RU2049152C1 - Apparatus for vacuum deposition of materials - Google Patents

Abstract

FIELD: ion-emitting deposition of materials. SUBSTANCE: apparatus has ion source, whose beam disperses target formed as gathering reflector. Substrate holder is arranged relative to ion source and target so as to provide focusing of maximum indicatrix of flow of target material to be dispersed on substratum surface to be treated. EFFECT: increased efficiency, wider operational capabilities and enhanced reliability in operation. 12 cl, 4 dwg

Description

 The invention relates to the processing of products in a vacuum, and in particular to devices for spraying materials in a vacuum with an ion beam, and can be used in the electronic, optical, instrument-making and other engineering industries when applying multilayer coatings from various, including expensive or toxic materials, engraving or shaping (adjusting the shape) of surfaces by means of directional spraying of materials.

 Known devices for spraying materials in vacuum by an ion beam, containing an ion source installed in a vacuum chamber, a mount of targets from the sprayed material and a holder with substrates.

The advantages of the ion beam atomization method are the ability to atomize any materials, high purity of the spraying process carried out under high vacuum (≈10 ^-4 mm Hg), high quality of sprayed films (uniformity of composition, uniformity of thickness, good adhesion, mechanical strength etc.), the ability to control and control the deposition process, the ability to obtain component films of any composition by spraying the corresponding target, or by spraying a set of targets from several materials in down process.

 The main disadvantages of this type of device are: their low productivity compared with ion-plasma spraying devices, as well as with spraying devices using, for example, resistive, electron-beam and other types of evaporators, the "wide" angular distribution of the sprayed material (close to " cosine law, which is characteristic of resistive and electron-beam sputtering methods), which does not allow the process of directed sputtering (local sputtering) of materials and, therefore, leads to a large consumption of target material and to contamination by the sprayed material of the walls of the chamber.

Known sources of intense ion beams-duoplasmatrons, on the basis of which atomizing devices with high productivity can be created (ion current density up to 10 A / cm ² ), not inferior, for example, to electron-beam evaporators (current density of the order of several A / cm ² ) .

 However, the main disadvantage of this type of device is the large angle of divergence of the ion beam, which also does not allow to localize the flow of the atomized substance into space and leads to a large consumption of the target material and to contamination of the chamber walls with the atomized material.

 A device for atomizing an ion beam containing an ion source installed in a vacuum chamber, a attachment site of a target with a spray material and a holder with a processed substrate, in which a diaphragm restricting the aperture of the ion beam is used to localize in the space the flow of the spray substance and reduce the pollution of the chamber walls with the spray material , and a spray trap.

The main disadvantages of this device are:
contamination of the treated surface of the substrate with the material of the diaphragm, which is located in the working area of the beam;
inefficiency of the trap of atomized material, since the limitation of the aperture of the ion beam does not change the angular distribution of the flow of atomized material, which remains "wide".

 The main disadvantages of all of the above devices, which worsen their operational characteristics, are the high consumption (unproductive use) of the sprayed target material, contamination of the walls of the working chamber with the sprayed material, which is crucial when spraying, for example, expensive and toxic materials.

 The purpose of the invention is the improvement of operational characteristics by reducing the contamination of the sprayed materials on the walls of the chamber, increasing the efficiency of the consumption of target material, expanding the technological capabilities of the device, increasing the life of the target.

 The goal is achieved in that in a known device containing an ion source installed in a vacuum chamber, a target attachment unit carrying at least one target with the sprayed material, and a substrate holder, the sprayed target surface has the shape of a collecting reflector, and the substrate holder is mounted so that the treated surface of the substrate was located at the maximum indicatrix of the flow of the sprayed target material.

 In addition, the sprayed target surface has the shape of a sphere, the center of which is aligned with the treated surface of the substrate.

 In addition, the sprayed target surface is optically coupled to the output aperture of the ion source and to the substrate surface being treated.

