JPH07248285A - Surface property evaluation device - Google Patents

Abstract

(57) [Summary] [Purpose] To evaluate the surface properties of the object to be evaluated without being affected by thermal expansion. In a surface physical property evaluation apparatus for calculating the relationship between the load applied to the indenter 10 by the load means 1 by the calculation means 14 and the displacement amount of the indenter measured by the displacement amount measurement means 4, the calculation means 14 covers the indenter. From the displacement amount due to thermal expansion of the indenter measured when the indenter was brought into contact with the surface of the evaluation object, the time change rate indicating the "displacement amount per hour of the indenter due to thermal expansion" is obtained. Then, from this rate of change, the displacement of thermal expansion included in the displacement amount measured when the indenter is pushed is assumed, and the displacement amount is removed from the displacement amount at the time of pushing to calculate the true displacement amount of the indenter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for evaluating the physical properties of a substance under high temperature by continuously pushing the surface of the substance under high temperature.

[0002]

2. Description of the Related Art Conventionally, as one method for evaluating the physical properties of a substance (hereinafter referred to as an object to be evaluated), there has been a method of measuring the hardness of the surface of the object to be evaluated. There are various types of hardness, such as Vickers hardness, Brinell hardness, and Knoop hardness, depending on the measuring method, and various hardness meters (hardness testers) are used according to the measuring method. For example, in the Vickers hardness tester, the indenter is pushed into the surface of the object to be evaluated with a predetermined load P,
Indentation of the evaluation object formed at that time (square in this case)
Is measured (diagonal length d) using an optical microscope or the like. Then, the hardness (Vickers hardness Hv) of the object to be evaluated was determined from the load P and the length d of the diagonal line of the indentation. When measuring the hardness of an object to be evaluated, such as a thin film, with a thickness of several μm or less, use a micro Vickers hardness tester (micro hardness tester) with a particularly small load value and indenter to measure the hardness with a micro load of several gf. The indenter was pushed into the evaluation object and the dimension of the indentation was measured. However, in this case, since the size of the indentation becomes small and measurement becomes difficult, an error easily occurs in the obtained hardness value, and there is a problem in accuracy. Further, even when measuring a hardness other than Vickers hardness, for example, in the case of obtaining Brinell hardness and Knoop hardness, it is necessary to measure the dimension of the indentation when obtaining the hardness, and therefore the same problem has occurred. .

Therefore, instead of measuring the size of the indentation,
A method of evaluating the physical properties (hardness) of the object to be evaluated by measuring the amount of indentation (indentation depth) of the object to be evaluated and determining the relationship between the indentation load and the amount of indentation has been proposed. In this method, the indenter is pushed into the surface of the object to be evaluated by a load means capable of changing a minute load arbitrarily. At that time, the pushing amount of the indenter is measured by the displacement amount measuring means, and based on the obtained pushing amount and the load applied by the loading means, the process of deformation on the surface of the object to be evaluated is related to the load and the pushing amount. Ask as. And
The physical properties of the object to be evaluated were evaluated from the relationship between the obtained load and the pushing amount.

[0004]

By the way, when the physical properties of the object to be evaluated are evaluated at high temperature, each component of the measuring system including the object to be evaluated causes thermal expansion. Therefore, in the conventional method for evaluating the physical properties of the evaluated object from the relationship between the indentation load and the indented amount, for example, when the support table supporting the evaluated object causes thermal expansion, the evaluated object is displaced. Therefore, the measured displacement amount (indentation amount) of the indenter includes this thermal expansion value. Further, when the indenter comes into contact with the object to be evaluated, heat of the object to be evaluated is transferred to the indenter, so that thermal expansion also occurs in this indenter. As a result, due to the effect of thermal expansion, the relationship between the measured displacement amount and the load applied when pushing with the indenter does not show the original relationship of the object to be evaluated, which causes a problem that the physical properties of the object to be evaluated cannot be accurately evaluated. . This problem has a great influence on the accuracy, particularly when evaluating the physical properties of an object to be evaluated, such as a thin film, having a thickness of several μm or less.
It is possible to prevent such a problem by measuring the displacement amount after equilibrating each component of the measurement system at a predetermined temperature. However, in this case, the evaluation work cannot be performed until the equilibrium state is reached, which causes a new problem that the efficiency is extremely deteriorated. The present invention aims to solve these problems.

