Method for preparing by thermal spraying a silicon- and zirconium-based target

The present invention relates to a method of producing a target by spray or ion source, the target of which is intended to be used in an inert or reactive atmosphere in a vacuum deposition process, especially by magnetically enhanced sputtering.

According to another embodiment of the invention, the invention also relates to a target obtained by performing the method and for the purpose of obtaining a film based on a material sputtered from the target, and the use of such a target, and the present invention. Depending on the method, the composition of the compound for producing the target is also involved.

Various techniques for producing a target produced by producing a powder mixture are known. Thus, the target in question may be provided in the process by which the mixture is cast or sintered, otherwise less conventional, but in thermal spraying techniques, and more particularly in plasma spraying techniques. ..

<p> Thermal spraying techniques are satisfactory in that they are used to produce targets made of a single component, but when the target is based on several components, the target is generally non-uniform in the deposited film. Shows structural heterogeneity that leads to sex.</p><p> More particularly, the powder has a powder-based mixture containing substantially different densities, such as silicon (density = 2.34), aluminum (density = 2.7) and another component M which can have a density of 5-10. In the case of powder mixtures, the inventors have found that differences in the density of M between Si, Al, and in other cases, on the one hand, pose the following problems: The risk of separation, and therefore the heterogeneity in the powder mixture prior to injection, eventually results in a compositionally heterogeneous target; Different orbits of each species in a plasma stream of powders of different densities separate particle beams into as many beams (or as many beams as species or components in a mixture) at different density levels. Give rise. These separated beams then become microstructurally heterogeneous in the target, resulting in a multi-layered type (superposition of layers A and B).</p><p> These heterogeneity in the target produces a negative effect (parasitic arc, heterogeneity in the composition of the thin film) during the formation of the thin film by sputtering. This can also increase the roughness of the target surface as a result of changes in spray efficiency in various areas within the target. This increase in roughness will, in extreme cases, result in the appearance of protrusions of considerable size (several mm in diameter / height) that give rise to surface arcs (enhancement of the electric field by the tip effect).</p><p> In addition, certain species that must be mixed with the ingredients are at high industrial risk (high industrial risk, especially if they are present in the form of pure powdered metal (in a fairly wide range) within the particle size range required for plasma spraying. Due to their extreme binding activity to oxygen, some powdery metals exhibit a risk of explosion).</p><p> Therefore, an object of the present invention is to alleviate these drawbacks by proposing a method of generating a target by heat spraying, especially plasma spraying, for each of the respective species constituting the initial powder mixture. It makes it possible to obtain a target with a homogeneous microstructure despite the difference in density.</p>

<p> To this end, the method according to the invention for producing a target by heat spray, especially plasma spray, is such that the target<u style="single">, Silicon and</u>(Zr, Mo, Ti, Nb, Ta, Hf, Cr)<u style="single">In a group</u>At least a portion of a compound that comprises at least one compound based on a different type of atom, specifically selected from the component M to which it belongs, and is a component that is bonded by a shared and / or ionic and / or metal bond, is the target. It is characterized in that it is injected into the plasma jet that sprays the components of the compound onto the target so as to deposit a coating of the compound on the surface portion of the compound.</p>

By injecting an alloy-type compound (or one having an intimate mixture of atoms) into a plasma stream, there is no longer a risk of any heterogeneity between the constituent atoms of the compound in the deposited material.

One or more, the following arrangements may also be optionally used in a preferred manner in which the methods of the invention are carried out: Another portion of the compound is injected in the form of a powder mixture; The particle size of each powder forming the mixture is selected by the respective density of the particles so that the average mass of each of the particles is as close as possible; Several injection channels are used, in which the injection parameters of the material injected into each channel are adjusted independently; The compounds are pre-vacuum purged and then sprayed in a chamber filled with an inert atmosphere; The compounds are vacuum purged and then filled with an inert gas at a pressure that can range from 50 mbar to 1000 mbar and sprayed in the chamber; Relative movement between the target and the plasma takes place; The target undergoes surface treatment prior to deposition of the compound; Surface treatment involves cleaning work performed on the surface portion of the target; The surface treatment involves the deposition of a layer of binder material on the surface portion of the target; The surface portion of the target is thermally regulated during the plasma spray; At least one silicide of the metal M is injected.

The subject matter of the present invention is also a sputtering target, particularly a magnetron sputtering target, which generally contains silicon in a composition of Si._xAl_yBeing M type (where M is a metal selected from Zr, Mo, Ti, Nb, Ta, Hf and Cr), and at least Si_xM_yIt is characterized by containing a type of compound.

