JP3624607B2 - Surface hardness measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface hardness measuring apparatus for measuring physical property values such as surface hardness of a sample.
[0002]
[Prior art]
For example, surface hardness measuring devices that measure the Vickers hardness, Knoop hardness, etc. of samples are known. In particular, local thin films or bulk materials of soft thin films or bulk materials formed on substrates such as semiconductor devices and magnetic disks are known. In order to measure the hardness of the surface, a surface hardness measuring device such as a micro hardness tester having a very small test load is used.
[0003]
In such a surface hardness measuring apparatus, the indenter is attached to the cantilever, and the indenter is moved toward the sample placed on the mounting table by a piezoelectric element or the like, and the indenter is located above the indenter from the time when the indenter contacts the sample. The displacement to the sample is measured on the order of μm or nm with a non-contact displacement meter such as an optical displacement meter or a capacitance displacement meter, and the load applied to the sample from the indenter is measured by the displacement of the indenter and the cantilever. The calculation is performed based on the spring constant, thereby measuring the hardness of the sample.
[0004]
Here, the contact of the indenter with the sample is detected as follows. That is, the moving speed of the indenter changes before and after the indenter contacts the sample. Therefore, as shown in FIG. 5, the displacement of the indenter with respect to the elapsed time is plotted, and the intersection point X0 between the straight line L1 connecting the points Q1 and Q2 before the speed change and the straight line L2 connecting the points Q10 and Q20 after the speed change. And this point X0 is detected as a point where the indenter contacts the sample.
Then, after detecting this contact point, the indenter is lowered at a predetermined load measure, while the load by the indenter is detected and the indenter is lowered at the load speed until a predetermined set load is reached, thereby forming an indentation on the sample. To do.
[0005]
[Problems to be solved by the invention]
However, in the case of detecting the contact point between the indenter and the sample as described above, the contact point is obtained by detecting two points Q10 and Q20 shown in FIG. 5 after the indenter and the sample are in contact with each other. For this reason, the measurement is actually started after the contact.
An object of the present invention is to provide a surface hardness measuring device capable of starting measurement immediately after contact between an indenter and a sample.
[0006]
[Means for Solving the Problems]
Referring to FIGS. 1 and 2 showing an embodiment, the invention of claim 1 includes an indenter 4, a cantilever 3 in which the indenter 4 is disposed, and load means 17 that distorts the cantilever 3. , a mounting table 20 for holding a sample T, and a displacement meter 11 which outputs a displacement signal by measuring the displacement of the indenter 4, pushing the indenter 4 in the sample T surface, the pushing force and pushing depth該圧Ko 4 Prior to measuring the physical property value of the sample based on the above, the indenter 4 is applied to a surface hardness measuring device having a measurement start position at a contact point where the indenter 4 and the sample T are in contact with each other. 4 is set as a reference position, the mounting table 20 is raised, the change of the displacement signal of the displacement meter 11 is judged, and the detection control means 30 for detecting that the indenter 4 has contacted the sample T is provided. Achieve the goal.
[0007]
In the invention of claim 2, the reference position is a position where the output of the displacement signal of the displacement meter 11 is zero, and the detection control means 30 moves the mounting table 20 upward by the first movement amount so that the displacement signal is zero. The movement of the mounting table 20 is stopped when the position of the mounting table 20 changes, the mounting table 20 is lowered from the stop position by the second movement amount, and the mounting table is moved in the vertical direction of the lowered direction to search for a contact point. The initial position is set.
[0008]
In the invention of claim 3, the reference position is a position where the indenter 4 is moved to the mounting table 20 side by a predetermined amount and a displacement signal is output from the displacement gauge 11, and the mounting table 20 is smaller than the first moving amount. When the displacement signal changes, the mounting table 20 is stopped, the stop position is detected as a position where the indenter 4 contacts the sample T, and the contact position is set as a measurement start position .
[0009]
In the section of the means for solving the above-described problems for explaining the configuration of the present invention, the drawings of the embodiments of the invention are used for easy understanding of the present invention. It is not limited.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a load mechanism in the surface hardness measuring apparatus according to the present embodiment.
As shown in FIG. 1, the load mechanism 6 of the surface hardness measuring apparatus according to the present embodiment has a displacement gauge adjusting mechanism 9 attached to a through-hole 8A formed in a U-shaped load mechanism main body 8. The displacement meter adjustment mechanism 9 is provided with a plunger 10 that reciprocates in the load axis Z direction by a moving mechanism (not shown). A mounting table 20 for mounting the sample T is attached to the upper surface of the lower portion 8B of the load mechanism main body 8. The mounting table 20 can be moved in a load axis Z direction and a two-dimensional direction (an X direction perpendicular to the paper surface and a Y direction which is the left-right direction of the paper surface) by a moving mechanism (not shown), and particularly in the load axis Z direction. The actuator 21 can be finely displaced. Further, the mounting table 20 can hold the sample T by magnetic force. The distal end of the plunger 10 is in contact with a displacement meter mounting portion 12 having a displacement meter 11 fixed to the lower surface. The displacement meter mounting portion 12 is urged upward in FIG. 1 by a spring 13, whereby the displacement meter 11 moves up and down along the load axis Z direction as the plunger 10 moves up and down.