[0005]

In order to solve the above-mentioned object, in the first invention (the invention according to claim 1), an indenter pushed into the surface of the object to be evaluated and a load for applying a predetermined load to the indenter. In the surface physical property evaluation device, which has a means, a displacement amount measuring means for measuring a displacement amount of the indenter, and a computing means for obtaining a relationship between a load applied to the indenter by the loading means and a displacement amount of the indenter, From the displacement amount due to the thermal expansion of the indenter measured when the indenter is brought into contact with the surface of the object to be evaluated by the calculating means, the time change rate indicating the "displacement amount per hour of the indenter due to thermal expansion" is obtained, Assuming the amount of displacement due to thermal expansion included in the amount of displacement measured when the indenter is pushed from this rate of change, the displacement due to thermal expansion is removed from the amount of displacement at the time of pushing and the true amount of displacement of the indenter is assumed. And calculate The true displacement to have to determine the relationship between the load.

Further, in the second invention (the invention according to claim 2), the indenter pushed into the surface of the object to be evaluated, the load means for applying a predetermined load to the indenter, and the displacement for measuring the displacement amount of the indenter. The surface physical property evaluation device is constituted by the amount measuring means and the calculating means for obtaining the relationship between the load applied to the indenter by the load means and the displacement amount of the indenter, and the calculating means moves the object to be measured. From the displacement amount in the predetermined direction due to the thermal expansion of the measured object measured by the displacement amount measuring means within the previously set first time, the "due to the thermal expansion of the measured object at the first time" is calculated. The relationship between the displacement amount and the time is obtained to calculate the rate of change over time of the displacement amount, and the displacement measured by the displacement amount measuring means within a second time set within the time range in which the relationship holds. The amount of displacement of the measured object in the predetermined direction is In addition to the amount of displacement measured within 1 time, the thermal expansion of the object to be measured in the predetermined direction generated within the 1st and 2nd time from the rate of change with time and the 1st and 2nd time. The true movement amount of the object to be measured is obtained by obtaining the total amount of the amounts and subtracting the total amount from the sum of the displacement amount measured in the first time period and the displacement amount measured in the second time period. Was calculated.

[0007]

When the object to be evaluated is in a certain high temperature state, the thermal expansion amount generated in the indenter in contact with the object to be evaluated can be approximated by a linear equation with time as a variable within a certain time. it can. For example, if the time change of the movement amount caused by the thermal expansion of the indenter is f (t), the time change f
(T) can be expressed as f (t) = α · t (α: constant) (hereinafter, this formula will be referred to as a formula). Α in the equation represents the rate of change in the amount of thermal expansion of the indenter per unit time (referred to as the rate of change over time), and is a value determined by the material of the indenter, the surrounding conditions, and the like.

When the indenter is pushed into the object to be evaluated, the indenter is pushed into the object to be evaluated by a load means or the like with the passage of time. Therefore, the displacement amount H of the indenter at this time can be expressed as a function of time, H = D (t) (hereinafter, this formula is a formula). Then, if the time for which the indenter is pushed into the object to be evaluated is within the range that can be approximated by the above-mentioned primary expression (equation), the thermal expansion amount generated in the indenter during this time can always be regarded as occurring based on the expression. . Therefore, the amount of thermal expansion generated in the indenter during the time when the indenter is pushed in can be obtained by using the formula by the product of the indenter pushing time (that is, the time when the pushing amount is measured) and the time change rate. . As a result, when the displacement amount of the indenter is continuously measured from the time when the indenter is contacted with the object to be evaluated, from the start of displacement amount measurement to the time when the indenter is pushed in with a predetermined load (time between these is t) In addition, the total amount of thermal expansion generated in the indenter is obtained from the product of the time change rate α and t.

