JPS5947783A - Formation of pattern of oxide superconductor - Google Patents

Abstract

PURPOSE:To enable pattern formation of a very small width of an oxide superconductor BPB by a method wherein an oxide superconductor thin film is deposited on a substrate, a resist pattern is formed thereon, and then the oxide superconductor is removed by sputter-etching with a sufficient flow amount of argon gas or argon gas added with hydrogen gas. CONSTITUTION:Etching speed increases with the increase of the flow amount of gas in BPB series composed of heavy metalls. On the other hand, reversely etching speed largely decreases in organic photo resist. From this result, it is sufficient to coat an organic photo resist approximately twice as thick as the thickness of the BPB in the flow amount 50 SCCM of argon gas. Next, the removal of the remnant resist is performed. Sputter etching in oxygen is effective, because the BPB is an oxide. To remove only the resist film by etching, sputter etching in oxygen can be performed by power at 0.16W/cm<2> or more.

Description

Detailed Description of the Invention The present invention provides an oxide superconductor BaPb(1-X)Bi(X
) Oa (o, o s≦X≦CL!l) (hereinafter abbreviated as BPB)-based fine pattern forming method.

Conventionally, in order to fabricate a BPB superconducting circuit, a method has been used in which a pattern is formed on a BPB thin film using an organic photoresist, and then the BPB is chemically etched using a mixture of hydrochloric acid and chloric acid (Japanese Patent Application No. 1983). -9569].

However, since this method utilizes the dissolution of the film in an aqueous solution, the side surface of the BPB under the resist is also etched at the same time, resulting in poor line width accuracy and poor line cutting ability. There were drawbacks such as:

In order to solve these drawbacks, the present invention uses a sputter etching method to remove 3PB and form a pattern. An object of the present invention is to provide a method for forming an oxide superconductor pattern that can produce fine patterns of N or less.

That is, to summarize the present invention, the present invention has the formula BaPb
(1-,)Bi(X)o3 (where 0.05≦X≦0.
30) In the method for forming a circuit using a dark compound superconductor, an oxide superconductor thin film is deposited on a substrate, and a resist pattern is formed using an organic photoresist on the oxide superconductor thin film.
The present invention relates to a method for forming an oxide superconductor pattern, characterized in that the oxide superconductor is removed by sputter etching with a sufficient flow rate of argon gas or argon gas added with hydrogen gas.

Among the constituent atoms of BPB, Ba, pb, and B1 are heavy metals, and the boiling point of chloride or fluoride is high, and the etching rate is low in normal plasma etching methods.
It becomes necessary to thicken the resist, and pattern accuracy deteriorates. Therefore, we attempted to apply a sputter etching method using argon gas or argon gas added with hydrogen.

When sputter etching is performed, the sputter etched atoms return to the substrate and re-deposit, resulting in a low etching rate and problems such as the pattern not being able to pass through the metal. Therefore, it has been found that by increasing the gas flow rate so as to separate the etched atoms from the substrate as quickly as possible, a difference in etching speed is created and etching can be carried out effectively.

The present inventors have found that by increasing the gas flow, the BPB film can be patterned with high precision, and the thickness of the organic photoresist coated with respect to the thickness of the BPB film can be increased as shown in the following example. I found a suitable range.

Embodiments of the present invention will be described below based on the accompanying drawings, but the present invention is not limited thereto.

Example 1 Figure 1 shows BPB and Fair resin photoresist (AZ
It is a graph showing the relationship between the etching rate (lH'm) of -1350J) and its speed ratio (PPP/AZ) (Book 11) and the argon gas flow rate (sccM) (horizontal axis). The pressure during sputter etching was 10
The power was set to 0.32 W/no at Pa. As is clear from FIG. 1, the etching rate increases in the BPB system composed of heavy metals as the gas flow increases. On the other hand, the etching rate of organic photoresists is significantly reduced. As a result, for example, the flow rate is 508 CCM.
In this case, it is sufficient to coat the organic photoresist about twice as thick as the BPB. Normal BPB is 0.5
Since tsrn J'F is less than 1μ, the cyst thickness is 1μ.
m or less is sufficient.

Next, the remaining 1/cyst is removed. BPB 75
:Since it is an oxide, star etching in oxygen is effective. FIG. 2 shows a graph of the relationship between the etching speed h (17 minutes) (vertical axis) of BPB and AZ-1350J resist in oxygen gas and the lower (W/-?) (intensity axis). The Sunoku-tsuta etching conditions were gas flow sweeping 10 BCCM, gas pressure 10 Pa, and power 0.
Changed from 05 W to 0.5 W/rrn''!

This result shows that it takes 0.16W/t to remove only the resist film without etching the BPB film.
It is sufficient to carry out suction etching in oxygen at a power above IN.In addition, due to suction etching in oxygen, the superconducting properties of the BPB bulk are not affected under the conditions described above. The above process was completed without any problem BPI
3) It is possible to turn the force into a turn.

Example 2 [When sputter etching a compound, a method of etching while reducing is effective. FIG. 6 shows the results of etching F3FB using a gas mixture of argon and hydrogen. In other words, Figure 5 shows BPB and phenol 4M.
+1tW photoresist (A, 7.-1350.1)
Etching speed (λ/min) (vertical axis) and speed ratio (BP
B/AZ) (1i (rl111+)) This is a graph showing the relationship between Iy4 and hydrogen pressure cuff (volume %) (horizontal axis). Among the sputter etching disputes, pressure cuff 0 Pa
', power 0.32 W/cy? , flow meter 1105C
C was fixed.

As the hydrogen content increases, the etching rate of BPB increases, and with 10% hydrogen addition, it becomes about twice as high. On the other hand, in the case of photoresist, the etching rate changes greatly with hydrogen addition, and decreases significantly around 3π. In this vicinity, the speed ratio of BPB and resist is 0.6, and patterning is possible by using a photoresist with a thickness approximately twice that of BPB. Note that the sputter etching in oxygen described in Example 1 was effective for removing the remaining resist.

As explained in detail above, according to the method of the present invention, it is possible to form a pattern with a minute width of the oxide superconductor BPB. It can be applied when manufacturing integrated circuits.

[Brief explanation of drawings]

FIG. 1 is a graph showing the etching rates of BPB and organic photoresist, and the relationship between the speed ratio and the flow rate of argon gas. FIG. 2 is a graph showing the etching rate of BPB and organic photoresist during sputter etching in oxygen gas. Graph showing the relationship between speed and sputter etching power FIG. 3 is a graph showing the relationship between the etching speed of BPB and photoresist, the speed ratio therebetween, and the hydrogen gas addition area. Patent applicant: Nippon Telegraph National Corporation agent Hirotoshi Nakamoto Bengami Akira Etch speed (6/min) Etch detour ratio (βP%Z): JL amount (SCCM) Fig. 1 Zhengichi power (W/cm diagram 2

Claims (1)

[Claims] 1. In a method for forming a circuit of an oxide superconductor expressed by the formula Barb(1-,)Bi(x)Os (0.05≦X≦0.50), an oxide 1iti conductor thin film is formed on a substrate. , forming a resist pattern thereon using an organic photoresist, and then removing the oxide superconductor by sputter etching with a sufficient flow of argon gas or argon gas added with hydrogen gas. An oxide superconductor pattern formation method characterized by: