MXPA00009560A - Method and apparatus for deposition of biaxially textured coatings - Google Patents

Abstract

A deposition method and apparatus is described for manufacture of biaxially textured coatings where the biaxial texturing is induced by bombardment during deposition by energetic particles under a specifically controlled angle. The method for deposition of biaxially textured coatings onto a substrate (6) utilizes one or more magnetron sputtering devices (1) generating both a flux of material to be deposited and a flux (5) of energetic particles with a controllable direction and thereby controllable angle of incidence on the substrate (6). The magnetron sputter source (1) generates a beam (5) of energeticparticles together with material to be deposited, said source being adapted so that said beam (5) is directed towards a substrate (6) under an angle controlled in such a way that a biaxially textured coating is deposited on the substrate (6).

Description

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METHOD AND APPARATUS FOR DEPOSITION OF BIAXALLY TEXTURED COATINGS BACKGROUND This invention relates to deposition methods of biaxially textured coatings, wherein biaxial texturing is induced by bombardment during deposition by energetic particles under a specifically controlled angle. The biaxially textured coating is a coating in which two crystallographic directions are parallel in adjacent grains. It is a known fact that the flow of directed energetic particles, during deposition, at an angle of less than 90 ° with respect to the substrate surface, can induce a biaxial texturing in a coating. It is also known that, depending on the crystal structure of the material to be deposited, there will be an optimum angle of incidence for the energetic particles which will result in the highest degree of biaxial texturing, and L.S. Yu, J.M. Harper, J.J. Cuomo and D.A. Smith, J. Vac. Sci. Technol. A 4 (3), p. 443, 1986, R.P. Reade, P. Berdahl, R.E. Russo, S.M. Garrison, Appl. Phys. Lett. 61 (18), p. 2231, 1992, N. Sonnenberg, A.S. Longo, N.J. Cima, B.P. Chang, K.G. Ressler, P.C. Mclntyre, Y.P. Liu, J. Appl.

