JP2011122223A - Vaporizer, cvd system, method for monitoring vaporized state, method for depositing thin film and method for producing superconducting wire rod - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique which is useful when a thin film of a superconductor or the like is deposited using a solution vaporization type CVD system and evades the inhibition in the deposition of a thin film of high quality caused by the abnormality of a vaporized state in a vaporizer. <P>SOLUTION: The vaporizer includes: a vaporization chamber; an introduction part introducing a raw material solution into the vaporization chamber; a derivation part deriving a raw material gas vaporized in the vaporization chamber to the outside; and a heater provided at the outer circumference of the vaporization chamber and heating the vaporization chamber by a heating element. The vaporizer further includes: a first temperature sensor measuring a first temperature T<SB>M</SB>in the vicinity of the heating element; and a second temperature sensor measuring a second temperature T<SB>b</SB>in the part corresponding to the vaporization chamber heated by the heating element, and the output of the heating element is controlled in such a manner that the second temperature T<SB>b</SB>is made constant. Then, the abnormality of the vaporized state in the vaporizer is detected based on the variation of the first temperature T<SB>M</SB>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vaporizer that vaporizes a raw material solution and supplies a raw material gas to a reaction chamber, a solution vaporization type CVD apparatus, a vaporization state monitoring method in the vaporizer, a thin film formation method, and a superconducting wire manufacturing method.

Metal organic chemical vapor deposition (MOCVD) is widely applied to film formation of semiconductors, dielectrics, and superconductors. In this MOCVD method, a film is formed by supplying a raw material gas to the surface of a substrate in a reaction chamber to cause a chemical reaction. However, if the vapor pressure of the organometallic raw material (hereinafter referred to as MO raw material) is low and solid at room temperature, the raw material is In order to gasify the gas and supply it to the reaction chamber, a method (solution vaporization method) is employed in which a solution in which the MO raw material is dissolved (raw material solution) is sprayed into a high-temperature vaporizer and sublimated.
This solution vaporization method is also used when a superconductor made of YBCO (hereinafter referred to as a Y-based superconductor) is formed. In this case, for example, a solution of a metal β-diketone complex (for example, dipivaloylmethane (DPM)) in a solvent of THF (tetrahydrofuran) is used as a raw material solution. M (DPM) _n .

In the solution vaporization method described above, the vaporization state of the MO raw material is important in order to grow a uniform thin film on the substrate surface. In particular, when forming a thin film of Y-based superconductor, because the composition of the superconductor thin film greatly affects the critical current characteristics (I _c characteristics), the vaporization state of the MO material this composition causes to change critical It becomes. Further, in order to use the superconducting wire for power transportation or superconducting magnetic energy storage (SMES), a superconducting thin film must be continuously formed on a long tape-like substrate. Therefore, various techniques for stabilizing the vaporization state of the MO raw material have been proposed.

  For example, Patent Documents 1 and 2 disclose a method in which a pressure sensor is provided in a pipe of a vaporizer, and a change in pressure of the carrier gas is detected to monitor a state of the vaporizer outlet (pipe clogging). Further, for example, Patent Document 3 discloses a method in which pressure sensors are provided at several locations inside the vaporizer and the vaporized state is observed in situ (in-situ observation). In addition, the vaporization state is often improved by a result-based observation method in which the film thickness after film formation, the growth form, the composition, and the like are observed in situ.

JP 2006-303534 A JP 2006-108230 A JP 2003-160869 A

By the way, the MO raw material used for the film formation of the Y-based superconductor thin film has a high sublimation point. Therefore, when the solvent evaporates or the temperature decreases, a solid raw material is deposited, and a nozzle for ejecting the raw material into the vaporization chamber May accumulate on interior walls. In particular, since Ba (DPM) ₂ has a vaporization temperature and a decomposition temperature close to each other, the decomposed raw material may adhere to the vaporization chamber wall in a paste form due to the slight decomposition that occurs during vaporization.
Then, if the MO raw material or decomposed raw material adheres to the inner wall of the vaporization chamber and the vaporization state deteriorates, the temperature in the vaporization chamber decreases, or the solid raw material is peeled off in the vaporization chamber and supplied to the reaction chamber. Problems arise. In either case, a stable source gas cannot be supplied to the reaction chamber.

