JP2009257845A - Temperature evaluating method of contact point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for evaluating the temperature of the contact point between an unknown sample and a thermal probe by a the calibration formula formed between a temperature in the thermal probe and the temperature of the contact point by directly measuring the temperature of the contact point using a reference sample. <P>SOLUTION: The temperature of the contact point of the reference substance which comprises the same material as that of a sample stand placed on the sample stand and the thermal probe is evaluated using a measuring instrument equipped with the thermal probe and the temperature of the contact point between the unknown simple placed on the sample stand and the thermal probe is evaluated from the temperature in the thermal probe on the basis of the correlation of the obtained temperature of the contact point and the temperature in the thermal probe. The temperature of the contact point of the reference substance and the tip of the probe rod constituting the thermal probe is evaluated as a thermocouple formed between a wire for measuring a voltage of the contact point issued from the sample stand and a wire for measuring a probe reference issued from the thermal probe. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for evaluating a contact point temperature between a sample surface and a thermal probe, and more particularly to a method for evaluating a contact point temperature of an unknown sample by calibration with a reference sample from a temperature in a thermal probe.

  In a semiconductor substrate such as a CPU, it is necessary to actually measure the state of heat dissipation in the substrate by observing the temperature at the contact point when the heating unit is brought into contact.

  The Seebeck coefficient is useful for evaluating the performance of thermoelectric conversion materials. Since the Seebeck coefficient is obtained by differentiating the change in electromotive voltage with the change in temperature, it is necessary to actually measure the contact point temperature in order to know the exact value of the change in temperature.

  As a technique related to the thermal measurement of a micro area using a thermal probe, for example, as a method for determining the Seebeck coefficient at the time of contact, a thermal probe method (for example, refer to Non-Patent Document 1, Patent Documents 1 and 2). Proposed. An SThM technique (for example, see Non-Patent Document 2) that measures a thermal image using the AFM technique, or an STP method that collects temperature information of the sample surface using a thermocouple with a thin tip as a cantilever and uses it for surface shape measurement (For example, refer nonpatent literature 3) etc. are proposed.

  Only when the Seebeck coefficient is measured by the thermal probe method, temperature measurement at the contact point has been reported. A probe provided with a heater is brought into contact with the material to be measured, and the surface temperature of the material to be measured is measured by a thermocouple provided at the tip of the probe. However, a temperature difference that cannot be ignored during measurement occurs between the temperature of the thermocouple and the surface temperature of the material to be measured. Since this method is not a method of directly measuring the temperature of the contact point, there is a problem that it is not necessarily an effective method. Moreover, when using a sheath thermocouple, there exists a problem that an actual measurement position and a contact point do not correspond. That is, in the conventional thermal probe method, the temperature of the contact point is determined by estimating from the temperature in the thermal probe.

JP 2004-003872 A JP 2008-057144 A Sussmann, et al., Proc. 12th Int. Conf. On Theremo-electronics, Yokohama, 86 (1993). Scanning Near-Field Optical Microscopy and Scanning Thermal Microscopy; Jpn.J.Appl.Phys.Vol.33, p.p.3785-3790 (1994); R.J.Pylkki, P.J.Moyer, and P.E. Scanning Thermal Profiler; Appl. Phys. Lett., Vol. 49, No23, pp. 1587-1589 (1986); C. C. Williams and H. K. Wickamasinghe.

Conventionally, the temperature of the contact point is estimated from the temperature in the thermal probe.
An object of the present invention is to solve the above-mentioned problems of the prior art, by directly measuring the temperature of the contact point using a reference sample, and a calibration formula between the temperature in the thermal probe and the contact point temperature. And providing a method of evaluating the temperature of the contact point between the unknown sample and the thermal probe using this calibration formula.

  The inventors can easily measure the contact point temperature between the sample and the thermal probe by using the reference sample, and create a calibration formula between the contact point temperature measured by the reference sample and the temperature in the thermal probe. As a result, it was found that the contact point temperature of the unknown sample could be evaluated, and the present invention was completed.

