(Ga) Zn Sn oxide sputtering target

Abstract

A sputtering target having a one-piece top coat comprising a mixture of oxides of zinc, tin, and optionally gallium, characterized in that said one-piece top coat has a length of at least 80 cm; a method for forming such a sputtering target and the use of such a target for forming films.

Claims

1. A sputtering target having a one-piece top coat, the one-piece top coat having a length of at least 80 cm, the one-piece top coat further comprising a mixture of oxides of zinc, tin, and optionally gallium, wherein the mixture of oxides comprises zinc stannate oxide and the proportion of tin in said mixture of oxides relative to the total amount of gallium, zinc and tin is from 15 to 55 at %.

2. The sputtering target according to claim 1, wherein the proportion of Ga in said mixture of oxides relative to the total amount of Ga, Zn and Sn is from 3 to 15 at %.

3. The sputtering target according to claim 1, wherein the proportion of Zn in said mixture of oxides relative to the total amount of Ga, Zn and Sn is from 15 to 85 at %.

4. The sputtering target according to claim 1, wherein the sum of all zinc stannate oxides in at % present in said top coat is higher than any other oxide present therein.

5. The sputtering target according to claim 1, wherein the material constitutive of said one-piece top coat has a resistivity lower than 10 Ω.Math.m, said resistivity being measured by a four points probe resistivity measuring device having two outer probes, said resistivity being measured on a one piece top coat of said material having a thickness of at least two times the outer probes distance of said device.

6. The sputtering target according to claim 1, wherein said top coat has a porosity of less than 10% as measured by cross-sectional SEM image analysis.

7. The sputtering target according to claim 1, wherein said mixture of oxides amounts for at least 99 at % of said top coat.

8. The sputtering target according to claim 1 having a cylindrical shape.

9. The sputtering target according to claim 1 wherein the sputtering target further comprises an inner backing tube and a bond coat bonding said backing tube with said top coat, said bond coat being a metal alloy having a melting temperature higher than 200° C.

10. A process for forming a coating on a substrate by sputtering wherein use is made of a sputtering target according to claim 1.

11. The process according to claim 10, wherein said sputtering is a DC sputtering, pulsed DC sputtering or an AC sputtering at a frequency below 350 kHz.

12. The process according to claim 10, wherein said sputtering is performed at a power density of at least 10 kW average DC power per meter target length.

13. A thermal spray method for manufacturing a sputtering target according to claim 1, said method comprising the steps of: a. Providing a mixture of oxides of zinc, tin and optionally gallium, the proportion of tin in said mixture of oxides relative to the total amount of gallium, zinc and tin being from 15 to 55 at % and said mixture comprising particles comprising oxides of Zn, Sn and optionally Ga,said oxides contacting each other within the same composite particle, b. Heating up said mixture to a temperature above 1000° C., thereby melting said mixture, c. Providing a sputtering target substrate, and d. Projecting, preferably spraying, said molten mixture onto said sputtering target substrate, thereby cooling and solidifying said molten mixture onto said sputtering target substrate.

14. A method according to claim 13, wherein the total time taken by the sum of steps b and d is less than 1 s.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 (left) is a schematic representation of a cross-section of a sputtering target tube; FIG. 1 (right) shows an enlarged portion of the tube.

(2) FIG. 2 is a cross-section micrograph of a top coat of a sputtering target according to an embodiment of the present invention.

(3) FIG. 3 is a cross-section micrograph of a top coat of a sputtering target according to an embodiment of the present invention.

(4) FIG. 4 is an XRD spectrum of a top coat of a sputtering target according to an embodiment of the present invention.

(5) FIG. 5 is a cross-section micrograph of top coat according to an embodiment of the present invention.

(6) FIG. 6 is an XRD spectrum of a powder used to form a top coat according to an embodiment of the present invention.

(7) FIG. 7 is a XRD spectrum of a top coat obtained by thermal spraying the powder of FIG. 6.

(8) FIG. 8 is a cross-section micrograph of the top coat obtained by thermal spraying the powder of FIG. 6 according to an embodiment of the present invention.

(9) FIG. 9 (top) is a transmission spectrum of a film obtained by sputtering a target with the top coat of FIG. 8 according to an embodiment of the present invention. FIG. 9 (bottom) shows the same spectrum after annealing.

(10) FIG. 10 is a XRD spectrum of a top coat obtained by thermal spraying according to an embodiment of the present invention.

(11) FIG. 11 is a cross-section micrograph of the top coat of FIG. 10 according to an embodiment of the present invention.