In the techniques described in Patent Literatures 1 and 2, nozzle clogging in the vaporizer can be detected, but the state of vaporization in the vaporization chamber cannot be monitored. In the technique described in Patent Document 3, the vaporization state can be observed in situ by the pressure sensor in the vaporization chamber, but it is difficult to detect that the raw material is attached to the vaporization chamber wall. In addition, the result-based observation method has a slow response and cannot quickly resolve the abnormality in the vaporized state, which is not suitable for continuous production of long products such as superconducting wires.
As described above, in the conventional vaporizer, it is difficult to quickly detect the abnormality of the vaporized state in the vaporizer, so that it is difficult to supply a stable MO source gas to the reaction chamber.

  The present invention is a technique useful for forming a thin film such as a superconductor using a solution vaporization type CVD apparatus equipped with a vaporizer, and obstructs the formation of a good quality thin film due to an abnormal vaporization state in the vaporizer. It aims at providing the technique for avoiding being done.

The invention described in claim 1 was made to achieve the above object,
A vaporization chamber;
An introduction part for introducing a raw material solution into the vaporization chamber;
A derivation unit for deriving the source gas vaporized in the vaporization chamber to the outside;
In a vaporizer provided with an outer periphery of the vaporization chamber and a heater that heats the vaporization chamber with a heating element,
A first temperature sensor for measuring a first temperature T _M in the vicinity of the heating element,
A second temperature sensor for measuring a second temperature T _b of the corresponding portion of the vaporizing chamber which is heated by the heating element, the provided
The output of the heating element is controlled so that the second temperature _Tb is constant.

The invention according to claim 2 is the vaporizer according to claim 1, wherein the heater has a plurality of heating elements individually controlled in temperature arranged in multiple stages on the outer periphery of the vaporization chamber,
The first temperature sensor and the second temperature sensor are provided corresponding to each of the plurality of heating elements.

According to a third aspect of the present invention, in the vaporizer according to the first or second aspect, the vaporization chamber and the heater are arranged concentrically,
The first temperature sensor and the second temperature sensor are spaced apart from each other in the same radial direction.

The invention according to claim 4 is the vaporizer according to any one of claims 1 to 3,
A raw material solution supply unit for supplying a raw material solution obtained by dissolving a solid raw material in a solvent to the vaporizer;
And a reaction chamber for forming a thin film by supplying a raw material gas vaporized by the vaporizer to the surface of the base material to cause a chemical reaction.

Invention of Claim 5 is the monitoring method of the vaporization state in the vaporizer as described in any one of Claim 1 to 3, Comprising:
Based on the amount of change of the first temperature T _M, vaporized state is characterized by determining whether it is abnormal.

The invention described in claim 6 is the method of monitoring the state of vaporization of claim 5, when the amount of change of the first temperature T _M with respect to the reference temperature exceeds a predetermined value, becomes vaporized state abnormality It is characterized by judging.

The invention according to claim 7 uses the CVD apparatus according to claim 4 to vaporize the raw material solution by controlling the output of the heater so that the second temperature _Tb is constant in the vaporizer, In the method of forming the thin film by supplying the vaporized source gas to the reaction chamber and causing a chemical reaction on the surface of the substrate,
When the amount of change of the first temperature T _M with respect to the reference temperature is equal to or larger than a predetermined value, it is determined that the vaporized state becomes abnormal,
When it is determined that the vaporization state has become abnormal, the supply of the raw material gas to the reaction chamber is stopped,
Stop supplying the raw material solution,
Only the solvent is introduced into the vaporization chamber and purged,
Restart the supply of the raw material solution,
After the first temperature _TM is restored to a predetermined value, the supply of the raw material gas to the reaction chamber is resumed.

The invention according to claim 8 is the method for forming a thin film according to claim 7, wherein when the supply of the raw material solution is stopped and only the solvent is introduced into the vaporizing chamber for purging,
The overall flow rate is kept constant by gradually decreasing the flow rate of the raw material solution and gradually increasing the flow rate of the solvent.

Invention according to claim 9, method of forming a thin film according to claim 7 or 8, when the first temperature T _M is not recovered to a predetermined value, stops the operation of the CVD apparatus wherein It is characterized by performing maintenance of the vaporizer.

  A tenth aspect of the present invention is a superconductivity characterized in that a superconducting thin film is formed on the surface of a long tape-like substrate by the method for forming a thin film according to any one of the seventh to ninth aspects. It is a manufacturing method of a wire.

  According to the present invention, it is possible to quickly detect an abnormality in the vaporization state in the vaporizer, so that it is possible to quickly recover to a normal vaporization state. Thereby, since stable source gas can be supplied to the reaction chamber, it can be avoided that the formation of a high-quality thin film is hindered due to the abnormality of the vaporization state in the vaporizer. Therefore, it is possible to uniformly form a thin film made of a superconductor or the like, and it is also suitable for continuously forming a film on a long tape-like substrate.