Phys. 74 (2), p. 1027, 1993, Y. Iijima, K. Onabe, N. Futaki, N. Tanabe, N. Sadakate, O. Kohno, Y. Ikeno, J. Appl. Phys. 74 (3), p. 1905, 1993, X.D. Wu, S.R. Foltyn, P.N. Arendt, D.E. Peterson, High Temperature Superconducting Tape Commercialization Conference, Albuquerque, New Mexico, Juy 5-7, 1995. Various deposition methods have been described for the preparation of biaxially textured coatings. An important drawback of these deposition methods is the fact that the supply of material to be deposited and the flow of energetic particles are generated by sources • different. This requires that both sources be in the same vacuum chamber. This can result in incompatibility between sources that require certain commitments in the operating intervals to obtain compatible work. Generally, an ion source is used to generate a flow of energetic ions directed under a controlled angle to the substrate and the coating that grows therein. A different deposition apparatus has been used (for example electronic deposition by ion beam, deposition by pulsed laser, deposition of a beam e, of electronic deposition by magnetron, see the references above), to generate the material to be deposited . This requires two different sources for the generation of the material to be deposited and the flow of generic particles, which makes the deposition method more difficult to follow, more difficult to control, less suitable for large-scale and more expensive applications . Effective ways to deposit material with bombardment of energetic particles (e.g. by ions) during deposition using plasma-assisted deposition methods have been described. These methods of plasma-assisted deposition or ion-assisted deposition are widely used to increase the density of the coatings, increase the hardness of the coatings, control the tensions in the coatings, alter the optical properties in the coatings, etc. The use of the magnetron electronic deposition apparatus for these purposes has also been described. It has also been described that the efficiency of the electronic magnetron deposition source can be greatly altered by changing the field configuration of the magnet. W.D. Sproul, for example, has described a method for increasing the density of energetic particles in the substrate by changing the field configuration of the magnet in Material Sciences and Engineering, vol. A136, page 187, (1993). Savvides and Katsaros go. Applied Physics letters, vol. 62, page 528 (1993) and S. Gnanaraj an et. alia in Applied Physics Letters, vol. 70, page 2816, (1997) describes a way to decrease the bombardment of energetic particles in the substrate and to grow the coating. However, in all these methods, a control between the direction of the energetic particles and the angle of incidence in the substrate is not described and, therefore, they are not suitable for biaxial texturing. The use of an unbalanced magnetron for ion-assisted deposition has been described for different applications, see B. Window, J, Vac. Sci. Tachnol, A 7 (5), page 3036, 1989, and B. Window, G.L. Harding, J. Vac. Sci. Technol. A 8 (3), page 1277, 1990. Therefore, there is a need for a deposition method and apparatus for biaxially texturing coatings, which involves simple equipment. Such an apparatus method will ideally be easy to master and control and will be very suitable for large-scale application. Prior to the present invention, there is no such method or apparatus for biaxial texturing using a single source for the material to be deposited and the flow of the energetic particles. Accordingly, it is the object of this invention to provide a method for depositing biaxially textured coatings which is easier to carry out and to control, as well as an apparatus for carrying out the method.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a method for deposition of biaxially textured coatings on a substrate using one or more magnetron electronic deposition devices as a source both of particles to be deposited and of a directed flow of energetic particles that induce biaxial texturing. The present invention also includes the use of an unbalanced magnetron that includes an electronic deposition gas and an objective to electronically deposit target material on a substrate, to generate an ion beam by ambipolar diffusion, the ion beam consists essentially of ions of electronic deposition gas. The present invention also provides a method for deposition of texturized coatings biaxially on a substrate using one or more electronic magnetron deposition devices generating both a flow of material to be deposited and a flow of energetic particles with a controllable direction and so both a controllable angle of incidence on the substrate. The present invention also includes a source of electronic magnetron deposition that generates a bundle of energetic particles together with material to be deposited, directed towards a substrate at a controlled angle such that the biaxially textured coating is deposited on the substrate. By using a single source for the ion beam used to texture the coating on the substrate and also to deposit the particles on the substrate to form a coating, problems of incompatibility between the different sources in a vacuum chamber for these two are eliminated you do different The dependent claims further define independent embodiments of the present invention. The present invention will be described below with reference to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a source of electronic flat magnetron deposition, according to one embodiment of the present invention. Fig. 2 is a schematic representation of an electronic deposition source of rotating cathode magnetron, according to one embodiment of the present invention. Figures 3a and b are schematic representations of the field lines of the magnet of a source of flat electronic deposition and rotating magnetron, according to the present invention. Figures 4a-d are schematic representations of electrostatic deflection covers which can be used with any of the embodiments of the present invention. Figures 5 and 6 are schematic representations of flat multiple and rotating cathode electronic deposition sources, according to one embodiment of the present invention. Figure 7 is a schematic representation of a source of electronic flat magnetron deposition, according to another embodiment of the present invention.

DESCRIPTION OF THE ILLUSTRATIVE MODALITIES The present invention will be described with reference to certain specific embodiments and certain drawings, but in the present invention is not limited to them but only by the claims. The method for the deposition of biaxially textured coatings according to the present invention, which will be explained in detail in the following, can be used for coating of stationary substrates, rotating substrates, batches of substrates and in continuous coating process. The electronic magnetron deposition device or devices used can be any suitable electronic deposition magnetron, for example magnetrons with flat circular lenses or flat rectangular lenses, or rotating devices. The general aspects of substrate assembly or movement of the substrate, or both, or of the electronic deposition devices and other components necessary to construct and operate a deposition system, such as a vacuum chamber, an apparatus for assembly and lens cooling, an apparatus for electrically connecting the target cathode to the power supply, the covers connected to ground to prevent unwanted electronic deposition of certain parts of the electronic deposition device and to prevent arcing, etc., are well known by people who have skill in the technique. Therefore, these components are not described in detail here. Those skilled in the art will also recognize the need to clean the substrate prior to deposition, for example by electronic deposition cleaning, exposure to a luminescent discharge, exposure to resonance cyclotron electron plasma or plasma generated in some other way, Vacuum heating, etcetera. As shown schematically in Figure 1 for a flat electronic deposition magnetron 1, a target material 3 is located in a vacuum chamber (not shown) with a magnet assembly 2 on one side thereof, and a substrate 6 which is to be covered by electronic deposition, which is located on the other side of it. The atmosphere of the vacuum chamber may include electron deposition gases such as argon, and may also include reactive gases such as oxygen and nitrogen when the reactive electronic deposition is to be carried out. The substrate 6 can be a stationary plate or it can be a moving strip of material. The target material 3 can be cooled, for example, by a water circuit (not shown), which is not accessible from the vacuum chamber. The negative pole of an electrical supply (not shown) is connected to the target 3. The combination of the electric and magnetic cross-fields above the target 3 generates a plasma 4 above the target 3. The plasma 4 is generally in areas of a field of high magnet generated by poles 8, 9 of magnet assembly 2. As shown, the magnet assembly 2 may include a central magnet array 9 which has a pole directed toward target 3 (either north or south) and outer magnet arrays 8 which have the other pole (south or north) directed towards objective 3. If objective 3 is circular, arrangements 8 and 9 of magnet can also be circular. The poles 8, 9 can be located in a retainer 7 of soft magnetic material, for example soft iron.

