A method for manufacturing a multi-domed structure

Abstract

A method for manufacturing a plurality of domes (26) is based on providing a carrier (2) having one or more chambers (6) and a plurality of openings (14) arranged on a first carrier side (10) of the carrier (2). The openings (14) communicate with the one or more chambers (6) of the carrier (1), and each opening (14) is framed by lateral walls (8) of the carrier (2). A film (16) having a first film side (18) and a second film side (20) to the first carrier side (10) by connecting the second film side (20) to the lateral walls (8). Thereby the one or more chambers (8) is / are closed hermetically. The film (16) is locally deformed at the openings (14) by means of a pressure difference between the first film side (18) and the one or more chambers (6). Finally, the film (16) is hardened, thereby forming the domes (26) at the open- ings. (14). A filler layer (32) may be applied to the first film side (18) for forming lenses.

Description

[0001] A method for manufacturing a multi-domed structure

[0002] Technical Field

[0003] The invention relates to a method for manufacturing a plurality of domes. It also relates to the use of this method for manufacturing various devices, such as lenses, domed mirrors, or light detectors and / or light sources with lenses or mirrors.

[0004] Background Art

[0005] Small, domed structures may, e.g., be used for the manufacturing of lenses or curved mirrors. Typically, casting is used to manufacture such components. However, casting may be inefficient or difficult, in particular when there is a need to precisely align the domed structures or to generate small, precise structures.

[0006] Disclosure of the Invention

[0007] The problem to be solved is to provide an efficient method for the precise manufacturing of a plurality of domes.

[0008] This problem is solved by the method of claim 1. Accordingly, the method for manufacturing a plurality of domes comprises at least the following:

[0009] - Providing a carrier having one or more chambers and a plurality of openings arranged on a first carrier side of the carrier. The openings communicate with the chamber(s) of the carrier. Each opening is framed, i.e., at least partially surrounded, in particular fully surrounded, by lateral walls. The lateral walls form part of the carrier.

[0010] - Providing a film having a first film side and a second film side.

[0011] - Laminating the film to the first carrier side by connecting the second film side to the lateral walls. In this step, the one or more chambers are closed hermetically, i.e., they now form one or more closed volumes.

[0012] - Locally deforming the film at the locations of the openings by means of a pressure difference between the first film side and the one or more chambers. The pressure difference exerts a force on the film, deforming it.

[0013] - Hardening the deformed film, thereby forming said domes at the openings. By hardening the film, the deformations created by the pressure difference of the previous step are made permanent and will, at least partially, be maintained even in the absence of the pressure difference.

[0014] From the point of view of the chambers, the domes may be convex or concave. Concave domes may be formed when, while deforming the film, the pressure on the first film side is larger than the pressure in the one or more chambers. Convex domes may be formed when, while deforming the film, the pressure on the first film side is smaller than the pressure in the one or more chambers

[0015] To more safely secure the film against the carrier, it may, when being laminated to the first carrier side, be bonded to the lateral walls. In this context, "bonding" is to be understood as a connection sufficiently strong to hold the film against the carrier while locally deforming the film.

[0016] In order to generate a defined pressure inside the hermetically closed chamber(s), at least the first carrier side of the carrier and the second film side of the film may be placed in a first cavity, and a pressure pl different from ambient pressure is established in the first cavity. The first carrier side and the second film side are then joined for lamination, thereby basically "trapping" the pressure pl in the chamber(s) of the carrier.

[0017] Pressure pl may be below ambient pressure, in particular by at least 10%. This makes it easier to subsequently handle the laminated assembly of the carrier and the film because ambient pressure will push the film against the carrier even if the lamination bond is only weak.

[0018] Alternatively, pressure pl may be above ambient pressure. In that case, if the carrier with the film is subjected to ambient pressure, an undesired release of the film may, e.g., be prevented by adhesively joining the film and the carrier.

[0019] For easier film handling, in particular if the film is thin, the film may be laminated to the first carrier side while it is still arranged on a liner. The liner is removed after laminating the film but before locally deforming the film

[0020] For laminating the film to the first carrier side, the film and / or the carrier may be heated up to a lamination temperature Tl, thereby softening the film and / or the lateral walls for expediting the lamination.

[0021] For softening the film while it is locally deformed, the film may be heated to a deformation temperature T2.

[0022] In an embodiment, the deformation temperature T2 is at least 10°C higher than the lamination temperature Tl, thereby additionally softening the film for local deformation. For hardening the film, the film may be heated to a hardening temperature TH. The hardening temperature may, e.g., be equal to or higher than the deformation temperature.

[0023] In an efficient process, the method may comprise a heating phase during which the film is heated while it is deformed and hardened.

[0024] For simple processing, the film, before hardening, may be a prepolymer, and the process of hardening comprises curing the prepolymer. Hardening occurs after deforming the film. In particular, however, hardening may occur at least concurrently with deforming the film.

[0025] After hardening the film, a filler layer may be added to the first film side, thereby making the domes thicker. The filler layer may have, over each dome, non-constant thickness, which is particularly useful for creating refractive or diffractive optical elements, in particular for manufacturing lenses.

