Films made from alloys and compounds including several components sometimes will have desirable properties. These properties may lead to improved mechanical and/or chemical durability of a deposited layer stack. Unfortunately, in some cases, manufacturing single sputtering targets that can be used in large-scale manufacturing to produce films of the appropriate composition may be technically challenging, and even cost-prohibitive.
Co-sputtering is a known method that can bypass these issues by sputtering from two targets simultaneously during film deposition. However, in certain instances, the conventional methods can produce a significantly graded layer with a strongly varying composition from the bottom to the top of the layer, rather than a true or substantial mixture of the two materials. To improve that, a larger target-to-substrate distance would be required. However, this would require a specially designed deposition chamber and may lead to a more porous film due to the larger target-to-substrate distance.
Therefore, it will be seen that there is a need in the art for an improved method and/or apparatus for sputtering alloys and/or compounds that will result in a true mixture of materials.
In certain example embodiments of this invention, there is provided a method of making a coated article comprising a film supported by a substrate, the method comprising: having first and second rotating cylindrical sputtering targets, the first sputtering target comprising a first sputtering material and the second sputtering target comprising a second sputtering material, and sputtering the first and second sputtering targets, and wherein at least one magnet bar of the second sputtering target is oriented so that during the sputtering of the second target second sputtering material from the second target is sputtered onto the first target, and during the sputtering of the first target the first sputtering material of the first target and second sputtering material which was sputtered onto the first target from the second target is sputter-deposited onto a substrate to form the film. The substrate may be a glass substrate in certain example embodiments.
The sputter-deposited film may be substantially transparent, may be dielectric or conductive, and may be part of a low-E coating for a window, or may be a transparent conductive oxide (TCO) film in certain example instances.
In certain example embodiments, there is provided a sputtering apparatus for sputter-depositing a film on a substrate, the apparatus comprising: first and second adjacent sputtering targets with no other sputtering targets between the first and second sputtering targets, wherein at least one magnet of the second sputtering target is oriented so that during sputtering of the second target second sputtering material from the second target is sputtered toward the first target, and during sputtering of the first target first sputtering material of the first target and second sputtering material which was sputtered onto the first target from the second target is sputtered toward the substrate to form the film; and wherein a plasma erosion zone of the first target is oriented so as to generally face a first direction which is substantially normal to the substrate, and a plasma erosion zone of the second target is oriented to generally face a second direction that is substantially toward the first target and is angled from about 70-170 degrees from the first direction.
The use of sputtering in order to deposit coatings on substrates is known in the art. For example, and without limitation, see U.S. Pat. Nos. 5,403,458; 5,317,006; 5,527,439; 5,591,314; 5,262,032; and 5,284,564, the entire contents of each of which are all hereby incorporated herein by reference. Briefly, sputter coating is an electric-discharge-type process which is conducted in a vacuum chamber in the presence of at least one gas (e.g., argon and/oxygen gas). Typically, a sputtering apparatus includes a vacuum chamber, a power source, an anode, and one or more cathode targets (see 1 and 2 in the figures) which include material used to create a coating on an adjacent substrate (e.g., glass substrate or substrate of other material). The sputtering target (1, 2) may include an outer rotatable tube enclosing a magnet bar assembly (5, 6) including and an associated inner magnet bar support tube (3, 4). More specifically, in certain known arrangements, the one or more magnet bar(s) of the magnet bar assembly (5, 6) are secured to the underside of the support tube along substantially the entire length of the support tube. In certain example instances, the magnet bar may also include the support tube. While magnet “bars” 5, 6 are used in many embodiments of this invention, this invention is not so limited and other types of magnets (other than “bars”) may instead be used in the magnet assemblies 5, 6 of the targets.
When an electrical potential is applied to the cathode target (1, 2), the gas forms a plasma that bombards the sputtering target, thereby causing particles of the sputtering material from the target to leave the exterior surface of the target. These particles fall onto the substrate (e.g., glass substrate) to form a coating thereon. The outer target tube typically rotates about the stationary magnets which are supported by the inner support tube so that particles are “sputtered” substantially uniformly from the substantially the entire periphery of the target tube as it rotates past the fixed magnet bar(s).