  The contact point temperature evaluation method of the present invention uses a measuring device equipped with a thermal probe, evaluates the contact point temperature between the reference material and the thermal probe of the same material as the sample stage placed on the sample stage, Based on the correlation between the obtained contact point temperature and the temperature in the thermal probe, the contact point temperature between the unknown sample placed on the sample stage and the thermal probe is evaluated from the temperature in the thermal probe. And

  The temperature of the contact point between the reference material and the tip of the probe rod constituting the thermal probe is determined by the contact point voltage measurement line coming out of the sample stage and the probe reference measurement line coming out of the thermal probe. It is characterized by being evaluated as a thermocouple formed between them.

  When evaluating the temperature of the contact point between the unknown sample and the tip of the probe rod constituting the thermal probe, before and after the contact between the reference material and the tip of the probe rod, a plurality of measurement locations in the probe rod Measure the temperature difference between adjacent measurement points and the temperature difference between the lowest measurement point and the contact point, change the control temperature of the probe block that constitutes the thermal probe, and measure the temperature. The contact point temperature evaluation calibration formula is the relationship between the difference between the temperature difference after contact and the temperature difference before contact, and the temperature difference between the lowermost measurement point and the contact point. For the unknown sample, in the same manner as the reference material, measure the difference between the temperature difference after contact and the temperature difference before contact at the adjacent points in the probe rod, and use the calibration formula for temperature evaluation of the contact point. , The temperature and contact of the bottom measurement point The difference between the temperature of the point and the temperature of the lowermost measurement point calculated from the difference between the temperature difference after contact and the temperature difference before contact between adjacent points in the probe rod and the contact point temperature The temperature of the contact point is evaluated from the difference and the temperature of the lowest measurement location.

  According to the present invention, the temperature error of the contact point temperature of an unknown sample can be reduced by measuring the temperature of the contact point between the reference material and the tip of the thermal probe to obtain a calibration formula. As an application example of this technique, there is an effect that the evaluation accuracy of the Seebeck coefficient can be increased by reducing the temperature error necessary for the Seebeck coefficient evaluation apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  According to the present invention, the temperature of the contact point between the reference material and the thermal probe is measured using the contact point measuring device, and the correlation between the obtained contact point temperature and the temperature in the thermal probe is used to determine the temperature inside the thermal probe. From this temperature, the temperature of the contact point between the unknown sample and the thermal probe can be evaluated.

  As the contact point measuring apparatus used in the present invention, an apparatus having a thermal probe and a sample stage provided with heating means such as a heater can be used.

  With reference to FIG. 1, the structure of the thermal probe in a contact point measuring device is demonstrated.

  As a typical example of the probe rod, a probe of a method for measuring a plurality of voltages and / or temperatures according to a patent application filed on the same day as the present patent application is used. A configuration diagram of a measuring apparatus using this representative example is shown in FIG.

The thermal probe 2 (material A: for example, constantan) is composed of a probe block 21 (material A: for example, constantan) and a probe bar 22 (material A: for example, constantan). Move together during measurement. The temperature (T _pb ) of the probe block 21 and the temperature (T _sb ) of the sample _stage 1 (material C: for example, copper) are maintained at a constant temperature during measurement by a temperature control means (not shown). It is configured.

Prior to measurement using the above apparatus, the temperature of the probe block 21 (T _pb ) and the temperature of the sample _stage 1 (T _sb ) are measured while the sample S and the tip of the probe rod 22 are not in contact with each other. Control. However, control is performed so as to satisfy the relationship of T _pb ≧ T _sb + 10 ° C. This is to make the tip of the probe rod sufficiently higher than the sample temperature. The measurement is started in a state where the probe rod 22 of the thermal probe 2 and the sample S to be measured are not in contact with each other, and after a predetermined time has passed, the tip of the probe rod 22 and the sample S to be measured are brought into contact with each other. After contacting for a certain time, the probe rod 22 of the thermal probe 2 is separated from the sample S to be measured. Voltage measurement and temperature measurement in the probe rod 22 are performed during measurement.

  A voltage measurement line 1a (material C: for example, copper) is provided for measurement from the sample stage 1, and is connected to a probe reference measurement line 2a (material A: for example, constantan) by a measuring instrument. Therefore, since the space between the probe reference measurement line 2a and the voltage measurement line 1a (material C: for example, copper) at the contact point can function as a thermocouple, temperature measurement and voltage measurement at the contact point can be performed.

