Method for Producing a Reflector Element and Reflector Element

Abstract

A method for producing a reflector element and a reflector element are disclosed. In an embodiment the method includes depositing a layer sequence on a substrate, wherein the layer sequence includes at least one mirror layer and at least one reactive multilayer system and igniting the reactive multilayer system in order to activate heat input in the layer sequence.

Claims

1-15. (canceled)

16. A method for producing a reflector element, the method comprising: depositing a layer sequence on a substrate, wherein the layer sequence comprises at least one mirror layer and at least one reactive multilayer system; and igniting the reactive multilayer system in order to activate heat input in the layer sequence.

17. The method according to claim 16, wherein the reactive multilayer system comprises a plurality of alternating layers of one of the following material pairs: Ti and B, Zr and B, Hf and B, V and B, Nb and B, Ta and B, Ti and C, Zr and C, Hf and C, V and C, Nb and C, Ta and C, Ti and Si, Zr and Si, Hf and Si, V and Si, Nb and Si, Ta and Si, Ti and Al, Zr and Al, Hf and Al, Ni and Al, Pd and Al, Pt and Al, Sc and Au, Sc and Cu, Sc and Ag, Y and Au, Y and Cu, Y and Ag, and Ru and Al.

18. The method according to claim 16, wherein the reactive multilayer system comprises at least 20 layers.

19. The method according to claim 16, wherein the reactive multilayer system comprises layers with thicknesses of between 5 nm and 500 nm.

20. The method according to claim 16, wherein the mirror layer comprises a metal layer.

21. The method according to claim 16, wherein the layer sequence comprises a protective layer arranged over the mirror layer, and wherein the protective layer is modified by the heat input.

22. The method according to claim 21, wherein the protective layer comprises MgF.sub.2, Y.sub.2O.sub.3 or Al.sub.2O.sub.3.

23. The method according to claim 16, wherein the layer sequence has at least one adhesive layer.

24. The method according to claim 16, wherein the mirror layer comprises a dielectric interference layer system.

25. The method according to claim 16, wherein the mirror layer comprises a partial open area in order to allow direct access to the reactive multilayer system.

26. The method according to claim 16, wherein the reactive multilayer system comprises alternating layers of a first material and a second material, and wherein the first material layer and the second material layer are separated from each other by a diffusion barrier of a third material.

27. The method according to claim 26, wherein the third material is carbon.

28. A reflector element comprising: a substrate; and a layer sequence disposed on the substrate, wherein the layer sequence comprises at least one mirror layer and at least one layer producible by ignition of a reactive multilayer system, and wherein the layer producible by ignition is arranged between the substrate and the mirror layer.

29. The reflector element according to claim 28, wherein the layer that is producible by ignition comprises at least one compound of one of the following material pairs: Ti and B, Zr and B, Hf and B, V and B, Nb and B, Ta and B, Ti and C, Zr and C, Hf and C, V and C, Nb and C, Ta and C, Ti and Si, Zr and Si, Hf and Si, V and Si, Nb and Si, Ta and Si, Ti and Al, Zr and Al, Hf and Al, Ni and Al, Pd and Al, Pt and Al, Sc and Au, Sc and Cu, Sc and Ag, Y and Au, Y and Cu, Y and Ag, Ru and Al.

30. The reflector element according to claim 28, wherein the layer producible by ignition comprises at least one of the following compounds: TiB.sub.2, ZrB.sub.2, HfB.sub.2, VB.sub.2, NbB.sub.2, TaB.sub.2, TiC, ZrC, HfC, VC, NbC, TaC, TisSi.sub.3, Zr.sub.5Si.sub.3, Hf.sub.5Si.sub.3, V.sub.5Si.sub.3, Nb.sub.5Si.sub.3, Ta.sub.5Si.sub.3, TiAl, ZrAl, HfAl, NiAl, PdAl, PtAl, ScAu, ScCu, ScAg, YAu, YCu, YAg, RuAl.

31. A reflector element comprising: a substrate; and a layer sequence disposed on the substrate, wherein the layer sequence comprises at least one mirror layer and at least one layer that is producible by ignition of a reactive multilayer system, and wherein the mirror layer is arranged between the substrate and the layer producible by ignition.

