JP2003130774A - Micro hardness meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micro hardness meter that can measure the hardness of a material with high resolution by measuring the pushing-in amount of an indenter against the material with high accuracy of a nm-level by using a laser displacement meter capable of measuring very small areas. SOLUTION: A small piece 9 composed of a nonmetallic material worked to have a surface roughness of <=10 nm is attached to the portion of an indentor holding member (plate spring) 32 upon which laser light is projected from the laser displacement meter 5. Consequently, the displacement of the indentor 2 can be measured with high accuracy without causing errors nor receiving influences from recessed and projecting sections in the portion of the member 32 irradiated with the laser light, even when the displacing direction of the indentor 2 is deflected more or less from the displacement measuring direction of the displacement meter 5. Therefore, the hardness of the material can be measured with high resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-fine hardness tester for measuring the hardness of a minute area of a material.

[0002]

2. Description of the Related Art As a hardness meter for measuring the hardness of a material in a minute area such as the hardness of a thin film on a substrate, a hardness meter called an ultra-fine hardness meter is known. This ultra-micro hardness tester measures the amount of pushing by pushing a minute indenter made of diamond polished into a triangular pyramid into the surface of the material to be measured under a minute pressing force of about 0.2 g or less. The hardness of the material to be measured is determined from the result.

In this type of ultra-fine hardness tester, the indentation amount is naturally extremely small, and the measurement is performed by using a laser displacement meter (a laser displacement meter or a laser light sensor). And a so-called optical critical angle sensor), or a capacitance type displacement meter that measures displacement from the capacitance between a pair of electrodes.

That is, in this type of ultra-micro hardness meter, when an indenter is fixed to one surface side of a metal leaf spring to which displacement is given by an actuator and pressed against the surface of the material to be measured, a laser displacement meter is used. In order to measure the pushing amount of the indenter by irradiating the backside of the indenter mounting surface of the leaf spring with the indenter, if one of the pair of electrodes is used, attach one of the pair of electrodes to the indenter of the leaf spring. An electrode is attached to the back side of the attachment surface and the amount of pushing of the indenter is measured.

[0005]

By the way, in the above-mentioned ultra-micro hardness meter, the hardness resolution of the material to be measured is also improved by measuring the indentation amount with a high resolution. However, there is a problem that as the measurement target area of the displacement meter becomes smaller and the measurement resolution improves, a displacement measurement error occurs due to minute irregularities in the measurement target area.

That is, although the actuator is designed to displace the indenter in a certain direction, such as the vertical direction, and the displacement meter measures the displacement in that direction, it may be erroneously mounted on the device. The displacement direction of the actuator and the displacement measurement direction are slightly displaced. The deviation between the displacement direction of the actuator and the displacement measurement direction is small enough to neglect the displacement measurement error by itself, but when using a laser displacement meter, the displacement of a minute area can be increased by reducing the spot diameter. Although it can be accurately measured, as schematically shown in FIG. 4, the spot position P of the laser light from the laser displacement meter on the leaf spring S changes laterally before and after the displacement by the actuator. I will end up. If there is unevenness due to the surface roughness of the leaf spring S, the difference in height of the unevenness at the spot position P of the laser light before and after the displacement is superimposed on the displacement measurement result, resulting in a measurement error.

Here, in a high-precision ultra-micro hardness meter, the accuracy required to measure the amount of indentation of the indenter is on the order of nm, but the surface of the metal leaf spring is carefully polished. Even if it exists, it is about several tens of nm, which is insufficient for measuring displacement on the order of nm.

The capacitance type displacement meter has a limitation on the size of the electrode and can measure only an average in a wide measuring range of mm order at most, and it is impossible to measure displacement in a minute region with high accuracy. Can not.

An object of the present invention is to be able to measure the indentation amount of an indenter in an ultra-fine hardness meter using a laser displacement meter capable of measuring a minute area with high accuracy on the order of nm, and thus with high resolution. An object of the present invention is to provide an ultra-micro hardness meter capable of measuring the hardness of a material.