Next, measurement is performed using the same material as the material of the sample table 1 (material C: for example, copper) as the reference sample S. When the tip of the probe rod 22 of the probe block 21 is brought into contact with the reference sample S, the location where the material C and the material A are joined is the contact point between the probe rod 22 and the reference sample S and the probe reference in the measuring instrument. There are two connection points between the measurement line 2a and the voltage measurement line 1a. Therefore, the temperature (T _cp ) of the contact point measured as a copper-constantan T thermocouple can be evaluated based on the electromotive voltage between the material A and the material C measured with reference to the junction temperature. it can.

  The correlation between the temperature at the contact point between the tip of the probe rod 22 and the reference sample S, obtained using the reference sample S, and the temperature in the thermal probe 2 will be described below.

Prior to contact with the reference sample S, the temperatures of T ₁ , T ₂ and T ₃ in the probe rod 22 can be measured. The temperature differences between the points in the probe rod 22 are T _1a -T _2a , T _2a -T _3a (T _1a , T _2a and T _3a are T ₁ , T ₂ and T ₃ before contact, respectively. The temperature is expressed as follows. After the contact with the reference sample S, not only the temperatures of T ₁ , T ₂ and T ₃ but also the temperature at the contact point (T _cp ) can be measured. The temperature difference between each point in the probe rod 22 and the temperature difference between the measurement bottom (T _3b ) and the contact point in the probe rod 22 are respectively T _1b -T _2b , T _2b -T _3b , T _3b. -T _cp (T _1b , T _2b and T _3b are the temperatures of T ₁ , T ₂ and T ₃ after contact, respectively). The temperature in the probe rod 22 changes before and after contact. The temperature difference between each point in the probe rod 22 before and after contact is ( _T1b - _T2b )-( _T1a - _T2a ), ( _T2b - _T3b )-( _T2a - _T3a ), respectively. Represented. Table 1 below summarizes the notation of the temperatures before and after the contact.

By changing the control temperature (T _tb ) of the probe block 21, the amount of heat transferred to the sample can be changed. Therefore, measurement is performed by changing the control temperature of the probe block 21.

Based on the results measurements made by changing the control _{temperature, (T} 1b -T _{2b) -} relationship between (T 1a _{-T 2a)} and _{T 3b -T cp, (T 2b} -T 3b) - (T 2a -T The relationship between _3a ) and T _3b -T _cp will be described. ( _T1b - _T2b )-( _T1a - _T2a ) and _T3b - _Tcp , ( _T2b - _T3b )-( _T2a - _T3a ) and _T3b - _Tcp will be described below. Each has a linear approximation relationship. These straight lines are used as calibration equations for contact point temperature evaluation.

From T ₁ , T _2, and T ₃ in the probe rod 22, voltage / temperature measurement lines (material B: for example, chromel) 22 a, 22 b, and 22 c are drawn out for measurement. The wire is connected to the probe reference measurement wire 2a (material A: for example, constantan) by a measuring instrument. Therefore, in the above temperature measurement, the temperatures of T ₁ , T ₂ and T ₃ are measured as an E thermocouple of chromel-constantan, the material of the reference sample S is, for example, copper (material C), and the temperature of the contact point is Measured as a copper-constantan T thermocouple. The measurement was performed with the control temperature of the probe block 21 being 40 ° C, 50 ° C, 60 ° C, and 70 ° C. The temperature of the sample stage 1 is controlled at 30 ° C.

2A shows the dependence of T _3b -T _cp on (T _1b -T _2b )-(T _1a -T _2a ), and FIG. 2B shows the T _3b -T _cp (T _2b -T _3b ) −. The measurement result of ( _T2a - _T3a ) dependence is shown. As is clear from FIGS. 2A and 2B, it can be seen that there is a linear approximation relationship.

A method for evaluating the contact point temperature T _cpcal between the unknown sample and the thermal probe 2 from the temperature in the thermal probe 2 obtained as described above will be described.