It is sectional drawing which shows schematic structure of the vaporizer | carburetor which concerns on embodiment. It is a figure for demonstrating the principle of abnormality detection of a vaporization state. It is a figure which shows schematic structure of the solution vaporization type CVD apparatus provided with the vaporizer. An example of operating procedure, I _c characteristics of the superconductor thin film was varied and formation of the first temperature T _M in the case of unrecoverable to a normal state of vaporization by purging with THF when the abnormality is detected in the state of vaporization It is a figure shown about. Working procedure for abnormal state of vaporization becomes restored the vaporized state without purging with THF be detected, showing an example of I _c characteristics of the superconductor thin film was varied and formation of the first temperature T _M FIG. Can not recover the normal state of vaporization is purged with THF when the abnormality is detected in the state of vaporization, in the case of performing maintenance work procedure was superconductor thin film is varied and the formation of the first temperature T _M it is a diagram showing an example of I _c characteristics. Working procedure for abnormal state of vaporization attempts to recover vaporized state purging with THF when detected, shows an example of I _c characteristics of the superconductor thin film was varied and formation of the first temperature T _M It is. It is sectional drawing shown about the modification of a vaporizer.

Hereinafter, embodiments of the present invention will be described in detail.
Drawing 1 is a sectional view showing a schematic structure of vaporizer 10 concerning an embodiment. As shown in FIG. 1, the vaporizer 10 includes a vaporization chamber 11, an introduction part 12, a cylindrical heater 13, and a lead-out part 14.
The vaporization chamber 11 is a hollow cylindrical body whose upper and lower surfaces are closed, and an introduction portion 12 is provided on the upper wall, and a lead-out portion 14 is provided on the bottom wall.
The introduction unit 12 introduces the raw material solution supplied from the raw material supply unit 30 into the vaporization chamber 11. Specifically, a spray nozzle is provided at the tip, and the raw material solution is sprayed from the spray nozzle into the vaporization chamber 11.

The heater 13 has a cylindrical shape that surrounds the outer periphery of the vaporizing chamber 11, and is configured such that the heating element 131 is covered with a muffle material (heat insulating material) 132. Heating element 131 is output as a second temperature T _b to be described later is constant at a set temperature is controlled, heating and holding the wall of the vaporization chamber 11 to a predetermined temperature.
The lead-out part 14 is a lead-out port provided substantially at the center of the bottom wall of the vaporization chamber 11, and leads the source gas vaporized in the vaporization chamber 11 to the reaction chamber 20. Further, a vent line 17 for exhaust / drainage is connected to the outlet 14 so that unnecessary gas in the vaporization chamber 11 can be exhausted.
In addition, the arrangement | positioning location of the derivation | leading-out part 14 is not limited to the bottom wall of the vaporization chamber 11, You may make it provide in a side wall. Further, the vent line 17 is not limited to a form branched from the lead-out part 14 into a T-shape, and may be any form that can exhaust unnecessary gas from the vicinity of the lead-out part 14. For example, you may provide in the lower part of the side wall of the vaporization chamber 11, and you may provide in parallel with the derivation | leading-out part 14 in the bottom wall of the vaporization chamber 11.

The vaporizer 10 of the present embodiment further includes a first temperature sensor 15 and a second temperature sensor 16. The first temperature sensor 15 and the second temperature sensor 16 are composed of, for example, a thermocouple.
The first temperature sensor 15 is disposed, for example, site as close as possible to the heating element 131, the temperature of the site, i.e., to measure the temperature (first temperature) T _M in the vicinity of the heating element 131. For example, the second temperature sensor 16 is disposed so as to be in contact with the outer wall surface of the vaporization chamber 11, and the temperature of the portion, that is, the temperature (second temperature) T _b of the corresponding portion of the vaporization chamber 11 heated by the heating element 131. Measure.

The first temperature sensor 15 and the second temperature sensor 16 are arranged at the center in the height direction of the heating element 131 so as to have the same height, that is, separated by a distance L (for example, 8 mm) in the same radial direction. ing. By measuring two temperatures T _M and T _b that are different in the radial direction by the first temperature sensor 15 and the second temperature sensor 16, a heat transfer path from the heating element 131 toward the vaporization chamber 11 based on the temperature difference. The heat flow at can be monitored.

