JPH0442584A - Manufacture of superconducting wiring - Google Patents

Abstract

PURPOSE:To minimize compositional dislocation produced by calcination by positioning a substrate to be processed with a wiring pattern to a position where the substrate is faced to another substrate with a dummy pattern in a calcining furnace after the wiring pattern is formed on the substrate to be processed by putting a high-temperature superconducting oxide substance on the substrate and calcining the substrate while the temperature of the dummy pattern is maintained equal to or little higher than that of the wiring pattern. CONSTITUTION:Calcination is performed by positioning a substrate printed with a wiring pattern 1 and another substrate printed with a dummy pattern 3 so that the substrates can face each other. It is necessary to bring the patterns 1 and 3 as close as possible. When the calcination is performed in such state, a fine wiring pattern having a high superconducting critical temperature can be formed, because the PbO actively evaporated from the pattern 3 suppresses the evaporation of PbO from the pattern 1. In case a superconducting pattern is calcined, superconducting wiring which is less in gap between crystal grains and compacter in film can be obtained when the pattern is calcined after the pattern is once calcined for a short time at a higher temperature than a prposed calcining temperature so that crystals can grow to larger sizes and the PbO evaporation cannot take place actively and the pattern is returned to the original state.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing superconducting wiring, the purpose is to form a wiring pattern with a minute line width made of an oxide superconductor with a high superconducting critical temperature, After forming a wiring pattern by depositing the body component on the substrate to be processed, the substrate is placed in a firing furnace facing the substrate on which the dummy pattern is formed, and the temperature of the dummy pattern is made equal to or equal to the temperature of the wiring pattern. Alternatively, the method for manufacturing superconducting wiring is characterized by holding the wire at a high temperature and firing it.

[Industrial application field]

The present invention relates to a method for manufacturing a wiring pattern with a minute line width made of an oxide superconductor having a high superconducting critical temperature.

Several metal 3 alloys, intermetallic compounds, and nitrides.

It has been known for a long time that oxides exhibit superconductivity, but the superconductivity critical temperature (abbreviation Tc) for metallic elements remains at less than 10, and for intermetallic compounds, Nb3Ge has a temperature of 23.5K. It was the best.

However, in 1986 Bednorz and I'1ulle
Rankon, barium, copper, oxygen (La - Ba
Since the discovery of high-temperature superconductivity in -Cu -0)-based oxide ceramics, research has been conducted in various places to develop oxide superconductors with high T and to put devices using them into practical use. There is.

In other words, for information processing equipment, especially computers that require high speed operation, it is extremely effective to construct the circuit wiring of the substrate on which electronic elements that operate at low temperatures are mounted using high-temperature superconductors.

[Conventional technology]

Various compositions of oxide-based high-temperature superconductors have been discovered so far.

That is, yttrium, barium, copper, oxygen (Y-B
a-Cu-0) system and rare earth elements containing Y-BaCu
An oxide superconductor exhibiting a Tc of about 90K for the -0 series has been discovered.

After that, B1-5r-Ca- exhibiting Tc of 100 or more
TI-Ha-Ca-C showing Tc in CuO system and 125
The u-0 series etc. have been announced.

A method for forming a conductor line made of an oxide superconductor on a substrate to be processed such as magnesia or alumina is to form a thin film pattern made of the oxide superconductor by mask evaporation or sintering, and then sintering it. One method is to convert it into a superconducting phase by crystallizing it.

Another method is to form a conductive paste using superconducting ceramic powder, screen print the paste to form a fine pattern, and then sinter it to crystallize it and convert it into a superconducting phase.

In research on forming conductor wiring using the latter method, the inventors obtained a value of 100 K or more by firing bulk samples of superconducting ceramics and paste.

However, upon careful consideration, it was found that the apparent value of T depends on the wiring width.

That is, as the line width becomes narrower, Tc decreases. Up to a line width of 1.0 m, Tc is greater than 100 K, but at line widths below this, TC rapidly shifts to the low temperature side.

On the other hand, circuit boards on which electronic components are mounted, such as in information processing devices, require high-density mounting, and Tc needs to be higher than the temperature of liquid nitrogen (77K) for fine line widths.