[0026] The present method maybe used for a various applications including, e.g., for manufacturing a plurality of lenses or for manufacturing a plurality of domed mirrors, in particular for manufacturing an array of lenses and / or an array of domed mirrors. In one embodiment, it can be used to manufacture an array of light sources or light detectors with lenses or mirrors.

[0027] The method may also be used for MEMS applications, where the top-side of a thick polymer layer should terminated with a flat surface, e.g., for coating it with a structured metal layer or another material with different mechanical properties. In this case, the disclosed method can be used to reduce the stress between the structured material and the underlying polymer. When structuring a metal on top of a thick, flat polymer layer, cracks may form in the metal and polymer due to stress. Furthermore, there can be substantial substrate warpage due to the stress formed between the thick polymer and the used base substrate (e.g. silicon). This stress can be reduced by forming most of the thick polymer layer from walls, e.g., in the form of honeycomb structures, and then covering those walls with a roofing comprising a thin polymer layer. The honeycomb structure will strongly reduce the warpage effect while the thin layer of polymer introduces less stress between the roofing polymer and the structured metal (or other material), which will result in a lower risk of cracking.

[0028] The controlled formation of the domed structures can be used to further reduce the stress between metal and polymer because the stress in comparison to a perfectly flat structure does not only form in-plane but can be additionally absorbed by out-of-plane components. At the same time, it is important to control the lamination and cross-linking procedure in the explained way since an uncontrolled processing may result in excessive doming, e.g. if the air entrapped within the laminate-roofed walls expands too strongly during the cross-linking process.

[0029] Hence, in an embodiment, the method comprises:

[0030] - Deforming the domes to have apexes facing away from the carrier.

[0031] - Connecting the flat cover layer to the domes at the first side of the film after hardening the film. The cover layer is connected to the apexes only. Hence, the apexes form the mounting points for the cover layer.

[0032] In particular, the method can further comprise adding metal structures to a side of the cover layer that faces away from the domes.

[0033] Brief Description of the Drawings

[0034] The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:

[0035] Fig. l is a schematic view of a carrier,

[0036] Fig. 2 shows the application of a film to the carrier,

[0037] Fig. 3 shows a lamination step,

[0038] Fig. 4 shows the removal of a liner,

[0039] Fig. 5 shows a curing step with a negative pressure difference,

[0040] Fig. 6 shows a curing step with a positive pressure difference,

[0041] Fig. 7 shows a carrier from the side,

[0042] Fig. 8 shows a carrier from the top,

[0043] Fig. 9 shows an alternative carrier from the top,

[0044] Fig. 10 shows a lamination cavity in a first step,

[0045] Fig. 11 shows a lamination cavity in a second step,

[0046] Fig. 12 shows another type of lamination process,

[0047] Fig. 13 shows an irradiation step,

[0048] Fig. 14 shows an example of how to apply a filler layer,

[0049] Fig. 15 shows a domed film with a filler layer,

[0050] Fig. 16 shows a step of releasing the domed film from the carrier,

[0051] Fig. 17 shows a manufacturing step for applying a domed structure over an array of light sources and / or light detectors or other integrated circuitry elements, Fig. 18 shows the light sources and / or light detectors integrated in a carrier,

[0052] Fig. 19 shows the domed structure over the array of light sources and / or light detectors,

[0053] Fig. 20 shows embodiments of lateral walls that support the formation of spherical domes,

[0054] Fig. 21 shows a step of locally irradiating the laminated film,

[0055] Fig. 22 shows a manufacturing step for non-spherical domes,

[0056] Fig. 23 illustrates the stacking of several domed structures,

[0057] Fig. 24 is a domed structure where individual domes have been separated,

[0058] Fig. 25 is a device having a cover layer mounted to the domes,

[0059] Fig. 26 shows the chambers and openings with passages,

[0060] Fig. 27 shows the formation of a filling hole,

[0061] Fig. 28 shows a way of filling the openings, and

[0062] Fig. 29 shows an embodiment having metal structures on the first film side.

[0063] Modes for Carrying Out the Invention

[0064] Definitions

[0065] A "prepolymer" a polymer precursor, e.g., a material comprising monomers or short-chain molecules that have not yet fully crosslinked.

[0066] "Curing" a prepolymer is the process of adding crosslinks to the prepolymer, thereby increasing the hardness of the prepolymer.

[0067] A layer, such as the film of the filler layer, is considered to be "transparent" if it has, perpendicularly to its layer plane, a transmission of at least 50%, in particular of at least 75%, over at least a subrange of the spectral range of 400 to 2000 nm.

[0068] General

[0069] Figs. 1 - 5 illustrate some steps of a process for manufacturing a plurality of domes.

[0070] Fig. 1 shows a carrier 2 having a substrate 4 and a plurality of chambers 6 separated by lateral walls 8. Carrier 2 has a first carrier side 10 and a second carrier side 12.

[0071] Substate 4 forms second side 12. The lateral walls 8 extend from substrate 4 to the first carrier side 10.

