KR20210064756A - Apparatus and method for testing properties of materials - Google Patents

Abstract

In accordance with the present invention, an apparatus and a method for testing the properties of a material comprises: a thermocouple having a junction part in which two types of metals are joined; a control unit for controlling power supplied to the thermocouple and measuring the temperature of the thermocouple; and a photographing device for photographing the behavior of an object to be measured while positioned at the junction part. The thermocouple receives power from the control unit so that the junction part generates heat, thereby heating the object to be measured. In addition, the method comprises: an object to be measured acquisition step of collecting an object to be measured; an object to be measured dissolving step of positioning the collected object to be measured on a thermocouple and supplying power to the thermocouple to heat the object to be measured to a predetermined temperature, dissolving same; a cooling step of cooling the object to be measured by stopping the supply of the power to the thermocouple; and a measurement step of observing processes of dissolving and cooling the object to be measured in the dissolving and cooling steps. In accordance with the present invention, the properties of a material can be measured using a simple structure and method.

Description

Apparatus and method for measuring material properties

The present invention relates to an apparatus and method for measuring the physical properties of a material, and more particularly, to a physical property measuring apparatus and method for simply and effectively measuring the dissolution and cooling characteristics of a memory material in a phase phase.

Currently, the mainstream of semiconductor memory is DRAM and flash memory, but these are limited in their miniaturization, so it is difficult to increase the degree of integration any more.

In order to solve this problem, various types of next-generation memories are being studied, and phase change memories, spin injection memories, resistance change memories, etc. are being developed as representative alternatives.

Among these, Phase Change Memories (PCM) store data by applying the difference in whether current flows (1) or not (0) in existing memories, but determines whether the laser is irradiated or non-deterministic. The data is stored in such a way that it becomes 1 or 0 depending on the

Phase-change memory is attracting attention because it is faster than flash memory, consumes less power, and has no limit on the number of writes. In particular, there is an advantage of easy development in terms of using a well-known material, it is known that chalcogenide-based metals such as germanium, antimony, tellurium, and the like cause a phase transition between crystal and amorphous.

An example of a typical PCM material is GST (Ge ₂ Sb ₂ Te ₂ ). Recently, it _{was confirmed that a superlattice obtained by stacking [Sb 2} Te ₃ /GeTe] in multiple layers exhibits more efficient memory characteristics than GST. Sb ₂ Te ₃ and GeTe form various phases and crystal planes depending on the temperature.

In order to commercialize such a phase change memory, it is necessary to control the phase change characteristics of the material as desired, and for this, it is necessary to first clarify the phase change characteristics.

In the case of Sb ₂ Te ₃ and GeTe, there is currently a case of studying the phase change by temperature under the in-situ conditions deposited during the process. However, in order to confirm more accurate physical properties, a study is needed to evaluate the stability of the phase according to the temperature after the superlattice is fabricated.

Moreover, for GeTe, a non-equilibrium TTT diagram (Temperature-Time Transformation diagram) has not yet been derived, so it is necessary to construct it, and for this, an apparatus and method capable of grasping the exact dissolution characteristics are required.

In addition, in order to measure the dissolution and cooling characteristics of a material, conventionally, a method of heating and cooling an object to be measured in a container such as a crucible is mainly used. In this case, expensive and complicated equipment is required. Moreover, the measurement object is in contact with the entire crucible inner surface, and there is a high possibility that a reaction product is formed, which makes the measurement inaccurate.

Korean patent application 2003-0007541 (2003.02.06) Korean Patent Application 2007-0027335 (2007.03.20)

The present invention is to solve the problems of the prior art, and to provide an apparatus and method for evaluating the physical properties of a material with a simple configuration.

Another object of the present invention is to provide an apparatus and method capable of stably and effectively measuring the dissolution and cooling properties of a material.

Another object of the present invention is to provide an apparatus and method capable of constructing a TTT diagram through a process of photographing a phase change process according to temperature and time during dissolution and cooling of a measurement object.

Another object of the present invention is to provide an apparatus and method capable of obtaining accurate experimental results by preventing a reaction between a thermocouple and an object to be measured when measuring the dissolution and cooling characteristics of a material.

Another object of the present invention is to provide an apparatus and method capable of obtaining accurate experimental results by blocking the reaction with the atmosphere in the chamber when measuring the dissolution and cooling characteristics of a material.

In order to achieve the above object, the present invention provides an apparatus for measuring physical properties of a material having the following configuration.

a thermocouple having a junction in which two types of metals are joined;

a controller for controlling the power supplied to the thermocouple and simultaneously measuring the temperature of the thermocouple; and

It includes a photographing device for photographing the behavior of the measurement object located in the junction,

The thermocouple receives power from the control unit and heats the object to be measured by generating heat at the junction.

The physical property measuring device of the present invention is characterized in that it simultaneously uses the exothermic characteristic and the temperature measuring characteristic of a thermocouple. Accordingly, even with a simple structure, the measurement object is heated and dissolved, and at the same time the temperature is maintained and measured. The solubility and dissolution behavior of specific substances can be easily observed.

The controller supplies power to the thermocouple to heat the thermocouple, and measures the temperature by measuring the thermoelectric force generated at the junction of the thermocouple according to the temperature.

As the thermocouple, it is preferable to use a B-type thermocouple having platinum as a main component. This is because the thermocouple should not be damaged even when the object to be measured with a high melting point is melted.

However, in this case, the reactivity of the platinum can be an issue. Although platinum is a stable metal with a fairly low reactivity, it reacts with some materials, for example, germanium (Ge) of GeTe, a phase change memory material, to form Pt-Ge. Therefore, when Pt-Ge is formed, it causes a problem in accurately measuring the dissolution and cooling properties of the material.

In the present invention, this problem can be solved by forming a coating on the thermocouple. The coating is preferably made of titanium nitride (TiN) or tungsten (W), which has excellent heat resistance so that it can be maintained even in a high-temperature process. The melting point of titanium nitride is 2,930°C, and the melting point of tungsten is 3,422°C, which is very high. Above all, titanium nitride or tungsten does not react with platinum or germanium, so it does not form compounds or alloys.

On the other hand, in the dissolution process for understanding the dissolution characteristics of the material, there is a risk of reaction with oxygen in the chamber. This is particularly problematic when the measurement target is a highly volatile material. To this end, in the present invention, a getter is installed in the chamber to control the process atmosphere.

In addition, the present invention provides a method for measuring physical properties comprising the following steps in order to measure the properties of an object to be measured using the physical property measuring device.

As a method of measuring physical properties using the physical property measuring device,

a measurement object acquisition step of collecting the measurement object;

dissolving the measurement object by placing the collected measurement object in a thermocouple and heating the measurement object to a predetermined temperature by supplying electric power to the thermocouple;

a cooling step of cooling the measurement object by stopping power supply to the thermocouple; and

It characterized in that it comprises a measuring step of observing the dissolution process and cooling process of the object to be measured in the dissolution and cooling step.

The method for measuring physical properties of the present invention is performed by measuring a phase change according to a temperature change when a measurement object is dissolved at a predetermined temperature and a phase change according to a temperature change when cooled.

Through this measurement, not only the mechanism by which the dissolution proceeds and the phase that is generated or disappears can be confirmed, but also the phase change according to the cooling rate, the cooling temperature, etc. can be grasped. Therefore, by repeating the experiment while changing conditions such as temperature and time, it is possible to grasp the material's dissolution and cooling behavior, and based on this, a TTT diagram can be created. As a result, it is possible to establish material properties data that can be used for the manufacture of phase-change memories.

According to the apparatus and method of the present invention configured as described above, it is possible to easily measure the dissolution and cooling behavior by heating and dissolving a material such as a phase change memory material with a simple structure, while maintaining the temperature and cooling it. .

In addition, according to the present invention, it is possible to continuously measure the phase transition behavior by photographing the dissolution and cooling process of the material in real time.