Figure 2 is a schematic representation of a rotating cathode electronic deposition magnetron 1, according to the present invention. A generally cylindrical objective 3 is provided in a vacuum chamber (not shown) with gas or electron deposition gases, as previously described. A magnet assembly 2 is provided within the objective 3 and a means for generating relative movement between the objective 3 and a magnet assembly 2 is also provided. Usually, the objective 3 is rotated and the assembly 2 of the magnet remains fixed. An electrical supply (not shown) keeps target 3 with a negative potential.

The poles 8, 9 of the magnet assembly 2 are located close to the inner surface of the objective 3 and generate magnet fields above the target 3. These magnet fields with the crossed electric field generate a plasma 4 usually in the form of a " race track "above the surface of the target 3. Opposite the target 3 and in the vacuum chamber, the substrate 6 is located. The substrate 6 may be a stationary plate or a moving strip of material. In order to obtain the object of the invention, described above, the electronic magnetron deposition device 1 and the substrate 6 can be configured as shown schematically in figures 1 or 2, with a flow 5 of energetic particles, which come from of the electronic deposition device 1 of the magnetron, directed towards the substrate 6 at a specific angle α that will provide the maximum degree of biaxial texturing. At an angle depends on the material to be deposited. For a cubic material in the coating, for example, a will be approximately equal to 54.74 °. The flow of the energetic particles is generated substantially uniquely by the electronic deposition device 1, which not only provides this flow, but also electronically deposits the coating on the substrate 6, which is to be texturized. The flow 5 can be substantially free of any ion of the target material. The flow 5 may consist substantially of ionized gas atoms or molecules, for example of the electron deposition gas. The directed flux 5 of the energetic particles from an electronic magnetron deposition device is obtained according to the present invention by using an unbalanced magnet configuration 2 which causes the secondary electrons emitted in the target 3 and the electrons generated in the plasma 4 moves along field lines of the magnet to the substrate 6, which results, through ambipolar diffusion, in a directed flux of energy ions towards the substrate 6. In a balanced magnetron, most of the field lines leave a pole of the magnet assembly and are collected at the opposite pole of the magnet assembly. In an unbalanced magnetron, some of the field lines of the pole magnet are not collected at the other pole. The imbalance can be obtained in various ways, for example by using magnets of different strengths, by using magnets of different sizes, by weakening part of the magnet assembly by placing magnets of opposite polarity close to the mounting poles, by placing an electromagnet that generates competition near one of the poles As schematically shown in Figures 3a or b, the magnet assembly 2 of the electronic magnet deposition device 1, either flat (Figure 3a) or rotating cathode (FIG. Figure 3b), in accordance with the present invention, is configured such that a substantial number of field lines 11 of the magnet arising from the outer magnet array 8 in the magnet assembly 2 pass through the surface of the substrate. Obtained by external magnets 8 considerably stronger compared to magnets 9. The result of imbalance of magnetron 1 in this way is to produce a three-dimensional volume 12 which is defined by the field lines 11 of the external magnets 8 that are not collected in the internal magnets 9. Some electrons in the plasma 4 flow following the field lines 11 so they also "drag" with them a flow of positive high-energy ions, typically ions of the surrounding gases. Such a flow can be called ambipolar flow. The flow 5 is directed towards the substrate 6 in and around the volume 12, and may texturize the coating which is placed by electronic deposition on the substrate 6 by a normal electronic deposition action. Therefore, according to the present invention, the flow 5 has a definable direction. In accordance with any embodiment of the present invention, the energy of the electrons following the field lines 11 to the substrate is preferably not such as to cause significant ionization. In particular, it is preferred if the electrons of the flow 5 do not initiate or sustain an important plasma at or near the surface of the substrate 6. By a significant plasma it is meant a plasma which can alter the directionality of the high ions. energy in flow 5 and which induces surface texturing of the coating. It is this directionality and its relation to the crystalline structure of the deposited coating that allows the texturing of this coating. Therefore, the ion beam 5 generated according to the present invention must impinge on the substrate 6 at a defined angle. It is anticipated that the electron energy in the flow 5 should preferably be greater than 30 eV, more preferably greater than 50 eV and more preferably between 50 and 70 eV. If an alteration plasma develops on the surface of the substrate, its effects can be reduced by changing the degree of imbalance of the magnetron 1 so that the energy of the particles is reduced, particularly the electrons in the flow 5. As shown schematically in Figures 4a-d, the directed flow 5 of energetic particles from an unbalanced magnetron electronic deposition device 1 can be improved by using electrostatic deflection covers 13 which increase the number of electrons reaching the substrate 6 as it moves along lines 11 of the magnet field. The deflection covers 13 are preferably kept at a negative potential in order to repel the electrons. Deflection covers 13 should preferably not extend too deeply into region 12 or otherwise start to trap positive ions in flow 5. Some examples of