probe Microscope), a technique capable of imaging even the atomic structure of the sample surface has been remarkably developed in recent years.

[0004]

The main origin of the frictional force is the adhesion force acting on the true contact surface of the two objects, and the true contact area is determined by the contact load when the two surfaces are in contact with each other, and the actual contact area.
The plastic flow pressure on the softer of the surfaces is largely determined.

[0005] Since the actual tribological phenomenon is a dynamic phenomenon including elastic deformation, a fairly complicated analysis is required to obtain an accurate understanding. In any case, the contact surface between the two objects is formed by deforming the tip of the relatively high protrusion on the two surfaces, and how low the protrusion depends on the contact load and the difference in the mechanical properties of the surface material. Is determined to be involved in contact.

That is, in understanding the tribological phenomena, the geometrical structure of the outermost surface of the sample (projection) composed of relatively high projection tips, rather than information reflecting the shape of the entire surface such as surface roughness. It is necessary to know the in-plane distribution, the spatial distribution of the protrusions and the shape of the protrusion tips.

[0007] This becomes more important as the microscopic phenomenon occurs under lighter loads. Nevertheless, the shape of the conventional sample surface has been evaluated in most cases merely based on the magnitude relationship of the surface roughness.

As described above, on the other hand, although a device for measuring an extremely fine surface morphology such as SPM has been remarkably developed, a micro-analysis system which handles information obtained therefrom in a tribological manner is scarce. At present, understanding of microscopic friction and wear phenomena on the order of nm (nanometer) or less called tribology is delayed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to combine a surface morphology analysis system with an SPM having an atomic-level resolution to form a relatively high protrusion tip that controls the tribological phenomenon. It is possible to accurately grasp the geometric structure (in-plane distribution of projections, spatial distribution of projections, and tip shape of projections) of the outermost surface of the sample.

[0010]

In order to achieve the above object, a surface morphology analyzer of the present invention is described in brief.
For example, a data processing device constituting an SPM (Scanning Probe Microscope) scans at least the in-plane distribution, spatial distribution, and projection of the sample surface projections as information representing the geometric structure of the outermost surface of the sample. A surface morphology analysis system for deriving an index related to the tip shape is provided.

In the surface morphology analyzer of the present invention, preferably, an SPM (Scanning Probe Microscope; scanning type) is used.
(Probe microscope)
In each case, the in-plane distribution, spatial distribution, and tip
A surface morphology analysis system that derives an index for the edge shape
A surface morphology analysis apparatus, wherein the surface morphology analysis system measures an SPM image of the surface of the sample to be analyzed and detects protrusions on the sample surface based on the obtained SPM three-dimensional profile data. In detecting the protrusions, the slice level of the protrusion height is determined in consideration of the mechanical properties including the contact load and the surface material, and only the protrusions higher than the slice level are extracted. Calculating the projection density (Dp) from the extracted number of effective projections, obtaining the projection height and the projection sharpness from the integral center plane of the surface profile for each of all the detected projections, The average value and standard deviation are calculated as the basic statistics from the data of the protrusion height and the protrusion sharpness regarding the center plane average protrusion height (μph), the standard deviation of the protrusion height (σph), and the average protrusion. A step of deriving a sharpness (μspn) and a standard deviation (σspn) of the protrusion sharpness, respectively. Features.

[0012]

According to the present invention, by using a surface morphology analyzer equipped with a surface morphology analyzer on a data processor such as a computer constituting an SPM having an atomic level resolution, the geometrical shape of the outermost surface of the sample can be improved. Five geometric parameters representing the structure are obtained, and the geometrical structure of the outermost surface of the sample (in-plane distribution of projections, spatial distribution of projections, It is possible to accurately grasp the shape of the projection tip), and it becomes extremely easy to understand the microtribological phenomenon that occurs at the interface between two objects.

That is, according to the present invention, the analysis of microtribological phenomena occurring between two surfaces has remarkably progressed, and the durability and energy saving of various mechanical drive units in which friction and wear are problematic are realized. Help.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments.

FIG. 1 schematically shows the configuration of a surface morphology analyzer according to one embodiment of the present invention when a typical atomic force microscope (AFM) is used as an SPM.