However, B1-Pb-5r- with a T, phase of more than 100
For CaCu-0 films, in the conventional firing method, the characteristics deteriorate as the wiring width becomes narrower, and countermeasures have been required.

[Problem to be solved by the invention]

A method of screen printing a conductor paste made using superconducting ceramics and firing it can also form a superconductor wiring exhibiting a Tc of 100 or more, but it is possible to form a superconductor wiring with a Tc of 100 or more. Then, To decreases rapidly and does not exhibit superconductivity even at the temperature of liquid nitrogen (N2) (77 K).

Therefore, the challenge is to solve this problem.

[Means to solve the problem]

The above problem is solved by depositing an oxide high-temperature superconductor component on a substrate to be processed to form a wiring pattern, and then placing the substrate between a substrate on which a dummy pattern is formed and placing it in a firing furnace.
This problem can be solved by configuring a superconducting wiring manufacturing method characterized in that the temperature of the dummy pattern is maintained at the same or higher temperature than that of the wiring pattern during firing.

[Effect]

T of oxide superconductor obtained by depositing superconducting components and firing
The inventors believe that the reason why c suddenly shifts to the lower temperature side as the wiring width decreases is due to a shift in the composition ratio due to evaporation of components with particularly high vapor pressure among the components constituting the superconductor.

In other words, B1-P, for which the inventors are conducting research on practical application.
Regarding the b-5r-Ca-Cu-0 system, the component that has a high vapor pressure and has a significant effect on the properties is pbo, and the relationship between temperature and vapor pressure is shown in Table 1.

Table 1 And the temperature at which the superconducting phase is formed by crystallization by firing is 8
Since the temperature is around 50°C, the vapor pressure of PbO is high;
During this process, evaporation occurs easily and compositional deviation occurs.

Furthermore, as the line width becomes narrower, the composition shift easily occurs and Tc decreases rapidly.The reason for this is that as the line width becomes narrower, the exposed area per unit volume increases, and therefore the amount of pbo evaporated increases. It was thought that this was because the partial pressure of PbO due to evaporation from the surroundings including 1 itself was low, so the evaporation of the components was not suppressed.

Therefore, as a method of preventing the evaporation of the components, the present invention is a method in which, as shown in the principle diagram of FIG. It is.

At the knee, it is necessary that the wiring pattern 1 and the dummy pattern 3 be placed as close as possible.

When baking is performed in this manner, the evaporation of PbO from the wiring pattern 1 is suppressed due to the active evaporation of PbO from the dummy pattern 3.

It is possible to create fine wiring patterns with high quality.

Note that when firing the printed superconducting pattern, the temperature is higher than the expected firing temperature due to grain growth.

By firing for a short time at a slightly elevated temperature to prevent active evaporation of the metal, and then returning to the original temperature and firing, it is possible to create superconducting wiring with fewer gaps in the grain boundaries and promote densification of the film. I can do it.

In the present invention, by firing the dummy patterns close to each other in this way, it is possible to suppress the evaporation of components with high vapor pressure, especially PbO, and even for wiring with a line width of less than inn, it is possible to suppress the evaporation of components with a high vapor pressure. Superconductor lines with similar T can be formed.

〔Example〕

Example 1: (Formation of wiring pattern and firing furnace) BizOs
, PbO, SrCO3, CaCO5 and CuO raw material powders were prepared, and Bi:Pb:Sr:Ca
: Cu molar ratio is 0.7 = 0.3 : 1 : 1
: t, s and mix the mixed powder at 845°.
Superconducting ceramics were produced by firing at C for 150 hours.

This ceramic was coarsely ground in a mortar and then sized using a ball mill.

To this powder, terpineol was added as a viscosity modifier, acetone was kneaded by cutting, the powder was dried to remove acetone, benzene was mixed, and the powder was dried to adjust the viscosity to create a superconducting paste.

Using this paste, make a 15 mm square with a thickness of 0.5 mm.
A plurality of single-crystal magnesia (MgO) substrates were prepared, and a conductor line with a line width of 0.5 m and a length of 10 am and a dummy pattern of 10 w square were separately screen printed on the substrates and dried.