In addition, according to the present invention, it is possible to obtain accurate experimental results by preventing the reaction between the thermocouple and the object to be measured when measuring the dissolution and cooling characteristics of a material.

In addition, according to the present invention, it is possible to obtain accurate experimental results by blocking the reaction with the atmosphere in the chamber when measuring the dissolution and cooling characteristics of the material.

In addition, according to the present invention, since only a small amount of the phase change memory material is collected and the properties are measured by heating and cooling, it is easy to experiment and the material cost can be reduced.

1 is a schematic diagram showing the structure of an apparatus for measuring physical properties according to an embodiment of the present invention.
2 is a photograph of a thermocouple used in an apparatus for measuring physical properties according to an embodiment of the present invention.
3 is a photograph illustrating a process of dissolving a phase-change memory material, which is a measurement object, according to an embodiment of the present invention.
FIG. 4 is a photograph showing an object to be measured and the tissue state of the thermocouple when an uncoated thermocouple is used according to a comparative example.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram showing the structure of an apparatus for measuring physical properties according to an embodiment of the present invention.

The measuring device 10 of the present embodiment is configured to include a thermocouple 100 , a controller 200 , and a photographing device 300 . The thermocouple 100 is located in the chamber (C) and the control unit 200 is located outside the chamber (C). Although the imaging device 300 is shown to be located in the chamber (C) in the drawings, it is also possible to photograph the interior of the chamber (C) through an observation hole formed in the chamber (C) while located outside the chamber (C).

A thermocouple is a device in which two types of metals are joined, and is widely used for measuring temperature using the Seebeck effect, in which thermoelectric power is generated in proportion to a temperature difference at a junction where two types of metals are joined. The thermocouple 100 of the present embodiment is used as a heater for heating a measurement object by using the characteristic that heat is generated at the junction when a current is applied, and simultaneously performs a function of measuring temperature. The function of the thermocouple 100 is obtained by applying an alternating current from the controller 200, and heat is generated at the contact portion of the thermocouple 100 by the current applied in the forward direction during the alternating current, and heat is generated with respect to the current applied in the reverse direction. Temperature can be measured by detecting the effect of power.

In a state where heat is generated from the thermocouple 100 and the measurement object S is positioned on the junction for measuring the temperature, the characteristics of the measurement object are evaluated. At this time, the thermocouple 100 is configured to be bent in a horseshoe shape or a U-shape, but the junction is positioned in the center of the U-shape.

The measurement object S is melted while being placed on the U-shaped junction. Due to the U-shaped structure, even when the measurement object S is liquefied, it can be continuously maintained in the U-shaped portion of the thermocouple 100 by surface tension without a separate fixing device.

The part other than the measurement part of the thermocouple 100 was wrapped with copper and fixed with an alumina holder to maintain the gap. In this embodiment, as the thermocouple 100, a B-type thermocouple using a Pt70/Rh30 alloy for the + wire and a Pt94/Rh6 alloy for the - wire was used.

The controller 200 controls and measures the alternating current applied so that the thermocouple 100 simultaneously performs a heating function and a temperature measurement function. The controller 200 controls the current applied to the thermocouple 100 , and measures the temperature by evaluating the effect of the thermoelectric force on the applied current. The controller 200 may control the temperature of the thermocouple 100 through the current applied to the thermocouple 100 , and in this case, the control is performed based on the temperature measured by the thermocouple 100 .

A data logger 210 is also configured in the control unit 200 to store measured data.

The photographing apparatus 300 is included to photograph the measurement object S located in the thermocouple 100 and analyze the characteristics. The photographing apparatus 300 may be an optical apparatus, and continuous photographing or periodic photographing at a desired point in time is all possible.

Since the physical property measuring apparatus of the present invention collects an object to be measured, places it on the U-shaped portion of the thermocouple 100 and measures the properties while heating, it is possible to measure the properties even by collecting a very small amount of material. Accordingly, there is an advantage in that only a small amount of an expensive phase change memory material is used.