The contact point temperature is evaluated using the above calibration formula for contact point evaluation obtained by measurement using the reference sample (material C) S. An unknown sample (material D) is measured in the same manner as the reference sample, and the temperature difference (T _1b −T _2b ) − (T _1a −T _2a ) between adjacent measurement points before and after contact in the thermal probe is ( _T2b - _T3b )-( _T2a - _T3a ) is evaluated. As a measurement condition at this time, the control temperature of the probe block 21 may be appropriately selected from the temperatures used in the measurement of the reference sample S. The control temperature of the sample stage 1 is the same as the temperature measured for the reference sample S. T _3b -T _cp is evaluated using a calibration formula for contact point temperature evaluation. _(T 1b _{-T 2b) -} and _T 3b _{-T cp} calculated from _{(T 1a -T 2a), (} T 2b -T 3b) - and _T 3b _{-T cp} calculated from (T 2a _{-T 3a)} On average, T _3b -T _cp of the contact point temperature evaluation is used. T _cpcal is evaluated from the measured temperature of T _3b and the calculated T _3b -T _cp .

Using Bi ₁₀ Sb ₃₀ Te ₆₀ as a sample whose Seebeck coefficient is unknown, the temperature T _{cpcal of the} contact point is calculated from (T _1b −T _2b ) − (T _1a −T _2a ) when measured as described above. FIG. 3 shows a comparison between the results obtained and the results _obtained by calculating the temperature T _cpcal at the contact point from (T _2b −T _3b ) − (T _2a −T _3a ). The difference in temperature at the contact point obtained from the two results is within 0.5 ° C.

  According to the present invention, it is greatly expected to develop a contact point temperature distribution measuring device and a Seebeck coefficient measuring device.

The block diagram which shows typically the structure of the thermal probe in a thermophysical property measuring device. Of _{T 3b -T cp (T 1b -T} 2b) - (T 1a -T 2a) Dependence (a), and _{T 3b -T cp (T 2b -T} 3b) - (T 2a -T 3a) depends The graph which shows the measurement result of property (b). Is a graph showing that an evaluation of the contact point temperature _{T Cpcal} of Bi ₁₀ Sb ₃₀ Te _60, the horizontal axis _{(T 1b -T 2b) - (} T 1a -T 2a) the value of the evaluation of the contact point temperature _{T Cpcal} from The vertical axis represents a value _obtained by evaluating the contact point temperature T _cpcal from (T _2b −T _3b ) − (T _2a −T _3a ).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample stand 1a Voltage measurement line 2 Thermal probe 2a Probe reference measurement line 21 Probe block 22 Probe rods 22a, 22b, 22c Voltage measurement line

Claims (3)

Using a measuring device equipped with a thermal probe, evaluate the contact point temperature between the reference material and the thermal probe made of the same material as the sample stage placed on the sample stage. A contact point temperature evaluation method, comprising: evaluating a contact point temperature between an unknown sample placed on a sample stage and a thermal probe from a temperature in a thermal probe based on a correlation with temperature. The contact point temperature between the reference material and the tip of the probe rod constituting the thermal probe is measured between the contact point voltage measurement line coming out of the sample stage and the probe reference measurement line coming out of the thermal probe. The contact point temperature evaluation method according to claim 1, wherein the contact point temperature is evaluated as a thermocouple formed on the surface. When evaluating the contact point temperature between the unknown sample and the tip of the probe rod constituting the thermal probe, before and after the contact between the reference material and the tip of the probe rod, a plurality of measurement points in the probe rod are measured. Measure the temperature, measure the temperature difference between adjacent measurement points and the temperature difference between the lowest measurement point and the contact point, change the control temperature of the probe block that constitutes the thermal probe, measure the temperature inside the probe rod The contact point temperature evaluation calibration formula is the relationship between the difference between the temperature difference after contact and the temperature difference before contact in the adjacent part of the contact point, and the temperature difference between the lowest measurement point and the contact point. For the unknown sample, like the reference material, measure the difference between the temperature difference after contact and the temperature difference before contact in the adjacent location in the probe rod, and use the calibration formula for temperature evaluation of the contact point, Temperature and contact point of the lowest measurement point The difference between the temperature and the difference between the temperature at the lowest measurement point calculated from the difference between the temperature difference after contact and the temperature difference before contact at the adjacent points in the probe rod and the contact point temperature The contact point temperature evaluation method according to claim 1, wherein the contact point temperature is evaluated from the temperature of the lowermost measurement location.

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