JPH02197565A - Target for laser vapor deposition apparatus - Google Patents

Abstract

PURPOSE:To form an oxide superconductor layer having superior adhesive strength by dividing a target in half and constituting the target of a material forming an oxide superconductor layer and a material forming a buffer layer, carrying out laser irradiation, and forming the superconducting layer via the buffer layer on a base material. CONSTITUTION:A target T1 is constituted of a section t1 forming an oxide superconductor layer 31 and a section t2 forming a buffer layer 30. The above target T1 is disposed in a vapor deposition treatment chamber 11 and preheated by means of a heater 14, and respective insides of the treatment chamber 11, a delivery chamber 21, and a winding chamber 22 are evacuated, and then, the target T1 is turned to locate the section t2 in the position of laser beam concentration. Subsequently, a base material 25 is fed from the delivery chamber 12 via the treatment chamber 11 into the winding chamber 22, and the base material 25 is heated by means of an auxiliary heater 15 and the section t2 is irradiated with laser beam, by which the buffer layer 30 is formed on the base material 25. After the completion of the butter layer 30 formation, the section t1 is located in the position of concentration and irradiated with laser beam and the base material 25 is fed in a backward direction, by which the oxide superconductor layer 31 is formed on the buffer layer 30. By this method, two layers 30, 31 can be formed by using one target.

Description

Detailed Description of the Invention "Field of Industrial Application" This invention is a laser evaporation device for forming oxide superconductors, which are being developed for use in superconducting devices such as Josephson elements and superconducting memory elements. Regarding targets for use.

"Conventional technology" Conventionally, methods for forming oxide-based superconducting layers include vacuum evaporation, sputtering, laser evaporation, and MBE (
molecular beam epitaxy method), CVD method (chemical vapor deposition method)
, IVD (ion vapor deposition) and other film forming methods are known.

Among these various film-forming methods, laser evaporation uses a target with a composition that is the same as or similar to that of the target oxide superconducting layer, and deposits particles evaporated from this target onto a substrate to form a film. This method is attracting attention as a method that can form a homogeneous oxide superconducting layer with good characteristics. This laser evaporation method is a technique in which a target is irradiated with a laser beam to evaporate a surface portion of the target, and the evaporated particles are deposited on a base material to form an oxide superconducting layer.

Further, the oxide-based superconductor is Y-Ba-Cu
- Any system such as 〇 system, B i-S r-Ca-Cu-0 system, or T iBa-Ca-Cu-0 system is a multi-component material, and its composition ratio is small. It is known that the superconducting properties will be significantly degraded if they differ. For this reason, in the laser vapor deposition method, a composition similar to that of the target oxide superconducting layer, or
An oxide target having the same composition and containing a large amount of components that easily escape during film formation is formed, and film formation is performed using this oxide target.

"Problem to be Solved by the Invention" When a superconducting layer is formed on a metal substrate or the like using the laser vapor deposition method, it is necessary to heat the superconducting layer to several hundred degrees Celsius at the same time or after the film formation in order to homogenize the superconducting layer. Modification of the superconducting layer has been attempted.

However, when such heat treatment is performed, atoms constituting the substrate may diffuse toward the superconducting layer, causing a problem in which the composition of the superconducting layer collapses and the superconducting properties are significantly deteriorated. For this reason, conventionally, in order to suppress element diffusion from the substrate, the reactivity with the elements constituting the superconducting layer between the substrate and the superconducting layer is low, and element diffusion toward the superconducting layer side is difficult to occur at the heat treatment temperature. A buffer layer made of such elements has been formed.

In order to manufacture a superconductor having a buffer layer and a superconducting layer on a substrate using the laser evaporation method, the buffer layer is formed on the upper surface of the substrate by the laser evaporation method, and then the upper surface of the buffer layer is re-formed. It is necessary to form an oxide superconducting layer by laser deposition.