such deflection cover configurations are shown schematically in Figure 4 in cross section for a clear magnetic configuration. For example, 13 straight covers can be used in Figure 4a which are oriented perpendicular to the target 3. If the target 3 is a circular target, the covers 13 can be in the form of a cylinder. In figures 4b and c the covers 13 have a "V" shaped cross section or are inclined inward towards the substrate, respectively. Such covers 13 can assist in channeling any electron with a broad path to the substrate 6. Alternatively, the covers can be tilted outwardly, as schematically shown in Figure 4d and therefore concentrate the flow of electrons near the target 3. The deflection covers 13 mounted in Fig. 4a ad can also be used with rotating magnetron devices. Any lack of homogeneity of the coating deposition on the substrate 6 in the configurations shown schematically in Figure 1 and Figure 2, can be resolved using multiple unbalanced magnetron electronic deposition devices 1 within the same vacuum chamber . The flow 5 of energetic particles of each of these devices is preferably directed such that it reaches the substrate 6 at the same angle to the substrate 6 in order to avoid the competition texturing process. One embodiment of the present invention with two unbalanced magnetron devices is shown schematically in Figure 5 for a flat magnetron., and in figure 6 for a rotating cathode magnetron. In this configuration, the normal to the surface of the substrate and the two normal to the targets 3 in the magnetron electronic deposition devices 1 are in the same plane. When more than two unbalanced magnetron devices are used, the configuration will be determined by the crystalline structure of the growing coating material on the substrate 6 and the desired biaxially textured structure. With four devices, for example for a cubic material, where the biaxial texturing with the axis (100) perpendicular to the normal substrate and another crystallographic axis (for example (lll) or (110)), parallel in adjacent grains, can be added two magnetron devices unbalanced to the previous configuration of figure 5 or 6, with the plane formed by the normals to the surfaces of the objective 3 and the substrate 6 that are perpendicular to the corresponding plane of the two original devices. For material with a cubic crystallographic structure, for example, it is shown that the optimum angle of incidence with respect to the normal substrate surface for energetic particles is equal to the inverse tangent of the square root of 2, which is approximately equal to 54.74 °, in order to obtain biaxial texturing with the crystallographic plane (100) of all the grains in the coating perpendicular to the substrate surface and another crystallographic direction (for example (111)) parallel in adjacent grains in the coating. In Figure 7 a further embodiment of the present invention is shown schematically, in which an additional magnet 10 is placed behind the substrate 6 in order to alter the flow of energetic particles directed towards the substrate 6. Using the configuration that is shown in Fig. 7, the field lines emanating in the outer magnet array 8 behind the target -3 will reach the magnet 10 behind the substrate 6 and the field of the magnet will focus more. This will result in a plasma flow approach and better control of the plasma flow direction. The addition of the magnet 10 behind the substrate 6 in this configuration will result in an increase in the field of the magnet in the substrate 6. This increase in the field of the magnet will result in an increased rotational speed of the electrons and, due to the conservation of energy, in a decreased speed parallel to the field lines. This can also result in a decrease in the number of energetic ions that are dragged along, by ambipolar diffusion. You can also reduce the energy of these ions. Depending on the amount of energetic particles needed and the energy needed to obtain the biaxial texturing of a specific coating, such additional magnet 10 behind the substrate 6 can be used for a fine adjustment of the biaxial texturing according to the present invention. The magnet 10 can be a controllable electromagnet. Experiments have been performed with the flow of energetic particles from an unbalanced magnetron electronic deposition device, according to the present invention. During the experiments, an electronic deposition source similar to that shown in Fig. 1 is used. The arrangement of the magnet is configured in such a way that the magnetic flux of the outer magnet 8 is much larger than the magnetic flux of the inner magnet 9. In this way, the unbalanced magnetron is strongly obtained with field lines of the magnet emanating from the outer magnet 8 that passes through the substrate 6. As described below, this configuration of the magnet field generates a flow of energetic particles towards the substrate 6. Three different magnet arrays are examined: one with a ratio of magnetic flux exterior to the inner magnetic flux of 9/1, one with a ratio of 4/1 and one with a ratio of 2/1. The electrons generated in objective 3 and in plasma 4 rotate around the field lines and are directed along these field lines towards the substrate 6. By ambipolar diffusion, the ions are dragged along and the ion flow is directed and neutral particles are generated (which result from ion neutralization). From measurements with a Faraday cup in an electron cyclotron resonance plasma, which is also based on ambipolar diffusion, it is known that, depending on the gradient of the magnetic fields and the total gas pressure, these ions (and particles) neutral) can obtain energy from 10 eV to 70 eV. Similar observations can be made to the visuals with ECR plasma, a flow of luminous plasma with the unbalanced magnetron. The shape of this plasma flow corresponds clearly to the line pattern of the magnet field and for the three different magnet arrays three different shapes are observed.