Therefore, assuming that the true displacement amount of the indenter that does not include thermal expansion is L (t), the true displacement amount L (t) is calculated from the displacement amount H at the time when the indenter is pushed at the time of starting the measurement. To the total amount of thermal expansion that has occurred up to that time. That is, L (t) is L (t) from the above equation.
= D (t) -f (t) = D (t) -α · t (hereinafter, this formula is referred to as a formula). This makes it possible to accurately obtain the true displacement amount H of the indenter that does not include thermal expansion.

The value of the time t to which the above equation can be applied when measuring the amount of displacement is determined in advance by conducting experiments or the like. In general, if the time for measuring f (t) (the time during which the indenter is kept in contact with the object to be evaluated) is several tens of seconds, the pushing amount of the indenter may be measured within a few seconds after that.

[0011]

EXAMPLE FIG. 1 is a schematic sectional view showing the structure of a surface physical property evaluation apparatus which is an example of the present invention. The surface physical property evaluation apparatus of the present embodiment includes a mounting table 2 on which an object 8 to be evaluated is placed, an indenter 10, a load means 1 for pushing the indenter 10 into the object 8 to be evaluated with a predetermined load, and an object 8 to be evaluated at a predetermined temperature. Heating means 3 for heating to a high temperature, displacement amount measuring means 52 for measuring the displacement amount of the indenter 10,
And a calculation means 14. In addition, the mounting table 2,
A vacuum vessel 5 accommodating the indenter 10, the loading means 1, and the heating means 3, and an exhaust means 2 for setting the inside of the vacuum vessel 5 to a predetermined pressure.
Equipped with 3. The indenter 10 has a diameter of about 10 mm and a length of about 30 mm.
One end of cylindrical tantalum (Ta) was formed into a triangular pyramid shape and used.

FIG. 2 shows the load means 1 and the displacement amount measuring means 52.
It is a schematic diagram showing a configuration of. The load means 1 includes a drive unit 11
And an A / D converter 13. The drive unit 11 is configured to apply a predetermined force to the indenter 10 in the direction in which the evaluation object 8 is pushed, and is connected to the calculation means 14 via the A / D converter 13. The drive unit 11 can be configured to use, for example, a solenoid, and in this case, the load applied to the indenter 10 is controlled by adjusting the value of the current passed through the coil. The load set by the calculation means 14 is analog-digital converted by the A / D converter 13 and input to the drive unit 11. The drive unit 11 inputs this converted output and applies an arbitrary load to the indenter 10,
0 moves in the direction in which this load is applied and is pushed into the object to be evaluated 8 by the arbitrary load. The information indicating the load applied to the indenter 10 is configured to be output to the calculation means 14.

The displacement amount measuring means 52 includes a measuring terminal 4 installed inside the vacuum container 5 and a displacement meter 15 installed outside the container 5.
And the amount of displacement of the indenter 10 is measured without contact. Indenter 1
The displacement amount of 0 is measured as the distance from the displacement reference surface 16 to the tip of the measurement terminal 4 with the upper part of the indenter 10 as the displacement reference surface 16. This displacement amount measuring means 52 is the second
It is connected to the calculating means 14 via the A / D converter 17 and outputs information indicating the measured displacement amount of the indenter 10 to the calculating means 14.

FIG. 3 shows the heating means 3 and the positioning mechanism 5.
3 is a schematic diagram showing the configuration of FIG. The heating means 3 is the mounting table 2
A heating unit 9 installed on the upper part of the
A voltage converter 21 and a temperature controller 22 are provided. The evaluation object 8 is placed on the heating unit 9. Heating part 9
Is composed of, for example, a heater controlled by electric power or the like, and can heat the evaluation object 8 to a predetermined temperature and keep the evaluation object 8 constant at that temperature. The temperature sensing means 20 is attached near the contact portion with the object to be evaluated 8 and measures the temperature of the object to be evaluated 8. This temperature sensing means 20
For example, a thermocouple or the like can be used. Heating part 9
Is connected to the temperature adjusting means 22 via the voltage converting means 21. Further, the temperature sensing means 20 is also the temperature adjusting means 2.
Connected to 2. In addition, these voltage conversion means 21,
Both the temperature adjusting means 22 are installed outside the vacuum container 5. The temperature adjusting means 22 is connected to the arithmetic unit 14, and the arithmetic unit 14 preliminarily sets a temperature increase program for the object 8 to be evaluated, thereby heating the object 8 to an arbitrary temperature. The temperature can be maintained.
That is, the temperature sensing means 20 inputs the temperature of the evaluation object 8 measured by the temperature sensing means 20, and this temperature is calculated by the computing means 1
By controlling the heating unit 9 via the voltage conversion means 21 so that the value set in 4 is obtained, the object 8 to be evaluated is set to a predetermined temperature.

