JP2679276B2 - Superconducting ceramic thin film forming single crystal wafer material for semiconductor device manufacturing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a superconducting ceramic thin film-formed single crystal wafer material used in the manufacture of semiconductor devices such as LSI and Josephson devices.

[Conventional technology]

Conventionally, for example, in atomic ratio, Tl ₂ Ba ₂ Ca ₁ Cu ₃ O ₁₀ , Tl ₂ Ba ₂ Ca ₂ Cu ₄ O ₁₂ , Tl ₁ Ba ₂ Ca ₁ Cu ₃ O ₈ , Tl ₁ Ba ₂ Ca ₂ Cu ₄ O ₁₀ , Tl ₁ Ba ₂ Ca ₃ Cu ₅ O ₁₂ , a target material having a composition of any one of Tl ₂ Ba ₃ Ca ₅ Cu ₁₂ and Tl _{2 on} the surface of a single crystal wafer material such as Si or Ga-As. Ba ₂ Ca ₁ Cu ₂ O ₈ , Tl ₂ Ba ₂ Ca ₂ Cu ₃ O ₁₀ , Tl ₁ Ba ₂ Ca ₁ Cu ₂ O ₇ , Tl ₁ Ba ₂ Ca ₂ Cu ₃ O ₉ , Tl ₁ Ba ₂ Ca ₃ Cu ₄ A superconducting ceramic thin film (hereinafter referred to as a superconducting thin film) mainly composed of a crystal phase having any one of O ₁₁ and O _{11 is} vapor-deposited by a sputtering method or a physical vapor deposition method, and then the crystal orientation of the thin film is performed. For the purpose, using an infrared heating furnace, in an atmosphere containing Tl vapor, at a temperature of 900 ℃ ± 2 ℃ 10 ~ 3
After holding for 0 minutes, heat treatment is performed under the conditions of rapid cooling to produce a superconducting ceramic thin film forming single crystal wafer material (hereinafter referred to as superconducting thin film forming wafer material), which is used in the manufacture of semiconductor devices such as LSI and Josephson devices. Attempts have been made to use it.

[Problems to be solved by the invention]

On the other hand, with the recent trend toward higher performance and higher density of semiconductor elements, there is a strong demand for superconducting thin films in wafer materials on which superconducting thin films are formed to have a much higher critical temperature (Tc).

[Means for solving the problem]

Therefore, the present inventors, from the above viewpoints, as a result of conducting research to improve the critical temperature of the superconducting thin film in the superconducting thin film forming wafer material, the surface of the single crystal wafer material such as Si and Ga-As In addition, prior to forming the above superconducting thin film, Tl ₁ Ba ₂ Ca _x O _y (where x: 1 to 2, y: 4.5 is preferable) as an intermediate layer with a thickness of 500 to 2000Å and an atomic ratio. ~ 5.5), Tl ₂ Ba ₂ Ca _v O _w (provided that v: 1 to 3, w: 6 to 8), a ceramic thin film mainly composed of a crystal phase is formed in advance. It has been found that the superconducting thin film in the wafer material on which the superconducting thin film is formed after the crystal orientation heat treatment has a much higher critical temperature.

The present invention was made based on the above findings, and is formed on the surface of a single crystal wafer material such as Si or Ga-As, preferably with a thickness of 500 to 2000 Å, in atomic ratio, Tl ₁ Ba ₂ Ca _x O _y (however, x: 1 to 2, y: 4.5 to 5.5), Tl ₂ Ba ₂ Ca _v O _w (however, v: 1 to 3, w: 6 to 8), The above-mentioned superconducting thin film, that is, the atomic ratio of Tl ₂ Ba ₂ Ca ₁ Cu ₂ O ₈ and Tl ₂ Ba ₂ Ca ₂ via the intermediate ceramic thin film (hereinafter referred to as the intermediate thin film) mainly composed of the crystal phase having the composition of Cu ₃ O ₁₀ , Tl ₁ Ba ₂ Ca ₁ Cu ₂ O ₇ , Tl ₁ Ba ₂ Ca ₂ Cu ₃ O ₉ , Tl ₁ Ba ₂ Ca ₃ Cu ₄ O ₁₁ , a crystal phase having a composition of It is characterized by a wafer material having a superconducting thin film formed by forming a superconducting ceramic thin film as a main component.

The composition of the crystal phase that constitutes the main body of the intermediate thin film in the superconducting thin film-formed wafer material of the present invention is empirically determined, and as shown as a comparative example in the following examples, If it deviates from the composition range, the desired high critical temperature cannot be obtained.