(12) FIG. 12 is a schematic representation of a single particle comprising oxide of Zn and oxide of Sn in a same particle according to embodiments of the present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(13) The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

(14) Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

(15) Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

(16) It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

(17) Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

(18) Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

(19) Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

(20) Furthermore, some of the embodiments are described herein as a method or combination of elements of a method that can be implemented by a processor of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the invention.

(21) In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

(22) The following terms are provided solely to aid in the understanding of the invention.

(23) As used herein and unless provided otherwise, the term “mixture of oxides of zinc, tin, and optionally gallium” refers to a mixture of two or more oxide compounds comprising at least an oxide compound comprising zinc and at least an oxide compound comprising tin (and optionally an oxide compound comprising gallium), said oxide compound comprising zinc and said oxide compound comprising tin (and optionally said oxide compound comprising gallium) being either as numerous as there are metals (e.g. two or optionally three) or are a lesser number of oxide compounds wherein at least one oxide compounds comprises at least two metals (e.g. Zn.sub.2SnO.sub.4 or ZnGa.sub.2O.sub.4).

(24) As used herein and unless provided otherwise, the term “zinc stannate oxide” relates to an oxide compound comprising at least zinc and tin in its composition. A typical example is Zn.sub.2SnO.sub.4 but other compounds such as non-stoichiometric compounds are included as well in this definition.

(25) The invention will now be described by a detailed description of several embodiments of the invention. It is clear that other embodiments of the invention can be configured according to the knowledge of persons skilled in the art without departing from the invention, the invention being limited only by the terms of the appended claims.

EXAMPLES

(26) The examples 1, 2, 4, 6, and 8 below were performed by thermal spraying a mixture on a sputtering target substrate, thereby obtaining a sputtering target 4 as schematised in FIG. 1. The sputtering target substrate was composed of a backing tube 1 and a high melting point Ni alloy bond coat 2. The backing tube 1 had a relatively high roughness and the bond coat 2 had a thickness of a few hundred μm. The thermal spray process consisted in accelerating and projecting (in the present case spraying) droplets of at least partially molten oxide material onto the sputtering target substrate, where they flatten upon impact and solidify to form a coating. The feedstock powder particles are typically in the size range from 10 to 90 microns and flow freely, which allows these powders to be fed consistently into the spray apparatus while being carried by a gas, typically argon, through the feeding hoses and injectors to the apparatus. In these examples a plasma spray system was used. The plasma spray system was operated with a mixture of argon, nitrogen and hydrogen gas at a power of 40 to 90 kW. They spray system had a feed capacity of 120 g/min,

Example 1

Thermal Spraying of a Simple Powder Blend of ZnO and SnO2 in a Zn:Sn Atomic Ratio of 65:35

(27) Commercial spray-agglomerated and sintered pure ZnO and pure SnO.sub.2 particles each with an average particle diameter of 10 to 90 microns, as measured by a Malvern particle size analyser, were blended to a Zn:Sn ratio of 65:35 at % in a rotating mixing jar for 20 min, then thermal sprayed as indicated above. Such particles for both ZnO and SnO.sub.2 are typically prepared from much finer raw material powder, typically smaller than 5 microns and with a metal purity of 99.99 wt %. The small raw material particles are typically dispersed in water with the addition of a chemical binder, spray-agglomerated, sintered and then sieved to a particle size suitable for thermal spraying. FIG. 2 shows the structure of the top coat after the thermal spray procedure. The deposited SnO.sub.2 particles were for the most part not molten and no Zn.sub.2SnO.sub.4 spinel was formed, as measured by X-Ray diffraction. The phase homogeneity was seen to be acceptable but non-optimal. The density of the top coat was below 4.7 g/cm.sup.3, as measured by an Archimedes method, which is acceptable but not optimal either. The coating had lower strength and integrity than in the following examples but a target of 30 cm could nevertheless be made.

Example 2

Thermal Spraying of a Powder with Intimate Contacted ZnO and SnO2 in a Zn:Sn Atomic Ratio of 41:59

(28) Commercial spray-agglomerated and sintered SnO.sub.2 powders with an average particle size of 10 to 90 microns from Example 1 were manually mixed and blended with much smaller commercial ZnO particles with an average size below 1 micrometer for 1 hour, sintered for 2 hrs and sieved to a size range of 10 to 100 microns. This procedure promoted that both Zn and Sn oxide components were present in single particles (see FIG. 12). Thermal spraying of this mixture gave a top coat comprising a Zn:Sn ratio of 41:59 at %. The strength of the obtained top coat was very good with a porosity of 8.3% and a density of at least 5.11 g/cm.sup.3. Zn and Sn elements were better distributed than in Example 1, as measured by EDX elemental mapping. FIG. 3 shows the structure obtained for the top coat when the procedure comprises an intimate contact of the constituents in single particles. White micron sized SnO.sub.2 particulates were uniformly dispersed in a grey matrix of zinc stannate oxide, as measured by EDX. The black regions are porosity. XRD demonstrated the presence of tin oxide and zinc stannate oxide (Zn.sub.2SnO.sub.4 spinel and other non-stochiometric species) in the top coat. No ZnO was observed in the top coat of this target. The target had a grey colour and presented parallel dark stripes. Some small pores were visible within said stripes and there were small cracks towards the ends of the target. The target had a length of 880 mm.