The surface characteristic evaluation apparatus of this embodiment has the optical microscope 7 and the positioning mechanism 53 so that the surface of the object 8 to be evaluated can be observed. The positioning mechanism 53
The object to be evaluated 8 is set at a predetermined position by moving the mounting table 2 by means of the support portion 54 which is installed outside the vacuum container 5 and is arranged in the container 5 so as to maintain the sealed state of the container 5. be able to. The positioning mechanism 53 is composed of a rotation mechanism section 25, a horizontal movement mechanism section 19, and a vertical mechanism section 18. The rotation mechanism unit 25 rotationally moves the mounting table 2 around the rotation axis C between below the objective lens (not shown) of the optical microscope 7 and below the center of the indenter 10. The horizontal movement mechanism unit 19 moves the mounting table 2 horizontally (XY directions in the drawing). The vertical mechanism unit 18 moves the mounting table 2 in the vertical direction (Z direction in the drawing). The positioning mechanism 53 is controlled by the calculating means 14 so that the evaluated object 8 is at a desired position. The optical microscope 7 is installed outside the vacuum container 5, and the evaluation object 8 can be observed through an observation window 6 made of quartz glass provided in a part of the vacuum container 5. With this optical microscope 7 and the stage 53, it is possible to confirm the position where the indenter 10 is pushed in and to observe the indentation state of the indenter 10.

The calculating means 14 obtains the time change of the load applied to the indenter 10 by the load means 1 in real time, and based on this time change and the displacement amount of the indenter 10 measured by the displacement amount measuring means 52, The true displacement amount of the indenter 10 is obtained. Then, the relationship between the true displacement amount and the load is obtained and stored, and when desired, the relationship is displayed on a display means (not shown). A personal computer or the like, for example, can be used as the computing means 14.

Here, an example of an evaluation procedure for the object 8 to be evaluated in this embodiment will be described. FIG. 4 shows the displacement amount measuring means 52.
FIG. 4 is a diagram showing a change with time of a measured value in, where the vertical axis represents the output value (unit of length, for example, μm) from the displacement meter and the horizontal axis represents time. In addition, the displacement amount measuring means 52 is the displacement reference plane 1
The output is set to increase as the distance from 6 to the tip of the measuring terminal 4 increases.

First, the object 8 to be evaluated is placed on the heating unit 9 provided on the placing table 2. Then, the heating means 3 heats the object 8 to be evaluated to a temperature preset in the calculating means 14 (here, the maximum is about 800 ° C.), and the temperature of the object 8 to be evaluated becomes constant at this set temperature. To maintain. After that, the positioning mechanism 53 moves the mounting table 2 so that the object to be evaluated 8 is positioned within the visual field of the optical microscope 7. Then, by controlling the positioning mechanism 53 and observing the surface of the object 8 to be evaluated, the evaluation position of the object 8 to be evaluated (the position where the indenter 10 is pushed) is determined. After that, the rotation mechanism unit 25 rotationally moves the mounting table 2 so that the evaluation position is located below the center of the indenter 10. The positioning mechanism 53 is preset so that the evaluation position determined by the microscope 7 before and after the rotational movement and the position below the center of the indenter 10 correspond to each other.

