JP2526852Y2 - Apparatus for vapor phase growth of oxide superconducting thin film - Google Patents

Description

[Detailed description of the invention] << Industrial application field >> The invention is based on a yttrium-barium-copper-oxygen system (Y-Ba-Cu-O) on a substrate such as strontium titanate.
The present invention relates to an improvement in a vapor phase growth apparatus used for forming an oxide superconducting thin film by a vapor phase method.

<< Conventional Technology >> As shown in FIG. 2, a conventional vapor phase epitaxy apparatus of this type comprises an oxygen gas supply pipe 2 on one side wall 1a on the upstream side of a reaction tube 1, and a Y-Ba- The supply pipes 3 for the source gas containing the Cu-O-based oxide superconductor are respectively connected, and the end ports 2a, 3a of the pipes 2, 3 are opened in the reaction tube 1 on the side wall 1a. At the same time, an intake pipe 5 for exhaust gas connected to a rotary pump 4 or the like is connected to a bottom wall on one end side, which is a downstream side of the reaction tube 1.

Further, a susceptor 6 made of SiC-coated carbon or the like is supported by a support rod 7 made of quartz or the like at a central portion in the reaction tube 1. A substrate P made of strontium titanate (SrTiO ₃ ) or the like can be placed so as to be detachable, and the substrate P is configured to be heated by an infrared lamp 8 in contact with the outside of the reaction tube 1. It is a thing.

By the way, the above oxide superconductor is an oxygen-deficient superconductor, and its structure is represented by Y ₁ Ba ₂ Cu ₃ O ₇ −δ, where δ indicates the amount of oxygen deficiency, δ It is also known that the smaller the is, the higher the critical temperature (Tc) is, and that at δ <0.1 Te> 90k can be obtained.

When producing a Y-Ba-Cu-O-based oxide superconducting thin film by a vapor phase method, it is common to use O ₂ gas as a supply source of O. In this case, more O is used. The incorporation into the thin film is important in the preparation of this kind of thin film, and as a result, the critical temperature (Tc) can be increased as described above, and a desired result can be obtained.

However, in the case of using the conventional vapor phase growth apparatus as described above, unless the O ₂ gas flow is supplied as much as possible from the end 2a of the oxygen gas supply pipe 2,
The critical temperature (Tc) cannot be increased, and as a result, the cost increases due to the amount of O ₂ used. Further, at this time, a large amount of gas must be exhausted from the reaction tube 1 by the rotary pump 4 or the like. The oil of the pump 4 also has a defect that the deterioration of the oil is accelerated and the life of the pump 4 is shortened.

More importantly, in the case of the above conventional apparatus, the O ₂ gas supplied from the end 2a of the supply pipe 2 and the source gas supplied from the end 3a of the supply pipe 3 for the source gas are mixed in the reaction tube 1. After being transported together in the horizontal direction, it reaches the substrate P in an inclined state, so that a reaction between the two gases can occur in the transfer path. As a result,
The reactant obtained by the above reaction adheres to the lower side of the reaction tube 1, thereby hindering the temperature rise of the substrate P heated by the infrared ray emitted from the infrared lamp 8, Useless consumption of the raw material gas is also involved.

<< Problems to be solved by the invention >> The present invention has been studied in view of the disadvantages of the above-described conventional apparatus, in which the O ₂ outlet in the oxygen gas supply pipe is provided on one side wall of the reaction tube as in the conventional example. The supply pipe is extended into the reaction tube without being formed by the end port,
The air outlet, in the vicinity of the substrate on the susceptor, properly by configuring so as to open, so can enhance the oxygen partial pressure on a substrate without the use of so many O _2, compared by this With a very small amount of O ₂ gas, the amount of oxygen taken into the oxide superconducting thin film to be formed on the substrate is increased, so that the thin film can be formed inexpensively, The first object of the pump is to solve the problems of oil deterioration and shortened service life of the pump.