When an abnormal reaction such as decomposition of the raw material or adhesion to the inner wall of the vaporizing chamber 11 occurs in the vaporizing chamber 11, heat of reaction is generated. Moreover, when a raw material adheres to the inner wall of the vaporization chamber 11, the thermal conductivity of the inner wall gradually changes. As described above, when reaction heat is generated or the thermal conductivity of the inner wall of the vaporizing chamber 11 is changed to cause thermal fluctuation in the vaporizing chamber 11, the second temperature _Tb is changed.
At this time, in order to hold the second temperature T _b at a constant (set temperature ± 3 ° C. or less), to compensate for the thermal variations in the vaporizing chamber 11 (change of the thermal conductivity of the heat of reaction generated and the reaction chamber 11) Therefore, the output of the heating element 131 is controlled. For example, the increased output of the second temperature T _b by thermal fluctuations in the vaporizing chamber 11 is lower than the set temperature the heating element 131, the output of the heating element 131 and the second temperature T _b is higher than the set temperature decreases Is done. The first temperature (the temperature in the vicinity of the heating element 131) T _M changes every moment according to the output of the heating element 131.

Here, the heat flow Q _(Mb) in the heat transfer path from the heating element 131 toward the vaporizing chamber 11 is given by the following equation (1).
Q _(M−b) = k · A · (T _M −T _b ) / L (1)
k: equivalent thermal conductivity in the heat transfer path A: heat transfer area L: distance between the first temperature sensor 15 and the second temperature sensor 16

If the first temperature T _M is changed from T _M1 to T _M2 as a result of controlling the output of the heating element 131 to compensate for the heat fluctuation in the vaporizing chamber 11, the heat flow rate is ΔQ from the equation (1). _(M−b) = k · A · (T _M2 −T _M1 ) / L (2)
Only fluctuated. That is, as shown in FIG. 2, by detecting the fluctuation amount (T _M2 −T _M1 ) of the first temperature T _M , the fluctuation ΔQ _(M−b) of the heat flow rate can be evaluated, and the heat in the vaporization chamber 11 can be evaluated. Can monitor fluctuations.

Since the thermal variation of the vaporizing chamber 11 due to changes in the state of vaporization, by measuring a first temperature T _M in the vicinity of the heating element 131 by the first temperature sensor 15 (situ measurement) in the vaporizing chamber 11 Changes in the vaporization state can be monitored, and abnormalities in the vaporization state can be detected. For example, with respect to the first temperature T _M obtained in advance as the reference temperature T _S and the difference (reference temperature T _S of the reference temperature T _S and the first temperature T _M measured in the thin film formation in a normal state of vaporization If the variation amount of the first temperature T _M) becomes a predetermined value or more, the vaporization state is determined to be abnormal.

Incidentally, the amount of change of the first temperature T _M of determining as abnormal, the capacity and size of the vaporization chamber 11, the position of the heating element 131 is appropriately set depending on the distance of the heating element 131 and the first temperature sensor 15.
In the present embodiment, in consideration of the experimental results with these influence factors, vaporized state is determined to be abnormal when the variation amount of the first temperature T _M becomes ± 5 ℃ or higher. For example, in FIG. 2, if the first temperature T _M1 (= 260 ° C.) is the reference temperature T _S , the variation amount is 10 ° C. when the first temperature T _M becomes T _M2 (= 270 ° C.). Therefore, it is determined that the vaporization state is abnormal.

FIG. 3 is a diagram showing a schematic configuration of a solution vaporization type CVD apparatus provided with the vaporizer 10. Here, an example of a CVD apparatus used when forming a Y-based superconductor thin film is shown.
As shown in FIG. 3, the CVD apparatus 1 includes a vaporizer 10, a reaction chamber 20, and a raw material solution supply unit 30. The raw material solution supply unit 30 includes raw material containers 31 to 33 for storing the raw material solution and a solvent container 34 for storing the solvent. In the raw material containers 31 to 33, Y (DPM) ₃ / THF, Ba (DPM) ₂ / THF in which DPM complexes of yttrium (Y), barium (Ba), and copper (Cu) are dissolved in THF as a solvent, respectively. Cu (DPM) ₂ / THF is stored. The solvent container 34 stores THF as a solvent.