[0072] The lateral walls 8 form a plurality of openings 14 at first side 10, with each opening 14 communicating with one of the chambers 6.

[0073] The openings 14 may, e.g., be hexagonal, circular, rectangular, etc., as will be described in more detail below.

[0074] In a next step, as illustrated in Figs. 2 and 3, a film 16 having a first film side 18 and a second film side 20 is laminated to first carrier side 10 of carrier 2. In this process, second film side 20 is connected to the lateral walls 8, thereby hermetically closing the chambers 6.

[0075] Lamination may take place in a first cavity 21 at a lamination temperature T1 at a defined pressure pl, thereby defining the pressure inside the chambers 6. Since lamination hermetically seals the chambers 6, this pressure stays well- defined in the subsequent deformation steps (see below).

[0076] Film 16 may, for easier handling, be arranged on a liner 22, with liner 22 located at first film side 18. Such a liner simplifies the handling of film 16 in particular if film 16 may be very thin.

[0077] Details of the lamination process are provided in section "Lamination" below.

[0078] After lamination, and as shown in Fig. 4, liner 22 (if present) is removed.

[0079] Now, the assembly of carrier 2 and film 16 is brought into a second cavity 24 (Figs. 5, 6), at a defined pressure p2 and a defined deformation temperature T2. If deformation temperature T2 is not equal to lamination temperature Tl, the pressure pl(T2) in the chambers 6 will be different from the pressure pl(Tl) during lamination, but it is still accurately defined. It can be estimated using the ideal gas law equation p(T) V(T) = n k-T, (1) with p being the pressure, V being the volume, n being the mole number (amount of gas), k being the Boltzmann constant, and T being the temperature (in Kelvin).

[0080] Assuming that V is substantially constant, we have pl(T2) = pl(Tl) T2 / T1. (2) More accurate estimates can be obtained by taking into account that the volume V varies slightly with temperature T in view of the deformation of film 16 during local deformation.

[0081] For local deformation of film 16, p2(T2) is chosen to be different from pl(T2), such that the pressure difference p2 - pl is non-zero.

[0082] Fig. 5 shows the situation where p2 < pl, i.e., the pressure difference p2 - pl is negative. In this case, film 16 is deformed to form domes 26 that are, from the point of view of their adjacent chamber 6, convex, i.e., the domes are arching away from carrier 2.

[0083] Fig. 6 shows the situation where p2 > pl, i.e., the pressure difference p2 - pl is positive. In this case, film 16 is deformed to form domes 26 that are, from the point of view of their adjacent chamber 6, concave, i.e., the domes are arching into carrier 2.

[0084] To soften film 16 to expedite deformation, deformation temperature T2 may be higher than lamination temperature Tl, in particular by at least 10°C.

[0085] During deformation and / or after deformation of film 16, film 16 is hardened, e.g., by means of thermo-curing and / or light-induced curing, thereby stabilizing the domes 26 such that they persist even if the pressure difference p2 - pl subsequently changes.

[0086] In the following sections, various aspects of the present technique are described in more detail.

[0087] Film

[0088] In order to be used in the present method, it must be possible to laminate film 16 to carrier 2, to locally deform film 16, and to harden film 16 after or during local deformation.

[0089] Lamination to carrier 2 can be implemented using inherent film properties and / or an adhesive as described in the section Lamination below.

[0090] In one embodiment, film 16 may, at the start of the process (i.e., before lamination), be a prepolymer in solid form.

[0091] In this case, hardening is implemented by curing the prepolymer.

[0092] If the (starting) material of film 16 has a glass-transition temperature, the temperatures Tl and T2 may be chosen to be higher than or close to the glass-transition temperature, in particular within 10°C.

[0093] To ease deformation, the thickness d of film 16 may be at least 5 times smaller than a smallest diameter D of the openings 14. (In this context, the "smallest diameter" is a diameter of an opening that extends between opposite lateral walls 8 and intersects the geometric center of the opening.)

[0094] In absolute terms, the thickness d of film 16 may, e.g., be smaller than 100 pm, in particular smaller than 10 pm, which again makes deformation easier.

[0095] One example of a suitable type of film is ADEX by DJ MicroLaminates, which is a i-line sensitive negative dry film epoxy photoresist. For example, ADEX-R with a thickness of, e.g., 5 micrometers may be used.

[0096] For this material, the lamination temperature T1 may, e.g., be chosen between 50 and 70°C.

[0097] After lamination, liner 20 is removed and film 16 is irradiated at a wavelength of approximately 365 nm (i-line) for activating subsequent crosslinking. Then, film 16 is locally deformed as shown in Figs. 5 and 6 while being heated to at least 85°C for curing. During the curing step the polymer will first cross-link wherever it was previously exposed. However, for a short period of time, the sudden increase in temperature will result in a softening of the polymer, which does promote the deformation. The deformation is quickly fixed, though, as the polymer cross-links within few minutes.

[0098] Another embodiment comprises the use of a temperature-curing polymer like BCB (e.g. Cylotene 3000 series of DuPont). Such polymer precursor solutions can be formed as films on a liner by processes known by those skilled in the art. This film may then be laminated at the appropriate temperature or prior to lamination but after removing the liner, be exposed to elevated temperature prior to lamination, to reach a desired cross-linking state.