 In addition, the sprayed surface of the target has the shape of a parabola, the focus of which is aligned with the treated surface of the substrate or with the output aperture of the ion source.

 In addition, the sprayed surface of the target has the shape of an ellipse, one focus of which is aligned with the output aperture of the ion source, and the other with the treated surface of the substrate.

 In addition, the sprayed surface of the target is made in the form of a recess, the bottom of which has the shape of a collecting reflector. The recess can be performed, for example, in the form of a hole or in the form of a gutter.

 At least one through hole is made in the target, the lateral surface of which has the shape of a collecting reflector. In this case, the output aperture of the ion source, the sprayed surface of the target, and the treated surface of the substrate can be aligned.

 The attachment site of the targets and / or the ion source are equipped with displacement drives with the possibility of changing sections of the sprayed surface.

 A comparative analysis of the proposed device for spraying materials in a vacuum with the known one shows that the proposed device is characterized in that the sprayed surface of the target has the shape of a collecting reflector, and the substrate holder is mounted so that the processed surface of the substrate is located at the maximum indicatrix of the flow of the sprayed target material, which allows reduce the contamination of the walls of the chamber with sprayed material and, therefore, improve the operational characteristics of the device. Moreover, the proposed device is also characterized in that the sprayed surface of the target can be in the form of a sphere, the center of which is aligned with the processed surface of the substrate, which also reduces the pollution of the walls of the chamber with the sprayed material.

 In addition, the proposed device is characterized in that the sprayed surface of the target can be optically connected with the output aperture of the ion source and with the treated surface of the substrate. In this case, the sprayed surface of the target can be in the form of a parabola, the focus of which is aligned with the treated surface of the substrate or with the output aperture of the ion source, or the shape of an ellipse, one of the foci of which is aligned with the output aperture of the ion source, and the other focus is aligned with the processed surface of the substrate. The indicated differences also make it possible to reduce the pollution of the chamber walls with the sprayed material.

 In addition, the proposed device differs so that the sprayed surface of the target can be made in the form of a recess, for example, in the form of a hole or trough, the bottom of which has the shape of a collecting reflector, which increases the efficiency of the consumption of the target material.

 In addition, the proposed device is characterized in that at least one through-hole can be made in the target, the side surface of which has the shape of a collecting reflector, while the output aperture of the ion source, the sprayed target and the treated surface of the substrate can be aligned, which extends the technological device capabilities.

 In addition, the proposed device is characterized in that the attachment site of the targets and / or ion source can be equipped with movement drives with the possibility of changing sections of the sprayed surface of the target, which increases the service life of the targets.

 Figure 1 shows a General view of the structural scheme of the proposed device for spraying materials in a vacuum; figure 2 options for the design of the device; figure 3 possible shape of the sprayed surface of the targets; in Fig.4 a variant of the design of the device with a ring target.

 The device (Fig. 1) contains a self-contained ion source 2 installed in the vacuum chamber 1 (for example, a duoplasmatron or Kauffman source), a target attachment unit 3, on which one or more targets 4 with sprayed material are located, and a substrate holder 5 with placed on it substrates 6 to be processed. The sprayed surface of the target 7 has the shape of a collecting reflector (concave mirror), the holder of the substrates 5 is installed so that when spraying any part of the target 4 with an ion beam with an output aperture 8, the treated surface of the substrate 9 is in the direction of the maximum 10 of the indicatrix (radiation pattern) of the stream 11 sprayed target material 4. The attachment site of the targets 3, the ion source 2 and the holder of the substrates 5 can be equipped with appropriate drives movements 12, 13, 14.

 The sprayed surface of the target 7 may have a spherical shape (Fig. 2, a), while the center F of this spherical surface is aligned with the treated surface of the substrate 9.