Conclusion on Examples 1 and 2

(29) The quality of the mixture was shown to have a positive influence on the homogeneity, density and strength of the obtained top coat. It was also shown to have a positive influence on the formation of zinc stannate oxides such as Zn.sub.2SnO.sub.4 spinel.

Example 3

Use of Sputtering Targets from Example 2 to Produce Films on a Substrate

(30) The sputtering target of example 2 has been used to produce sputtered films via a DC sputtering process. To test the stability of the target, sputtering was performed at 18 kW/m for more than 20 h in an oxygen-free atmosphere. The sputter process was stable. For the film production, the sputtering was performed at 18 kW/m for 1 h 20 min in an oxygen-free atmosphere. The coater opening time between two depositions was limited as much as possible. The arc rate was about 10 μarcs/s @18 kW/m. This is a low arc rate for such a high power. The maximum ramping speed used was 4 kW/min/m. The pressure during deposition was 3.0*10.sup.−3 mbar. The deposition rate was 6.5 nm per meter and per minute for a power density of one kW/m. No damages, cracks or dust formation were introduced on the target. The glass substrate was heated to 400° C. during deposition. The table below shows the properties of two samples obtained with the above procedure. In this table, “Th.” stands for thickness, as measured by ellipsometry; “4 p resist.” stands for electrical resistance, as measured with a four-point probe, μ is the carrier mobility, as measured from the Hall effect with a van der Pauw method; “Gr. XRD” is the phase (amorphous or crystalline) as determined by grazing angle XRD at an incident angle of 0.6°; “n” stands for refractive index; “k” stands for extinction coefficient, as measured by ellipsometry, (Sentech) from 190 nm to 2500 nm at an incident angle of 50°; “Am” stands for amorphous; and “Cr.” stands for crystalline. The coatings obtained with this procedure were crystalline, which is not optimal for the use in semiconductor channel layers in thin film transistors.

(31) TABLE-US-00001 4 p n k Target Th. resist. μ Gr. 550 550 Sample Zn:Sn (nm) (Ω .Math. m) (cm.sup.2/Vs) XRD nm nm BAC-3 41:59 290 1.5 .Math. 10.sup.−3 5 Cr. 2.02 0.0057 BAC-4 41:59 217 3.2 .Math. 10.sup.−3 4 Cr. 2.02 0.0030

Example 4

Thermal Spraying of SnO2 Powder Blended with ZnO Powder in a Zn:Sn Ratio of 68:32

(32) SnO.sub.2 particles containing ZnO components, as prepared in Example 2, were blended in a rotating mixing jar for 20 min with commercial spray-agglomerated and sintered ZnO particles with a particle size of 10 to 90 microns in such a way as to increase the overall Zn content in the blend to a Zn:Sn ratio of 68:32. Thermal spraying of this mixture gave a top coat comprising a corresponding Zn:Sn ratio. The density of the obtained top coat was at least 5.11 g/cm.sup.3. The presence of tin oxide, zinc oxide and zinc stannate oxide (Zn.sub.2SnO.sub.4 spinel and other non-stochiometric species) in the top coat was observed (see FIG. 4). In FIG. 4, the XRD peaks indicated by a plain arrow correspond to SnO.sub.2 in its cassiterite phase; the peaks indicated by a dotted arrow correspond to spinel of the Zn.sub.2SnO.sub.4 type (or similar but non-stochiometric species) and the dashed arrows correspond to ZnO in its hexagonal phase for the top coat in example 4. FIG. 5 shows the structure obtained for the top coat. The structure is similar to Example 2, in such that white microns sized SnO.sub.2 particulates are uniformly dispersed in a grey matrix of zinc stannate, but this matrix is now interspersed with larger ZnO molten particles. The target had a grey colour and presented parallel dark stripes. Some small pores were visible within said stripes but there were no cracks. The target had a length of 880 cm.