[0099] After lamination, the liner may be removed, and the carrier 2 may be introduced in a chamber with controlled pressure p2 and temperature T2. In the case of the mentioned polymer, the temperature T2 should eventually reach >200°C to fully cross-link the polymer. However, to assist better process-control the temperature T2 may be ramped up over time such that the polymer does not get too soft. Essentially, the temperature may be ramped up such that it follows the increased glasstransition temperature for the increasingly cross-linked film. Also, pressure p2 may be adapted during this process. Once the temperature reaches >150°C, in the particular case of this polymer, further curing may be executed under inert conditions, i.e., under exclusion of oxygen. The curing procedure may proceed for a duration in the range of a day or more. Carrier

[0100] Figs. 7 and 8 show examples of carrier 2 as they can be used with the current method. Here, the lateral walls 8 separate the chambers 6 from each other in a gas-tight manner.

[0101] The lateral walls 8 stand on substrate 4, and substrate 4 closes the chambers 6 towards the second carrier side 12.

[0102] The openings 14 lie in a common, flat plane at first carrier side 10.

[0103] As can be seen from Fig. 8, the lateral walls 8 may be arranged in a hexagonal pattern for forming the chambers 6 and the openings 14. Such a pattern has high mechanical stability.

[0104] The minimum diameter D of the openings 14 may be in a range of 5 micrometers.

[0105] The height H of the chambers 6 is at least 3 micrometers, thereby trapping enough gas in the chamber (after lamination) such that the formation of the domes 26 contain enough gas to make the film deformation easier.

[0106] For sufficient stability, the thickness of the lateral walls 8 may, e.g., be at least 1 micrometer. On the other hands, too thick walls may generate mechanical strain in the carrier under temperature variations, and therefore, the lateral walls 8 may, e.g., have a thickness of less than its height.

[0107] As mentioned, the chambers 6 can be separated, by means of the lateral walls 8, in a gas-tight manner such that, after lamination, the chambers 6 are hermetically sealed from teach other.

[0108] Hence, in one embodiment, carrier 2 comprises a plurality of chambers 6 separated by the lateral walls 8. In this case, each opening 14 may be connected to one chamber 6 only.

[0109] In an alternative embodiment, at least some of the lateral walls may have passages, such as illustrated, by way of example, at reference numbers 30a or 30b of Fig. 8 in order to interconnect the chambers, or several subsets of the chambers, and forming one or more larger chambers. Such interconnections help to equalize the pressure between the openings 14, thereby allowing for a more homogeneous formation of domes 26.

[0110] For more details, see the section "Passages in the Lateral Walls" below.

[0111] Hence, in another embodiment, several of the openings 14 may be connected to the same chamber 6. In this case, carrier 2 may even comprise a single chamber 6 only. In the embodiments shown so far, the lateral walls 8 form a hexagonal pattern. However, and as mentioned, different geometries may be used.

[0112] For example, Fig. 9 shows walls 8 forming a rectangular pattern, with the chamber 6 and the openings 14 being rectangular.

[0113] Substrate 4 may be a semiconductor substrate, which, e.g., allows forming integrated circuit elements therein, which then can be aligned precisely with the lateral walls 8 and therefore with the domes (see examples in section “Applications” below). The alignment between the integrated circuit elements may be better than a tenth of the minimum diameter of the openings, thereby aligning the circuit elements with the domes.

[0114] In other embodiments, substrate 4 may, e.g., comprise glass and / or a polymer.

[0115] The lateral walls 8 may be directly etched into substrate 4. For example, if substrate 4 is of silicon, SF6 and a Bosch process may be used for manufacturing the lateral walls 8.

[0116] In another embodiment, the lateral walls 8 may be of a material different from substrate 4. For example, they may be of a photoresist, such as SU8, which has been structured by means of photolithography.

[0117] Lamination

[0118] In the lamination process, the one or more chambers 6 are closed hermetically from the environment by creating a connection between film 16 and the lateral walls 8.

[0119] This can, e.g., be implemented at an elevated lamination temperature Tl, i.e., film 16 and / or carrier 2 are heated to this lamination temperature Tl. T1 may be, e.g., between 30°C and 100°C. As mentioned, for ADEX, lamination temperature Tl may, e.g., be between 50°C and 70°C, e.g., at 55°.

[0120] In more general terms, if film 16 has a glass transition temperature, lamination temperature Tl may be within 20°C, in particular within 10°C, of this glass transition temperature. If it is much lower, film 16 may not stick well to the lateral walls 8. If it is much larger, it will become hard to deposit film 16 homogeneously on carrier 4 as the film 16 will start to flow by capillarity.

[0121] In another embodiment, an adhesive between film 16 and the lateral walls 8 may be used to support lamination.

[0122] As mentioned, for controlling the pressure pl during lamination, carrier 2 and film 16 may be placed in a first cavity 21.