In the CVD apparatus 1, the raw material solution stored in the raw material containers 31 to 33 or the THF stored in the solvent container 34 is pumped out of the container by increasing the pressure in the container with an inert gas such as He. The The flow rates of the raw material solution and the solvent are adjusted by a flow meter. In the raw material solution transport pipe 35, the raw material solution Y (DPM) ₃ / THF, Ba (DPM) ₂ / THF, and Cu (DPM) ₂ / THF are mixed at a predetermined ratio.
The mixed raw material solution is combined with a spraying gas such as Ar, introduced into the vaporizer 10, and sprayed from a spray nozzle. Then, it collides with the inner wall of the vaporizer 10 and is instantly vaporized, and this vaporized gas is supplied to the reaction chamber 20 as a raw material gas together with O ₂ gas (not shown). The raw material gas introduced into the reaction chamber 20 is supplied to the surface of the substrate and chemically reacted to form a Y-based superconductor thin film.
The form of the raw material solution transport pipe 35 may be any form in which the raw material solution of Y, Ba, Cu and THF are mixed at a predetermined ratio and sent to the vaporizer 10. For example, the three types of raw material solutions may be configured to be independently transportable, and may be mixed at a portion where they merge with a spraying gas such as Ar. In this case, THF is supplied to the transport pipes of the respective raw material solutions so that the mixed solution of the raw material solution and THF is transported.

In the Y-based superconductor thin film forming process, constantly monitors the state of vaporization in the vaporizer 10 based on the variation amount of the first temperature T _M with respect to the reference temperature T _S.
When the fluctuation amount of the first temperature T _{M with} respect to the reference temperature T _S becomes a predetermined value (for example, ± 5 ° C.) or more, it is determined that the vaporization state in the vaporization chamber 11 is abnormal, and the derivation path from the vaporizer 10 is vented. Switching to the line 17 side stops the supply of the source gas to the reaction chamber 20. That is, when a thermal fluctuation occurs in the vaporization chamber 11 due to decomposition of the raw material or the like and an abnormality in the vaporized state is detected, the introduction of the raw material gas having an unstable vaporized state into the reaction chamber 20 is blocked. Thus, the film formation on the substrate surface is stopped.

Next, the supply of the raw material solution to the vaporizer 10 is stopped, and only THF is introduced into the vaporization chamber 11 and purged for a predetermined time (for example, 40 min). Thereby, since the solid raw material etc. which have adhered to the inner wall of the vaporization chamber 11 are removed, it can recover to a normal vaporization state.
At this time, it is desirable to keep the overall flow rate constant by gradually decreasing the flow rate of the raw material solution and gradually increasing the flow rate of THF. When the flow rate introduced into the vaporizer 10 changes abruptly, the pipe for introducing the raw material solution and the solvent into the vaporizer 10 is clogged, or the pressure in the vaporization chamber 11 fluctuates rapidly, and the vaporization state further deteriorates. It is because there is a possibility of doing.
After purging with THF, the supply of the raw material solution to the vaporizer 11 is resumed. After the first temperature T _M and it was confirmed that the recovered to a predetermined value (reference temperature ± 5 ° C.), it resumes the supply of the source gas into the reaction chamber 20.

Figure 4 is a work procedure when able to recover to a normal state of vaporization by purging with THF when the abnormality is detected in the vaporized state, I of the superconducting thin film which is varied and the deposition of the first temperature T _M It is a figure shown about an example of _c characteristic.
In the example illustrated in FIG. 4, the output of the heating element 131 is controlled so that the second temperature _Tb is constant at 210 ° C. in the vaporizer 10. At this time, the first temperature T _M in normal vaporized state was 260 ° C.. Therefore, when the reference temperature T _{S is set} to 260 ° C. and the first temperature T _M fluctuates by ± 5 ° C. or more with respect to the reference temperature T _S (that is, 265 ° C. or more or 255 ° C. or less), the vaporization state is changed. Judged to be abnormal.

As shown in FIG. 4, the first temperature _{T M,} begins to rise from 260 ° C. When the operation time becomes 23.5 hours, became 265 ° C. at the time point when 23.8 hours. At this time, it was determined that the vaporization state was abnormal, the supply path from the vaporizer 10 was switched to the vent line 17 side, and the supply of the raw material gas to the reaction chamber 20 was stopped.
Then, the supply of the raw material solution to the vaporizer 10 was stopped, and only THF was introduced into the vaporization chamber 11 and purged for 0.7 hours. After purging with THF, the supply of the raw material solution to the vaporizer 10 was resumed. After the first temperature T _M and it was confirmed that the recovered to 260 ° C., it was resumed supply of the source gas into the reaction chamber 20.