With a highly unbalanced magnetron (ratio 9/1), a flow directed to energetic particles is obtained and the electrons that move towards the fields are more than just ionizing the gas atoms. The influence of the total gas pressure on the lateral distribution of the deposition rate of the metal layers of Zr + Y with different compositions is examined. During these experiments, the RF electronic deposition is performed with an input power of 100 watts, and a target distance of 50 mm, an Ar pressure between 0.2 Pa and 0.7 Pa, and without substrate heating or with substrate cooling. For these experiments, glass substrates are used. In the configuration with a ratio of 2/1 for the magnetic flux, the deposition rate is somewhat reduced (-10%) by reducing the total gas pressure to 0.7 Pa to 0.2 Pa. The lateral distribution does not change as a function of gas pressure. In the case of the configuration with a magnetic flux ratio of 9/1, however, the deposition rate is much reduced by reducing the pressure at the center of the substrate (-35%) than at the edges of the substrate (- fifteen%) . This indicates that electronic redeposition occurs in the center from the growing film. The area with the strongest electronic redeposition corresponds to the area where the directed plasma flow reaches the substrate 6. These experiments show that the energy of the particles in the plasma flow is high enough (probably> 50 eV) to provoke electronic redeposition. Due to the directionality of the flow of energetic particles, the incidence of energetic particles in a growing film at a controlled angle can be examined. These experiments are carried out with both DC and RF electronic deposition with an input power of 50 and 25 watts. The target-substrate distance varies between 6.5 cm and 13.5 cm. A gas mixture of approximately 150 sccm Ar and 10 sccm 02 is used at a total gas pressure of approximately 0.4 Pa. The oxide layers of hydrostabilized with zirconia are deposited by electronic deposition from a metal target Zr + Y with different compositions (from Zr / Y = 85/15 to Zr / Y = 55/45) in a reactive process. Most layers are deposited at a 55 ° angle between the plasma flow and the normal substrate. From the measurements of figure 1 of X-ray diffraction, biaxial texturing is produced on both metallic substrates (NiFe, Ti, Fecralloy) and on glass substrate. With a magnetic flux ratio of 9/1, a full width is obtained at semi-maximal values of -11 ° for the angle psi (characteristic for an off-plane orientation) and -22 ° for the angle phi (characteristic for the orientation in the plane), on glass substrates. With the 9/1 ratio and the metal substrates, less biaxial texturing is observed. (, F_WHM psi ~ 25 ° / FWHM phi -30 ° =, which can be caused by the higher roughness of the surface compared to glass.) At a magnetic flux ratio of 4/1, the biaxial texturing is reduced by Some measure, but it is still clearly present A decrease in the distance of the target substrate results in an iased bombardment of energetic particles.Using electronic RF deposition instead of electronic DC deposition, it also results in an iase in particle bombardment. At small target-substrate distances and with a higher power RF electronic deposition, such severe bombardment of particles can be obtained so that the deposited layer is completely attacked by electron deposition, resulting in a negative deposition rate These experiments show that biaxial texturing is produced by directing the flow of energetic particles generated by bipolar diffusion in a source of electronic deposition strongly unbalanced on a controlled angle towards the substrate. By tuning the different parameters involved, it is possible to optimize the process and obtain a high degree of biaxial texturing with a reasonably high deposition speed as well as a scalable process.