The sprayed surface of the target 7 can be located so that it has an optical connection with both the output aperture 8 of the ion source 2 and the surface of the substrate 9 to be treated (Fig. 2, b, c, d). In this case, the sprayed surface of the target 7 can have, for example, a parabolic shape, while the focus of the parabola F can be combined either with the output aperture 8 of the ion source 2 (Fig. 2, b) or with the surface of the substrate 9 being processed (Fig. 2, c ) The sprayed surface of the target 7 can also be made in the form of an ellipse (Fig. 2, d), while the output aperture 8 of the ion source 2 can be located in one focus (F ₁ ), and the treated surface 9 of the substrate 6, respectively, in the second focus (F ₂ ) ellipse.

 The sprayed surface 7 of the target 4 can be made in the form of a recess (Fig. 3, a), the bottom of which has the shape of a collecting reflector. In this case, the recess can be performed, for example, in the form of a hole (Fig.3, b) or in the form of a groove (Fig.3, c).

 The target 4 can also be made with one (or several) through holes, for example, in the form of a ring (Fig. 3, d), the inner side surface of which has the shape of a collecting reflector. In this case, the output aperture 8 of the ion source 2, the sprayed surface 7 of the target 4, and the machined surface 9 of the substrate 6 can be coaxial (Fig. 4).

 The operation of the device is as follows.

The vacuum chamber 1 (figure 1) is pre-pumped to a high vacuum (10 ^-5 -10 ^-6 mm RT. Art.). After supplying a working gas, for example, Ar, and the corresponding voltages to the electrodes of an ion source inside it (in its discharge chamber), a plasma discharge appears containing the working gas ions. Using an ion-optical system, the formation of an “ion beam” (acceleration, acceleration, focusing) takes place, which, being directed through the output aperture 8 to the surface 7 of the target 4, sprays it. Thus created stream 11 of the sprayed material of the target 4, reaching the surface 9 of the substrate 6 and deposited on it, forms a film of the sprayed material with the necessary structure and other characteristics (thickness, uniformity, density, etc.).

 Due to the fact that the sprayed surface 7 of the target 4 has the shape of a collecting reflector, the flow of sprayed material 11 is substantially non-isotropic, i.e., there is a direction 10 in which the indicatrix (radiation pattern) of the flow of sprayed material 11 has a pronounced maximum.

 It is in this direction of the maximum indicatrix of the flow of sprayed material that the processed substrate is installed, so the bulk of the sprayed material is deposited on the substrate, and the pollution of the walls of the chamber by the sprayed material is reduced.

 To increase the service life of the targets, one or more targets 4 can be located on a common attachment point 3 connected to the displacement drive 12, which provides replacement of the sprayed surface 7 of the target 4 as it “triggers” (changes in shape) to an adjacent section with the original surface shape .

 If there are several targets on the attachment site 3 containing various materials, the change of targets (or sprayed areas) can be performed according to a given program directly during the spraying process. In some cases (for example, when the ion source is in the focus of the collecting reflector), it is more expedient to replace the areas of the sprayed surface with the help of a displacement drive 13 connected to the ion source 2. At the same time, a combined hardware version is also possible, in which, for example, the change of sections the sprayed surface of one target 4 is carried out by moving the ion source 2, and the change of various targets is carried out by moving the attachment node 3.

 Using the movement drive 14, which can be equipped with the holder 5 of the substrates 6, it is possible to provide, if necessary, a more uniform deposition of the sprayed material on the surface of the substrate, or the deposition of films with a certain relief, or processing several substrates in one process, all of which can made automatically according to a given program.

 When choosing a particular embodiment of the device, in particular, the relative position of the ion source, the target being sprayed, and the substrate to be treated, numerous factors should be taken into account that determine both the shape of the ion beam bombarding the target and the spatial distribution of the stream of atomized material. In particular, the shape of the ion beam is determined by the type of ion source, the mode of its operation (potentials on the electrodes of the ion-optical system), the size and shape of the output aperture, and the distance to the sprayed target.

