CS245243B1 - Cathode target for reactive magnetron sputtering - Google Patents

Abstract

The cathode target for reactive magnetron sputtering, in particular of thin superconducting layers on strip metal substrates, consists of individual parts, composed of parts, each of which contains only a single element represented in the chemical compound of the superconducting layer. The partial areas of the individual elements are in the stoichiometric ratio of the desired compound.

Description

BACKGROUND OF THE INVENTION The present invention relates to a cathode target for reactive magnetron correction of particularly thin superconducting layers onto powdered metal substrates.

It has hitherto been known that for magnetron sputtering of metals or metal alloys onto semiconductor wafers, a cathode target of circular or rectangular shape made of metal or of a metal alloy to be sputtered is used. In the case of some compounds whose production is difficult and very expensive to produce in the desired purity, or in the case of compounds whose mechanical properties are unsuitable for their processing, for example by molding or machining, making the cathode target is unrealistic.

This disadvantage is overcome by a cathode target for reactive magnetron sputtering, in particular thin superconducting layers on the powdered metal substrates according to the invention, characterized in that the individual parts of the mosaic target are composed of parts each containing only one element present in the chemical compound of the superconducting layer. The partial areas of the individual elements are in the stoichiometric ratio of the desired compound.

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According to another aspect of the invention, the distribution of the individual parts is regular over a selected number of smaller areas.

The cathode target according to the invention has the advantage that the target is produced from individual partial surfaces of the elements of the future compound, thus eliminating the need to prepare the compound in advance and then making the target therefrom. The resulting compound is highly pure and its degradation is avoided as can be the case when separating the chemical synthesis of the compound and then processing it into a target.

The front face of the target, from which the individual elements present in the target are dedusted successively in the course of a glowing rotating discharge, is formed by a mosaic of these elements. Front surface

The 245 243 individual target elements are in the ratio of their stoichiometric representation in the desired compound. The individual surfaces are then adjusted in proportion to the atomic number of the positive ion of the diluted gas in the magnetron to the atomic number of the respective target element. The individual surfaces of the elements are adapted to the requirement for optimum composition of the sputtered superconducting phase, which need not be stechioraetric.

It is usually used for argon sputtering.

The reactive sputtering may be, for example, nitrogen, ammonia, methane. The magnetron glow discharge rotates very quickly under the action of Lorenz force, mixing the individual elements ejected from the target, which in a suitable amount corresponding to the optimum composition of the superconducting phase merge during the transition to the sputtered surface and fall on the surface to capture the superconducting compound.

Example 1

The niobium-germanium superconductor, which is one of the best superconductors with regard to the critical temperature level of the superconducting state, due to unsuitable mechanical properties, cannot be manufactured other than by applying it in a thin layer, for example to a copper carrier in the shape of a tape. In this case, a magnetron material of a cathode plenary target of circular or other shape is preferably used. For example, the tetóe area is divided into four fields. Two opposites are of niobium and two opposites are of germanium. In determining the area ratio, the first step is based on the stoichiometric composition of the desired compound - the niobium atomic number is 41, and is represented three times in the compound, i.e. 123; germanium I is an atomic number 32, the stoichiometric ratio is thus 123 i 32 = niobium; germanium i.e. about 4: 1.

Example 2

The Nb ^ Sn superconductor is one of the best superconductors with respect to all superconducting state parameters. Due to the unsuitable mechanical properties of the compound Nb-Sn, it is not possible to give it the shape of wire or tape by forming technology. Therefore, a magnetron sputtering of a composite cathode target is preferably used. The target area is divided into four fields; two opposing ones are niobium and

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- 3 two opposites are made of tin. In determining the ratio of niobium to tin areas in the target, the first step is based on the stoichiometric composition of the compound NbgSn. The atomic number Nb is 41, there are 3 Nb atoms in the compound, i.e. we obtain 123. The tin has an atomic number 50. Thus the area ratio will be Nb: Sn = 123: 50 i.e. about 2.5: 1.

In the case of a binary compound, the target area consists of at least two fields or 2 χ n fields. The larger the integer, the more homogeneous the resulting mixture and the easier its chemical synthesis during reactive sputtering. Improvement of homogeneity is ensured by the relative movement of the tape substrate relative to the target.

Claims (2)

Cathodic target for reactive magnetron sputtering, in particular thin superconducting layers on strip metal substrates, characterized in that the individual parts of the mosaic target are composed of parts each containing only one element represented in the chemical compound of the superconducting layer, the partial surfaces of the individual elements they are in a stoichiometric ratio of the desired compound. 2. A cathode target according to claim 1, wherein the distribution of the individual parts is regular over a selected number of smaller sheets.