[0123] Figs. 10 and 11 show an example for a setup for performing lamination. It comprises the first cavity 21 and a third cavity 32 with a flexible wall 34 between them. The pressure in each of the cavities 21, 32 may be controlled individually, or at least the pressure in one of them may be controlled in order to control the pressure difference p2 - pl.

[0124] Film 16 is mounted to and along flexible wall 34 as shown in Fig. 10, with first film side 18 facing flexible wall 34. Carrier 2 is placed in cavity 21, with second film side 20 located at a distance M to first carrier. Distance M may be sufficiently large to prevent film 16 from touching carrier 2 while the flexible wall 34 is in its substantially flat configuration. However, distance M should not be too large in order to simplify the procedure described in the following. Hence, M may be larger than L / 100 but smaller than L / 10, with L being a minimum diameter of carrier 2 but in general not larger than 5 cm and not smaller than 0.5 mm.

[0125] In a next step, and as illustrated in Fig. 11, membrane 34 is deformed towards carrier 2, thereby pushing film 16 against carrier 2.

[0126] The deformation of membrane 34 towards carrier 2 may be generated by mechanical means, i.e., by applying a body against the side of flexible wall 34 that faces away from first cavity 21. In the embodiment of Fig. 11, however, membrane 34 is deformed by controlling the pressure p3 in third cavity 32, thereby generating a gas pressure difference between the pressure p3 at side of flexible wall 34 that faces away from first cavity 21 (i.e., the pressure in third chamber 32) and the pressure pl in first cavity 21, with p3 > pl.

[0127] By gradually increasing pressure p3, the procedure of Fig. 11 allows to generate, in controlled manner, a contact between film 16 and carrier 2 that starts at one location, e.g., close to the center of carrier 2, and then spreads outwards, thereby avoiding "blisters" and trapping the same amount of gas in each chamber 6.

[0128] To avoid damaging film 16, the pressure difference p3 - pl may be limited to, e.g., 1 bar.

[0129] Fig. 12 shows an alternative method for lamination. Here, roll-on lamination is used, where a roller 36 pushes a section of film 16 against carrier 2 as the carrier is moved relative to roller 36 past the roller. In this case, all the components (roller 36, film 16, and carrier 2) may be placed in first cavity 21 at a controlled pressure pl.

[0130] In the embodiments of Figs. 10 - 12, all of carrier 2 and all of film 16 is placed in first cavity 21. However, it is sufficient to place only first carrier side 10 and second film side 20 in first cavity 21 such that the openings 14 are at the pressure pl. Local Deformation and Hardening

[0131] If film 16 needs to be optically activated before curing, it may, as illustrated in Fig. 13, be irradiated. As mentioned, such an irradiation is, e.g., used for activating films of ADEX.

[0132] The steps of local deformation and hardening are shown in Figs. 5 and 6. In particular, and as mentioned, the laminated film 16 and carrier 2 may be placed in a second cavity 24 at a deformation temperature T2 and a pressure p2. The pressure difference p2 - pl locally deforms film 16 for forming the domes 26.

[0133] If p2 is ambient pressure, cavity 24 may be dispensed with and, e.g., a hotplate or infrared radiation may be used for setting temperature T2.

[0134] The local deformation of film 16 and its curing may be implemented as individual steps or as two overlapping steps, or in a common step.

[0135] For example, if film 16 is thermo-curing, raising temperature T2 will typically first soften the film, allowing for the domes 26 to form quickly. Crosslinking, which sets in at T2, is a slower process.

[0136] In more general terms, film 16 may be heated to a deformation temperature T2 in order to locally deform it.

[0137] This deformation temperature T2 may be larger than the lamination temperature Tl, in particular by at least 10°C.

[0138] A typical deformation temperature depends on the material of film 16 and may, e.g., be at least 50°C. It should not exceed a temperature where film 16 melts and / or is damaged. For many materials, in particular prepolymers, it should be no more than 150°C.

[0139] For thermo-curing, film 16 is heated to a hardening temperature T3. This may be the same temperature as the deformation temperature T2, or it may be an even higher temperature. If temperature T3 is higher than T2, the increase in temperature may follow a defined ramp, e.g., a linear increase in temperature over time.

[0140] If film 16 is a prepolymer, hardening may comprise a curing of the prepolymer, i.e., crosslinking the prepolymer. This curing may be based on thermocuring and / or on light-induced curing:

[0141] - Thermo-curing includes, as described, heating film 16 to the hardening temperature T3 and leaving it at this temperature for a time sufficient to harden it. An example for a thermo-curing film (with additional irradiation activation) is ADEX as mentioned above.

[0142] - Light-induced curing includes irradiation of film 16 with curing radiation, such as shown in Fig. 13. An example for a film that can be cured by light is Ordyl SY 300, although also in this case a hard-cure can be used to improve mechanical properties after UV exposure.

[0143] Other film materials may be hardened using a drying process.

[0144] Filler Layer

[0145] The processes shown so far result in a film forming a plurality of domes, but the thickness of the film changes, over each dome, only weakly. For some applications (see below) this is sufficient. For other applications, such as refractive or diffractive optical applications, the thickness variation over dome should be larger.