In order to evaluate the characteristics of a small amount of measurement object, the measurement may be performed by attaching a magnifying glass 310 to the photographing device 300 , and the measurement object S located in the thermocouple 100 using the support 320 . ) to fix the shooting position.

Meanwhile, FIG. 2 is a photograph of a thermocouple used in an apparatus according to an embodiment of the present invention.

The U-shaped end of the thermocouple of FIG. 2 is coated with titanium nitride (TiN) to a thickness of about 4-5 μm only at the portion where the sample is dissolved. The method of coating titanium nitride is not specifically limited. In this embodiment, the coating was performed by magnetron sputtering, but other methods may be used.

Hereinafter, a process of measuring the dissolution and cooling behavior of the object to be measured by the physical property measuring device configured as described above will be described.

3 is a photograph showing a process of dissolving GeTe, a phase change memory material, as a measurement object in an embodiment of the present invention.

First, it is obtained by cutting and collecting a small amount for an experiment in bulk GeTe.

The obtained GeTe piece is placed on the U-shaped end of the thermocouple 100 as shown in FIG. 3(a). And when the temperature of the thermocouple 100 is increased by supplying power from the controller 200, the thermocouple 100 is heated and the heat starts to be transferred to the GeTe piece as shown in FIG. 3B. When GeTe reaches the melting point of 725°C, melting begins.

At this time, since the thermocouple 100 simultaneously performs temperature measurement, the measurement object can be heated to a desired temperature and maintained at that temperature. In this example, it was heated and maintained at a rate of 500°C/min to 900°C. In a state where the temperature of the thermocouple 100 is maintained at 900° C., GeTe is positioned in the U-shaped portion of the thermocouple in a molten state as shown in (c) of FIG. 3 .

And the phase change of the dissolution process is confirmed by photographing this process at regular time intervals using the imaging device 300 positioned above the device.

On the other hand, the U-shaped portion of the end of the thermocouple 100 is coated with titanium nitride.

Accordingly, germanium constituting GeTe does not react with platinum constituting the thermocouple to form Pt-Ge.

For comparison, the results of using an uncoated thermocouple are shown in FIG. 4 . 4 is a photograph showing a reaction state between a measurement object and a thermocouple when the thermocouple is not coated.

Compared with the thermocouple-coated embodiment of the present invention, in FIG. 4 , it can be seen that platinum and germanium reacted to form Pt-Ge during the dissolution of GeTe. That is, position 1 shown in the drawing is a thermocouple, position 2 is the interface between the thermocouple and GeTe, and position 3 is GeTe. At position 1, only platinum exists, but at position 2 where the thermocouple and the measurement object are in contact, platinum is It was confirmed that 54.52 wt% was mixed. It can be seen that platinum is present in 2.49wt% even in position 3, although it is small. That is, it can be confirmed that platinum is diffused at positions 2 and 3 to form a Pt-Ge alloy.

Therefore, it was confirmed that by coating the thermocouple, the dissolution and cooling behavior of pure GeTe could be accurately measured without the formation of Pt-Ge.

This fact can be seen in more detail in Table 1 below. Even when the thermocouple 100 is not coated, there is no problem in the measurement of dissolution and cooling behavior for general oxides or some mixed oxides. However, some of the mixed oxides, semiconductors, alloys, metals, etc. may react with the thermocouple electrode during dissolution, which may decrease the accuracy of measurement, making it difficult to use.

Therefore, by coating the thermocouple as in the present invention, it is possible to accurately measure the dissolution and cooling behavior even when the object to be measured is a semiconductor, an alloy, or a metal.

material world oxide
(GeO2, etc.) Mixed oxide 1 (CaO-SiO2-Al2O3, etc.) Mixed oxide 2 (CaO-SiO2-Al2O3-FeO, etc.) semiconductor
(Ge) alloy system
(GeTe, etc.) metallic
(Fe) Pt electrode o o x x x x Pt/coated electrode o o o o o o

Next, the process of cooling a measurement object is demonstrated.