[0011]
A piezoelectric actuator 17 attached in the frame 14 is provided on the left side of the load mechanism 6 in FIG. The upper end of the piezo actuator 17 is fixed to the load mechanism main body 8 with a screw 16 via a ball seat 15, and the frame 2 is attached to the lower end. An indenter 4 is attached to the frame 2 via a double-supported cantilever 3 made of a leaf spring. The frame 14 extends in the load axis Z direction when the piezo actuator 17 is energized, and contracts in the load axis Z direction when the energization is interrupted. Thereby, the indenter 4 attached to the frame 2 moves up and down along the load axis Z direction according to the displacement of the piezo actuator 17. Further, a gauge (not shown) for measuring the displacement of the piezo actuator 17 is attached to the frame 14.
[0012]
Next, the operation of the present embodiment will be described. FIG. 2 is a block diagram showing the configuration of the processing unit in the surface hardness measuring apparatus according to the present embodiment, and FIGS. 3 and 4 are flowcharts for explaining the operation of the present embodiment. As shown in FIG. 2, the processing unit includes a CPU 30 and a memory 31. The above-described piezo actuators 17 and 21 and the displacement meter 11 are connected to the CPU 30.
First, the sample T is mounted on the upper surface of the mounting table 20 in step S1. Then, the surface of the sample T is brought into focus with an optical microscope (not shown). In step S3, the mounting table 20 is once lowered for safety when the mounting table 20 is moved. In step S4, the mounting table 20 is moved in the X and Y directions to move the sample T below the indenter 4. The steps S1 to S4 are not performed by the CPU 30, but are performed when the user manually drives the mounting table 20.
[0013]
In the next step S5, the piezo actuator 21 of the mounting table 20 is driven to move the mounting table 20 upward by one step (for example, 21 nm). In step S <b> 6, it is determined whether or not the sample T has contacted the indenter 4 and a displacement signal has been output from the displacement meter 11. When step S6 is denied, it returns to step S5 and repeats the process of step S5 and step S6. When step S6 is affirmed, the position of the mounting table 20 in the Z direction at the time when the displacement signal is output from the displacement meter 11 in step S7 is stored as the initial position. In the next step S8, the mounting table 20 is lowered by 5 μm to separate the sample T from the indenter 4, and in step S9, the mounting table 20 is moved in the XY direction, for example, 20 μm, and the indenter 4 and the sample T in the above step S6 are moved. The position of the indentation formed on the sample T by the contact is moved from below the indenter 4. In step S10, the cantilever 3 is moved downward by one step (for example, 1 nm). In this state, the output from the displacement meter 11 is a position that is lowered by 1 nm from the initial position.
[0014]
In the next step S11 (see FIG. 4), in order to detect contact between the indenter 4 and the sample T, the mounting table 20 is moved upward by one step (for example, 1 nm). Then, in the next step S12, whether or not the cantilever 3 has been displaced from the displacement of 1 nm is determined from the displacement signal output from the displacement meter 11. When step S12 is denied, it returns to step S11 and repeats the process of step S11 and step S12. If step S12 is affirmed, it is assumed that the indenter 4 is in contact with the sample T at this time point, and in the next step S13, the piezo actuator 17 is extended according to a predetermined load speed. In step S13, the displacement meter 11 is also reset to zero. In step S14, it is determined whether the output of the displacement meter 11 is positive, negative, or zero.
[0015]
When the output of the displacement meter 11 is positive in step S14, that is, when the indenter 4 is pressed by the sample T and the cantilever 3 is displaced upward, the position in the Z direction is not displaced regardless of the extension of the piezoelectric actuator 17. In step S15, the mounting table 20 is feedback-controlled so that the mounting table 20 is lowered. If the output of the displacement meter 11 is zero in step S14, the mounting table 20 is stopped in step S16. When the output of the displacement meter 11 is negative in step S14, the mounting table 20 is raised in step S17, contrary to the case where the output of the displacement meter 11 is positive. In this way, by performing feedback control of the movement of the mounting table 20 in the Z direction, the strain applied to the cantilever 3 can maintain a value corresponding to the load speed.