Next, the displacement reference surface 16 (that is, the indenter 10)
While the displacement amount measuring means 52 measures the distance (displacement amount) moved by, the calculating means 14 controls the loading means 1 to apply a predetermined (here, downward) load to the indenter 10. As a result, the indenter 10 gradually moves downward (in the direction of the applied force), so that the distance from the displacement reference surface 16 to the tip of the measuring terminal 4 increases. During this time, the time change of the measured value by the displacement amount measuring means 52 is displayed on the display means of the calculating means 14 as a curve AB in FIG. And
When the indenter descends to a certain distance, the indenter 10 becomes the object to be evaluated 8
Touch the surface of. When the indenter 10 comes into contact with the object 8 to be evaluated, the load required to move the indenter 10 increases, so that the relationship between the measured value and time changes (point B in FIG. 4). When this change is confirmed on the display means of the calculation means 14, the load applied to the indenter 10 by the load means 1 at that time is kept constant, and the indenter 10 is evaluated for several tens of seconds (time T1).
Keep in contact with the surface of. In the present embodiment, this T1 is 10 to
It was set in the range of 20 seconds. The contact between the indenter 10 and the object to be evaluated 8 causes heat to be transferred from the object to be evaluated 8 to the indenter 10, and the indenter 1
0 causes thermal expansion. Further, the evaluation object 8 itself and the mounting table 2 on which the evaluation object 8 is mounted are also thermally expanded. The displacement amount measuring means 52 measures the displacement amount (measured value) of the reference surface 16 due to this thermal expansion, and outputs the result to the calculating means 14. During the T1, the displacement reference surface 16 moves toward the measurement terminal 4, so that the distance between the two becomes narrower and the output (voltage value) from the displacement meter decreases. The calculation means 14 obtains the time change of the displacement amount of the reference surface 16 based on this displacement amount. At this time, the time change f (t) of the displacement amount due to thermal expansion
Becomes like a straight line BC in FIG. 4, and can be expressed by a linear expression like the above expression. The calculation means 14 measures the measured value f
The time change rate α of the displacement amount is calculated from (t) and the time t, and this is stored. This time change is a value indicating the time change of the thermal expansion amount including the evaluated object 8, the mounting table 2, and the indenter 10. Then, even after a certain period of time (several seconds), it can be considered that the linear equation (formula) is established and α is constant (dotted line portion in FIG. 4).

Attach the indenter 10 to the object 8 to be evaluated for 10 to 20 seconds (T1)
After the contact, the load means 1 is controlled by the calculation means 14 and the indenter 10 is pushed into the object to be evaluated 8 with a predetermined load within 1 to 4 seconds (T2) and pulled out. As a result, a depression by the indenter 10 is formed on the surface of the evaluation object 8. The displacement amount measuring means 52 measures the distance to the displacement reference plane 16 while the indenter 10 pushes in the object 8 to be evaluated and pulls it out (during T2), and outputs the result to the calculating means 14. The calculation means 14 obtains the time change of this measured value from the measured value sent from the displacement amount measuring means 52. The time change of the measured value during T2 is represented as the curve CD in FIG. In addition, the calculation means 14 changes the measured value with time and the load means 1 uses the indenter 10
The load applied to is stored in association with. Further, the calculating means 14 calculates from the time change rate α and time (T1 + T2),
When the pushing of the indenter 10 is completed based on the formula (D
The total amount S (see FIG. 4) of the displacement amount (the above f (t)) due to thermal expansion at the point is calculated. The time (T1 + T2) at the time when the pushing of the indenter 10 is completed (point D)
By subtracting the total amount S from the value of the time change of the measured value (D (t)), the value of the time change of the true pushing (or withdrawing) amount of the indenter 10 with respect to the object 8 to be evaluated (L (the above L ( t)) is obtained and displayed (see the above equation and FIG. 5). In addition, the time change of the stored measured value and the indenter 1
Based on the relationship with the load applied to 0, the time change of the true push-in (or pull-out) amount and the change of the load due to the indenter are obtained, and the relationship diagram is created and displayed. From this relationship diagram,
The physical properties of the surface of the evaluated object 8 can be evaluated. Indenter 1
When the pushing of 0 is completed, the mounting table 2 may be moved by the positioning mechanism 53 and the surface of the evaluation object 8 may be observed by the optical microscope 7.

