JPH02160609A - Target for forming oxide superconductor - Google Patents

Abstract

PURPOSE:To enable the formation of a multi-component superconducting layer even with a sputtering or laser-evaporation apparatus which can hold only one target and to facilitate the exchange of target by dividing a target into plural sections and including an element constituting a superconducting layer in each section. CONSTITUTION:For example, a disk-shaped target T1 produced by integrating plural plate sections t1-t3 each having a sector form is used as the target T of a sputtering apparatus 1. The target T1 has a structure divided into 3 sections in a direction crossing the sputtering direction. Each section t1-t3 is formed of one or more kinds of elements or metal elements selected from plural elements constituting an oxide superconductor. For example, in the case of forming a Bi-Sr-Ca-Cu-O superconducting layer, the sections t1, t2 and t3 are made of Bi-Cn alloy, Ca-Cu alloy and Sr-Cn alloy, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION J Field of the Invention The present invention relates to a target for forming an oxide superconductor, which is being developed for use in superconducting devices such as Josephson elements and superconducting memory elements.

"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, subuckling uses a target with a composition that is the same as or similar to the composition of the target oxide superconducting layer, and deposits particles generated from this target on a base material to form a film. method or laser evaporation method is 1. This method is attracting attention as a method that can form a homogeneous oxide superconducting layer with good characteristics.

The sputtering method is a technique in which plasma is generated in the vicinity of a target serving as a deposition source by orthogonal electromagnetic discharge, the target is sputtered, and sputtered particles are deposited on a base material. Further, the laser vapor deposition method is a technique in which a target is irradiated with a laser beam to evaporate the surface portion of the target, and the evaporated particles are deposited on a base material.

"Problems to be Solved by the Invention" By the way, the oxide-based superconductor is Y-BaCu-
0 series, B i-S r-Ca-Cu-0 series, or T
Any system such as the IB a-Ca-Cu-0 system is a multi-component material, and it is known that if the composition ratio differs even slightly, the superconducting properties will deteriorate significantly. .

Conventionally, in the sputtering method and laser vapor deposition method, an oxide target with a composition similar to or the same as that of the target oxide superconducting layer is formed, and the film is formed using this oxide target. ing.

However, even when sputtering is performed using the above-mentioned target, the oxide superconducting layer obtained due to differences in melting points, vapor pressures, or reactivity of the constituent elements cannot be achieved. There was a problem that the composition could deviate from the composition.

For this reason, when forming an oxide-based superconducting layer, in order to strictly control the composition ratio of each component, a sputtering device is equipped with multiple targets for each component element, and Equipment is used that performs sputtering independently and adjusts the amount of sputtering from each target to form a superconducting layer that matches the desired composition.

However, a sputtering apparatus using such a large number of targets requires a mechanism for generating plasma for each target, making the apparatus complicated and expensive. Furthermore, when forming multiple types of oxide superconducting layers using one sputtering device, it is necessary to replace all of the multiple targets depending on the type of target superconducting layer, and sputtering conditions must also be changed for each target. This has to be done individually, making it complicated to replace targets and changing sputtering conditions extremely time consuming.

The present invention has been made to solve the above problems, and even when using a sputtering device or a laser evaporation device that can be equipped with only one target, it is possible to form a multi-component oxide superconducting layer, and It is an object of the present invention to provide a target that can be easily replaced and can also easily change sputtering conditions or vapor deposition conditions.

[Means for Solving the Problems] The invention set forth in claim 1 solves the above problems (hereinafter, in a sputtering target for forming an oxide superconductor, the target is sputtered in a direction crossing the direction to be sputtered). The target is divided into a plurality of parts, and each divided body is made of an alloy consisting of one or more elements among the plurality of elements constituting the oxide superconductor, or an alloy consisting of one or more elements constituting the oxide superconductor. It is composed of simple metal elements.

[Claim 21] In order to solve the above-mentioned problem, the invention described above irradiates a laser onto the circumferential surface of a circularly rotating cylindrical or columnar target to evaporate the circumferential surface portion of the target to remove evaporated particles. In a target for a laser evaporation device that forms an oxide superconductor by depositing it on a base material, the target is divided into a plurality of parts in the circumferential direction, and each divided part of the target is divided into a number of constituent elements of the oxide superconductor. The oxide superconductor is composed of an alloy of a plurality of elements selected from the above, or a single metal element among the plurality of elements constituting the oxide superconductor.