Further, in the present invention, the raw material gas supplied in the horizontal direction and the oxygen gas delivered to the substrate from the supply pipe are configured to be first encountered on the substrate, so that each of these is provided. Prevents gas from reacting in the supply process up to the substrate in the reaction tube and reaching the substrate, thereby contaminating the reaction tube with reactants and thereby hindering the heating efficiency of the substrate by infrared rays This is the second purpose.

<< Means for Solving the Problems >> The present application is intended to achieve the above object, and a supply pipe for an oxygen gas and a supply pipe for a raw material gas are connected to an upstream side of a reaction tube. A raw material gas is supplied in the horizontal direction by connecting an intake pipe for exhaust gas to the downstream side of the reactor, and a susceptor capable of mounting a substrate in an inclined state in which the upstream side descends is provided in the reaction tube. An infrared lamp for heating the substrate is adjacent to the outside of the reaction tube, and the supply pipe for the oxygen gas is provided through the reaction tube, and the outlet is provided near the substrate on the susceptor. Vapor-phase growth of the oxide superconducting thin film, which is opened toward the substrate at the upstream side so that the oxygen gas and the raw material gas in the horizontal direction can be encountered on the substrate. Equipment It is to try.

<< Operation >> In the case of the vapor phase growth apparatus according to the present invention, the O ₂ gas supplied by the oxygen gas supply pipe is not simply discharged from the reaction tube and from the side wall away from the substrate, On the upstream side near the substrate, O ₂ gas will be released from the outlet opened toward the substrate side, and as a result, the supply amount of O ₂ gas flowing out from the outlet,
Even if it is not so large, the oxygen partial pressure on the upper surface side of the substrate becomes large, so that the amount of O taken in the oxide superconducting thin film formed on the substrate can be increased, so that the amount of exhaust gas in the reaction tube can be increased. However, since it is not so large, the pump for exhaust can also maintain a long life.

Further, in the present invention, the source gas is supplied in the horizontal direction in the reaction tube, and is supplied to the substrate tilted on the susceptor, and at the same time, the oxygen gas is sent out to the source gas. Only when the gas is on the substrate will it encounter and react. Therefore, prior to the encounter, the two gases react with each other, and the generated reactant adheres to the lower portion of the reaction tube, thereby solving the problem that the heating of the substrate by the infrared lamp is unintentionally reduced. And
It will be possible to provide highly reliable products for a long time.

<< Embodiment >> The present invention will be described in detail with reference to an embodiment shown in FIG. 1. In FIG. 1, reference numeral 1 denotes a reaction tube, reference numeral 2 denotes an oxidation gas supply pipe, Source gas supply pipe, 4 rotary pump, 5 intake pipe, 6 susceptor, 7 support rod, 8 infrared lamp, 1a
Of the side wall, the end opening of 3a, and the inclined mounting surface 6a of 6a have the same configuration as that of the conventional example.

The amount of the O ₂ gas supplied to the supply pipe 2 is controlled by the mass flow controller 9, while the branch pipes 3 a, 3 b, 3 c in the supply pipe 3 for the source gas are controlled.
Are disposed in the gas phase of the raw material containers 10a, 10b, and 10c, respectively.
Raw materials 11a, 11 stored in the raw material containers 10a, 10b, 10c
An inert gas such as Ar supplied from the outside is introduced into the b and 11c through the mass flow controllers 12a, 12b and 12c, which is the same as the conventional one.

Here, in practice, as raw materials 11a, 11b, and 11c, Y (DPM) ₃ , Ba (DPM) ₂ , Cu
(DPM) ₂ are used, which are 120 ° C, 250 ° C, and 120 ° C, respectively.
The steam generated by this is fed into the reaction tube 1 by the Ar gas as a raw material gas through the supply pipe 3 to the end 3a.
From the substrate to the substrate P in the horizontal direction.

According to the present invention, the oxygen gas supply pipe 2 not only extends through the side wall 1a of the reaction tube 1 in a gas-tight manner and extends to the central part in the reaction tube 1 but also in the device. An outlet 13 is located near the substrate P placed on the susceptor 6, and is open on the upstream side and toward the substrate P.