However, in order to carry out the above method using a laser evaporation apparatus equipped with only one target holder, a target for forming a buffer layer is set in a processing container, and the inside of the processing container is evacuated. After forming the buffer layer on the substrate, the vacuum inside the processing container is released, the target is replaced with a target for forming an oxide superconducting layer, and then the inside of the processing container is evacuated again to deposit the oxide on the buffer layer. Since it is necessary to form a superconducting layer, there is a risk that the buffer layer may be contaminated when replacing the target within the processing container.

The present invention has been made to solve the above problems, and even when using a laser evaporation apparatus that can mount only one target, the buffer layer and oxide superconductor can be removed without releasing the vacuum in the processing chamber. An object of the present invention is to provide a target for a laser vapor deposition apparatus that can form a layer.

"Means for Solving the Problems" In order to solve the above problems, the present invention irradiates the peripheral surface of a cylindrical or cylindrical target that is rotated around the circumference with a laser to evaporate the peripheral surface portion of the target. , in a target for a laser evaporation apparatus that forms an oxide superconductor by depositing evaporated particles on a base material, the target is divided into a plurality of parts in the circumferential direction, and at least one of the divided parts of the target is an oxide superconductor or It is made of a composite oxide containing elements constituting an oxide superconductor, and is made of a material equivalent to the element constituting at least one of the divided bodies of the target or the base material.

"Operation" The target is divided into a plurality of parts, and at least one of the divided parts is formed from a material for forming an oxide superconducting layer, and at least one of the other divided parts is formed from a material for forming a buffer layer. By appropriately rotating this target and performing laser deposition, a buffer layer and an oxide superconducting layer are generated on the substrate using one target without releasing the vacuum.

Further, by using the target of the present invention, it becomes possible to continuously generate a buffer layer and a superconducting layer on a substrate with a laser evaporation apparatus configured to install only one target, thereby improving the efficiency of use of the apparatus.

"Embodiment" FIG. 1 shows a laser vapor deposition apparatus 10 equipped with a target T according to an embodiment of the present invention, and FIG. 2 shows a cylindrical target T.
, and the target T in this example is formed by joining a vertically divided cylindrical divided body,
By setting the temperature to O, a buffer layer and an oxide superconducting layer can be formed on the base material as described later.

The divided body t1 constituting the target T has a composition equivalent to or similar to that of the oxide superconducting layer to be formed, or a sintered body of a composite oxide containing a large amount of components that easily escape during film formation, or , is formed from the bulk of an oxide superconductor, etc., and the dividing body t is formed from the same material as the one layer of buff to be formed on the base material. Specifically, currently known oxide superconducting layers with high critical temperatures include Y-Ba-Cu-0 system, B i-9r-Ca-Cu
-0 series, TI-BaCa-Cu-0 series, etc.
For the divided body L1, those of these systems can be used.

The laser evaporation apparatus IO shown in FIG. 1 has a evaporation processing chamber II, and this evaporation processing chamber 11 is connected to a vacuum evacuation device (not shown) through an upper exhaust hole 12 so that the inside can be evacuated. It has become. Further, in the upper part of the vapor deposition processing chamber 11, a target T is detachably fixed to a substrate fixing member (not shown) and is rotatably held around a central axis.
A preheating heater 14 is provided for preheating the target T1, and a base material 25 (described later) is provided below the target T1.
An auxiliary heater I5 is arranged to heat the.

The preheating heater 14 preheats the entire target T1 to several hundred degrees Celsius in order to prevent thermal damage to the target T1 due to partial concentrated heating of the target T1 by the laser beam, and also preheats the target T1 by preheating. This is to uniformly evaporate the outer peripheral surface of the

Further, the auxiliary heater 15 is located below a base material 25, which will be described later, and is used to heat the base material 25.

Meanwhile, the deposition processing room! A laser device 17 and a condensing lens 18 are arranged on the upper side of (2), and the laser beam generated by the laser device 17 is directed to the vapor deposition processing chamber! Light can be focused on the target T1 through a transparent window 19 attached to the side wall of the target T1.