Example 5

Use of Sputtering Targets from Example 4 to Produce Films on a Substrate

(33) The sputtering target of example 4 has been used to produce sputtered films via a DC sputtering process analogous to example 3. To test the stability of the target, sputtering was performed at 18 kW/m for more than 20 h in an oxygen-free atmosphere. The sputter process was stable. For the film production, the sputtering was performed at 18 kW/m for more than 2 h 40 min in an oxygen-free atmosphere. The coater opening time between two depositions was limited as much as possible. The pressure during deposition was 3.0*10.sup.−3 mbar. The arc rate was about 15 μarcs/s @18 kW/m. The maximum ramping speed used was 4 kW/min/m. The deposition rate was 6.5 nm per meter and per minute for a power density of one kW/m. No damages, cracks or dust formation was observed. The glass substrate was heated to 400° C. during deposition. The table below shows the properties of two samples obtained with the above procedure. The samples produced with this procedure show high carrier mobility and are XRD amorphous, suitable for amorphous metal oxide thin film transistors.

(34) TABLE-US-00002 4 p n k Target Th. resist. μ Gr. 550 550 Sample Zn:Sn (nm) (Ω .Math. m) (cm.sup.2/Vs) XRD nm nm BAC-1 68:32 225 1.2 .Math. 10.sup.−4 26 Am. 2.05 0.0060 BAC-2 68:32 223 1.6 .Math. 10.sup.−4 27 Am. 2.05 0.0062

Example 6

Thermal Spraying of Powder with Intimately Mixed ZnO and SnO2 in a Zn:Sn Atomic Ratio of 68:32

(35) Agglomerated and sintered powder containing ZnO and SnO.sub.2 components in intimate contact within single powder particles were thermal sprayed as indicated above. The Zn:Sn ratio was 68:32. The powder had an average particle diameter of 10 to 90 microns. These thermal sprayed powders are prepared from much finer raw material smaller than 5 microns with a metal purity of 99.99 wt %. The small raw material particles are dispersed in such a way as to obtain an intimate mixture suitable for agglomeration. The resulting agglomerates are typically sintered at a temperature not exceeding 1300° C. A fraction of this powder is sieved to a particle size suitable for thermal spraying as above. Using such a procedure allows to have Zn and Sn oxide components in intimate contact within single spray particles. Zn.sub.2SnO.sub.4 spinel can be created during this sintering step of the powder production. For the powder in this example, FIG. 6 shows the presence of zinc stannate oxide (spinel), while it still contains significant amounts of SnO.sub.2 and ZnO. This powder was used to form a top coat for a sputtering target in a way analogous to example 2. Thermal spraying of this mixture gave a top coat comprising a Zn:Sn ratio of 68:32. The phase homogeneity of the obtained top coat was very good. The density of the obtained top coat was at least 5.37 g/cm.sup.3. The target had a homogeneous appearance, without stripes, pores or cracks. The target was 880 mm long. FIG. 7 shows the spectrum of the resulting top coat. It shows predominantly the presence of zinc stannate spinel with only small amounts of SnO.sub.2 and ZnO. In FIG. 8, it can be seen that this top coat is more phase-homogeneous than the top coat of FIG. 5.

Example 7

Use of Sputtering Targets from Example 6 to Produce Films on a Substrate

(36) The sputtering target of example 6 has been used to produce sputtered films via a DC sputtering process analogous to example 5. To test the stability of the target, sputtering was performed at 18 kW/m for more than 20 h in an oxygen-free atmosphere. The sputter process was stable. The arc rate was about 5 μarcs/s @18 kW/m. This is a very low arc rate for such a high power. The maximum ramping speed used was 4 kW/min/m. The deposition rate was from 7 to 10 nm per meter and per minute for a power density of one kW/m. No damages, cracks or dust formation was observed. Sputtered films were then produced at power densities of 6 to 18 kW/m at a pressure of 2.10.sup.−3 to 8.10.sup.−3 mbar with oxygen in argon gas from 0 to 10%. The substrates were not externally heated during deposition. The samples were, however, post annealed in vacuum at 180° C. The table below shows the properties of two samples obtained with the above procedure. The transmission spectrum of a 180 nm thick film on glass, as measured with a spectrophotometer, is shown FIG. 9 (before (top, dashed dotted line) and after (bottom, dotted line) annealing at 180° C.). The samples had high optical transmission. The samples were XRD amorphous. The initial resistivity of the film on a Si/SiO.sub.2 substrate suitable for the fabrication of TFTs was from 0.0023 to 0.013 Ω.Math.m.