"Operation" The target is divided into multiple parts, each of which contains an element that forms an oxide superconducting layer, so by sputtering or laser evaporation using one target, multiple parts can be deposited using one target. A component-based oxide superconducting layer is produced. Further, by using the target of this invention, only one target can be installed. It becomes possible to generate a multi-component oxide superconducting layer using a sputtering device or a laser evaporation device according to the present invention, and the efficiency of using the device is improved. Furthermore, if the film is formed while rotating the target at a predetermined speed, the amount of sputtering or the amount of evaporation by the laser becomes uniform for each divided body.

Furthermore, if the target is rotated so that the amount of sputtering and the amount evaporated by the laser differs for each segment, the composition ratio of the oxide superconductor to be formed can be adjusted.

"Embodiment" FIG. 1 shows a sputtering apparatus I equipped with a target T according to an embodiment of the invention as set forth in claim I, and FIG. 2 shows a planar shape of the target T. The target T1 is a planar fan-shaped plate-shaped divided body 1. ．． 1. ．．
13 are joined together to form a disk shape.

Since the thickness direction of this target T is the direction to be sputtered, the target T has a structure in which it is divided into three parts in a direction intersecting the direction to be sputtered (in this case, circumferentially).

The target T is A-B-Cu-0 (However, A
represents one or more of the group 111a elements of the periodic table such as Y, Bi, and TI, and B represents one or more of the elements of group IIa of the periodic table such as Ba, Sr, and Ca. ) type oxide superconducting layer by sputtering, the target T1 needs to contain elements necessary to form a superconducting layer having the desired composition.

Therefore, when forming a Y-B a-Cu-0 based superconducting layer, for example, the divided body 1. is formed from a Ba-Cu alloy, the divided body t is formed from a Ba-Cu alloy, and the divided body t is formed from a Y-Cu alloy. Also, B i-S
When forming an rCa-Cu-0 based superconducting layer, for example, the segment t is made from a B1-Cu alloy, the segment t is made from a Ca-Cu alloy, and the segment t3 is made from a 5r-Cu alloy. Form. Furthermore, when forming a T iB a-Ca-Cu-0 based superconducting layer, for example, the divided body t is
A split body t is formed from a Ca-Cu alloy, and a split body t is formed from a Ba-Cu alloy.

The target T formed as described above is mounted on a sputtering apparatus 1 as shown in FIG. 1 and used to generate a superconducting layer.

The sputtering apparatus 1 shown in FIG. 1 is comprised of a substrate holder 2 that holds a substrate A, and a target T1 that is installed to face the substrate holder 2 with a predetermined distance between the substrate holder 2 and the target T1. An electric field and a magnetic field can be generated in the space between the substrate holder 2 and the target T by the connected bias power supply 6.

Further, both the substrate holder 2 and the target T+ are provided so as to be rotatable forward and backward in the direction of the arrow a in FIG. 1, so that the substrate A or the target T1 can be rotated forward and backward about their respective central axes. Further, the space surrounding the substrate holder 2 and the target T1 are both surrounded by a vacuum exhaust device and a container connected to a gas supply source, and the space between them is filled with a gas atmosphere consisting of argon gas or the like or a non-containing gas atmosphere containing oxygen. It is designed to create an active gas atmosphere. In addition,
The substrate A can be heated to a temperature suitable for film formation by a heater along the illustrated path attached to the substrate holder 2. Furthermore, what is indicated by the reference numeral 3 in FIG. 1 is an ion gun that can irradiate the substrate A with ionic oxygen, atomic oxygen, molecular oxygen, etc. in the form of a beam.