 The shape of the spatial distribution of the sprayed material flow depends on the ion energy, the ratio of the atomic weights of the working gas substance and the target material, the angle of incidence of ions on the target surface, the structure of the sprayed surface of the target (amorphous, polycrystalline, crystalline) and other factors. Among the possible types of spatial distribution of the sprayed material flow, three main types can be distinguished: isotropic (distribution according to the law of cosine), “normal” (with a pronounced maximum on the radiation pattern-indicatrix of the density of the sprayed material flow in the direction normal to the target surface) and “mirror” (with a maximum of the indicatrix in the direction of specular reflection of the beam axis from the target surface). As the analysis shows, during the ion sputtering of most amorphous and polycrystalline materials, in particular metals, the last two types of distribution are “normal” and “mirror”. A "normal" or "cosine" distribution occurs when sputtering with lighter ions with high energies (E> 10 keV) and at small beam angles of incidence (relative to the normal to the surface. With a decrease in ion energy (up to 1 keV or less) and with an increase their masses when ions fall at an angle to the sprayed surface, the direction of preferential emission (maximum indicatrix) shifts from the normal to the surface in the direction corresponding to the mirror reflection of the bombarding ions.

 In the case of a "normal" or close to it angular distribution of the flux density of the sprayed target material, the most appropriate design of the spray device in which the sprayed surface 7 of the target 4 has spheres (Fig. 2, a), in the center of which the triggered surface 9 of the substrate 6 is installed In this case, for any beam shape (parallel or diverging) and regardless of the angle of incidence of the beam on the target surface, the direction of the maximum density (indicatrix) of the sprayed material from any area aspylyaemoy target surface will be the direction to the sphere center, and where the substrate is located, i.e., there will be a "focusing" of the flow of the sprayed material to a given point on the surface of the substrate. This design of the device provides, in addition to reducing the pollution of the chamber walls and increasing the productivity of the ion-beam spraying process, the possibility of carrying out the process of directed spraying (local spraying) of materials, for example, to create a relief or for shaping (or shaping) optical and other high-precision surfaces.

 In the case of an angular distribution of the flux density of the atomized material close to the “mirror” one, the design of the atomization device is more effective in which the main system of elements is the output aperture of the ion source, the sprayed target surface, the processed surface of the substrate is an optically coupled system (Fig. 2, b, c, d). For ion sources with a diverging beam (such as an ultrasonic diffusion detector, duoplasmatron, etc.), it is more expedient to make the sprayed surface of the target in the form of an ellipse or parabola, the focus of which is set to the output aperture of the ion source (more precisely, the conditional point of the beam's "beginning"). In this case, in the case of an elliptical target surface (FIG. 2, d), the substrate is installed in a different focus of the ellipse, and in the case of a parabolic target (FIG. 2, b), the substrate is set so that the straight target-substrate line is parallel to the axis of the parabola.

 For ion sources with a parallel or slightly diverging beam (for example, a Kauffman source), it is advisable to place the substrate in the focus of the parabola of the sprayed surface of the target, and set the ion source so that the axis of the ion beam is parallel to the axis of the parabola (Fig. 2, c).

 For the purpose of more economical consumption of the target material, its sprayed surface can be made in the form of a recess (Fig. 3, a), the bottom of which has the shape of a collecting reflector, and the side walls have a shape that redistributes the material from their surface to the bottom of the recess. In addition, the presence of side walls, i.e. "deepening" of the sprayed surface of the target, further limits the angular distribution of the sprayed material, i.e. further reducing the contamination of the chamber walls with the sprayed material. The deepening can be performed, for example, in the form of a hole (Fig.3, b) or in the form of a gutter (Fig.3, c).