Referring to FIG. 1, the present apparatus comprises an xyz-scanning system 1, a force-displacement converter 2, an optical interference displacement detector 3, and a z-
It comprises an AFM main body composed of a control circuit 4, a computer 5, and a display device 6. The xyz-scanning system 1 includes a drive circuit that performs two-dimensional scanning of the probe in the X and Y directions and maintains a predetermined distance between the sample surface and the probe in the Z direction. Servo control is performed. Also,
The light-wave interference displacement detector 3 detects the displacement of the probe of the force-displacement converter 2 using light interference, and makes the interatomic force on the surface of the sample (sample) constant through the force-displacement converter 2. Try to keep.

The computer 5 is responsible for measurement control and data processing, and incorporates an analysis system 7 for surface morphology analysis.

Referring to FIG. 3, an analysis flow of the surface morphology analysis system according to the present embodiment will be described below.

(1) An SPM image of the sample surface is measured (step 301), and surface protrusions are detected based on the obtained SPM three-dimensional profile data. In detecting the protrusion, the slice level of the protrusion height is determined in consideration of the contact load and the mechanical property value of the surface material, and only protrusions higher than that are extracted (step 302). From the number of extracted effective protrusions,
(A) The projection density Dp is calculated (step 303).

(2) For each of the detected projections, the projection height and the projection sharpness from the integral center plane of the surface profile (the definition of the projection sharpness will be described later) are obtained (step 304).

(3) An average value and a standard deviation are calculated from the data of the projection height and the projection sharpness of the projection obtained in step 304, and (b) the center plane average projection height μph,
(C) The standard deviation σph of the projection height, (d) the average projection sharpness μspn, and (e) the standard deviation σspn of the projection sharpness are derived (step 305).

Here, the protrusion sharpness SPN will be described. Referring to FIG. 2, the inclination angle (tan) from the protrusion apex to ± 50 nm is shown.
θ) are k + and k-, respectively, SPN '= 1/2 (| k + |
+ | K- |), and the SPN ′ is determined in the radial direction of the surface of the sample such as a disk and the circumferential direction orthogonal thereto, and the average value of both is defined as the projection sharpness SPN.

In this way, five shape parameters that accurately represent the geometric structure of the outermost surface of the sample are obtained.

As an actual application example of the surface morphology analyzer according to the present embodiment, an example in which the surface morphology of the hard magnetic disk surface is analyzed will be described below.

The hard magnetic disk device employs a start / stop method called contact start / stop (CSS). In the CSS method, when the disk is stopped, the floating head slider with the magnetic head mounted on the trailing edge is in contact with the disk, and as the disk starts up and the rotational speed increases, the floating head slider changes from the contact sliding state to the hydrodynamic effect. Transition to the complete floating state. For this reason, the tribological characteristics at the interface between the disk and the slider hold the key to the reliability and durability of the device, and the technology for evaluating and controlling the disk surface morphology is extremely important.

A 3.5-inch sputtered carbon disk analyzed using the surface morphology analyzer according to the present embodiment is composed of the following two disks having different substrate surface texture methods. One was subjected to buff polishing with diamond free abrasive grains as substrate texture processing, and this was designated as disk A. The other is obtained by performing a predetermined processing as a two-stage texture after the above-described texture processing.

First, the friction coefficient μ of the disks A and B was measured. Use a slider made of Al ₂ O ₃ TIC for measurement,
The test was performed under a load pressure of 59 mN and a relative speed of 3.14 m / sec. The friction coefficient μ shown below is the average μ per rotation of the disk.
It is.

The coefficient of friction μ of the disk A was 0.18, while the coefficient μ of the disk B was 0.42, which was more than twice that of the disk A.

Next, after AFM measurement of both disks, surface morphology analysis was performed. The AFM measurement conditions are described below. The measurement area is 10 × 10 μm ² , the number of samples is 400 × 400, the in-plane spatial resolution during measurement is 25 nm, and the vertical spatial resolution is 3.052 × 10 ⁻³ nm. Table 1 shows the analysis results. In this analysis, in consideration of the slider load pressure and the plastic flow pressure of the sputtered carbon protective film, the slice level for detecting the protrusion was set to a surface having a relative load area ratio of 0.5%.