Next, a firing furnace as shown in FIG. 3 was prepared.

That is, a heat source (heater) is attached to the frame 7 made of quartz glass.
After inserting the alumina ceramic plate 8.9 with the 5.6 on the back, the substrate 2.4 is placed facing the ceramic plates 8 and 9 using MgO spacers 10 as shown in the figure. Placed.

By doing this, the distance between the wiring pattern 1 and the dummy pattern was maintained at 0.5 tm.

Example 2: As described in Example 1, the line width was 0.5 mm and the thickness was 3 mm.
0. ! /Il+, two MgQ substrates printed with conductor lines 10 mm in length were mounted in the firing furnace shown in FIG.
They were placed facing each other at five intervals, and the conductor line at the bottom was made into a dummy pattern.

Then, as shown in Figure 1, the heat source 5.6 is energized in the atmosphere,
After heating both at 860°C for 10 minutes, the upper substrate 2
The temperature of the lower substrate 4 was lowered to 840°C, while the lower substrate 4 was fired for 6 hours at a temperature of 850°C to change it to a superconducting phase, and the temperature dependence of the resistivity of the conductor line of the upper substrate 2 was investigated. It was measured.

Example 3: Line width is 0.5mm, thickness is 30μ, length is 10+++
Place the MgO substrate printed with conductor lines of 10 m on top, and
[The MgO substrate printed with a one-sided solid pattern was placed face down in the firing furnace shown in FIG. 3, and the substrates were placed facing each other with an interval of 0.511 I81, and the lower conductor line was used as a dummy pattern.

Then, the heat source 5.6 is energized in the atmosphere, and both are heated to 86
After heating at 0°C for 10 minutes, the temperature of both substrates 2.4 was increased to 8°C.
The temperature was lowered to 40°C, and the temperature was then fired for 6 hours to change it to a superconducting phase, and the temperature dependence of the resistivity of the conductor line on the upper substrate 2 was measured.

Comparative Example 1: An MgO substrate with a conductor line printed with a line width of Q, 5 mm, a thickness of 30 μm, and a length of 10 m is placed on top, and an MgO substrate without pattern printing is placed on the bottom, as shown in Figure 3. It was installed in the firing furnace, and the heat source 5,
6 and heated both at 860°C for 10 minutes, the temperature of both substrates 2.4 was lowered to 840°C, and fired in that state for 6 hours to change it to a superconducting phase. The temperature dependence of resistivity was measured for the conductor line.

Figure 2 shows the results for Example 2.3 and Comparative Example 1, where the Tc of Example 2.3 is approximately 98 and approximately 100, whereas in Comparative Example 1, a phase transition is observed. \, the residual resistance is as large as 12 mΩ・Cl11, and it is not in a superconducting state.

〔Effect of the invention〕

As described above, by carrying out the present invention, it is possible to minimize the compositional deviation that occurs during firing to form a superconducting phase, thereby forming a fine pattern with a line width of 0.5 mm or less. Even in this case, it is possible to create superconducting wiring with a line width of 1 mm or more and a high Tc.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a diagram showing the temperature dependence of resistivity for Examples, and FIG. 3 is a cross-sectional view of a firing furnace used to implement the present invention. In the figure, 1 is a wiring pattern, 2.4 is a substrate, 3 is a dummy pattern, and 5.6 is a heat source. Principle diagram of the present invention? pierced r5 i t〉 and 1 1 degree (K)

Claims (2)

[Claims] (1) After depositing an oxide high temperature superconductor component on a substrate to be processed to form a wiring pattern, the substrate is placed in a firing furnace facing a substrate on which a dummy pattern is formed, and the temperature of the dummy pattern is A method for manufacturing superconducting wiring, characterized in that the temperature of the wiring pattern is maintained at a temperature equal to or higher than that of the wiring pattern. (2) A method for manufacturing superconducting wiring, characterized in that the dummy pattern according to claim 1 is a wiring pattern or a solid pattern.