To form a superconducting layer on the substrate A, the substrate A held on the substrate holder 2 is heated with a heater to a temperature suitable for film formation, and the substrate A is irradiated with oxygen ions or the like from the ion gun 3. Furthermore, the sputtering device 1 is operated to generate an electric field and a magnetic field in the space between the substrate holder 2 and the target T1, and the ionized argon is caused to collide with the target T, thereby destroying the constituent atoms of the target T. Spatter. By this sputtering, constituent atoms of the target T can be deposited on the substrate A to generate an oxide superconducting layer. At the same time as the film is formed, oxygen is supplied to the oxide superconducting layer from oxygen in the atmosphere and further by irradiation with oxygen from the ion gun 3. Note that during film formation, the target T is rotated at a predetermined speed in the direction of arrow a in FIG. Due to this rotation, the divided body 1. which constitutes the target T. ．． 11°ts is sputtered uniformly,
The atoms constituting the target T1 are uniformly sputtered, and a sufficient amount of atoms necessary and sufficient to form an oxide superconducting layer are sputtered and deposited on the substrate A at a predetermined ratio. Therefore, a homogeneous oxide superconducting layer with a uniform composition can be formed on the substrate A.

Furthermore, if we avoid changing the rotational speed of target T,
The amount of sputtering of the divided bodies t+, tt, and t3 can be changed, and the composition of the oxide superconducting layer can also be delicately controlled.

Here, the target of the invention described in claim 1 only needs to be divided into a plurality of parts in a direction intersecting the direction to be specified, so that it can take various divided states. For example, as shown in FIG.
+, ts, and as shown in FIG.
, t7. ts,t,,t,o,t,.

Alternatively, as shown in FIG. 5, it may be divided concentrically into divided bodies j1ffi+tl5. t+4, and as shown in Fig. 6, it is divided concentrically and further divided into two along the diameter, resulting in a total of six divided bodies L+.
6. L+s, j+7. j+s, L+*, t,. It may be composed of

FIG. 7 shows a laser vapor deposition apparatus IO equipped with a target T6 according to an embodiment of the invention described in claim 2, and FIG. 8 shows a target T6.
r is a divided body L++t2 with a fan-shaped annular cross section! +L23
It is formed into a cylindrical shape by joining them together. Note that since the laser is irradiated onto the peripheral surface of the target T6, the target T8 has a structure in which the circumference is divided into three parts.

Each divided body L21 . t22
tt3 is the divided body t1. of the embodiment described above. tt, t3
Constructed from materials equivalent to.

The laser evaporation apparatus IO shown in FIG. 7 has a evaporation processing chamber 11, and this evaporation processing chamber II is connected to a vacuum evacuation device (not shown) via an evacuation hole I2 so that the inside can be evacuated. There is. Further, in this vapor deposition processing chamber 11, there are a target T6 which is removably fixed to a substrate fixing member (not shown) and rotatably held around a central axis, a preheating heater 14 for preheating this target T6, and a preheating heater 14 which will be described later. An auxiliary heater 15 is arranged to heat the base material 25 to be heated.

Preheat heater! 4, the target T,
In order to prevent thermal damage to the target T due to partial concentrated heating of the target T, the entire target T is preheated to several hundred degrees Celsius. It is something. The auxiliary heater 15 is arranged below a base material 25, which will be described later, and heats it.

Further, 1. A laser device 17 and a condensing lens 18 are arranged on the side of the vapor deposition processing chamber 11.
The laser beam generated by the transparent window attached to the side wall of the vapor deposition processing chamber 11! 9, the light can be focused on the target To.

Further, on both sides of the vapor deposition chamber 11, a delivery chamber 21 and a winding chamber 22 are arranged, which are connected to the vapor deposition chamber 11 through a passage hole 20.

The delivery chamber 2I is provided with a delivery device 23, and the take-up chamber 22 is provided with a winding device 24.
5 and target T, and then can be wound up in the winding chamber 22. In addition, delivery chamber 2
1 and the winding chamber 22 are each connected to a vacuum evacuation device via an exhaust hole 26. Moreover, what is shown by the reference numeral 27 in FIG. 7 is a mass spectrometer, and this mass spectrometer 27 uses a fixed ion collector electrode combined with a slit, and collects ions by a measuring section 28 directed toward the target T8. It is an analyzer that detects electrically, and during film formation,
When a portion of the target T8 is evaporated by irradiation with a laser beam, the composition of the evaporated components is analyzed.

Next, a case will be described in which an oxide superconducting layer is formed using the laser evaporation apparatus.

The target T8 is placed in the position shown in FIG. 7, and the preheater 14 is used to heat the target T8.