Claims (16)

CLAIMS-

1. A method for the deposition of texturized coatings biaxially on a substrate using an electronic magnetron deposition device as a source of both particles to be deposited and directed flow of energetic particles directed against the substrate that induce biaxial texturing, where The magnetron electronic deposition device includes a target and further comprises the step of unbalancing the magnetron so that the magnetic flux generated in an outer portion of the target differs from the magnetic flux generated in an inner portion of the target, thereby generating the flow of energetic particles by ambipolar diffusion.

2. The method as described in claim 1, further comprising the step of: controlling the direction and therefore controlling the angle of incidence on the substrate of the directed flow of energetic particles.

3. The method as described in claim 1 or 2, wherein the directed flow of energetic particles is substantially free of ions from the target material.

4. The method as described in any of claims 1 to 3, wherein the magnetron includes an electron deposition gas and a directed flow of energetic particles consisting essentially of ion of the electron deposition gas.

5. The method as described in any of claims 1 to 3, wherein the flow of energetic particles includes electrons, the electrons are directed towards the substrate following force lines of the unbalanced magnetron magnet field.

6. The method as described in any of the previous claims, further comprising the step of generating a plasma discharge above the target.

7. The method as described in claim 6, wherein the plasma discharge is generated by magnetic and electric cross fields.

8. The method as described in any of the previous claims, further comprising the step of controlling the energy of the flow of energetic particles so that it is not sufficient to cause substantial ionization in the front part of the substrate which may alter the direction of the beam of energetic particles.

9. A source of electronic magnetron deposition that generates a beam of energetic particles together with material to be deposited, the source is adapted so that the beam is directed towards a substrate at a controlled angle such that the biaxially textured coating is deposited on the substrate, the source further comprises a target and a magnet assembly that includes a magnet array located towards an inner portion of the target and which generates a magnet field of a magnet pole and an additional magnet array located towards a external portion of the objective and that generates a field of the magnet of the other pole, the magnet assembly is adapted so that the lines of the magnet field generated by the outer magnet arrangement cut to the substrate and an ambipolar flow of energetic particles against the substrate.

10. The magnetron electronic deposition source, as described in claim 9, further comprising at least one electrostatic cover located around the energetic particle beam.

11. The magnetron electronic deposition source, as described in claim 9 or 10, wherein the source is a flat or rotating cathode magnetron.

12. The electronic magnetron deposition source, as described in any of claims 9 to 11, further comprising an electron deposition gas and the directed flow of energetic particles consists essentially of electron deposition gas ions.

13. The magnetron electronic deposition source, as described in any of claims 9 to 11, wherein the ambipolar flow includes electrons and the electron energy is not sufficient to cause substantial ionization at the front of the substrate which may alter the beam direction of energetic particles.

14. The source of electronic magnetron deposition, as described in any of claims 9 to 13, wherein the directed flow of energetic particles is substantially free of ions from the target material.

15. The magnetron electronic deposition source, as described in any of claims 9 to 14, further comprising a plasma discharge above the target.

16. The electronic magnetron deposition source, as described in claim 15, further comprising magnetic and electric cross fields to generate the plasma discharge.