Abstract
The invention relates to a method for producing a structured coating on a substrate, wherein the method comprises the following steps: providing a substrate having a surface to be coated and producing a structured coating on the surface of the substrate to be coated by depositing at least one evaporation coating material, namely aluminium oxide, silicon dioxide, silicon nitride, or titanium dioxide, on the surface of the substrate to be coated by means of thermal evaporation of the at least one evaporation coating material and using additive structuring. The invention further relates to a coated substrate and a semi-finished product having a coated substrate.
Claims
1. A method comprising the following steps: providing a substrate having a surface to be coated; and depositing only a layer structure on the substrate, the layer structure consisting of three layers on the substrate, the three layers being a first layer deposited on the substrate, a second layer deposited on the first layer, and a third layer deposited on the second layer: wherein each of the first layer, the second layer, and the third layer is formed by depositing a single evaporation coating material, such that the first layer, the second layer, and the third layer each comprise one evaporation coating material, the evaporation coating material comprising: aluminium oxide, silicon nitride, silicon dioxide, or titanium dioxide by means of thermal evaporation of the evaporation coating material; and wherein the second layer is structured using a lift-off process and additive structuring on the deposited evaporation material, the second layer forming an optical waveguide; wherein the thermal evaporation is carried out as plasma-enhanced thermal electron beam evaporation using oxygen, nitrogen, and/or argon; wherein the evaporation coating material of the first layer has a refractive index which is lower than a refractive index of the evaporation coating material of the second layer, and wherein the evaporation coating material of the third layer has a refractive index which is lower than the refractive index of the evaporation coating material of the second layer; wherein, during evaporation of the three layers, a property gradient provided in a form of a gradual transition is generated at least one of: between the first layer and the second layer and between the second layer and the third layer.
2. The method according to claim 1, wherein the step for the thermal evaporation of the evaporation coating material comprises a step for the co-evaporation using at least two evaporation sources.
3. The method according to claim 1, wherein at least one conductive area is produced on the substrate.
4. The method according to claim 1, wherein the substrate exhibits a maximum substrate temperature of 120 C. during deposition of the at least one evaporation coating material.
5. The method according to claim 1, wherein the substrate comprises at least one of the following materials: glass, metal, plastics, ceramics, inorganic insulator, dielectric and a semiconductor material.
6. The method according to claim 1, wherein a layer thickness of the second layer is between 0.1 m and 10 m.
7. The method according to claim 6, wherein the layer thickness is between 0.5 m and 3 m.
8. The method according to claim 4, wherein the substrate exhibits a maximum substrate temperature of 100 C., during deposition of the at least one evaporation coating material.
9. The method of claim 1, wherein a pretreatment takes place in situ prior to the thermal evaporation.
10. The method of claim 1, wherein the first layer and/or the third layer are structured using additive structuring.
11. The method of claim 1, wherein the third layer is deposited on the second layer such that the second layer is enclosed by the first layer and the third layer.
12. The method of claim 1, wherein the first layer is made of silicon dioxide.
13. The method of claim 1, wherein the second layer is made of aluminium oxide.
14. The method of claim 1, wherein the third layer is made of silicon dioxide.
Description
DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS
(1) The invention is described in greater detail below using preferred exemplary embodiments with reference to figures in a drawing. In these:
(2) FIG. 1 shows a schematic representation of a substrate on which a structured layer is to be deposited by means of plasma-enhanced thermal electron beam evaporation of an evaporation coating material,
(3) FIG. 2 shows a schematic representation of the substrate from FIG. 1 with resist deposited on it, which exhibits micro-structuring that corresponds to a negative image of the structured layer being deposited, said structuring being formed by means of lithography,
(4) FIG. 3 shows a schematic representation of the substrate from FIG. 2 with a layer of an evaporation coating material now deposited on it,
(5) FIG. 4 shows a schematic representation of the substrate from FIG. 3, wherein the resist has been removed,
(6) FIG. 5 shows a semi-finished product in which a layer of resist with a negative structure and an evaporated layer are formed on a substrate,
(7) FIG. 6 shows a further semi-finished product, in which a layer of resist with a negative structure and an evaporated layer are formed on a substrate,
(8) FIG. 7 shows a schematic representation of a configuration in which structured evaporation layers are formed on a substrate by means of multiple additive structuring,
(9) FIG. 8 shows a schematic representation of a configuration in which multiple evaporation layers are deposited by means of multiple additive structuring,
(10) FIG. 9 shows a schematic representation of a configuration in which a structured coating is formed on a substrate by means of additive structuring, wherein an intermediate section is provided with material filling in the structured coating,
(11) FIG. 10 shows a schematic representation of a configuration in which an unstructured and a structured evaporation layer are produced,
(12) FIG. 11 shows a schematic representation of a substrate section,
(13) FIG. 12 shows a schematic representation of a configuration in which an evaporated layer produced by means of additive structuring is formed on a substrate, which is provided with a bond/seed layer,
(14) FIG. 13 shows the configuration from FIG. 12 diagonally from above,
(15) FIG. 14 shows a schematic representation of a configuration in which the resist applied to a substrate with the negative image is completely enclosed by an evaporated layer,
(16) FIG. 15 shows the configuration according to FIG. 14 following mechanical planarisation,
(17) FIG. 16 shows a schematic representation of a configuration in which the edge surfaces of negative structures of a resist material run obliquely and
(18) FIG. 17 shows the configuration according to FIG. 16 following a lift-off process for detaching the resist material.
