A method for forming a polymer-substrate-based structure and a polymer-substrate-based structure

Abstract

A method for forming a polymer-substrate-based structure comprises depositing a metal layer on a polymer substrate and structuring the metal layer. The polymer substrate comprises a thickness of at least 100 µm.

Description

[0001] A method for forming a polymer-substrate-based structure and a polymer-substratebased structure

[0002] Field

[0003] Examples relate to the manufacturing of structures on a polymer substrate.

[0004] Background

[0005] Many processes for forming structures on semiconductor substrates or glass substrates are known.

[0006] There may be a demand for forming structures on alternative substrates.

[0007] Summary

[0008] This demand is a met by a method for forming a polymer-substrate-based structure in accordance with the independent claim. Advantageous embodiments are defined by the dependent claims.

[0009] An example relates to a method for forming a polymer-substrate-based structure. The method comprises depositing a metal layer on a polymer substrate and structuring the metal layer. The polymer substrate comprises a thickness of at least 100 pm and the metal layer may comprise more than 80 % silver, more than 80 % aluminum, more than 80 % chrome, more than 80 % gold, more than 80 % platinum, more than 80 % copper or more than 80 % of a steel alloy.

[0010] Brief description of the Figures

[0011] Some examples of apparatuses and / or methods will be described in the following by way of example only, and with reference to the accompanying figures, in which Fig. 1 shows a flow chart of a method for forming a polymer-substrate-based structure; and

[0012] Fig. 2-7 show schematic cross sections of a polymer-substrate-based structure during manufacturing.

[0013] Detailed Description

[0014] Some examples are now described in more detail with reference to the enclosed figures. However, other possible examples are not limited to the features of these embodiments described in detail. Other examples may include modifications of the features as well as equivalents and alternatives to the features. Furthermore, the terminology used herein to describe certain examples should not be restrictive of further possible examples.

[0015] Throughout the description of the figures same or similar reference numerals refer to same or similar elements and / or features, which may be identical or implemented in a modified form while providing the same or a similar function. The thickness of lines, layers and / or areas in the figures may also be exaggerated for clarification.

[0016] When two elements A and B are combined using an “or”, this is to be understood as disclosing all possible combinations, i.e. only A, only B as well as A and B, unless expressly defined otherwise in the individual case. As an alternative wording for the same combinations, "at least one of A and B" or "A and / or B" may be used. This applies equivalently to combinations of more than two elements.

[0017] If a singular form, such as “a”, “an” and “the” is used and the use of only a single element is not defined as mandatory either explicitly or implicitly, further examples may also use several elements to implement the same function. If a function is described below as implemented using multiple elements, further examples may implement the same function using a single element or a single processing entity. It is further understood that the terms "include", "including", "comprise" and / or "comprising", when used, describe the presence of the specified features, integers, steps, operations, processes, elements, components and / or a group thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, processes, elements, components and / or a group thereof. Fig. 1 shows a flow chart of a method for forming a polymer-substrate-based structure according to an example. The method 10 comprises depositing I l a metal layer on a polymer substrate and structuring 12 the metal layer. The polymer substrate comprises a thickness of at least 100 pm. The metal layer may comprise more than 80 % silver, more than 80 % aluminum, more than 80 % chrome, more than 80 % gold, more than 80 % platinum, more than 80 % copper or more than 80 % of a steel alloy.

[0018] By using a deposition and structuring method on a polymer substrate, a metal structure may be provided on a polymer substrate with high reliability and / or accuracy. By using a silverbased, aluminum-based metal layer, chrome-based metal layer, gold-based metal layer, platinum-based metal layer, copper-based metal layer or steel alloy-based metal layer, an opaque or optically dense metal layer may be provided even after running through the different manufacturing processes.