[0030]

[Table 1]

From the analysis results shown in Table 1, there is almost no difference between the disks A and B in the index Ra representing the conventional surface morphology, and this index indicates the significant friction coefficient μ between the two disks. It turned out that no information was given to explain the difference.

On the other hand, focusing on the shape parameters obtained by the surface morphology analysis system of the present invention, the standard deviation σ
There is a remarkable difference between the two disks in ph and average protrusion sharpness μspn.

The standard deviation σph and the average protrusion sharpness μspn of the disk B are smaller than those of the disk A. In other words, it can be said that the disc B has a smaller variation in the height of the projections on the outermost surface and the tip of the projection has a flat shape.

The following is presumed from these analysis results. The protrusion height of the outermost surface portion of the disk B is relatively uniform as compared with the disk A, and since the shape of the protrusion tip is flatter, the real contact area with the slider is large. The friction coefficient μ is increased due to the larger capillary force due to the liquid lubricant or the meniscus of the adsorbed water existing at the contact interface of.

[0035]

As described above, according to the present invention (claim 1), the SPM having the resolution of the atomic level derives the shape parameters that carry information on the in-plane distribution, the spatial distribution and the shape of the tip of the projection. By combining the surface morphology analysis system, the geometrical structure of the outermost surface of the sample composed of the relatively high protruding tip that governs the actual tribological phenomenon can be appropriately represented.

For this reason, according to the present invention, the analysis of microtribological phenomena occurring between two surfaces has remarkably progressed, and the durability and energy saving of various mechanical drive units in which friction and wear are problematic are improved. Help in realization.

When the surface morphological analysis system according to the present invention (claim 2) is provided, the SPM
Since five shape parameters that accurately represent the geometric structure of the outermost surface of the sample can be obtained from the image, the analysis of the microtribological phenomenon occurring between the two surfaces is significantly facilitated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a surface morphology analyzer according to one embodiment of the present invention, wherein a surface morphology analyzer is mounted on a data processor (computer) of an atomic force microscope (AFM). FIG.

FIG. 2 is a diagram showing a definition of a projection sharpness evaluated by an analysis system mounted on a surface morphology analyzer according to the present invention.

FIG. 3 is a flowchart showing an analysis flow of the surface morphology analysis system according to one embodiment of the present invention.

[Explanation of symbols]

 1 xyz-scanning system 2 force-displacement converter 3 light wave interference displacement detector 4 z-control circuit 5 computer (with surface morphology analysis system) 6 display device 7 surface morphology analysis system

Continuation of front page (56) References JP-A-8-82632 (JP, A) JP-A-4-113257 (JP, A) JP-A-2-311709 (JP, A) “Nanometer-scale morphology of ductile” mode ground sur face of silicon carbide ceramics with atomic force microscopic ", Yoshio ichida et al. Prog. Cut. Grinding, pp187-192, (1992) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 37/00 G01B 21/30 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A surface morphology analysis system in which a data processing device constituting an SPM (Scanning Probe Microscope) derives at least indices relating to an in-plane distribution, a spatial distribution, and a projection tip shape of a sample surface projection. A surface morphology analysis apparatus comprising: a surface morphology analysis system, wherein the surface morphology analysis system performs S
A step of measuring a PM image and detecting protrusions on the sample surface based on the obtained SPM three-dimensional profile data. In detecting the protrusions, a contact load and a mechanical property value composed of a surface material are taken into consideration. Determining the slice level of the projection height, extracting only the projections higher than the slice level, and calculating the projection density (Dp) from the extracted number of effective projections; Calculating the projection height and the projection sharpness from the integral center plane of the surface profile for each of the above, from the data of the projection height and the projection sharpness of all the projections, calculate the average value and the standard deviation as basic statistics thereof. Deriving a center plane average protrusion height (μph) and a protrusion height standard deviation (σph), an average protrusion sharpness (μspn) and a protrusion sharpness standard deviation (σspn), respectively. From each step, the surface morphology analysis apparatus characterized by deriving the parameters of shapes representing the geometry of the sample outermost surface.