Further, a delivery chamber 21 and a winding chamber 22 are arranged on both sides of the lower side of the vapor deposition chamber 11, which are connected to the lower side of the vapor deposition chamber 11 through a passage hole 20. This delivery chamber 2
1 is provided with a feeding device 23, and the winding chamber 22 is provided with a winding device 24, and the tape-shaped base material 25 fed out from the feeding device 23 is placed between the preliminary heater 15 of the vapor deposition processing chamber 11 and the target T. The film can then be sent to a winding chamber 22 and then wound up. Also, in the sending chamber 2 and in the winding chamber 2.
2 are connected to a vacuum evacuation device via exhaust holes 26, respectively. Furthermore, the base material 25 is made of a Ni-based alloy such as Hastelloy, or Ni.

This base material 25 is preferably made of a material that can withstand the temperature of the heat treatment described later and has low reactivity with the constituent elements of the oxide superconductor.

On the other hand, what is indicated by the reference numeral 27 in FIG. 1 is a mass spectrometer, and this mass spectrometer 27 has a fixed ion collector electrode combined with a slit. This is an electrically detected analyzer that analyzes the composition of evaporated components when a portion of the target T is evaporated by irradiation with a laser beam during film formation.

Next, a case will be described in which a buffer layer and an oxide superconducting layer are formed on a base material using the laser vapor deposition apparatus.

A target T is placed inside the vapor deposition chamber 11 as shown in FIG. 1, and the target T1 is further heated by a preheater 14. Next, the vapor deposition processing chamber 11, the delivery chamber 21, and the winding chamber 22 are evacuated by a vacuum evacuation device to create a vacuum atmosphere.

Next, the target TI is rotated by a predetermined angle and the divided body L! of the target T is placed at the laser beam focusing position. At the same time, the base material 25 is moved and sequentially sent into the vapor deposition processing chamber II, and the target T1 is irradiated with a focused laser beam emitted from the laser device 17 to evaporate the surface of the target T, producing evaporated particles. The evaporated particles are then deposited on the base material 25.

The laser beam irradiated onto the surface of the divided body t of the target T heats and evaporates the peripheral surface of the divided body t, so that the elements constituting the divided body are deposited on the base material 25. A buffer layer 30 is deposited as shown in FIG.

When the deposition of the buffer layer 30 is completed, the target T1 is rotated again and the divided body 1. and irradiate the divided body t with a laser beam, and at the same time, the sending device 23 and the winding device 24 are reversed to send the base material 25 to the vapor deposition processing chamber 11 again, and the buffer layer 30 is
An oxide superconducting layer 3I is deposited thereon. The composition of the deposited particles is measured continuously or intermittently using a mass spectrometer 6, and the output of the laser beam and the temperature of the target T are adjusted based on the measurement results to oxidize the target composition. It is preferable to generate the oxide superconducting layer 31, and by doing so, it is possible to form the oxide superconducting layer 31 with a uniform composition and excellent characteristics.

As explained above, the buffer layer 30 and the oxide superconducting layer 3
When forming I, the buffer layer 30 and the oxide superconducting layer 31 can be continuously formed without breaking the vacuum state inside the vapor deposition processing chamber 11, so that the film can be formed without contaminating the surface portion of the buffer layer 30. . Moreover, if the target T having the above structure is used, the target mounting device is 1
Even if the laser evaporation apparatus is equipped with only one buffer layer 30,
The oxide superconducting layer 31 can be formed continuously.

FIG. 4 shows a second embodiment of the target, and the target T in this example has four segmented bodies 1+ in the shape of a fan-shaped annular body,
11,1. ．． 1. This is an example formed from

To perform laser vapor deposition using the target T in this example, the target T is rotated appropriately according to the vapor deposition layer to be formed, and vapor deposition is performed using the divided body 1. ．． 1. and the divided body Lt, L
It is sufficient to perform the vapor deposition so that x is not consumed uniformly.

FIG. 5 shows a third embodiment of the target, and the target T3 in this example has a nine-segment structure consisting of three segments t, t, t3.

In the case of this target T3, the divided bodies t+ and Lx are made of the same materials as in the above example, and the divided bodies are made of the same material as the material constituting the base material 25.