In a preferred embodiment of the invention, one or more of the following arrangements may optionally be used: Targets also include compounds of the type consisting of silicides of the metal; The target has a planar or tubular geometry; The target is based on a support made of copper or copper alloy; The target is coated with a bond layer based on a copper alloy; The target is based on a support made of stainless steel; The target is coated with a bonding layer based on nickel alloy.

Yet another subject of the invention, which follows its characteristics, is characterized in that the composition of the compound, which is defined below and contains components represented by weight percentage, consists of: It is to be: Al: 2 ~ 20%; Si: 25 ~ 45%; and ZrSi₂:45~70%。

According to the preferred method of making a target according to the present invention, the target comprises a cylindrical or planar support made of a support material alloy or stainless steel. This metal support is essentially by blasting its surface with abrasive particles (eg, 36 or 24 grit) or by processing lines or streaks to facilitate the adhesion of the bonding sublayer. Receives surface treatment consisting of cleaning work.

A different material will be used for this binding sublayer, which depends on the nature of the material forming the target support. Therefore, for copper-based support plates, the sublayers are, for example, Cu-Al-Fe or Cu-Al type (80-95% Cu, 5-20% Al and 0-5% Fe) copper-based alloys. On the other hand, the steel support is made of an alloy based on sublayer Ni (eg NiAl with 75-100 wt% Ni) (ratio is expressed by weight).

This sublayer may be deposited by conventional plasma spray techniques. It can also be applied by electric arc spray or oxyacetylene frame spray. If necessary, several injection channels are used and the injection parameters are adjusted independently according to the material injected into each channel. This also makes it possible to eliminate the negative effects of density differences.

Therefore, this support, coated with a bonding sublayer, is placed inside the chamber, and the chamber is first evacuated at a pressure of 50-1000 mbar, before the chamber is filled with an inert atmosphere (eg argon). It has been done.

Compounds of SiZrAl composition after relative movement between the support intended to form the target and plasma spray device, and after heat regulation by circulation of the heat transfer fluid in the metal support Is injected and the compound is obtained from a powder mixture having the following composition: ZrSi₂: Particle size = 15 ~ 50μm; Density = 4.88g / cm³; Si: Particle size = 30 ~ 90μm; Density = 2.34g / cm³And Al: Particle size = 45 ~ 75μm; Density = 2.7g / cm³.. The three powders were mixed in the required proportions, ie: 60% by weight ZrSi₂; 34.5% by weight Si; and 5.5% by weight Al.

In this example, the selected metal M that binds to silicon in the form of silicide is zirconium, but of course the components in the form of metal M selected from Zr, Mo, Ti, Nb, Ta, Hf and Cr. It would be possible to use it.

The functional Si-M-Al layer has a microstructure consisting of juxtaposition of regions whose composition is mainly Si, a region of composition MaSib and a region of composition Al, which are uniformly dispersed. , The size of these regions ranges from a few μm to about 100 μm.

This target is a film based on the material on which the target is formed within a vacuum film deposition depositor (magnetron in an inert or reactive atmosphere, especially by magnetically enhanced sputtering, by corona discharge or by ion spray). This film is based on a mixed silicon zirconium nitride and has a refractive index of 2.10 to 2.30, preferably 2.15 to 2.25. This film can be made of an organic material (PMMA or PC) or an inorganic material (silica-based glass) (ie, deposited directly on the substrate or indirectly on another film that itself contacts the substrate). The purpose is to bond to the base material.

As can be seen in Figures 1 and 2, the structure is thin plate-like. The phase with a darker gray color is ZrSi₂Or ZrN, while the white or light gray layer corresponds to aluminum. Black spots are residual holes.

The sheet-like microstructures in these figures should be compared to the structures shown in FIG. While the black phase corresponds to the pores and the white phase is Zr and Al, this Figure 3 shows that the microstructure is not lamellar (no tinted or gray layer) and the gray phase is Si. Shown. The material appears in the form of particles that are uniformly dispersed within the structure.

The conclusion of this qualitative analysis is that it is perfectly possible to characterize the method of making the target thus analyzed, based on the microstructure.

Other features and advantages of the present invention, the non-limiting example and the following figures specifically described are given by will become apparent Erareru following description:<figref num="1">FIG. 1 is a cross-sectional view showing the microstructure of the SiZrNAl target obtained by the manufacturing method according to the present invention;</figref><figref num="2">FIG. 2 shows ZrSi obtained by the manufacturing method according to the present invention.₂FIG. 2 is a cross-sectional view showing the microstructure of the Al target;</figref><figref num="3">FIG. 3 is a cross-sectional view showing the microstructure of the ZrSiAl target obtained by a conventional manufacturing method (by sintering).</figref>