JP2930036B2 - High temperature superconducting element and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature superconducting element which can be used for a high-frequency passive element such as a filter element, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a filter element using a high-temperature superconducting film, Y ₁ Ba ₂ Cu _{3 is} deposited on a LaAlO ₃ substrate.
A high-temperature superconducting film having an _Oy composition is formed in a pattern, and a metal electrode such as Au is formed on the high-temperature superconducting film in the power supply section.

[0003]

When a high-temperature superconducting film having a composition of Y ₁ Ba ₂ Cu ₃ O _{y is formed} on a LaAlO ₃ substrate, the high-temperature superconducting film is formed to reduce the surface resistance of the high-temperature superconducting film. Although a dense film is used, the high-temperature superconducting film of the power supply section is also a dense film, and there is a problem that the metal electrode is easily peeled off from the high-temperature superconducting film and the contact resistance in the power supply section is increased.

The present invention has been made in view of the above problems, and has as its object to reduce the contact resistance while making it difficult for a metal electrode to be peeled off at a power supply portion.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, the height of the element body is increased.
A thermal superconducting film (2a) is formed on the substrate (1),
Poor lattice matching of high-temperature superconducting film (2b) compared to substrate (1)
The high-temperature superconducting film (2b) of the power supply section is formed on the lower layer film (5) and has a larger gap than the high-temperature superconducting film (2a) of the element body. In this case,
Due to the lattice matching between the ground and the high-temperature superconducting film,
The high-temperature superconducting film in the part and the high-temperature superconducting film in the feeding part
Differently, the high-temperature superconducting film in the element body is made a dense film and power is supplied.
The high-temperature superconducting film in the portion can be a film having many voids.
By making the high-temperature superconducting film of the power supply portion a film with many voids in this way, the contact area with the metal electrode formed thereon increases, the bonding strength increases, and the metal electrode becomes difficult to peel off, Contact resistance is reduced.

[0006]

[0007] The above-mentioned features are specifically described in the claims.
As in the invention described in Item 2, the substrate is a LaAlO ₃ substrate or a substrate in which CeO ₂ is laminated on LaAlO ₃ , the high-temperature superconducting film is a high-temperature superconducting film having a Y ₁ Ba ₂ Cu ₃ O _y composition, It can be obtained by making the lower layer film an MgO film. Further, according to the invention described in claims 3 to 5, it is possible to produce a high temperature superconducting device having the features described above.

[0008]

FIG. 1 shows a configuration of a filter element according to an embodiment of the present invention. (A) is a plan view,
(B) is AA sectional drawing of (a). Note that FIG.
1 schematically shows a filter element. On a LaAlO ₃ substrate 1 as a dielectric substrate, Y
A high-temperature superconducting film 2 having a composition of ₁ Ba ₂ Cu ₃ O _y is patterned to form a distributed constant filter.

The high-temperature superconducting film 2 forms an element main body 2a and a power supply section 2b, and the high-temperature superconducting film 2a of the element main body has a plurality of resonance elements forming a filter. An Au electrode 3 is formed on the high-temperature superconducting film 2b of the power supply unit. On the back surface of the LaAlO ₃ substrate 1, a high-temperature superconducting film 4 forming a ground plane and a Au ground electrode 7 are formed.
Are formed, the Au electrode 3 is connected to a connector (not shown), the ground electrode 7 is connected to a case (not shown), and power is supplied to the filter element.

On the LaAlO ₃ substrate 1, an MgO film 5 is partially formed, and a high-temperature superconducting film 2
b is formed on the MgO film 5, and the high-temperature superconducting film 2 a of the element body is formed on the LaAlO ₃ substrate 1. here,
The high-temperature superconducting film 2a formed on the LaAlO ₃ substrate 1 is a dense film, and the high-temperature superconducting film 2b formed on the MgO film 5 is a film having voids, that is, a porous film. .

FIG. 2 is an enlarged plan view of the high-temperature superconducting film 2b formed on the MgO film 5. FIG. In FIG. 2, reference numeral 20 denotes a crystal grain, which is indicated by a hatched numeral 2 in the figure.
1 indicates a void. FIG. 3 shows a schematic cross-sectional configuration of the high-temperature superconducting films 2a and 2b. FIG. 2, FIG.
As can be seen from FIG. 2, the high-temperature superconducting film 2b formed on the MgO film 5 has a two-dimensionally connected structure with voids 21 between crystal grains 20, whereas LaAlO
₍₃ ) The high-temperature superconducting film 2a formed on the substrate 1 has no gaps between the crystal grains, or at least has very few gaps than the high-temperature superconducting film 2b formed on the MgO film 5. Film.