32. The reflector element according to claim 31, wherein the layer producible by ignition comprises at least one compound of one of the following material pairs: Ti and B, Zr and B, Hf and B, V and B, Nb and B, Ta and B, Ti and C, Zr and C, Hf and C, V and C, Nb and C, Ta and C, Ti and Si, Zr and Si, Hf and Si, V and Si, Nb and Si, Ta and Si, Ti and Al, Zr and Al, Hf and Al, Ni and Al, Pd and Al, Pt and Al, Sc and Au, Sc and Cu, Sc and Ag, Y and Au, Y and Cu, Y and Ag, Ru and Al.

33. The reflector element according to claim 31, wherein the layer producible by ignition contains at least one of the following compounds: TiB.sub.2, ZrB.sub.2, HfB.sub.2, VB.sub.2, NbB.sub.2, TaB.sub.2, TiC, ZrC, HfC, VC, NbC, TaC, TisSi.sub.3, Zr.sub.5Si.sub.3, Hf.sub.5Si.sub.3, V.sub.5Si.sub.3, Nb.sub.5Si.sub.3, Ta.sub.5Si.sub.3, TiAl, ZrAl, HfAl, NiAl, PdAl, PtAl, ScAu, ScCu, ScAg, YAu, YCu, YAg, RuAl.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The invention is explained in greater detail below with respect to embodiments in connection with FIGS. 1 through 4.

[0037] The figures are as follows:

[0038] FIGS. 1A through 1G show a schematic representation of an embodiment of the method for the production of the reflector element by means of intermediate steps,

[0039] FIG. 2 shows a schematic representation of a section through a reflector element according to a first embodiment,

[0040] FIG. 3 shows a schematic representation of a section through a reflector element according to a second embodiment, and

[0041] FIG. 4 shows a schematic representation of a section through a reflector element according to a third embodiment.

[0042] Identical components or components having the same action are indicated in the figures with the same respective reference numbers. The components shown and the size ratios of the components to one another are also not to be understood as being to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0043] In the embodiment of the method, in the first step shown in FIG. 1A, an adhesive layer 2 is applied to a substrate 1. The substrate 1 can be a flat or curved substrate and, for example, contain glass, plastic, metal, or a ceramic. The substrate 1 preferably has a surface with low roughness, it is also possible to apply a preferably polished technical-grade layer to substrate 1 (not shown). Like the subsequent layers described below, the adhesive layer 2 can be applied, for example, by means of a PVD method (such as thermal evaporation, electron beam evaporation, plasma-assisted evaporation, magnetron sputtering, or ion beam sputtering), a CVD method or an ALD method.

[0044] The adhesive layer 2 is more particularly used to improve adhesion of the subsequent layers to the substrate 1. The adhesive layer 2 can simultaneously serve as a diffusion barrier. Moreover, the adhesive layer 2 can be used to regulate the heat input that is released by the reaction of the reactive multilayer system and can also affect the substrate 1. The adhesive layer 2 can be an individual layer or a combination of a plurality of thin layers. Suitable layer materials are all materials that ensure favorable adhesion of the reactive multilayer system to the substrate. More particularly, these can be metals such as Cr, Ti, Cu, Ru, Mo, W, low melting metals such as soldering material, semiconductors such as Si or SiC, dielectric layers such as SiO.sub.2, Si.sub.3N.sub.4, Al.sub.2O.sub.3, AlN, ZrO.sub.2, ZrN, HfO.sub.2, HfN, Ta.sub.2O.sub.5, TaN, Nb.sub.2O.sub.5, NbN, Y.sub.2O.sub.3, YN or mixtures of these materials. The thickness of the adhesive layer 2 is between 5 nm and 2000 nm, preferably between 10 nm and 100 nm.

[0045] In the second step shown in FIG. 1B, at least one reactive multilayer system 3 is applied to the adhesive layer 2. The reactive multilayer system 3 contains a preferably periodic layer stack of alternating layers, the materials of which can form a compound in an exothermic reaction. More particularly, suitable material combinations for the reactive multilayer system 3 are as follows: Ti and B (reacting to TiB.sub.2), Zr and B (reacting to ZrB.sub.2), Hf and B (reacting to HfB.sub.2), V and B (reacting to VB.sub.2), Nb and B (reacting to NbB.sub.2), Ta and B (reacting to TaB.sub.2), Ti and C (reacting to TiC), Zr and C (reacting to ZrC), Hf and C (reacting to HfC), V and C (reacting to VC), Nb and C (reacting to NbC), Ta and C (reacting to TaC), Ti and Si (reacting to Ti.sub.5Si.sub.3), Zr and Si (reacting to Zr.sub.5Si.sub.3) Hf and Si (reacting to Hf.sub.5Si.sub.3), V and Si (reacting to V.sub.5Si.sub.3), Nb and Si (reacting to Nb.sub.5Si.sub.3), Ta and Si (reacting to Ta.sub.5Si.sub.3), Ti and Al (reacting to TiAl), Zr and Al (reacting to ZrAl), Hf and Al (reacting to HfAl), Ni and Al (reacting to NiAl), Pd and Al (reacting to PdAl), Pt and Al (reacting to PtAl) Sc and Au (reacting to ScAu), Sc and Cu (reacting to ScCu), Sc and Ag (reacting to ScAg), Y and Au (reacting to YAu), Y and Cu (reacting to YCu), Y and Ag (reacting to YAg), and Ru and Al (reacting to RuAl).