[0019] The polymer substrate may comprise or consist of any polymer. For example, the polymer substrate may comprise or consist of a thermoplastic polymer layer. The polymer substrate may comprise or consist of polymethyl methacrylate (PMMA), cyclo-olefin polymer (COP), polycarbonate (PC), or optical silicone. The polymer substrate may comprise a thickness of at least 100 pm (or at least 150 pm, at least 200 pm, at least 300 pm or at least 500 pm) and / or at most 5 mm (or at most 3 mm, at most 2 mm or at most 1 mm). The polymer substrate may comprise a single polymer layer or multiple polymer layers. The polymer substrate may be attached to a carrier during deposition 11 of the metal layer and / or structuring 12 the metal layer. The polymer substrate may be circular-shaped, disc-shaped or may comprise any other geometry. The polymer substrate may comprise a maximal lateral dimension (e.g. a diameter of a circular polymer substrate) of at least 2 cm (or at least 5 cm or at least 10 cm) and / or at most 50 cm (or at most 30 cm or at most 20 cm).

[0020] The metal layer may comprise or consist of silver, aluminum, chrome, gold, platinum, copper or a steel alloy. The metal layer may comprise more than 80 % (or more than 90 % or more than 95 %) silver, more than 80 % (or more than 90 % or more than 95 %) aluminum, more than 80 % (or more than 90 % or more than 95 %) chrome, more than 80 % (or more than 90 % or more than 95 %) gold, more than 80 % (or more than 90 % or more than 95 %) platinum, more than 80 % (or more than 90 % or more than 95 %) copper or more than 80 % (or more than 90 % or more than 95 %) of a steel alloy. The metal layer may comprise a thickness of at least 80 nm (or at least 100 nm or at least 120 nm) and / or at most 200 nm (at most 150 nm or at most 130 nm). The metal layer may have a thickness so that the metal layer is opaque or optically dense for a light with an operating wavelength of the polymer-substrate-based structure to be manufactured. For example, the polymer-substrate-based structure may be used for applications with visible light, infrared light and / or ultraviolet light. The metal layer may have a thickness so that the metal layer is opaque or optically dense for visible light, infrared light and / or ultraviolet light. The metal layer may be opaque or optically dense for light of a wavelength if no light or less than 90 % (or less than 95 % or less than 99 %) of incident light can penetrate the metal layer.

[0021] The metal layer may be deposited 11 on the polymer substrate by sputtering or any other suitable method for depositing a metal layer. For example, the metal layer may be deposited 11 at a rate of at most 2000 nm per minute. By using a low deposition rate, an optical dense metal layer may be obtained and / or a deformation of the polymer substrate may be avoided or kept low. The metal layer may be deposited 11 directly on the polymer substrate. The polymer substrate may comprise a flat surface at the start of the deposition of the metal layer. For example, the metal layer is deposited 11 on a flat surface of the polymer substrate.

[0022] The metal layer is structured 12 after deposition on the polymer substrate. For structuring the metal layer a patterned etch mask layer may be formed on the metal layer. The patterned etch mask layer may be formed by forming a photoresist layer on the metal layer, exposing the photoresist layer by patterned light, and partially removing the photoresist layer to obtain the patterned etch mask layer. The photoresist layer may be formed on the metal layer by dispensing photoresist by a spin coating device. The photoresist layer may comprise a thickness of at least 200 nm and / or at most 800nm. The photoresist layer may comprise or consist of diazo- naphthoquinone-based photoresist or any other suitable photoresist. The patterned light may be collimated light. The patterned light may have a wavelength of at least 365 nm and / or at most 436 nm and / or may be ultraviolet light. The patterned light may be generated from light of a light source (e.g. xenon lamp or mercury lamp) propagating through a lithographic mask (e.g. glass mask). The lithographic mask may be placed in close proximity to the photoresist layer during exposing the photoresist layer by light. For example, the lithographic mask may be placed at a distance from the photoresist layer of at most 50 pm (or at most 30 pm or at most 20 pm). The photoresist layer may be partially removed from the surface of the metal layer to obtain the patterned etch mask layer. For example, the etch mask layer may be removed from areas exposed or unexposed by light. The photoresist layer may be partially removed by applying developer liquid to the photoresist layer. For example, the etch mask layer is partially removed using a solvent-free developer liquid. For example, the developer liquid may be an aqueous alkaline developer or an acidic developer. For example, the polymer substrate may be protected by using a solvent-free developer liquid. The exposed photoresist layer may be additionally processed between the exposure and the partially removal (e.g. by heating or light exposure). For example, the exposed photoresist layer may be heated to a temperature of at least 50 °C and / or at most 70 °C (e.g. 60 °C) before the partial removal.