Also, the first temperature _{T M,} begins to rise from 260 ° C. When the operation time becomes 27.5 hours, because a 265 ° C. at the time point when 27.8 hours, in the same manner as described above THF Purging with was performed. Then, after purging with THF, the supply of the raw material solution to the vaporizer 10 is restarted, and it is confirmed that the first temperature _TM is 260 ° C. (recovery of the vaporized state). Gas supply resumed.
Thus, it was confirmed that the Y-based superconductor thin film formed under the normal vaporization state has almost uniform Ic characteristics at about 200 A and has good superconducting characteristics.

5, I _c characteristics of work procedures, superconductor thin film was varied and formation of the first temperature T _M in the case where even if an abnormality is detected in the vaporized state was restored the vaporized state without purging with THF It is a figure shown about an example.
In the example shown in FIG. 5, the output of the heating element 131 is controlled so that the second temperature _Tb is constant at 210 ° C. in the vaporizer 10.

As shown in FIG. 5, the first temperature T _M began to rise from 260 ° C. when the operation time reached 23.5 hours, and reached 265 ° C. when it reached 23.8 hours. At this point, it can be determined that the vaporized state is in an abnormal, was it continued formation of Y-based superconductor thin film, the first temperature T _M rose to around 275 ° C..
The Y-based superconductor thin film formed after the abnormality of the vaporized state was detected had an Ic characteristic of about 70 or less, which was significantly lowered. It is considered that because the vaporized state is abnormal, the stable source gas is not supplied to the reaction chamber 20 and the composition of the formed Y-based superconductor thin film is shifted.

As described above, when an abnormality in the vaporized state is detected, purging with THF can efficiently remove the solid raw material or the like adhering to the inner wall of the vaporization chamber 11 and restore the vaporized state. it can.
However, there is a case where the vaporized state cannot be recovered as expected due to, for example, solid material or the like firmly adhering to the inner wall of the vaporization chamber 11. In this case, it is desirable to stop the operation of the CVD apparatus 1 and perform maintenance. Specifically, the vaporizer 10 is disassembled, the inner wall of the vaporization chamber 11 is cleaned, and the deposits are removed.
After the maintenance, the supply of the raw material solution to the vaporizer 11 is restarted, and the supply of the raw material gas to the reaction chamber 20 is restarted. Based on the fluctuation amount of the first temperature T _{M with} respect to the reference temperature T _S, it can be easily confirmed that the vaporized state cannot be recovered only by purging with THF. In this case, the normal vaporized state can be efficiently recovered by maintenance. be able to.

6 can not recover the normal state of vaporization be purged with THF when the abnormality is detected in the vaporized state, it is work procedures, variation and formation of the first temperature T _M in the case of performing maintenance it is a diagram showing an example of I _c characteristics of the superconducting thin film.
In the example shown in FIG. 6, the output of the heating element 131 is controlled so that the second temperature _Tb is constant at 210 ° C. in the vaporizer 10. Further, when the reference temperature T _S was 260 ° C. and the first temperature T _M fluctuated by ± 5 ° C. or more with respect to the reference temperature T _S , it was determined that the vaporization state was abnormal.

As shown in FIG. 6, the first temperature _{T M,} begins to rise from 260 ° C. When the operation time becomes 23.5 hours, became 265 ° C. at the time point when 23.8 hours. At this time, it was determined that the vaporization state was abnormal, the supply path from the vaporizer 10 was switched to the vent line 17 side, and the supply of the raw material gas to the reaction chamber 20 was stopped.
Then, the supply of the raw material solution to the vaporizer 10 was stopped, and only THF was introduced into the vaporization chamber 11 and purged for 0.7 hours. After purging with THF, the supply of the raw material solution to the vaporizer 10 was resumed. However, since the first temperature _TM was higher than 270 ° C. and no recovery of the vaporized state was observed, the operation of the CVD apparatus 1 was stopped. Maintenance was performed.

After the maintenance, the supply of the raw material solution to the vaporizer 11 was restarted, and the supply of the raw material gas to the reaction chamber 20 was restarted. First temperature T _M after maintenance is 260 ° C., was recovered to normal state of vaporization.
Thus, it was confirmed that the Y-based superconductor thin film formed under the normal vaporization state has almost uniform Ic characteristics at about 200 A and has good superconducting characteristics.

7, work procedure when an abnormality in the vaporized state attempts to recover vaporized state purging with THF when detected, the I _c characteristics of the superconductor thin film was varied and formation of the first temperature T _M It is a figure shown about an example.
In the example illustrated in FIG. 7, the output of the heating element 131 is controlled so that the second temperature _Tb is constant at 210 ° C. in the vaporizer 10. Further, when the reference temperature T _S was 260 ° C. and the first temperature T _M fluctuated by ± 5 ° C. or more with respect to the reference temperature T _S , it was determined that the vaporization state was abnormal.