[0046] The thickness of the reactive multilayer system 3 is between 0.1 m and 200 dm, preferably between 0.5 m and 5 m.

[0047] In an optional third step shown in FIG. 1C, a second adhesive layer 4 can be applied to the reactive multilayer system 3 that can simultaneously serve as a diffusion barrier that prevents diffusion between the reactive multilayer system 3 and the metal layer applied in the following method step. Advantageous embodiments of the second adhesive layer 4 correspond to the above-described adhesive layer 2. Preferably, as in all subsequent layers, there is at least one partial open area in the second adhesive layer 4 in order to allow local direct access to the reactive multilayer system 3. This may be necessary for ignition of the reaction.

[0048] In a fourth step shown in FIG. 1D, a broad-band reflecting metal layer 5 is applied as a mirror layer to the second adhesive layer 4. The metal layer 5 preferably contains a high-reflective metal such as Au, Al, Ag, Cu, Rh, Pt or Ir or an alloy of these metals. The thickness of the metal layer 5 is preferably adapted to the energy being released from the reactive multilayer system 3, and, for example, can be between 10 nm and 5000 nm. Preferably, as for all of the subsequent layers, there is a partial open area in the metal layer 5 in order to allow local direct access to the reactive multilayer system 3. This may be necessary for ignition of the reaction.

[0049] In an optional fifth step shown in FIG. 1E, a third adhesive layer 6 can be applied to the reflecting metal layer 5 that can simultaneously serve as a diffusion barrier that prevents diffusion between the metal layer 5 and a subsequent protective layer. The third adhesive layer 6 may be both a single layer or a combination of a plurality of thin layers. Suitable layer materials are all materials that ensure favorable adhesion of the protective layer to the metal layer 5. At the same time, the third adhesive layer 6 must have as little effect as possible on the reflectance of the underlying high-reflective metal layer 5. The third adhesive layer 6 is therefore preferably as thin as possible and/or composed of a material having suitable optical properties. Suitable are metals such as Cr, Ti, Cu, Ru, Mo, W, semiconductors such as Si or SiC, dielectric layers such as SiO.sub.2, Si.sub.3N.sub.4, Al.sub.2O.sub.3, AlN, ZrO.sub.2, ZrN, HfO.sub.2, HfN, Ta.sub.2O.sub.5, TaN, Nb.sub.2O.sub.5, NbN, Y.sub.2O.sub.3, YN, fluorides such as MgF.sub.2, AlF.sub.3, LiF, LaF.sub.3, GdF.sub.3, or mixtures of these materials. The thickness of the third adhesive layer 6 is between 0.5 nm and 100 nm, preferably between 1 nm and 30 nm. Preferably, as for all of the subsequent layers, there is a partial open area in the adhesive layer 6, in order to allow local direct access to the reactive multilayer system 3. This may be necessary for ignition of the reaction.

[0050] In a sixth step, which is shown in FIG. 1F, a protective layer 7 is deposited on the metal layer 5 or on the third adhesive layer 6. The protective layer 7 may be composed of one or a plurality of dielectric layers. In order to obtain a high degree of reflectance or a uniform and wavelength-independent optical performance, the protective layer 7 has a plurality of dielectric layer materials that are transparent in the spectral range in which the reflector element is to be used. More particularly, the protective layer 7 can contain oxides or nitrides such as SiO.sub.2, Si.sub.3N.sub.4, Al.sub.2O.sub.3, AlN, ZrO.sub.2, ZrN, HfO.sub.2, HfN, TiO.sub.2, TiN, Ta.sub.2O.sub.5, TaN, Nb.sub.2O.sub.5, NbN, Y.sub.2O.sub.3, YN, MgO, fluorides such as MgF.sub.2, LiF, AlF.sub.3, LaF.sub.3, GdF.sub.3, semiconductors such as Si or SiC, conductive transparent such as ITO or AZO, or mixtures of these materials. Preferably, there is a partial open area in the protective layer 7 in order to allow local direct access to the reactive multilayer system 3. This may be necessary for ignition of the reaction.