Using the above device, the mass flow controller 12
a, 12b, and 12c, the flow rate of Ar gas was set to 200 cc / min.
At a rate of 100 cc / min, and each of them was introduced into the reaction tube 1. At this time, the outlet 13 was placed 2 cm upstream of the substrate P (actually 5 cm).
(preferably within about cm), exhaust gas in the reaction tube 1 is exhausted by the rotary pump 4, thereby keeping the pressure in the reaction tube 1 at 3 Torr, and the susceptor 6 by the infrared lamp 8. When heated to 800 ° C., a Y—Ba—Cu—O superconducting thin film was formed on the substrate P by strontium titanate.

Next, after film formation for one hour, oxygen gas is introduced into the reaction tube 1 for 1 hour.
The substrate P was introduced until the pressure reached the atmospheric pressure, and the substrate P was cooled at a rate of 10 ° C./min in this state.

The thickness of the thin film thus obtained was about 1 μm, the composition was approximately Y ₁ Ba ₂ Cu ₃ O ₇ -δ, and the critical temperature Tc of the thin film was about 70K.

On the other hand, the device according to the conventional example, that is, the end opening 2a of the supply pipe 2 is opened at the side wall 1a,
When an oxide superconducting thin film was formed on a substrate under the same conditions as above, its critical temperature was 50K,
It is possible to obtain a material having a critical temperature as high as about 10 K. According to the apparatus according to the present invention in which the blowout port 13 is provided near the substrate P, the incorporation of oxygen into the obtained thin film is
I was able to confirm that it was considerably increased.

Moreover, according to the present invention, the outlet 13 is opened to the substrate P side as described above, so that the oxygen gas on the substrate and delivered from the outlet 13 and the inside of the reaction tube 1 in the horizontal direction. Since the supplied source gas encounters for the first time, a reactant is generated on the substrate, and therefore, the two gases react in a process until reaching the substrate, Thus, the generated reactant is prevented from adhering to the lower part of the reaction tube 1.

<< Effects of the Invention >> Since the present invention is configured as described above, the oxygen partial pressure on the substrate can be reduced by selecting the position of the outlet, without increasing the supply amount of oxygen gas to the reaction tube. It is possible to form an oxide superconducting thin film having a high critical temperature and sufficiently taking in oxygen gas on the substrate, thereby performing low-cost vapor growth by reducing the consumption of oxygen gas. Since the pump for exhaust does not need to process a large amount of exhaust gas, the life of the pump is prolonged and the deterioration of oil can be reduced.

Furthermore, in the present invention, the source gas and the oxygen gas are configured to come into contact with each other at the time of reaching the substrate, so that a reactant is generated in a process before reaching the substrate or at a higher position of the substrate, and this is generated in the reaction tube. Since the adhesion to the lower part can be prevented, the heating efficiency of the substrate based on infrared rays can be maintained in a good state for a long time, and a highly reliable product can be produced with a long life.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the overall structure of a vapor phase growth apparatus for an oxide superconducting thin film according to the present invention, and FIG. 2 is a schematic view showing the structure of a main part of the conventional vapor phase growth apparatus. DESCRIPTION OF SYMBOLS 1 ... Reaction tube 2 ... Oxygen gas supply pipe 3 ... Source gas supply pipe 5 ... Intake pipe 6 ... Susceptor 8 ... Infrared lamp 13 ... Outlet P ... Substrate

Claims (1)

(57) [Scope of request for utility model registration] An oxygen gas supply pipe and a raw material gas supply pipe are connected to an upstream side of a reaction tube, and an exhaust gas intake pipe is connected to a downstream side of the reaction tube. Is supplied in the horizontal direction, a susceptor capable of mounting the substrate in the reaction tube, and a susceptor that can be mounted in an inclined state in which the upstream side is lowered, is provided outside the reaction tube with an infrared lamp for heating the substrate. In adjacent ones,
A supply pipe for the oxygen gas is passed through the reaction tube, and the outlet is located near the substrate on the susceptor, and is opened toward the substrate side on the upstream side, whereby the oxygen is supplied on the substrate. An apparatus for vapor-phase growth of an oxide superconducting thin film, wherein oxygen gas and the raw material gas in the horizontal direction are encountered.