(19) FIG. 1 shows a schematic representation of a substrate 1 on which a structured layer of an evaporation coating material, namely aluminium oxide, silicon dioxide, silicon nitride or titanium dioxide, is to be deposited by means of thermal evaporation, wherein plasma-enhanced electron beam evaporation is used. In the exemplary embodiment described here, the structured layer is produced with the help of a lift-off process described in greater detail below.
(20) FIG. 2 shows a schematic representation of the substrate 1 from FIG. 1, on which a negative image of microstructuring required for the layer to be deposited is applied in a photoresist 2 by means of known lithography.
(21) An evaporation coating material is then deposited by means of thermal evaporation, so that an evaporated layer 3 is produced in accordance with FIG. 3. In one embodiment, plasma-enhanced thermal electron beam evaporation is used in this case for layer deposition. The evaporated layer 3 is a single layer or multi-layered.
(22) During deposition of the dielectric layer, the substrate 1 is held at a substrate temperature that is lower than roughly 120 C., preferably lower than roughly 100 C. Deposition of the evaporation coating material is enhanced by plasma, for which the process gases oxygen and argon are used, for example. In a preparatory step, the surface onto which the evaporation coating material is to be deposited is pre-cleaned or conditioned using plasma comprising argon and oxygen. During the different intervals of time involved in depositing layer 3, the plasma used has different settings, particularly with regard to its gas composition and the plasma output, in order to produce the desired layer properties in the evaporated layer.
(23) FIG. 4 shows a schematic representation of the substrate 1 from FIG. 3, wherein the photoresist layer 2 is removed.
(24) Further exemplary embodiments are explained below with reference to FIGS. 5 to 17. In this case, the same reference numbers are used for the same features as in FIGS. 1 to 4.
(25) If the thermal evaporation is plasma-enhanced, a corresponding material and properties gradient can be achieved through the targeted variation of plasma parameters. Hence, for example, different compacting can be used within an evaporation coating material, so as to design the closing area hermetically, for example. The material and property gradient may be produced gradually in the form of a smooth transition (cf. FIG. 5) or abruptly by means of a sudden change in the evaporation material deposited, for example the application of a further material, which can also be deposited with the help of another process, or a sudden change in plasma parameters (FIG. 6). In this way, structured anti-reflex coatings can be produced by means of multiple applications of layers with different refraction indexes.
(26) FIGS. 5 and 6 each show a semi-finished product in which the resist layer 2 with the negative structure and the evaporated layer 3 are formed on the substrate 1, said evaporation layer being formed with a gradual or smooth material transition (cf. FIG. 5) or a sudden material transition (cf. FIG. 6). In accordance with FIG. 3, the structured evaporation layer may be exposed with the help of a removal process.
(27) FIG. 7 shows a schematic representation of a configuration in which structured evaporation layers 70, 71, 72 are formed on the substrate 1 by means of multiple additive structuring. A lift-off process was carried out multiple times. In one exemplary embodiment the structured layer 72 with a low optical refraction index is first deposited on the substrate 1, which is in an embodiment of silicon dioxide (SiO.sub.2). Next follows the structured deposition of the evaporation layer 70 of an evaporation coating material, which has a higher optical refraction index than the evaporation coating material in layer 72, for example aluminium oxide (Al.sub.2O.sub.3). The vapour evaporation layer 71, for example of a material which has a lower optical refraction index than the evaporation material in the layer 70, for example silicon dioxide, is finally deposited by means of new structured deposition. The evaporation layer 70 is completely enclosed in this case, so that an optical waveguide can be formed, for example.