Co-sputtering of materials is an alternative to complex alloying of metallic materials in a single sputtering target. Dual C-MAG rotatable cylindrical magnetron sputtering targets can accomplish the co-sputtering of materials, e.g., by using two sputtering targets placed in relative proximity to one another in the apparatus (e.g., within a common chamber of the sputtering apparatus). The two target tubes may rotate through the plasma, which is substantially confined by the stationary magnet assemblies located inside of the target tubes. Two independently operated power supplies may be used in connection with a dual C-MAG apparatus for co-sputtering. The required ratio of materials may be adjusted by applying different power levels to the cathodes, and by applying appropriate shielding.
Conventional co-sputtering using adjacent sputtering targets aligned in the same manner to sputter downward onto the substrate may result in a significantly graded layer with a strongly varying composition from the bottom to the top of the layer, rather than a true or substantial mixture. It has surprisingly been found that existing dual C-MAG cathodes and cathode arrangements can be modified to produce a much-improved sputter-deposited layer(s) that comprises a better and/or more uniform mixture of the different components.
By modifying the position of at least one of the magnet bars (e.g., 6) in at least one of the two rotatable sputtering targets, a film 40 comprising material(s) from both targets (1 and 2) that is a more uniform mixture of composition can be formed. More particularly, in certain example embodiments of this invention, at least two rotatable sputtering targets (1, 2) are provided in a dual C-MAG apparatus. The magnet bar(s) 6 in the second target 2 may be moved from its conventional position to an angled position (e.g., directed toward the first target; e.g., see
In certain example embodiments of the invention, a first target 1 that comprises target materials 7, 8 from a first and second target will sputter a substantially uniformly mixed film 40 onto a substrate 30. This is surprisingly advantageous because it may reduce the need for an expensive pre-mixed target, and the current dual C-MAG target set up may be modified (in certain example embodiments by moving the position of one of the magnet bar(s)) without any significant need to significantly change many other conditions or aspects of the targets. Moreover, the film formed from co-sputtering in this manner will have a substantially uniform composition in certain example embodiments, because the target materials will form a film comprising a more evenly distributed mixture of the target materials from both targets.
Another example advantage is that the ratio of target materials in the film's composition can be altered simply by changing the position of one or more of the magnet bars in certain example embodiments. In changing the position of at least one of the magnet bars in a target, its plasma erosion zone can be moved, and for example the second target can be directed to sputter either directly or indirectly toward and/or onto the first target. In certain example embodiments at least second and third sputtering targets may have their magnet bar(s) positions modified so as to sputter material therefrom onto the first target.
In certain example embodiments, which may be combined with any other embodiments herein, different magnetic field strengths may be applied to each of the targets respectively. For example and without limitation, using a stronger magnetic field on the second (modified) target 2 may restrict the plasma erosion zone 10 of the second target 2 to a narrower region, thus avoiding excessive material losses on the sputtering chamber's walls or onto the substrate directly. This arrangement may also, in certain example embodiments, allow a shorter distance between the two targets 1 and 2. Such embodiments may reduce the amount of material 8 from the second target 2 that is sputtered directly onto the substrate 30, and therefore may increase the amount of material from the second target 2 that is sputtered onto the first target 1 before being sputtered from the first target onto the substrate 30 either directly or indirectly.