To perform vapor deposition using the target T in this example, a coating layer made of the same material as the base material 25 is formed on the upper surface of the base material 25, and then a buffer layer 30 and a superconducting layer 31 are formed.

With such a laminated structure, the adhesion between the coating layer made of the same material and the base material 25 is good, and the adhesion between the active coating layer formed by laser vapor deposition and the buffer layer 30 is improved. There is.

"Manufacturing Example" In the device shown in Figure 1, the upper surface of the auxiliary heater has a width of 10 mm.
A square substrate with a thickness of 0.5 mm and a thickness of 0.5 inches is installed.
A buffer layer with a thickness of 171 m and an oxide superconducting layer with a thickness of 1 μm were laminated on this substrate. The substrates used were one made of Hastelloy and the other made of Ni, and the buffer layers formed on each substrate were made of Au, 5rTi03, Ag, M.
The oxide superconducting layer selected from g O and formed on each buffer layer has a composition of Y IB at Cu30 t-6, and B I! S rtc atc 1+30
The one with the composition X and the one with the composition T Li2 atCatc ut
The composition was ox. The target is made up of two vertically divided cylindrical parts, and has an outer diameter of 3.
0 mIIl was used.

In addition, when forming a Y-based oxide superconducting layer, the conditions were such that oxygen gas was flowed into the vapor deposition chamber, the film was formed at 10-' Torr, and the film was heat-treated at 800° C. after the film formation.

When forming a Bi-based oxide superconducting layer, Ar gas containing 7% oxygen gas is flowed into the vapor deposition chamber, and 10-'To
The conditions were set such that a film was formed at rr and then heat treated at 750° C. after film formation. When forming a Tl-based oxide superconducting layer, oxygen gas is flowed into the evaporation processing chamber, the film is formed at IO-'Torr, and the temperature is 850°C after film formation.
The conditions for heat treatment were as follows.

Critical temperature (Tc) and critical current density (Jc) at 77K of the oxide superconducting layer obtained using the above target
The results of the measurements are shown in Table 1.

(Hereinafter, blank space) Table 1 "Effects of the Invention" As explained above, in the present invention, the target is composed of a divided body for forming an oxide superconducting layer and a divided body for forming a buffer layer. By using one target for laser deposition, a buffer layer and an oxide superconducting layer can be produced on a substrate using one target. Therefore, it becomes possible to generate a buffer layer and an oxide superconducting layer with a laser evaporation apparatus that can install only one target, and the efficiency of use of the laser evaporation apparatus is improved. Furthermore, since the oxide superconducting layer can be formed after forming the buffer layer without breaking the vacuum atmosphere in the vapor deposition chamber, the oxide superconducting layer can be formed on it without contaminating the buffer layer. can. Therefore, an oxide superconducting layer with a well-organized crystal structure can be formed on the buffer layer, and an oxide superconducting layer having good adhesion to the buffer layer can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a laser evaporation apparatus equipped with a target according to an embodiment of the present invention, Fig. 2 is a plan view of the target of the first embodiment, and Fig. 3 is a diagram showing a buffer layer formed on a base material and a superconducting layer. FIG. 4 is a plan view of the second embodiment of the target, and FIG. 5 is a plan view of the third embodiment of the target. T + , T t , T a...Target, t
+, tt, Li... Divided body, IO... Laser deposition device, 11... Vapor deposition processing chamber, 17... Laser device, 2
5... Base material, 30... Buffer layer, 3 Summer... Oxide superconducting layer. Figure 1

Claims (1)

[Claims] Laser vapor deposition involves irradiating the peripheral surface of a cylindrical or cylindrical target that is rotated around the circumference to evaporate the peripheral surface of the target, and depositing the evaporated particles onto the base material to form an oxide superconductor. In a target for a device, the target is divided into a plurality of parts in the circumferential direction, and at least one of the divided parts of the target is made of an oxide superconductor or a composite oxide containing an element constituting the oxide superconductor,
A target for a laser vapor deposition apparatus, characterized in that at least one of the divided bodies of the target is made of a material equivalent to an element constituting the base material.