As shown in FIG. 7, the first temperature T _M began to rise from 260 ° C. when the operation time reached 23.5 hours, and reached 265 ° C. when it reached 23.8 hours. At this time, it was determined that the vaporization state was abnormal, the supply path from the vaporizer 10 was switched to the vent line 17 side, and the supply of the raw material gas to the reaction chamber 20 was stopped.
Then, the supply of the raw material solution to the vaporizer 10 was stopped, and only THF was introduced into the vaporization chamber 11 and purged for 0.7 hours. After purging with THF, the supply of the raw material solution to the vaporizer 10 was resumed. However, since the first temperature _TM was higher than 270 ° C. and no recovery of the vaporized state was observed, the purge with THF was performed again. While thereafter was purged by several THF, the first temperature T _M becomes constant at around 275 ° C., vaporized state remained abnormal.
The Y-based superconductor thin film formed after the abnormality of the vaporized state was detected had an Ic characteristic of about 70 or less, which was significantly lowered. It is considered that because the vaporized state is abnormal, the stable source gas is not supplied to the reaction chamber 20 and the composition of the formed Y-based superconductor thin film is shifted.

Thus, the vaporizer 10 of the embodiment, the first temperature sensor 15 for measuring a first temperature T _M in the vicinity of the heating element 131, a second temperature of the corresponding portion of the vaporization chamber 11 heated by the heating element 131 And a second temperature sensor 16 for measuring _Tb . The output of the heating element 131 is controlled so that the second temperature Tb is constant.
According to the vaporizer 10, since the abnormality of the vaporization state can be easily detected by in-situ measurement by the first temperature sensor 15, it is possible to quickly recover the normal vaporization state.

  In addition, according to the CVD apparatus 1 and the thin film forming method according to the embodiment, a stable source gas can be supplied to the reaction chamber 20, so that formation of a high-quality thin film is hindered due to an abnormal vaporization state in the vaporizer 10. Can be avoided, and the thin film can be formed uniformly.

  Furthermore, when a superconductor thin film is formed on the surface of a long tape-like substrate, the film formation is stopped once an abnormality in the vaporized state is detected, and the film formation is resumed after the vaporized state is recovered. Therefore, a uniform superconductor thin film can be continuously formed on the tape-shaped substrate. Therefore, a superconducting wire having good Ic characteristics can be manufactured.

As mentioned above, although the invention made by this inventor was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.
For example, in the above-described embodiment, the heater 13 of the vaporizer 10 has a configuration having one heating element 131. However, as shown in FIG. 8, the heater 13 has a plurality of heating elements 131a to 131c. The temperature may be individually controlled. In this case, the 1st temperature sensors 151-153 and the 2nd temperature sensors 161-163 are arranged corresponding to each heating element 131a-131c.
By adopting such a configuration, it is possible to independently control the temperature of the vaporization chamber inlet (upper part) and outlet (lower part) where the solid raw material easily deposits and adheres, and the vaporization state in the vaporizer 10 is more accurate. Can be monitored.

Further, for example, in the above embodiment, the first temperature T _M and monitor for detecting an abnormality of the state of vaporization, a second temperature T _b although the for constant temperature control, the first temperature T _M and a constant temperature control , it may be a monitor for determining the second temperature T _b of vaporization abnormal state.
In this case, although the heat fluctuation generated in the vaporization chamber 11 can be detected sensitively, it is difficult to detect the material adhesion that gradually occurs on the inner wall of the vaporizer. In addition to detecting abnormalities in the vaporization state, in order to maintain a stable vaporization state as much as possible, a portion near the vaporization chamber 11 is used as a temperature control point as in the embodiment, and the temperature of the vaporization chamber 11 is kept constant. It is desirable to do.

In the above embodiment, an example of using He as pumping gas, it is possible to use an inert gas such as Ar or N _2. Similarly, an inert gas such as He or N ₂ can be used as the atomizing gas instead of Ar.
Moreover, although the example which used THF as a solvent was shown, organic solvents, such as xylene, alcohols, ethers, ketones, amines, boiling point 100 degrees C or less, and hydrocarbons, can be used. Specifically, diethyl ether, diethyl ketone, ethanol, tetraglyme (tetraglyme), 2,5,8,11,14-pentaoxapentadecane and the like can be applied.