[0146] This can be achieved by adding a filler layer to first film side 18 after curing, with the filler layer having non-uniform thickness over each dome.

[0147] An example is illustrated in Figs. 14 and 15.

[0148] Here, the filler layer is applied to first film side 18, e.g., by first laminating a layer 62 first surface 18 of the locally deformed and hardened film 16. Layer 62 may, e.g., again be arranged on a liner 64 and be applied in a process as shown in Fig. 11 or 12.

[0149] Layer 62 is then reshaped to fill the recesses formed by the or between the domes 26. This may, e.g., be implemented by heating layer 62 in order to at least partially liquefy it and to make it fill recesses in first surface 18 of the locally deformed and hardened film 16. Then, layer 62 is cooled down to solidify it.

[0150] Liner 64 may be removed after lamination or after reshaping filler layer 62.

[0151] Filler layer 62 has a first filler side 66 facing away from the domes 26 and a second filler side 68 facing the domes 26. The second filler side 68 is shaped to fit the domes 26, i.e., the shape of the second filler side 68 matches the shape of the first film side 18.

[0152] First filler side 66 may, on the other hand, be flat.

[0153] In another embodiment, filler layer 62 may, e.g., be formed by a spin coating process.

[0154] The resulting combination of filler layer 62 and film 16 may be used to form concave or convex shapes. For example, the embodiment of Fig. 15 forms convex shapes. Other examples are described in the following "Applications".

[0155] Filler layer 62 may be applied under vacuum conditions, thereby reducing the risk of forming gas pockets between filler layer 62 and the domes 26. Hence, in more general terms, the filler layer 62 may be added to the first film side 18 under vacuum conditions. The temperature for applying filler layer 62 may be higher than the temperature used for applying film 16 to carrier 2 because the goal of applying the filler layer is to make it adapt to the surface of the domes 26. When using ADEX, for example, a temperature of around 75°C may be used.

[0156] Passages in the Lateral Walls

[0157] As mentioned in the section "Carrier" above, the openings 14 may be interconnected by passages 30a, 30b (cf. Fig. 8), e.g., in order to equalize the pressure between the openings 14.

[0158] Such passages may, however, also be used for other purposes, such as for filling the openings 14 and chamber(s) 6, respectively, after forming the domes 26.

[0159] In the embodiment of Fig. 26, passages 30c through the lateral walls 8 form a defined path between the openings 14, such that following the hardening of the film 16, a liquid polymer precursor may be introduced into the openings 14 to fill them.

[0160] To execute this, and as shown in Figs. 27 and 28, after curing of film 16, at least one hole 58 may be formed, e.g., at a single position or several positions, in the cured film 16. The at least one hole 58 is used to introduce the liquid polymer precursor, e.g., under vacuum conditions (p = 0) that cause the polymer precursor to be sucked through the openings 14.

[0161] If the filling is not executed under vacuum, at least one second hole may be formed within the cured film 16 to degas the chamber(s) 6 while filling.

[0162] The polymer precursor may then be cured by whatever means necessary. In an embodiment, the polymer precursor is solvent-free.

[0163] The filling and degassing holes 58 inside the cured film 16 may be formed by simple development if a photocurable polymer was used for film 16 that can simply be developed at the selected position, or laser irradiation may be used to form the hole(s) 58, or any other suitable method may be used.

[0164] Alternatively, holes 60 (as indicated by dotted lines in Fig. 27) in substrate 4 of carrier 2 may be used, in which case the holes 60 would need to be hermetically sealed during the process of dome-formation and only be opened following the curing of the film 16 to fill in the liquid polymer.

[0165] In more general terms, passages 30a, 30b, 30c may be located in the lateral walls 8 to interconnect at least some of the openings 14. Such passages may, as described here and above, provide more homogeneous pressure in the openings, and / or they may be used to fill the openings 14 with a liquid.

[0166] In this case, the method may further comprise: - after hardening the film 16, filling a liquid into the openings 14 using the passages 30a, 30b, 30c, and

[0167] - hardening the liquid.

[0168] To ease filling the liquid into the openings 14, the method may comprise using filling and / or degassing holes 58, 60 arranged in the film 16 and / or the substrate 4 of the carrier 2 for filling the liquid into the openings 14.

[0169] In this case, the passages 30a, 30b, 30c may form at least one path between the filling holes and the degassing holes.

[0170] Applications

[0171] The present method has various applications.

[0172] In one class of applications, it can be used for forming a plurality of lenses, with each dome forming a lens.

[0173] In this case, film 16 and (if used) filler layer 62, may be transparent as defined above.

[0174] For example, the embodiment of Fig. 15 forms a plurality of planoconcave lenses 40.

[0175] The lenses 40, be they convex or concave, may be used in-situ on carrier 2 (examples follow below), or they may be separated from carrier 2 to be used without carrier.