[0051] In a seventh step shown in FIG. 1G, the reaction of the reactive multilayer system 3 is ignited by an energy input, for example, by means of a laser 10 or application of electric voltage. In the self-propagating exothermic reaction occurring as a result, an amount of heat is released. The released amount of heat acts on the layers surrounding the reactive multilayer system 3, causing them to be modified. As this is a local heat input, the thermal load on the substrate 1 is so low that there is no warping and thus no deviation in shape.

[0052] The reflector element produced in this manner is shown in FIG. 2. The reflector element contains a layer 8 produced by ignition of the reactive multilayer system, which comprises a compound of the layer material previously contained in the reactive multilayer system. More particularly, the layer 8 produced by ignition of the reactive multilayer system may contain at least one of the following compounds: TiB.sub.2, ZrB.sub.2, HfB.sub.2, VB.sub.2, NbB.sub.2, TaB.sub.2, TiC, ZrC, HfC, VC, NbC, TaC, TisSi.sub.3, Zr.sub.5Si.sub.3, Hf.sub.5Si.sub.3, V.sub.5Si.sub.3, Nb.sub.5Si.sub.3, Ta.sub.5Si.sub.3, TiAl, ZrAl, HfA, NiAl, PdAl, PtAl, ScAu, ScCu, ScAg, YAu, YCu, YAg, and RuAl.

[0053] In the embodiment of FIG. 2, the reflector element is a so-called front side reflector, in which an incident light beam 11 is reflected by the mirror layer 5 before it strikes the substrate 1. The third adhesive layer 6 and the protective layer 7 are advantageously transparent, so that the incident light beam 11 is not reflected until it strikes the mirror layer 5. In the embodiment of the reflector element as a front side reflector, the reactive multilayer system 3 or the layer 8 produced by ignition of the reactive multilayer system 3 are arranged between the substrate 1 and the mirror layer 5.

[0054] In the following, three examples A, B, C for the production of a reflector element will be described according to FIGS. 1A through 1G and 2.

Example A: Reflector Element with a Silver Coating and an Al.SUB.2.O.SUB.3 .Protective Layer

[0055] In a first step, an adhesive layer 2 of Cr is applied to a substrate 1 for precision optical applications that has a polished technical-grade layer of NiP. In a second step, a reactive multilayer system 3 of Pd and Al is applied. The reactive PdAl multilayer system 3 is composed of a layer stack with 20 periods and a period thickness of 200 nm. A 10 nm thick Cr layer is applied to the reactive multilayer system 3 as a second adhesive layer 4, and a 150 nm thick Ag layer is deposited thereon as a mirror layer 5. An approx. 100 nm thick Al.sub.2O.sub.3 layer is deposited on the Ag layer 5 as a protective layer 7. After deposition of these layers, the reactive multilayer system 3 is ignited. Ignition of the reactive multilayer system 3 briefly produces an adiabatic temperature of up to 2380 C. This temperature is sufficient to melt the silver layer 5 applied to the reactive multilayer system 3 (melting point: 962 C.). The amorphous Al.sub.2O.sub.3 protective layer 7 applied to the silver layer 5 is also modified by the effect of heat. The amorphous Al.sub.2O.sub.3 protective layer 7 is converted to the more stable -Al.sub.2O.sub.3 phase (phase transition at 750 C.-800 C. in PVD layers). By means of melting the Ag layer 5, an extremely smooth interface can be achieved on solidification on the protective layer 7 (Al.sub.2O.sub.3), which is advantageous for high and directed reflection. The conversion of the amorphous Al.sub.2O.sub.3 protective layer 7 to the more stable -Al.sub.2O.sub.3 phase leads to substantially improved resistance. The -Al.sub.2O.sub.3 phase shows substantially lower water-solubility than amorphous A.sub.2O.sub.3. The reflector thus shows improved stability compared to conventional reflectors, more particularly in moist environments.