[0023] The metal layer may be structured 12 by etching portions of the metal layer being not covered by the patterned etch mask layer. The metal layer may be etched using an etchant comprising Iodide and Alkaline Salts of Iodide or perchloric acidin combination with ceric ammoinium nitrate. The metal layer may be etched at an etch rate of at most 1 pm per minute (or at most 800 nm per minute or at most 500 nm per minute). By using a low etch rate, the metal layer may be accurately removed from areas uncovered by the patterned etch mask layer.

[0024] The structured metal layer may comprise structures with a minimal dimension of at most 5 pm (or at most 2 pm or at most 1 pm). The minimal dimension may be the smallest lateral dimension of a portion of the structured metal layer.

[0025] The patterned etch mask layer may be removed after structuring 12 the metal layer. For example, the patterned etch mask layer may be removed after structuring the metal layer by using a solvent-free liquid. For example, the solvent-free liquid may be an aqueous alkaline liquid or a metal-ion-containing liquid. The polymer substrate may be protected by using a solvent- free liquid.

[0026] For example, the polymer-substrate-based structure to be formed may be an optical element (e.g. an aperture, a lens, a lens array or a micro-lens array). A maximal temperature occurring during forming the polymer-substrate-based structure may be at most a glass transition temperature of the material of the polymer substrate. For example, the maximal temperature occurring during forming the polymer-substrate-based structure may be at most 100 °C (or at most 90 °C or at most 120 °C). By keeping the temperature low during the manufacturing of the polymer-substrate-based structure, a change (e.g. deformation or warpage) of the polymer substrate may be avoided.

[0027] More details and aspects are mentioned in connection with the examples described above or below. The example shown in Fig. 1 may comprise one or more optional additional features corresponding to one or more aspects mentioned in connection with the proposed concept or one or more examples described above or below (e.g. Fig. 2-7).

[0028] Fig. 2-7 show schematic cross sections of a polymer-substrate-based structure during manufacturing. Fig. 2 shows a polymer substrate 21 after sputtering a metal layer 22 on the polymer substrate 21. After forming the metal layer 22, a photoresist layer 33 is formed on the metal layer 22 as shown in Fig. 3. Fig. 4 shows that portions of the photoresist layer 33 are exposed to light propagating through a lithographic mask 44. Afterwards, the exposed portions of the photoresist layer 33 are removed as shown in Fig. 5 resulting in a patterned photoresist layer 53. The metal layer 22 is then etched away from the surface of the polymer substrate 21 in areas not covered by the patterned photoresist layer 53, as shown in Fig. 6, resulting in the structured metal layer 62. The surface of the polymer substrate 21 is uncovered in the areas in which the metal layer 22 was removed. Further, the patterned photoresist layer 53 is removed after structuring the metal layer as shown in Fig. 7.

[0029] More details and aspects are mentioned in connection with the examples described above or below. The example shown in Fig. 2-7 may comprise one or more optional additional features corresponding to one or more aspects mentioned in connection with the proposed concept or one or more examples described above (e.g. Fig. 1) or below.

[0030] Some examples relate to a polymer-substrate-based structure formed by a method described above or below. For example, a polymer-substrate-based structure as schematically shown in Fig. 7 may be obtained. The polymer-substrate-based structure may comprise additional layers or structures.

[0031] In the following, some examples of the proposed concept are presented:

[0032] An example (e.g., example 1) relates to a method for forming a polymer-substrate-based structure, the method comprising depositing a metal layer on a polymer substrate, wherein the polymer substrate comprises a thickness of at least 100 pm, wherein the metal layer comprises more than 80 % silver, more than 80 % aluminum, more than 80 % chrome, more than 80 % gold, more than 80 % platinum, more than 80 % copper or more than 80 % of a steel alloy, and structuring the metal layer.