In certain example embodiments, it has surprisingly been found that through rotation or movement of at least one of the magnet bars (e.g., 6) of at least one of the targets, a target can be altered to deposit a substantial portion (e.g., at least about 20%, more preferably at least about 30%, even more preferably at least about 40%, even more preferably at least about 50%, and most preferably at least about 60%) of its target material at and/or onto the first target—rather than directly onto the substrate. Then the first target with materials from both targets on it, can sputter deposit the materials onto the glass substrate to form a film, coating, or layer with a substantially uniform composition. The above descriptions of example embodiments of in this invention apply to both the
Thus,
In certain example embodiments, e.g., when the desired ratio of material 7 to material 8 in the final film 40 is desired to be high, the position of magnet bar(s) 6 of target 2 may form a substantially obtuse angle with the position of magnet bar(s) 5 of target 1. In certain example embodiments, magnet bar 5 may be facing substantially toward the substrate 30, while magnet bar(s) 6 is facing substantially toward target 1 as shown in
Referring to
The arrangement is particularly advantageous because it can be obtained simply by rotating the magnetic arrangement (the magnetic bar assembly 6) of target 2, which substantially confines the plasma erosion zone 10 to a position which ejects the material generally toward the first target 1. The magnet bar assembly 6 of the modified target may be rotated anywhere from just above 0 to about 180 degrees, depending on the ratio of target materials desired in the film. In the
Therefore, in
In certain example embodiments, the flux 11 (which will include target materials 7 and 8 falling toward the substrate 30) will have substantially the same ratio of material 7 to material 8 as in the sputter-deposited film 40.
In certain example embodiments such as that in
It has been discovered that positioning the magnet bars 5 and 6 on existing cathodes as discussed herein and as shown in
In certain example embodiments, referring to
The methods described herein may be applied to alloys where the two target materials are conductive metals or semiconductors, as well as to situations where one or both of the targets are already made of alloys, to form ternary compounds, or compounds containing more than two elements.
For example and without limitation, to form a nickel chromium titanium alloy as a film 40 (which may or may not be oxided), a nickel chromium alloy target material 8 may be used on tube 3 for the first rotating target, and titanium target material 8 may be used on tube 4 for the second rotating target. Another example could include silver doped with small amounts of titanium, nickel, and/or zirconium to improve durability and stability. These materials are provided for purposes of example only, and are in no way considered to be limiting. The target material(s) 7, 8 may be metal or metal oxides in different example embodiments of this invention.
The arrangements described in
It has been found that moving the plasma, and thus, the reaction zone of target 2 away from the reaction zone of target 1 as described in certain example embodiments of this invention (see
Another example embodiment of this invention involves feeding the reactive gas (e.g., oxygen and/or nitrogen) primarily through the top inlet(s) 21 and/or 22. This leads to a ceramic layer of material 8 being deposited on the surface/outer tube 13 of target 1. Thus, the discharge from target 1 toward the substrate 30 would be very similar to a target that was originally made with ceramic material. In certain example embodiments, this method could be used to deposit conductive oxide films (e.g., ITO or Al-doped ZnO) 40, or alternatively dielectric films 40.
In certain example embodiments, both target materials 7, 8 may be made from a metallic alloy. For example and without limitation, the metallic alloy may comprise indium tin or zinc aluminum. Sputtering target 2, with enough reactive gas from the top gas inlet(s) 21 and/or 22 toward target 1, can create an oxide layer on the outer tube/surface 13 of target 1, which would then be deposited to the substrate 30 as if from a ceramic oxide target. In this case, the bottom gas inlet/feed 23 may be used to balance the remaining oxygen as is generally done in the case of ceramic targets with small oxygen flows. The deposition of transparent conductors is typically done using expensive ceramic targets, as the deposition from metallic targets is very unstable and difficult to control. Thus, accordingly, in certain example embodiments of this invention, the deposition method may combine the cost advantages of metal targets with the process stability seen from ceramic targets. However, both targets and target materials may also remain metallic, with the oxygen reacting with the target materials only after it has been freed from the target, in other example embodiments of this invention.
The film 40 formed in certain example embodiments of this invention may comprise target materials 7 and 8 in a ratio of from about 99:1 to 50:50 (with 50:50 being 1:1) in certain examples of this invention. In other example embodiments, the film 40 may comprise a ratio of target material 7 to target material 8 of from about 75:25 to 25:75, including all sub-ranges therebetween. The film may further comprise oxygen and/or nitrogen in certain example embodiments. However, this invention is not so limited, and any ratio of target materials desired may be obtained. Moreover, more than two target materials and more than two targets may be used, in any ratio desired, in other example embodiments.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.