[0016]
In step S18, it is determined whether or not a predetermined test condition such as the holding time of the indenter 4 and the maximum load has been reached. That is, the displacement amount after the indenter 4 contacts the sample T is measured by the displacement meter 11, and the product of the displacement amount and the spring constant of the cantilever 3 is calculated by the CPU 30, and the load on the sample T is calculated. . Then, when the calculated load becomes a predetermined maximum load or is held at a predetermined load for a predetermined time, step S18 is affirmed as having reached a predetermined test condition. On the other hand, when Step S18 is denied, it returns to Step S13 and repeats processing of Step S13-Step S17.
[0017]
In this manner, after the load on the sample T by the indenter 4 is completed, the energization to the piezo actuator 17 is interrupted, the indenter 4 is moved away from the sample T, and the load on the sample T is terminated. Then, the sample T on which the indentation 4 is formed is removed from the mounting table 20, and the shape of the indentation is measured with a microscope or the like provided separately, and the shape and the load on the sample T calculated by the calculation device are used. The hardness of the sample T is calculated. Then, the test result data is stored in the memory 31 in step S19, and the process is terminated.
[0018]
As described above, when the test is started by lowering the cantilever 3 and applying a displacement to the indenter 4 before the indenter 4 and the surface of the sample T come into contact with each other, the displacement of the indenter 4 is restored by the feedback control described above. Therefore, the mounting table 20 rises. When the sample T comes into contact with the indenter 4 and a load is generated, the cantilever 3 is distorted, and the position of the indenter 4 changes. Therefore, this displacement is detected by the displacement meter 11 and the sample T and the indenter 4 are brought into contact with each other. Can be detected.
Therefore, in this embodiment, the indenter 4 and the sample T are compared with those in which measurement is started after a while after the indenter 4 and the sample T are actually in contact with each other as in the conventional surface hardness measuring device. Since the measurement can be started immediately after contact with each other, that is, the position where the indenter 4 and the sample T are in contact can be set as the measurement start position, the hardness of the sample T can be accurately measured. it can.
[0019]
In the above embodiment, the CPU 30 performs processing in accordance with the flowcharts shown in FIGS. 3 and 4. However, the circuit for performing the feedback control described above is provided, and hardware processing is performed by this circuit. You may make it perform.
Moreover, in the said embodiment, although the cantilever 3 was made into the cantilever type, a cantilever type may be sufficient.
[0020]
In correspondence between the above embodiment and the claims, the piezo actuator 17 constitutes a load means, and the CPU 30 constitutes a detection control means.
[0021]
【The invention's effect】
As described above in detail, according to the present invention, since the output change of the displacement signal of the displacement meter is determined and it is detected that the indenter has contacted the sample, the indenter contacts the sample as in the prior art. Obtain a straight line indicating the change in the speed of the indenter before and after the test, and compare the point where the intersection of this line is the contact point between the indenter and the sample, and start measuring the hardness immediately after the contact between the indenter and the sample. That is, the position where the indenter 4 and the sample T are in contact can be set as the measurement start position, and the hardness of the sample can be measured more accurately.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a load mechanism of a surface hardness measuring device according to the present embodiment. FIG. 2 is a block diagram showing a configuration of a processing unit in the surface hardness measuring device according to the present embodiment. Flowchart showing the processing performed in this embodiment (part 1)
FIG. 4 is a flowchart (part 2) showing processing performed in the embodiment.
FIG. 5 is a diagram for explaining a conventional example for obtaining a contact point between an indenter and a sample.
3 Cantilever 4 Indenter 6 Load mechanism 11 Displacement meter 17, 21 Piezo actuator 20 Mounting table 30 CPU
31 memory

Claims (3)

With an indenter ,
A cantilever provided with the indenter;
Loading means for distorting the cantilever;
A mounting table for holding the sample;
And a displacement gauge for outputting a displacement signal by measuring the displacement of the indenter,
Prior to measuring the physical property value of the sample based on the indentation force and indentation depth of the indenter, and pressing the indenter into the sample surface, a surface having a contact point where the indenter and the sample are in contact as a measurement start position A hardness measuring device,
In order to set the measurement start position, the indenter is set to a reference position and the mounting table is raised, and the change in the displacement signal output from the displacement meter is determined to detect that the indenter has contacted the sample. A surface hardness measuring apparatus comprising a detection control means. The reference position is a position where the output of the displacement signal of the displacement meter is zero,
The detection control means moves the mounting table upward by a first movement amount, stops the upward movement of the mounting table when the displacement signal changes from zero, and moves the mounting table to the stop position. 2. The surface hardness measuring device according to claim 1, wherein the second movement amount is lowered , and the mounting table is moved in the vertical direction of the lowered direction to set the contact point search initial position. The reference position is a position where the indenter is moved to the mounting table side by a predetermined amount and a displacement signal is output from the displacement meter, and the mounting table is moved by a third movement amount smaller than the first movement amount. When the displacement signal changes, the mounting table is stopped, the stop position is detected as a position where the indenter contacts the sample, and the contact position is set as the measurement start position. The surface hardness measuring device according to claim 2 .

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