[0010]

In order to achieve the above-mentioned object, the ultra-micro hardness meter of the present invention is such that the indenter is pushed into the surface of the material to be measured, and the hardness of the material to be measured is determined from the measurement result of the pushing amount. In addition, in the indenter holding member, the amount of pushing of the indenter is measured by a laser displacement meter that irradiates a laser beam to the back side of the indenter mounting surface of the indenter holding member on which the indenter is mounted. Is characterized in that a small piece made of a non-metallic material having a surface roughness of 10 nm or less is attached to the laser light irradiation site of (1).

Here, in the present invention, either a silicon wafer chip or a glass chip can be suitably used as the non-metallic material attached as a small piece to the laser beam irradiation site of the indenter holding member. (Claim 2).

The present invention does not suppress the surface roughness of a holding member such as a metal leaf spring to which the laser beam from the laser displacement meter is irradiated in order to measure the pushing amount of the indenter, but the laser of the holding member is suppressed. By attaching a small piece of non-metal capable of easily reducing the surface roughness to the light irradiation site, the intended purpose is achieved.

That is, a silicon wafer, glass, or the like can be relatively easily polished to have a surface roughness on the order of nm. In the present invention, the indenter holding member, such as a metal leaf spring, is irradiated with a laser beam. , Surface roughness is 10 nm
A small piece of non-metallic material made of the above-mentioned material or the like that has been polished is attached below. As a result, the surface roughness of the indenter holding member such as a metal leaf spring, which is difficult to reduce the surface roughness, can be improved to some extent in the displacement imparting direction by the actuator and the displacement measuring direction by the laser displacement meter without improving the surface roughness. Even if there is a shift and the irradiation site of the laser light changes, it is possible to eliminate the measurement error of the pushing amount of the indenter due to the unevenness of the irradiation site.

Here, in the present invention, when a glass chip is used as a small piece attached to a laser light irradiation site, it is preferable to deposit a metal thin film on the surface.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of an embodiment of the present invention, in which a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration are shown together.

A sample W, which is a material to be measured, is placed on a sample / sample stage 1 which is electrically movable in the x and y directions which are orthogonal to each other in the horizontal direction, and the vertical z direction.

Above the sample stage 1, an indenter 2 composed of a diamond tip polished in the shape of a triangular pyramid is arranged in a state of being held by an indenter holding mechanism 3. This indenter 2
Is driven in the z direction by driving the actuator 4 together with the indenter holding mechanism 3. The actuator 4 uses a piezoelectric element as a drive source and is displaced by an amount according to the voltage signal supplied from the piezoelectric driver 4a.

A laser displacement gauge 5 is arranged directly above the indenter 2 via the indenter holding mechanism 3. This laser displacement meter 5 is a known one, and it is possible to measure a minute displacement of the measurement site by irradiating the measurement site with a minute laser beam in a spot shape and capturing the reflected light. As the laser displacement meter 5, a so-called optical critical angle sensor, a sensor utilizing interference of laser light, or the like can be used.

The output of the laser displacement meter 5 is amplified by an amplifier 5a, and then taken into a control device 6 mainly composed of a CPU. The control device 6 also supplies a drive control signal to the piezoelectric driver 4a that drives the actuator 4 and the sample stage 1. The control device 6 is also connected to a personal computer 7 for data processing, and the displacement measurement data and the control status of the actuator 4 that are captured by the control device 6 are sequentially captured by the personal computer 7. The hardness of the sample W is obtained by being subjected to data processing, and the result and the like are displayed on the CRT 8.

The detailed structure of the indenter holding mechanism 3 is shown in FIG.
In FIG. 2, (A) is a front view seen from the left side of FIG. 1, (B) is a right side view thereof, (C) is a plan view, and (D).
Is a back view.

The indenter holding mechanism 3 includes an actuator 4
Indenter base 31 attached to the indenter base 3
The indenter 2 is fixed to the lower surface of the plate-shaped spring 2.

The indenter base 31 has a rectangular frame portion 31a.
And the arm portion 3 protruding in one direction from the frame-shaped portion 31a
1b, and the arm portion 31b is attached to the actuator 4. The leaf spring 32 is rectangular and has two slits 32a formed along the longitudinal direction thereof. The frame-shaped portion 31 of the indenter base 31 is provided at both ends in the longitudinal direction.
It is fixed to a. The indenter 2 is fixed to the central portion of the lower surface of the leaf spring 32 with an adhesive or the like. Then, the silicon chip 9 is attached to the central portion of the upper surface of the leaf spring 32, that is, at the position where it directly contacts the indenter 2. The silicon chip 9 is a silicon wafer whose surface has been polished in advance and is cut into small pieces, and the surface roughness is finished to the nm order. Then, the spot of the laser light from the laser displacement meter 5 is irradiated onto the surface of the silicon chip 9 at a position corresponding to the center of the indenter 2.