Cooling may be accomplished by stopping or lowering the power supply from the control unit 200 . When the power is lowered, the measurement object may be cooled slowly, and when the power supply is completely cut off, the temperature of the thermocouple 100 is rapidly lowered to obtain an effect of quenching.

In addition, by photographing and analyzing the measurement object during the cooling process, it is possible to measure the temperature and time at which the phase transformation takes place, and the composition change accordingly.

On the other hand, the dissolution and cooling of this embodiment is made in an inert gas, specifically, an Ar gas atmosphere with a purity of 6N, but before the Ar gas reaches the reaction chamber (C) or during the process, oxygen present in the chamber (C) is germanium or Tellurium can react to form oxides and the like. Therefore, the measurement of the dissolution and cooling behavior of pure GeTe may be inaccurate. In particular, since tellurium (Te) is highly volatile, it evaporates and reacts with oxygen in the chamber (C) _{to form TeO 2} and pollute the atmosphere, which is a factor hindering the results of the physical properties of GeTe.

To prevent this, the atmosphere inside the chamber was stabilized through Ar gas purging for 1 hour before dissolution of the measurement object. In addition, during the dissolution reaction, the reaction between GeTe and the atmosphere was minimized by continuous purging.

In addition, a getter was installed in the chamber C to control the process atmosphere.

The getter was installed in the Ar gas pipe to remove impurities from the Ar gas supply. The type of the getter is not particularly limited, and it can be used by selecting from various commercially available types such as a zirconium getter.

Before the 6N Ar gas was introduced into the reaction chamber by the getter, _{the concentrations of O 2} , H ₂ O, CO, CO ₂ , CH ₂ and the like were reduced to 10 ppb or less.

As described above, the TTT diagram of GeTe, which has not yet been completely constructed, can be derived through the process of photographing the phase change process according to the temperature and time of the object to be measured during dissolution and cooling. In particular, it was confirmed that GeTe had a β-phase rhombohedral structure at 573K, transformed into a γ-phase rhombohedral structure at 700K with increasing temperature, and changed to a β-phase cubic structure at 873K.

As described above, through the present invention, the behavior of the material, for example, the conditions for forming an amorphous state, etc. can be grasped, and through this, a foundation can be built that can be utilized for the manufacture and control of the material.

The present invention has been described above through preferred embodiments, but the above-described embodiments are merely illustrative of the technical spirit of the present invention, and various changes are possible without departing from the technical spirit of the present invention in this field. Those of ordinary skill in the art will be able to understand. Therefore, the protection scope of the present invention should be interpreted by the matters described in the claims, not specific embodiments, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present invention.

10: measuring device
100: thermocouple
200: control unit
210: data logger
300: shooting device
310: magnifying glass
320: support
c: chamber
S: object to be measured

Claims (4)

a thermocouple having a junction in which two types of metals are joined;
a controller for controlling the power supplied to the thermocouple and simultaneously measuring the temperature of the thermocouple; and
It includes a photographing device for photographing the behavior of the measurement object located in the junction,
The thermocouple receives power from the control unit and heats the object to be measured by generating heat at the junction.
The method according to claim 1,
An apparatus for measuring physical properties of a material using a thermocouple technology, characterized in that the junction of the thermocouple is coated with a material that does not react with the measurement object.
A method for measuring the physical properties of a material using the apparatus of claim 1, comprising:
a measurement object acquisition step of collecting the measurement object;
dissolving the measurement object by placing the collected measurement object in a thermocouple and heating the measurement object to a predetermined temperature by supplying electric power to the thermocouple;
a cooling step of cooling the measurement object by stopping power supply to the thermocouple; and
and a measuring step of observing a dissolution process and a cooling process of the object to be measured in the dissolution step and the cooling step.
4. The method according to claim 3,
The method for measuring physical properties of a material, wherein the dissolving step and the cooling step are performed in a chamber, and impurities in the chamber are removed by a getter.

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