Further, the desired thickness of the intermediate thin film in the superconducting thin film forming wafer material of the present invention is 500 ~ 2000 Å, the desired critical temperature improving effect is not obtained in the thickness less than 500 Å, while the thickness is 2000 Å This is because the effect of improving the critical temperature of the superconducting thin film is saturated even if it exceeds the above range, and it is not economical to form a thicker film.

[Examples] Next, the superconducting thin film-formed wafer material of the present invention will be specifically described by way of examples.

First, prepare a Si single crystal wafer material with a diameter of 50.0 mm and a thickness of 0.35 mm as a substrate, mount it on an ordinary sputtering device, and measure the diameter of 127 mm and the thickness of 6 mm, and Table 1 for each. Using a target material for forming an intermediate thin film with the composition shown in Fig. 1, high-frequency power: 200 W, vacuum degree: 20 mtorr, atmosphere gas: O ₂ / (Ar + O ₂ ) = 1/5 by volume ratio, between substrate and target material Sputtering was performed under the following conditions: distance: 70 mm, substrate temperature: 680 ° C, and
After forming an intermediate thin film having substantially the same composition as the target material and each having the average layer thickness shown in Table 1, in an infrared heating furnace, in a Tl atmosphere, at a temperature of 700 ° C.
After holding for 10 minutes, it is subjected to crystallization heat treatment by rapid cooling, and subsequently,
A target material for forming a superconducting thin film having a diameter of 127 mm and a thickness of 6 mm, and also having the composition shown in Table 1, high frequency power: 200 W, vacuum degree: 10 mtorr, atmosphere gas: O ₂ / (Ar + O ₂ ) = 1/10 in capacity ratio, sputtering between the substrate and target material: 70 mm, substrate temperature: 720 ° C. A superconducting thin film having a major crystal phase having the composition and proportion shown in Table 1 and an average layer thickness shown in Table 1 is formed on the above, and further, in an infrared heating furnace,
In a Tl atmosphere, the temperature was kept at 900 ° C. for 30 minutes and then a crystal orientation heat treatment was performed under the conditions of rapid cooling, so that the superconducting thin film forming wafer materials 1 to 6 of the present invention and the comparative superconducting thin film forming wafer materials 1 to
5 were each manufactured.

In each of the comparative superconducting thin film-formed wafer materials 1 to 5, the composition of the intermediate thin film is out of the range of the present invention.

Then, the resulting superconducting thin film-formed wafer materials 1 to 6 of the present invention and comparative superconducting thin film-formed wafer materials 1 to 1 are obtained.
The critical temperature (Tc) of the superconducting thin film of No. 5 was measured. The results are shown in Table 1.

〔The invention's effect〕

From the results shown in Table 1, the superconducting thin film-formed wafer materials 1 to 6 of the present invention are all formed by the formation of the intermediate thin film.
The comparative superconducting thin film forming wafer material 1 without the formation of the intermediate thin film, and the comparative superconducting thin film forming wafer materials 2 to 5 in which the composition of the intermediate thin film is out of the scope of the present invention have a much higher critical temperature than the superconducting thin films. It is clear that

As described above, in the superconducting ceramic thin film-forming single crystal wafer material of the present invention, the superconducting ceramic thin film forming the superconducting ceramic thin film exhibits a remarkably high critical temperature. It has industrially useful properties such as being able to fully satisfy the densification requirements.

Claims (1)

(57) [Claims] 1. An atomic ratio of Tl ₁ Ba ₂ Ca _x O _y (where x: 1 to 2, y: 4.5 to 5.5) and Tl _{2 on} the surface of a single crystal wafer material such as Si or Ga-As. Ba ₂ Ca _v O _w (provided that v: 1 to 3, w: 6 to 8), through an intermediate ceramic thin film mainly composed of a crystalline phase having the composition of ₂ Ba ₂ Ca ₁ Cu ₂ O ₈ , Tl ₂ Ba ₂ Ca ₂ Cu ₃ O ₁₀ , Tl ₁ Ba ₂ Ca ₁ Cu ₂ O ₇ , Tl ₁ Ba ₂ Ca ₂ Cu ₃ O ₉ , Tl ₁ Ba ₂ Ca ₃ Cu _A single-crystal wafer material for forming a superconducting ceramic thin film for manufacturing a semiconductor device, which comprises a superconducting ceramic thin film mainly composed of a crystal phase having a composition of any of ₄ O ₁₁ and.