[0033] Another example (e.g., example 2) relates to a previous example (e.g., example 1) or to any other example, further comprising that the metal layer is deposited directly on the polymer substrate.

[0034] Another example (e.g., example 3) relates to a previous example (e.g., one of the examples 1-

[0035] 2) or to any other example, further comprising that the metal layer is deposited by sputtering the metal layer on the polymer substrate.

[0036] Another example (e.g., example 4) relates to a previous example (e.g., one of the examples 1-

[0037] 3) or to any other example, further comprising forming a patterned etch mask layer on the metal layer.

[0038] Another example (e.g., example 5) relates to a previous example (e.g., example 4) or to any other example, further comprising that forming the patterned etch mask layer comprises forming a photoresist layer on the metal layer, exposing the photoresist layer by patterned light, partially removing the photoresist layer to obtain the patterned etch mask layer.

[0039] Another example (e.g., example 6) relates to a previous example (e.g., one of the examples 4-

[0040] 5) or to any other example, further comprising that the photoresist layer is partially removed using a solvent-free developer liquid.

[0041] Another example (e.g., example 7) relates to a previous example (e.g., one of the examples 4-

[0042] 6) or to any other example, further comprising that the photoresist layer is a diazonaphthoqui- none-based photoresist layer.

[0043] Another example (e.g., example 8) relates to a previous example (e.g., one of the examples 4-

[0044] 7) or to any other example, further comprising that the metal layer is structured by etching portions of the metal layer uncovered by the patterned etch mask layer. Another example (e.g., example 9) relates to a previous example (e.g., one of the examples 4- 8) or to any other example, further comprising that the metal layer is etched at an etch rate of at most 1 pm per minute.

[0045] Another example (e.g., example 10) relates to a previous example (e.g., one of the examples 4-9) or to any other example, further comprising removing the patterned etch mask layer using a solvent-free liquid after structuring the metal layer.

[0046] Another example (e.g., example 11) relates to a previous example (e.g., one of the examples 4-10) or to any other example, further comprising exposing the patterned etch mask layer after structuring the metal layer by ultraviolet light.

[0047] Another example (e.g., example 12) relates to a previous example (e.g., one of the examples 1-11) or to any other example, further comprising that the metal layer comprises a thickness of at least 80 nm and at most 200 nm.

[0048] Another example (e.g., example 13) relates to a previous example (e.g., one of the examples 1-12) or to any other example, further comprising that the polymer substrate is a thermoplastic polymer layer.

[0049] Another example (e.g., example 14) relates to a previous example (e.g., one of the examples 1-13) or to any other example, further comprising that the polymer substrate comprises a polymethyl methacrylate (PMMA), cyclo-olefin polymer (COP), polycarbonate (PC), or optical silicone.

[0050] Another example (e.g., example 15) relates to a previous example (e.g., one of the examples 1-14) or to any other example, further comprising that the polymer substrate is disc-shaped.

[0051] Another example (e.g., example 16) relates to a previous example (e.g., one of the examples 1-15) or to any other example, further comprising that the polymer substrate comprises a maximal lateral dimension of at most 50 cm and at least 2 cm. Another example (e.g., example 17) relates to a previous example (e.g., one of the examples 1-16) or to any other example, further comprising that the metal layer is deposited on a flat surface of the polymer substrate.

[0052] Another example (e.g., example 18) relates to a previous example (e.g., one of the examples 1-17) or to any other example, further comprising that maximal temperature occurring during forming the polymer-substrate-based structure is at most a glass transition temperature of the material of the polymer substrate.

[0053] Another example (e.g., example 19) relates to a previous example (e.g., one of the examples 1-18) or to any other example, further comprising that the polymer-substrate-based structure is an optical element.

[0054] Another example (e.g., example 20) relates to polymer-substrate-based structure formed by a method according to a previous example (e.g., one of the examples 1-19).