In the test, the indenter 2 is moved downward in the z direction by driving the actuator 4, and the indenter 2 is pushed into the surface of the sample W. The momentary lowering amount of the indenter 2 at this time is measured by the laser displacement meter 5 which irradiates the silicon chip 9 on the upper surface of the leaf spring 32 with a laser spot. At this time, as described above, even if the laser spot position on the silicon chip 9 changes due to the displacement of the indenter 2 due to an assembly error of the device, etc., the silicon chip 9 has a surface of nm order. Since it is finished in roughness, the measurement error due to the unevenness of the surface is significantly smaller than in the past.

Polishing the surface roughness of the silicon chip 9 to the nm order is extremely easy as compared with the case of polishing the surface of a metal such as the leaf spring 32. This can be achieved, and therefore mounting the silicon chip 9 having such a surface roughness on the order of nm does not lead to an increase in the device cost.

Here, in the above embodiment, the leaf spring 3 is used.
The silicon chip 9 was used as a small piece having a surface roughness of nm order attached to the upper surface of No. 2, but the present invention is not limited to this, and the surface roughness can be relatively easily polished to nm order. Even if a metal material such as a glass chip is used, the same effect can be obtained.

When using a glass chip, practically,
As shown in the schematic cross-sectional view of FIG.
It is preferable to use the glass chip 90 in which the metal thin film 92 is vapor-deposited on the glass substrate 91 whose surface roughness is finished to the order of nm, and this configuration can ensure the reflection of the laser beam.

[0027]

As described above, according to the present invention, an ultrafine device equipped with a laser displacement gauge for irradiating the surface of the member holding the indenter on the side opposite to the indenter mounting surface with laser light to measure the displacement In the small hardness tester, a non-metallic small piece such as a silicon chip having a surface roughness of 10 nm or less is attached to the laser light irradiation position. Therefore, the displacement measurement direction by the laser displacement meter and the displacement direction of the indenter Even when the laser beam irradiation position moves due to the displacement of the indenter due to device assembly error, etc., the displacement measurement error caused by the unevenness of the laser beam irradiation surface is Can be significantly reduced. As a result, the pushing amount of the indenter can be measured with high accuracy on the order of nm, and the hardness of the material can be measured with high resolution.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, in which a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration are shown together.

FIG. 2 is an explanatory diagram of a detailed structure of an indenter holding mechanism 3 according to an embodiment of the present invention, (A) is a front view, (B) is a right side view thereof, (C) is a plan view, and (D) is. It is a back view.

FIG. 3 is a schematic cross-sectional view of another example of a small piece having a surface roughness of nm order that can be adopted in the present invention.

FIG. 4 is an explanatory diagram of a displacement measurement error caused by movement of a laser spot position of a laser displacement meter.

[Explanation of symbols]

1 Sample stage 2 indenter 3 Indenter holding mechanism 31 Indenter base 32 leaf spring 4 actuators 4a driver 5 Laser displacement meter 5a amplifier 6 control device 7 personal computer 8 CRT 9 Silicon chip 90 glass chips 91 glass substrate 92 Metal thin film W sample

Claims (2)

[Claims] 1. An indenter is pressed into the surface of a material to be measured, the hardness of the material to be measured is determined from the measurement result of the amount of indentation, and the indentation amount of the indenter is the indenter of an indenter holding member to which the indenter is mounted. In an ultra-fine hardness meter that measures with a laser displacement meter that irradiates a laser beam on the back side of the mounting surface, the surface of the indenter holding member where the laser beam is irradiated has a surface roughness of 1
An ultra-fine hardness tester, to which a small piece made of a non-metal material processed to 0 nm or less is attached. 2. The ultra-fine hardness tester according to claim 1, wherein the small piece made of a non-metallic material is one of a silicon wafer chip and a glass chip.