After the indenter 10 is pushed into the object to be measured 8 and pulled out, the indenter 10 is kept in contact with the object to be measured 8 for several tens of seconds to maintain the indenter 1.
It is also possible to measure the time change of 0 or the thermal expansion of the mounting table 2. Accordingly, not only when the time change of the displacement amount due to thermal expansion is represented by a linear expression, but also when the time change rate changes, the time change rate for each change can be obtained.
Therefore, it is possible to more accurately predict the thermal expansion when the indenter 10 is pushed.

[0022]

According to the present invention, when the physical properties of the surface of the object to be evaluated are evaluated from the relationship between the amount of indentation of the indenter with respect to the object to be evaluated and the load applied to the indenter at the time of pressing, the amount of indentation of this indenter is accurately determined. You can ask. Therefore, it becomes possible to accurately evaluate the physical properties of the surface of the object to be evaluated.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the configuration of an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a load means used in this embodiment.

FIG. 3 is a schematic diagram showing a configuration of a heating unit and a displacement amount measuring unit used in this example.

FIG. 4 is a diagram showing a change with time of a measurement value obtained by a displacement amount measuring means, in which the vertical axis represents the output value of the displacement meter and the horizontal axis represents time.

FIG. 5 is a diagram showing a change with time of a measured value after calibrating a thermal expansion component, in which a vertical axis represents a corrected displacement meter output value and a horizontal axis represents time.

[Explanation of symbols for main parts]

 DESCRIPTION OF SYMBOLS 1 load means 2 mounting table 3 heating means 4 measuring terminal 5 vacuum container 8 evaluation object 9 heating part 10 indenter 11 driving part 14 computing means 15 displacement gauge 16 displacement reference surface 20 temperature sensing means 22 temperature adjusting means 23 exhausting means 52 displacement Quantity measuring means 53 Positioning mechanism

Claims (2)

[Claims] 1. An indenter pressed into the surface of an object to be evaluated,
Load means for applying a predetermined load to the indenter, displacement amount measuring means for measuring the displacement amount of the indenter, and computing means for obtaining the relationship between the load applied to the indenter by the load means and the displacement amount of the indenter. In the surface physical property evaluation apparatus having, the calculation means, from the displacement amount due to thermal expansion of the indenter measured when the indenter is brought into contact with the surface of the object to be evaluated, "the displacement amount per hour of the indenter due to thermal expansion". Is obtained, the displacement due to thermal expansion included in the displacement measured when the indenter is pushed is assumed from the time variation, and the displacement due to the thermal expansion is the displacement during pushing. A surface physical property evaluation apparatus, characterized in that the true displacement amount of the indenter is calculated by removing it from the above, and the relationship between the true displacement amount and the load is obtained. 2. An indenter pressed into the surface of the object to be evaluated,
Load means for applying a predetermined load to the indenter, displacement amount measuring means for measuring the displacement amount of the indenter, and computing means for obtaining the relationship between the load applied to the indenter by the load means and the displacement amount of the indenter. Wherein the computing means is a displacement amount in a predetermined direction due to thermal expansion of the measured object measured by the displacement amount measuring means within a first time set before moving the measured object, A "relationship between the amount of displacement due to thermal expansion of the object to be measured and the time" at the first time is calculated to calculate the rate of change over time of the displacement, and the time is set within the range where the relationship holds. The displacement amount in the predetermined direction of the measured object measured by the displacement amount measuring means within the time period of 2 is added to the displacement amount measured within the first time period, and the time change rate and the first, The predetermined time that occurs within the first and second time periods from the second time period Direction, the total amount of thermal expansion of the measured object is obtained, and the total amount is calculated by adding the displacement amount measured in the first time period and the displacement amount measured in the second time period. An apparatus for evaluating physical properties of a surface, wherein the true movement amount of an object to be measured is calculated by subtracting it.