Example B: Reflector Element with an Aluminum Coating and a Fluoride Protective Layer

[0056] In a first step, a Ti adhesive layer 2 to 10 nm in thickness is applied to a polished substrate 1 composed, for example, of silicon, quartz glass or CaF.sub.2. In a further step, a reactive multilayer system 3 is deposited on the Ti adhesive layer 2. The reactive multilayer system 3 is composed of a layer stack of alternating Ti layers and Al layers with 20 periods having a period thickness of 100 nm. A 50 nm to 200 nm thick Al layer is applied as a mirror layer 5 to the reactive multilayer system 3 by evaporation. A fluoride protective layer 7, for example, a MgF.sub.2 layer or a combination of fluoride layers, one of which is a MgF.sub.2 layer, is vapor deposited on the mirror layer 5 at a low process temperature (<150 C.). MgF.sub.2 is transparent up to far into the deep UV range. It is known that by vapor deposition at high process temperatures, it is possible to achieve significantly reduced absorption of the layer and increased environmental stability. The reduced absorption and increased environmental stability of MgF.sub.2 could also be achieved by means of subsequent annealing. However, this is frequently impossible due to temperature-sensitive substrates or resulting high thermal layer stress. Ignition of the reactive multilayer system 3 results in a local adiabatic temperature of 1227 C., causing the at least one fluoride layer to be converted to a stable state and simultaneously reducing the absorption of the fluoride layer in the deep UV region. For this reason, compared to conventional reflectors, the reflector shows improved stability, more particularly in moist environments.

Example C: Reflector Element with a Gold Layer

[0057] In a first step, by means of magnetron sputtering, an adhesive layer 2 of Cr or Ti is applied to a substrate 1 for precision optical applications that has a polished technological layer of NiP. In a second step, a reactive multilayer system 3 is applied that has a layer stack of alternating Pd layers and Al layers with 15 periods with the period thickness of 80 nm. On the reactive multilayer system 3, a thin Cr or Ti layer is applied as an adhesive layer 4, and a 350 nm thick Au layer is deposited thereon as a mirror layer 5 with a subsequent approx. 400 nm thick Y.sub.2O.sub.3 protective layer 7. After deposition of these layers, the reactive multilayer system 3 is ignited. Ignition of the reactive multilayer system 3 produces a local adiabatic temperature of up to 2380 C. The temperature is sufficient to briefly melt the gold, which is in direct contact with the reactive multilayer system 3. The amorphous Y.sub.2O.sub.3 protective layer 7 applied to the mirror layer 5 is also modified by the effect of heat. This allows a favorable adhesion of the mirror layer 5 to the substrate and the Y.sub.2O.sub.3 protective layer 7 to the mirror layer 5 of gold.

[0058] FIG. 3 shows an alternative embodiment of the reflector element in which the mirror layer is configured as a dielectric interference layer system 9. Production can essentially take place analogously to the method described above, wherein after the method step presented in FIG. 1C, the dielectric interference layer system 9 can be directly applied to the reactive multilayer system 3. In this embodiment, the second adhesive layer 4, the third adhesive layer 6 and the protective layer 7 can be dispensed with. In the completed reflector element, for example, the dielectric interference layer system 9 functioning as a mirror layer can be directly arranged on the layer 8 produced by ignition of the reactive multilayer system. As in the previous embodiment, the embodiment of FIG. 3 comprises a front side reflector in which an incident light beam 11, before striking the substrate 1, is reflected by the mirror layer in the form of the dielectric interference layer system 9.

[0059] FIG. 4 shows a further possible embodiment of the reflector element. In this embodiment, the reflector element has a so-called back side reflector, in which an incident light beam 11 passes through the substrate 1 before being reflected by the mirror layer 5. The back side reflector differs from the front side reflector shown in FIG. 2 in its altered layer arrangement. For example, a layer sequence of the advantageously transparent first adhesive layer 2, the metal layer 5 as a mirror layer, the second adhesive layer 4, the layer 8 produced by ignition of the reactive multilayer system, the third adhesive layer 6 and the protective layer 7 is arranged on the substrate 1. In this embodiment, the mirror layer 5 is advantageously arranged between the substrate 1 and the layer 8 produced by ignition of the reactive multilayer system. The production of the back side reflector can take place analogously to the method steps described in connection with FIG. 1, with the exception of the different sequence of layers.

[0060] The invention is not limited by the description by means of the embodiments. Rather, the invention comprises every new feature and every combination of features, which more particularly includes every combination of features in the patent claims, even if said feature or combination per se is not explicitly mentioned in the patent claims or embodiments.