Next, the vapor deposition chamber 11 and the delivery chamber 21 are vacuum-exhausted.
The winding chamber 22 is evacuated to create a vacuum atmosphere.

Subsequently, while rotating the target T6, the base material 25
The target T8 is irradiated with a laser beam emitted from the laser device 17 to evaporate the surface of the target T8 to generate evaporated particles, and the evaporated particles are deposited on the base material 25. to be deposited.

The laser beam irradiated onto the circumferential surface of the rotating target T6 is transmitted to the divided body tt++t! Since the peripheral surfaces of t and tt3 are sequentially heated and evaporated, the divided body L2++ is attached to the base material 25.
Elements constituting Lt* and Lt3 are deposited to form an oxide superconducting layer. Here, if the rotation speed of the target 're is appropriately adjusted, the evaporated particles can be made uniform and uniform particles can be deposited. In addition, the composition of the deposited particles is measured continuously or intermittently using a mass spectrometer 6, and based on the measurement results, the output of the laser beam and the target T,
It is preferable to generate an oxide superconducting layer having a desired composition by adjusting the rotation speed of the oxide superconducting layer, and by doing so, it is possible to form an oxide superconducting layer with a uniform composition and excellent properties. can.

Incidentally, since the target may be divided into a plurality of parts around the circumference, it may be divided into 12 parts as shown in FIG. 9 instead of 3 parts as in this example.

"Effects of the Invention" As explained above, the present invention divides the target into a plurality of parts and avoids containing elements that form an oxide superconducting layer in each of the divided parts, so sputtering or By laser deposition, a multi-component oxide superconducting layer can be produced using one target. Therefore, it becomes possible to generate a multi-component oxide superconducting layer using a sputtering apparatus or a laser evaporation apparatus configured to install only one target, and the efficiency of use of the apparatus is improved. Furthermore, if the target is formed by appropriately adjusting the size ratio of each segment containing the constituent elements of each oxide superconductor to match the composition of the oxide superconductor layer, the composition of the oxide superconductor layer can be adjusted. can do.

Furthermore, by setting the target in a sputtering device or laser evaporation device and forming a film while rotating it at a predetermined speed, the amount of sputtering or the amount of evaporation by the laser can be made uniform for each segment. , it is possible to form an oxide superconducting layer with a uniform composition.

Further, if the target is rotated so that the amount of sputtering and the amount evaporated by the laser differ for each segment, the composition ratio of the oxide superconductor to be formed can be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a sputtering apparatus equipped with a target according to an embodiment of the invention as set forth in claim 1, FIG. 2 is a plan view of a surface target, and FIG. 3 is a second embodiment of the target. A plan view, FIG. 4 is a plan view showing a third embodiment of the target, FIG. 5 is a plan view showing the fourth embodiment of the target, and FIG. 6 is a plan view showing the fifth embodiment of the target. , FIG. 7 is a block diagram of a laser evaporation apparatus equipped with a target according to an embodiment of the invention described in claim 2, FIG. 8 is a perspective view of the same target, and FIG. 9 is a diagram showing a second embodiment of the target. FIG. 1...Sputtering equipment, A...Substrate, TI-T? −・
・Target, t, ~tt3...divided body, lO...
Laser deposition device, 11... Vapor deposition processing chamber, 17... Laser device, 25... Base material.

Claims (2)

[Claims] (1) In a sputtering target for forming an oxide superconductor, the target is divided into a plurality of parts in a direction crossing the direction to be sputtered, and each divided part of the target is divided into a plurality of parts constituting the oxide superconductor. Among the elements,
A target for forming an oxide superconductor, characterized in that it is made of an alloy consisting of one or more types of elements, or a single metal element among a plurality of elements constituting the oxide superconductor. (2) A laser is irradiated onto the circumferential surface of a cylindrical or columnar target that is rotated around the circumference to evaporate the circumferential surface of the target, and the evaporated particles are deposited on the base material to form an oxide superconductor. In the target for laser evaporation equipment,
The target is divided into a plurality of parts in the circumferential direction, and each divided part of the target is made of an alloy of a plurality of elements selected from among the constituent elements of the oxide superconductor, or an alloy of a plurality of elements constituting the oxide superconductor. A target for forming an oxide superconductor characterized by being composed of a single metal element among the elements.