In the above embodiment, the case where a Y-based superconductor thin film is formed has been described. However, the present invention is commonly used when a thin film is formed by MOCVD using a raw material having a low vapor pressure and a room temperature solid. Applicable technology. For example, the present invention can be applied to a case where an organic metal raw material in which a metal atom and an organic group are bonded through an oxygen atom is used as the solid raw material. Here, the organic group may be any one of acetylacetonate, dipivaloylmethanate, alkoxide, hexafluoroacetylacetonate, and pentafluoropropanoylpivaloylmethanate.
As raw materials for forming a ferroelectric thin film such as barium titanate or strontium titanate, barium dipivaloylmethanate “Ba (DPM) ₂ ”, strontium dipivaloylmethanate “Sr” (DPM) ₂ ”, bis (dipivaloylmethanate) diisopropoxytitanium“ Ti (iPrO) ₂ (DPM) ₂ ”and the like. Alternatively, a raw material in which TTIP (Titanium Tetra Isopropoxide “Ti (OC ₃ H ₇ ) ₄ ”) or the like is dissolved in THF may be used.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 CVD apparatus 10 Vaporizer 11 Vaporization chamber 12 Introducing part 13 Heater 14 Deriving part 15 1st temperature sensor 16 2nd temperature sensor 20 Reaction chamber 30 Raw material solution supply part 131 Heating body 132 Muffle material (insulation material)

Claims (10)

A vaporization chamber;
An introduction part for introducing a raw material solution into the vaporization chamber;
A derivation unit for deriving the source gas vaporized in the vaporization chamber to the outside;
In a vaporizer provided with an outer periphery of the vaporization chamber and a heater that heats the vaporization chamber with a heating element,
A first temperature sensor for measuring a first temperature T _M in the vicinity of the heating element,
A second temperature sensor for measuring a second temperature T _b of the corresponding portion of the vaporizing chamber which is heated by the heating element, the provided
The vaporizer characterized in that the output of the heating element is controlled so that the second temperature _Tb is constant. The heater has a plurality of heating elements individually controllable arranged in multiple stages on the outer periphery of the vaporization chamber,
The vaporizer according to claim 1, wherein the first temperature sensor and the second temperature sensor are provided corresponding to each of the plurality of heating elements. The vaporization chamber and the heater are arranged concentrically;
3. The vaporizer according to claim 1, wherein the first temperature sensor and the second temperature sensor are spaced apart from each other in the same radial direction. A vaporizer according to any one of claims 1 to 3;
A raw material solution supply unit for supplying a raw material solution obtained by dissolving a solid raw material in a solvent to the vaporizer;
A CVD apparatus comprising: a reaction chamber that forms a thin film by supplying a raw material gas vaporized by the vaporizer to a surface of a base material to cause a chemical reaction. It is the monitoring method of the vaporization state in the vaporizer as described in any one of Claim 1 to 3,
On the basis of the amount of change of the first temperature T _M, the method of monitoring the state of vaporization vaporized state is characterized by determining whether it is abnormal. When the amount of change of the first temperature T _M with respect to the reference temperature exceeds a predetermined value, the method of monitoring the state of vaporization of claim 5 vaporized state is characterized in that it is determined that an abnormal. The raw material solution is vaporized by controlling the output of the heater so that the second temperature _Tb becomes constant in the vaporizer using the CVD apparatus according to claim 4, and the vaporized raw material gas is reacted with the reaction. In a method of forming a thin film by supplying a chemical reaction on the surface of a substrate supplied to a chamber,
When the amount of change of the first temperature T _M with respect to the reference temperature is equal to or larger than a predetermined value, it is determined that the vaporized state becomes abnormal,
When it is determined that the vaporization state has become abnormal, the supply of the raw material gas to the reaction chamber is stopped,
Stop supplying the raw material solution,
Only the solvent is introduced into the vaporization chamber and purged,
Restart the supply of the raw material solution,
After the first temperature _TM is restored to a predetermined value, the supply of the raw material gas to the reaction chamber is restarted. When the supply of the raw material solution is stopped and only the solvent is introduced into the vaporizing chamber and purged,
8. The method of forming a thin film according to claim 7, wherein the overall flow rate is kept constant by gradually decreasing the flow rate of the raw material solution and gradually increasing the flow rate of the solvent. Wherein when the first temperature T _M is not recovered to a predetermined value, forming a thin film according to claim 7 or 8, characterized in that to stop the operation of the CVD apparatus performing maintenance of the vaporizer .   A method for producing a superconducting wire comprising forming a superconductor thin film on the surface of a long tape-like substrate by the method for forming a thin film according to any one of claims 7 to 9.

Images