[0055] The aspects and features described in relation to a particular one of the previous examples may also be combined with one or more of the further examples to replace an identical or similar feature of that further example or to additionally introduce the features into the further example.

[0056] It is further understood that the disclosure of several steps, processes, operations or functions disclosed in the description or claims shall not be construed to imply that these operations are necessarily dependent on the order described, unless explicitly stated in the individual case or necessary for technical reasons. Therefore, the previous description does not limit the execution of several steps or functions to a certain order. Furthermore, in further examples, a single step, function, process or operation may include and / or be broken up into several sub-steps, - functions, -processes or -operations.

[0057] If some aspects have been described in relation to a device or system, these aspects should also be understood as a description of the corresponding method. For example, a block, device or functional aspect of the device or system may correspond to a feature, such as a method step, of the corresponding method. Accordingly, aspects described in relation to a method shall also be understood as a description of a corresponding block, a corresponding element, a property or a functional feature of a corresponding device or a corresponding system.

[0058] The following claims are hereby incorporated in the detailed description, wherein each claim may stand on its own as a separate example. It should also be noted that although in the claims a dependent claim refers to a particular combination with one or more other claims, other examples may also include a combination of the dependent claim with the subject matter of any other dependent or independent claim. Such combinations are hereby explicitly proposed, unless it is stated in the individual case that a particular combination is not intended. Further- more, features of a claim should also be included for any other independent claim, even if that claim is not directly defined as dependent on that other independent claim.

Claims

Claims1. A method for forming a polymer-substrate-based structure, the method comprising: depositing a metal layer on a polymer substrate, wherein the polymer substrate comprises a thickness of at least 100 pm, wherein the metal layer comprises more than 80 % silver, more than 80 % aluminum, more than 80 % chrome, more than 80 % gold, more than 80 % platinum, more than 80 % copper or more than 80 % of a steel alloy; and structuring the metal layer.

2. The method of claim 1, wherein the metal layer is deposited directly on the polymer substrate.

3. The method of claim 1, wherein the metal layer is deposited by sputtering the metal layer on the polymer substrate.

4. The method of claim 1, further comprising forming a patterned etch mask layer on the metal layer.

5. The method of claim 4, wherein forming the patterned etch mask layer comprises: forming a photoresist layer on the metal layer; exposing the photoresist layer by patterned light; partially removing the photoresist layer to obtain the patterned etch mask layer.

6. The method of claim 4, wherein the photoresist layer is partially removed using a sol- vent-free developer liquid.

7. The method of claim 4, wherein the photoresist layer is a diazonaphthoquinone-based photoresist layer.

8. The method of claim 4, wherein the metal layer is structured by etching portions of the metal layer uncovered by the patterned etch mask layer.

9. The method of claim 8, wherein the metal layer is etched at an etch rate of at most 1 pm per minute.

10. The method of claim 4, further comprising removing the patterned etch mask layer using a solvent-free liquid after structuring the metal layer.

11. The method of claim 4, further comprising exposing the patterned etch mask layer after structuring the metal layer by ultraviolet light.

12. The method of claim 1, wherein the metal layer comprises a thickness of at least 80 nm and at most 200 nm.

13. The method of claim 1 , wherein the polymer substrate is a thermoplastic polymer layer.

14. The method of claim 1, wherein the polymer substrate comprises a polymethyl methacrylate (PMMA), cyclo-olefin polymer (COP), polycarbonate (PC), or optical silicone.

15. The method of claim 1, wherein the polymer substrate is disc-shaped.

16. The method of claim 1, wherein the polymer substrate comprises a maximal lateral dimension of at most 50 cm and at least 2 cm.

17. The method of claim 1, wherein the metal layer is deposited on a flat surface of the polymer substrate.

18. The method of claim 1, wherein maximal temperature occurring during forming the polymer-substrate-based structure is at most a glass transition temperature of the material of the polymer substrate.

19. The method of claim 1, wherein the polymer-substrate-based structure is an optical element.

20. A polymer-substrate-based structure formed by a method according to claim 1.

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