This is because the LaAlO ₃ substrate 1 and the Y ₁ Ba ₂
It has good lattice matching with the high temperature superconducting film 2 of Cu ₃ O _y composition,
This is because the MgO film 5 and the high-temperature superconducting film 2 having the composition of Y ₁ Ba ₂ Cu ₃ O _y have poor lattice matching. If the lattice matching is good, the high-temperature superconducting film becomes a dense film,
When the lattice matching is poor, the high-temperature superconducting film becomes a film having many voids.

Therefore, the Au electrode 3 is formed on the high-temperature superconducting film 2b.
Is formed, the Au electrode 3 enters the gap 21 and the contact area increases. Therefore, the bonding strength is increased, the Au electrode 3 is hardly peeled off, and the contact resistance is reduced. As a result, the input power from the power supply unit can be increased. Further, since the high-temperature superconducting film 2a formed on the LaAlO ₃ substrate 1 is a dense film, the surface resistance can be reduced. In addition, since the area of the ground electrode 7 is large between the high-temperature superconducting film 4 forming the ground plane and the ground electrode 7, it is not necessary to interpose the MgO film.

Next, a method of manufacturing the above-described filter element will be described. First, as shown in FIG.
An MgO film 5 is partially formed on an AlO ₃ substrate 1. In this case, the MgO film 5 is partially formed using a mask, or an MgO film is formed on the entire surface, and then patterned to form the MgO film 5 partially.

Next, as shown in FIG.
High-temperature superconducting films 2 and 4 having a composition of Y ₁ Ba ₂ Cu ₃ O _y are formed on the front and back surfaces of the O ₃ substrate 1 by sputtering.
Specific sputtering film forming conditions in this case will be described. Target (T): Y ₁ Ba ₂ Cu ₃ O _y composition, diameter 4 inch, thickness 2 mm Substrate (S): LaAlO ₃ [100] substrate Distance between TS: 50 mm Ar flow rate: 10 sccm O ₂ flow rate: 30 sccm Gas pressure: 0.15 Torr Substrate temperature: 730 ° C. Applied power: DC 150 W Here, the high-temperature superconducting film on the LaAlO ₃ substrate 1 is a dense film, and the high-temperature superconducting film on the MgO film 5 is a porous film. For this purpose, the total gas pressure is the largest factor among the above sputter deposition conditions. As its total gas pressure,
It is desirable that the pressure be 0.15 Torr or more and 0.4 Torr or less. This is because when the total gas pressure is lower than 0.15 Torr, LaA
A void is formed in the high-temperature superconducting film on the 10 ₃ substrate 1 to form a porous film. If the total gas pressure is higher than 0.4 Torr, the high-temperature superconducting film on the MgO film 5 becomes a dense film. is there.

Then, an Au ground electrode 7 is formed on the high-temperature superconducting film 4 by a vacuum evaporation method, and thereafter, an Au electrode 3 is formed on a power supply portion by a lift-off method. In this case, as shown in FIG. 4C, after a resist 6 is formed on the surface side, a power supply unit is opened, and thereafter, an Au film 3 is formed on the entire surface by a vacuum deposition method. Then, by removing the resist 6, the Au electrode 3 is formed only on the power supply section as shown in FIG.

Then, the high-temperature superconducting film 2 is patterned by etching to form an element body 2a and a power supply 2b as shown in FIG. As the substrate 1, in addition LaAlO ₃ substrate described above, CeO ₂ on the LaAlO ₃
Can be used. As the metal electrode, Ag or the like other than Au can be used, and other metals can be used as long as they can make ohmic contact with the high-temperature superconducting film.

As the lower layer film of the high-temperature superconducting film 2b of the power supply unit, a Y ₂ O ₃ film, a NdAlO film,
₃ film, YAlO ₃ film, YSZ (yttrium stabilized zirconia: about 7% Y ₂ O _{3 in} ZrO ₂ )
Can be used, but Y ₁ B
The MgO film is most preferable in terms of poor lattice matching with the high-temperature superconducting film 2 having a ₂ Cu ₃ O _y composition and increasing the number of voids.