[0176] Fig. 16 illustrates a process for separating the lenses 40 (or, in more general terms, the domes 26 in other applications) from carrier 2. In this case, the stack of carrier 2 and film 16 (optionally including filler layer 62) is brought into a bath 42 that separates the two components. This process can be supported by coating the lateral walls 8 and / or film 16, prior to lamination, with a release layer, e.g., OmniCoat by MicroChem or kayakuam.com, e.g., by means of spin-coating. In this case, bath 42 may, e.g., comprise the agent 1 -Methyl -2 -Pyrrolidone (NMP).

[0177] Hence, in more general terms, the present method may comprise the step of, after hardening, separating film 16 from the lateral walls 8.

[0178] Other applications, however, may be used for manufacturing devices where the final device includes both, film 16 as well as carrier 2.

[0179] In a particularly useful combination, carrier 2 may comprise, at least in some of the chambers 6, a light source (e.g., an LED) and / or a light detector 44 (e.g., a photodiode) and or other integrated circuitry, in which case the domed structure may form optics to process light from the light source or to the light detector or the other circuitry, respectively. An example for manufacturing a device of this type is shown in

[0180] Figs. 17 - 19.

[0181] Here, an array of light sources and / or light detectors and / or other circuitry elements 44 may be integrated on substrate 4 of future carrier 2, as shown in Fig. 17.

[0182] The lateral walls 8 are formed by first applying a photoresist layer 46, e.g., of SU-8, on top of the light sources and / or light detectors 44. Photoresist layer 46 may be arranged on a liner 48,

[0183] After removal of (optional) liner 48, the photoresist 46 is patterned to form the lateral walls 8, e.g., using photolithography as known to the skilled person, as shown in Fig. 18.

[0184] Next, film 16 and, optionally, a filler layer 62, may be added to the lateral walls 8 using the techniques described herein. In the embodiment of Fig. 19, each dome forms a concave lens.

[0185] Hence, in more general terms, the method may comprise the steps of providing the carrier by

[0186] - providing a substrate 4 with light sources and / or light detectors and / or other circuitry elements 44 integrated thereon, and

[0187] - forming the lateral walls 8 on the substrate 4.

[0188] In some embodiments, it may be desired to form spherical domes, e.g., for manufacturing spherical lenses. While lenses built on a hexagonal pattern of lateral walls 8 may, in first approximation, be spherical, the hexagonal shape of the opening will cause film 16 to slightly deviate from a spherical design.

[0189] For manufacturing more spherical domes, the lateral walls may be provided with fingers 46, as shown in Fig. 20 A, that reach into opening 14 and end, approximately, in a circle 48. The fingers 46 may be evenly distributed over the circumference of opening 14, e.g., with their being at least N fingers, with N being the order of rotational symmetry of opening 14. The film 16 is laminated to the fingers 46.

[0190] In another embodiment, the openings 14 may be circular as illustrated in Fig. 20B. In this case, e.g., the lateral walls 8 may be circular as well.

[0191] In yet another embodiment, one or more columns may be placed in each of at least some of the openings 14 in order to change the shape of the dome, e.g., in order to create a doughnut-shaped dome. The columns may, e.g., stand on substrate 4. The film 16 is laminated to the columns. In some embodiments, it may be desired to more accurately control the local curvature of the dome 26 over each opening 14. This can, e.g., be implemented by using a material that can be cured by means of light irradiation.

[0192] In this case, the method may comprise the step of hardening film 16 by irradiating the film, at each opening 14, in inhomogeneous manner before or while deforming the film.

[0193] An example to do so is shown in Fig. 21, where a mask 50 is introduced between the curing light source and film 16. Mask 50 is structured to shadow part of each opening 14 while allowing for the passage of irradiating light in another part of each opening 14. This renders some parts of film 16 harder than others and, when the pressure difference p2 - pl is applied, as shown in Fig. 22, this will affect the curvature of the domes. Once the domes are fully formed, final curing may be performed on film 16 either by temperature or by homogeneous irradiation.

[0194] Even further shaping properties can be obtained by using gray-scale lithography, e.g., by laser-lithography, where essentially a random exposure profile can be created across the resist. Such processing can work well with resists such as SU8 or the mentioned ADEX above, where the exposure is done prior to hardening. Areas receiving a higher light dose will harden faster during the post-exposure bake than areas receiving less light.

[0195] Fig. 23 shows yet another application, similar to the one of Fig. 19, where several sets 26a, 26b domes 26 are arranged on top of each other.

[0196] This kind of structure may, e.g., be used to manufacture more complex optics that reduce aberrations and / or dispersive effects.

[0197] To manufacture a structure of the type of Fig. 23, in a first step, the first set 26a of domes 26 may be formed as described above. Then, the technique of Figs. 17, 18 may be used to manufacture a second tier of lateral walls 8' on the first side (top side of Fig. 23) of the first lateral walls 8, and then the second set 26b of domes 26 may be manufactured.

[0198] This process can be repeated to stack more than two sets of domes on top of each other.

[0199] Hence, the present method may comprise manufacturing a first set 26a of domes and then, on a side of the first set of domes 26a that faces away from carrier 2, a second set 26b of domes, in particular at a distance from the first set 26a of domes.