 Further limitation of the non-productive part of the flow of atomized material and the expansion of the technological capabilities of the device can be achieved by making a through hole in the target (for example, a target in the form of a ring) whose inner side surface has the shape of a collecting reflector, which provides preferential sputtering of the target material through the ring opening. In this case (figure 4), the ion source 2, the spray target 4 and the substrate 6 can be installed on the same axis. Since in the latter case the sprayed surface of the target is the inner side surface 7 of the ring, and the treated surface 9 of the substrate 6 may be in the zone of direct action of the ion beam, the sputtering process will have some features. In the case of using a metal target 4 and a dielectric substrate 6, the sputtering process will proceed without any special features if a “pure” ion beam not neutralized by electrons is used. In this case, the treated surface of the dielectric substrate accumulates a positive charge and “reflects” the ion beam. At the same time, neutral atoms of the sputtered metal target can be deposited on the substrate without hindrance.

When sputtering metal targets on a metal substrate or dielectrics on a dielectric substrate (with neutralization of the ion beam), the deposition process will also occur, however, at a slightly lower speed. The possibility of sputtering here is due to the well-known dependence of the sputtering rate on the angle of incidence of ions: the maximum sputtering rate of most materials is observed at large angles of incidence of ions relative to the normal to the surface (at α 50-75 ^о ), and this maximum speed is 2-4 times higher than the sputtering rate at normal fall. In our case, therefore, the sputtering speed of the target, and hence the speed of sputtering on the substrate, will be higher than the speed of sputtering of this material from the substrate due to direct bombardment by beam ions (with normal incidence). By selecting the appropriate conditions (the shape of the sprayed surface, the shape of the aperture of the beam, the distance of the target substrate, etc.), you can control the speed of the spraying process.

 Thus, the proposed device improves performance by reducing the pollution of the sprayed material on the walls of the chamber.

 In addition, the proposed device improves the efficiency of the consumption of material of the target by reducing the unproductive part of the flow of sprayed material.

 In addition, the proposed device has wider technological capabilities due to the large selection of design options for the execution of the spray targets and the relative position of the elements of the system; ion source sprayed target substrate in the framework of the proposed technical solution of the device for spraying materials in vacuum.

Claims (12)

 1. DEVICE FOR SPRAYING MATERIALS IN VACUUM, including an ion source installed in a vacuum chamber, a target attachment site, carrying at least one target with the sprayed material and a substrate holder, characterized in that the sprayed target surface has the shape of a collecting reflector, and the substrate holder is installed relative to the target and source so as to ensure focusing of the maximum indicatrix of the flow of the sprayed target material on the treated surface of the substrate.  2. The device according to claim 1, characterized in that the sprayed surface of the target is optically coupled to the output aperture of the ion source and the surface of the substrate to be treated.  3. The device according to p. 2, characterized in that the sprayed surface of the target has the shape of a sphere, the center of which is aligned with the processed surface of the substrate.  4. The device according to p. 2, characterized in that the sprayed surface of the target has the shape of a paraboloid, the focus of which is aligned with the processed surface of the substrate.  5. The device according to p. 2, characterized in that the sprayed surface of the target has the shape of a paraboloid, the focus of which is aligned with the output aperture of the ion source.  6. The device according to p. 2, characterized in that the sprayed surface of the target has the shape of an ellipsoid, one focus of which is aligned with the output aperture of the ion source, and the other focus is aligned with the processed surface of the substrate.  7. The device according to paragraphs. 1-6, characterized in that a depression is made in the target, the bottom and walls of which form the sprayed surface of the target, the bottom of the depression having the shape of a collecting reflector, and the shape of the walls providing redistribution of the sprayed target material to the bottom of the depression.  8. The device according to p. 7, characterized in that the recess is made in the form of a hole.  9. The device according to p. 7, characterized in that the recess is made in the form of a gutter.  10. The device according to paragraphs. 1-3, characterized in that the target has at least one through hole, the side surface of which has the shape of a collecting reflector.  11. The device according to p. 10, characterized in that the output aperture of the ion source, the sprayed surface of the target and the processed surface of the substrate are aligned.  12. The device according to p. 1-11, characterized in that, in order to increase the life of the target, the attachment site of the target and / or ion source are equipped with displacement drives with the possibility of changing sections of the sprayed surface of the target.

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