(37) TABLE-US-00003 Dep. rate Sputter (nm 4 p Power O.sub.2 in Arcs/ Pres. m/min)/ Th. resist. μ Gr. Sample (kW/m) Ar (%) sec (μbar) (kW/m) (nm) (Ω .Math. m) (cm.sup.2/Vs) XRD n@550 nm SAC 12 4 0.8 4 8.7 180 2.33 .Math. 10.sup.−3 18.8 Am. 2.05 5-6H SAC 12 6 0.5 4 7.7 179 1.23 .Math. 10.sup.−2 20.57 Am. 2.05 6-7H

Example 8

Thermal Spraying of a Ga2O3—ZnO—SnO2 Intimate Mixture in a Ga:Zn:Sn Atomic Ratio of 7:60:33

(38) Agglomerated and sintered powder containing Zn, Sn and Ga oxide components in intimate contact within single powder particles were thermal sprayed as indicated above. The Ga:Zn:Sn ratio was 7:60:33. A typical procedure for preparation of agglomerated and sintered powder was used whereby micron-sized Ga.sub.2O.sub.3, particles were introduced into the intimate mixture for agglomeration. The sintering was typically such that the particles would not break or disintegrate. A fraction of this powder was sieved to a particle size suitable for thermal spraying as above. The inventors observed that long sintering an intimate mixture of micron-sized ZnO, SnO.sub.2 and Ga.sub.2O.sub.4 particles at temperatures high enough for substantial Zn.sub.2SnO.sub.4 spinel formation breaks a sintered body or powder. Breakage would make the powder unsuitable for thermal spraying. Surprisingly, the thermal spraying of this powder having no or only a small amount of Zn.sub.2SnO.sub.4 spinel resulted in a uniform and strong top coat consisting of predominantly Zn.sub.2SnO.sub.4 spinel. The coating could be obtained with a length much larger than 50 cm and no upper limit for the length could be detected. The gallium species were well dispersed within the coating as evidenced by element mapping in cross-section micrographs. The phase homogeneity of the obtained top coat was good with predominantly Zn.sub.2SnO.sub.4 and smaller amounts of ZnO.sub.2 and SnO.sub.2 components. FIG. 10 shows the XRD spectrum of the obtained top coat. The Ga oxide is dissolved in the zinc stannate oxide spinel and is therefore not visible in the XRD spectrum. FIG. 11 shows a cross-sectional micrograph of the top-coat of the target. The density of the obtained top coat was at least 5.7 g/cm.sup.3. The target had a macroscopically homogeneous appearance, without stripes, pores or cracks. The target was 880 mm long. The porosity was lower than 3%. The resistivity of the target was 1.94*10.sup.−2 Ω.Math.m.

Example 9

Use of Sputtering Targets from Example 8 to Produce Films on a Substrate

(39) The sputtering target of example 8 has been used to produce sputtered films via a DC sputtering process analogous to example 7. To test the stability of the target, sputtering was performed at 18 kW/m for more than 20 h in an oxygen-free atmosphere. The sputter process was stable. The arc rate was less than 5 μarcs/s @18 kW/m. This is a very low arc rate for such a high power. The maximum ramping speed used was 4 kW/min/m. The deposition rate was from 7 to 10 nm per meter and per minute for a power density of one kW/m. No damages, cracks or dust formation was observed. Sputtered films were then produced at powers of 6 to 18 kW/m at a pressure of 2.10.sup.−3 to 8.10.sup.−3 mbar with oxygen in argon gas from 0 to 10%. The substrates were not externally heated during deposition. The samples were post annealed in vacuum at 180° C. The table below shows the properties of a sample obtained with the above procedure. The transmission spectrum of a 170 nm thick film on glass, as measured with a spectrophotometer, is shown FIG. 9 (before (top, dashed line) and after (bottom, plain line) annealing at 180° C.). The samples had high optical transmission. The samples were XRD amorphous. The initial resistivity of the film suitable for the fabrication of TFTs was from 0.02 to 0.5 Ω.Math.m.

(40) TABLE-US-00004 Dep. rate Sputter (nm 4 p Power O.sub.2 in Arcs/ Pres. m/min)/ Th. resist. Gr. Sample (kW/m) Ar (%) sec (μbar) (kW/m) (nm) (Ω .Math. m) XRD n@550 nm SAC 12 4 0.7 4 8.1 171 2.6 .Math. 10.sup.−2 Am. 2.05 7-4H

(41) It is to be understood that although preferred embodiments, specific constructions and configurations, as well as materials, have been discussed herein for devices according to the present invention, various changes or modifications in form and detail may be made without departing from the scope and spirit of this invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

(42) The work leading to this invention has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° NMP3-LA-2010-246334.