As the high-temperature superconducting film, Y ₁ Ba ₂
In addition to the Y-based high-temperature superconducting film having a Cu ₃ O _y composition, a high-temperature superconducting film having another composition may be used. Further, the filter may be not only a distributed constant type filter but also a lumped constant type filter. In addition, as a high-temperature superconducting element,
In addition to a high-frequency passive element such as a filter element, an element such as an antenna or a delay line may be used.

[Brief description of the drawings]

1A and 1B show a configuration of a filter element according to an embodiment of the present invention, wherein FIG. 1A is a plan view, and FIG.
It is -A sectional drawing.

FIG. 2 is an enlarged plan view of a high-temperature superconducting film 2b formed on an MgO film 5. FIG.

FIG. 3 is a diagram showing a schematic cross-sectional configuration of high-temperature superconducting films 2a and 2b.

FIG. 4 is a process chart showing a process of manufacturing the filter element shown in FIG. 1;

[Explanation of symbols]

1 ... LaAlO _{3 substrate, 2 ... Y 1 Ba 2 Cu} 3 O y composition of high temperature superconducting films, 2a ... element main body section of the high temperature superconducting film, 2
b: High-temperature superconducting film of a power supply unit, 3: Au electrode, 4: High-temperature superconducting film forming a ground plane, 5: MgO film.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H01L 39/00 H01L 39/22-39/24 H01B 12/00-12/16 H01B 13/00 561-565 H01L 21 / 28-21/288 ZAA H01L 29/40-29/43 ZAA H01L 21/3205 ZAA C30B 29/22 501 H01P 1/203 ZAA C01G 1/00 C01G 3/00

Claims (5)

(57) [Claims] A high-temperature superconducting film (2) is formed on a substrate (1) so as to have an element body and a power supply portion, and a metal electrode (3) is formed on the high-temperature superconducting film (2b) of the power supply portion. Is formed, the high-temperature superconducting film (2a) of the element body is formed on the substrate.
The high-temperature superconducting film (2b) of the power supply unit is
The lattice matching of the high-temperature superconducting film is lower than that of the substrate.
Layer film (5) is formed on, and characterized in that high-temperature superconducting film of the power supply section (2b) is void from high temperature superconducting film (2a) of the device body portion is in the large film High-temperature superconducting element. 2. The method according to claim 1, wherein the substrate is a LaAlO ₃ substrate or L
a a substrate in which CeO ₂ is laminated on aAlO ₃ , the high-temperature superconducting film is a high-temperature superconducting film having a composition of Y ₁ Ba ₂ Cu ₃ O _y , and the lower film is an MgO film. The high-temperature superconducting element according to claim 1 . 3. A high-temperature superconducting film (2) is formed on a substrate (1) so as to have an element body portion and a power supply portion, and a metal electrode (3) is formed on the high-temperature superconducting film (2b) of the power supply portion. Forming a lower layer film (5), which has poorer lattice matching with the high temperature superconducting film than the substrate, on a part of the substrate, and then forming the high temperature superconductor on the entire surface. A superconducting film is formed, and thereafter, the high-temperature superconducting film on the lower film is used as the power supply unit, and the high-temperature superconducting film on the substrate is used as the element body. A method for manufacturing a high-temperature superconducting element, comprising patterning. 4. A LaAlO ₃ substrate or LaAlO ₃
A high-temperature superconducting film (2) having a composition of Y ₁ Ba ₂ Cu ₃ O _y is formed on a substrate (1) on which CeO ₂ is laminated so as to have an element main body and a power supply portion. A method for manufacturing a high-temperature superconducting element comprising forming a metal electrode (3) on a superconducting film (2b), comprising: forming an MgO film (5) on a part of the substrate (1); Then, the high-temperature superconducting film is formed so that the high-temperature superconducting film on the MgO film is used as a power supply unit and the high-temperature superconducting film on the substrate is used as an element body. A method for manufacturing a high-temperature superconducting element, comprising patterning. 5. The method according to claim 1, wherein after forming the high-temperature superconducting film, the metal electrode is formed on the high-temperature superconducting film serving as the power supply unit, and thereafter, the patterning is performed.
5. The method for producing a high-temperature superconducting element according to 3 or 4 .