(28) FIG. 8 shows a schematic representation of a configuration in which multiple evaporation layers 80, 81, 82 are deposited on the substrate 1 by means of multiple additive structuring, a structured coating thereby being formed. The multi-layered formation of the structured coating on the substrate 1 enables there to be multi-layered diffractive elements in one embodiment, for example. Of the plurality of evaporation layers 80, 81, 82, one, two or even all three evaporation layers may be made from the same material. It may also be provided, however, that two or even three different evaporation materials are used to produce the multiplicity of evaporation layers 80, 81, 82. In an alternative embodiment, it may be provided that one or two layers of the multi-layered coating are produced on the substrate 1 not by means of thermal evaporation but with the help of other production methods, for example sputtering or CVD. In addition, one of the multiple evaporation layers 80, 81, 82 may be a metallisation layer.
(29) FIG. 9 shows a schematic representation of a configuration in which a structured coating 90 is formed on the substrate 1 by means of additive structuring, wherein an intermediate area 91 in the structured coating 90 is provided with a material filling 92, which is produced by deposition of an electrically conductive and/or optically transparent material, for example. A buried strip conductor made from an electrically conductive material can thereby be formed, for example. To achieve this, a thin seed layer made from TiW/Cu, for example, is applied to the structured coating 90 and in the intermediate area 91 by means of sputtering. Following on from this, photoresist masking is carried out, which is freely structured over the intermediate area 91 to be filled. Next, copper is deposited up to the upper edge of the structured coating 90 in an electrogalvanic process. By exposing the masking and removing the seed layer on the structured coating 90, which is formed by means of thermal evaporation, the areas on the substrate 1 previously exposed, particularly the intermediate area 91, are filled with a copper strip conductor.
(30) FIG. 10 shows a schematic representation of a configuration in which an unstructured evaporation layer 100 is produced on the substrate 1. Strip conductors 101 formed on this from an electrically conductive material are at least partly covered by means of a structured evaporation layer 102, which is produced with the help of additive structuring. Electrical contacting is possible via an opening 103 in the structured evaporation layer 102.
(31) FIG. 11 shows a schematic representation of a substrate section, which shows how the electrical strip conductors in the configuration in FIG. 10 can be used for redistribution. Peripherally disposed contact pads 110 are wired across strip conductors 111 with larger, two-dimensional contact areas 112. The metal structures are applied to an unstructured base layer (cf. FIG. 10) and are covered by a layer which is only opened via the large contact areas 112. A configuration of this kind is advantageous particularly in conjunction with the flip-chip assembly of components.
(32) FIG. 12 shows a schematic representation of a configuration in which an evaporated layer 120, to which a seed or bond layer 121 is applied, is formed on the substrate 1 by means of additive structuring. For example, the seed or bond layer may be an adhesive layer, with which the configuration with the substrate 1 is adhered to a further substrate (not shown). Hence, a closed cavity can be formed between a first substrate with a frame structure and a second substrate. This may be used, for example, to encapsulate optically active areas on the substrate 1.
(33) A selective application of a seed layer to a frame structure of this kind may also be provided, the frame structure being made from copper, for example. When the two substrates are linked, the second substrate may have metallised areas made from tin, for example. The two substrates may then be joined by an eutectic bond. FIG. 13 shows the configuration in FIG. 12 diagonally from above.
(34) FIG. 14 shows a schematic representation of a configuration in which the resist 2 applied with the negative image to the substrate 1 is completely enclosed by an evaporated layer 140. In a process step following this, the composite layer on the substrate 1 is planarised by means of mechanical processing, for example lapping, grinding and/or polishing. The result for mechanical working is shown in FIG. 15. By dissolving away the residual mask 2 the structured evaporation layer 140 can be exposed.
(35) FIG. 16 shows a schematic representation of a configuration in which edge areas 160 of the negative structures of the resist material 2 run obliquely, so that in accordance with FIG. 17 edge areas 170 of the structured coating 3 are likewise formed obliquely, but with the reverse slant. The configuration according to FIG. 17 emerges as a result of the removal of the resist material 2. The edge areas 170 have a positive angle of bevel. A structured coating 3 designed in this manner is advantageous for subsequent metallisation, for example, in which one or more strip conductors (not shown) are guided via the edge areas 170.
(36) In conjunction with the exemplary embodiments described above, reference was made to the additive structuring, which is optionally carried out by means of the lift-off process. Alternatively, additive structuring may be carried out using shadow mask technology. One or several masks are customarily used in this case to shadow areas on the substrate being coated, which are to remain free of the evaporation coating material. Multiple use for depositing multi-layered, structured coatings is also possible in conjunction with shadow mask technology.
(37) The features of the invention disclosed in the preceding description, in the claims and in the drawing may be important both individually and also in any combination for the realisation of the invention in its different embodiments.