[0200] In the embodiments shown so far, the domes 26 are, after hardening, left in one assembly. Alternatively, and as illustrated in Fig. 24, lithographic masking can be used for segmenting film 16 above the lateral walls 8. A release process similar to the one illustrated in Fig. 16 may then be used for separating the domes 26, thereby, e.g., manufacturing a plurality of individual lenses. A release chemical, as described in respect to Fig. 16, may be used to expedite the process.

[0201] In another embodiment, instead of manufacturing lenses, the present method may be used to manufacture a plurality of domed mirrors. This this case, domes as shown in Fig. 5 or 6 may be formed and then be coated, on first film side 18, by a reflective coating.

[0202] In yet another embodiment, as illustrated in Fig. 25, the domes 26 can be used for attaching a cover layer 52, e.g., a polymer layer. Cover layer 52 may, e.g., be used as a substrate for further components, such as at least one metal structure 54 arranged on the side of cover layer 52 that faces away from the domes 26.

[0203] To attach cover layer 52, the domes 26 may be deformed to have apexes 56 facing away from carrier 2, i.e., the convex side of the domes 26 faces away from carrier 2. The apexes 56 form the points of contact between the domes 26 and the cover layer 52.

[0204] As described above, this type of design reduces stress in the structure.

[0205] In yet other embodiments, as shown in Fig. 29, metal structures 54 can directly applied to the first film side (outer side) 18 of the domes 26, e.g., using evaporation deposition or inkjet printing. By applying at least one metal structure 54 to the first film side 18, the metal structures 54 will be curved along the domes, which is found to reduce the risk of cracks, e.g., under thermal strain, in the metal structure^) 54 and / or the domes 26 as compared to some embodiments where the metal structures are applied to a flat substrate.

[0206] If the at least one metal structure 54 is applied after hardening the film 16, deformation of the film is easier and stress is further reduced.

[0207] Notes

[0208] While there are shown and described presently preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Claims

Claims1. A method for manufacturing a plurality of domes (26) comprising providing a carrier (2) having one or more chambers (6) and a plurality of openings (14) arranged on a first carrier side (10) of the carrier (2), wherein said openings (14) communicate with the one or more chambers (6) of the carrier (2), and wherein each opening (14) is framed by lateral walls (8) of the carrier (2), providing a film (16) having a first film side (18) and a second film side (20), laminating the film (16) to the first carrier side (10) by connecting the second film side (20) to the lateral walls (8), thereby hermetically closing the one or more chambers (6), locally deforming the film (16) at the openings (14) by means of a pressure difference between the first film side (18) and the one or more chambers (6), hardening the film (16), thereby forming said domes (26) at the openings (14).

2. The method of claim 1 wherein, while deforming the film (16), a pressure on the first film side (18) is larger than a pressure in the one or more chambers (6).

3. The method of claim 1 wherein, while deforming the film (16), a pressure on the first film side (18) is smaller than a pressure in the one or more chambers (6).

4. The method of any of the preceding claims wherein, when laminating the film (16) to the first carrier side (10), the film (16) is bonded to the lateral walls (8), thereby forming a connection that holds the film (16) against the carrier (2) while locally deforming the film (16).

5. The method of any of the preceding claims wherein laminating the film (16) comprises placing at least the first carrier side (10) of the carrier (2) and the second film side (20) of the film (16) in a first cavity (21) and establishing a pressurepl in the first cavity (21), wherein the pressure pl is different from ambient pressure, and joining the first carrier side (10) and the second film side (20).

6. The method of claim 5 wherein all of the carrier (2) is placed in the first cavity (21).

7. The method of any of the claims 5 or 6 comprising mounting the film (16) to a flexible wall (34) of the first cavity (21), with the second film side (20) at a distance to the first carrier side (10) and deforming the flexible wall (34), thereby pushing the film (16) against the carrier (2).

8. The method of claim 7 wherein the flexible wall (34) is deformed by generating a gas pressure difference (p3 - pl) between a side of the flexible wall (34) facing away from the first cavity (21) and the pressure pl.

9. The method of any of the claims 7 or 8 wherein the flexible wall is deformed by locally by applying a body against a side of the flexible wall (34) facing away from the first cavity (21).

10. The method of any of the claims 5 to 9 wherein the pressure pl is below ambient pressure, in particular by at least 10%.

11. The method of any of the preceding claims comprising laminating the film (16) to the first carrier side (10) while the film(16) is arranged on a liner (18), and removing the liner (18) after laminating the film (16) but before locally deforming the film (16).

12. The method of any of the preceding claims comprising heating at least one of the film (16) and the carrier (2) to a lamination temperature T1 for laminating the film (16) to the first carrier side (10).

13. The method of claim 12 wherein the lamination temperature T1 is at least 30°C, in particular no more than 100°C.

14. The method of any of the preceding claims comprising, for locally deforming the film (16), heating the film (16) to a deformation temperature T2.

15. The method of claim 14 and of any of the claims 12 or 13 wherein the deformation temperature T2 is at least 10°C higher than the lamination temperature Tl.

16. The method of any of the claims 14 or 15 wherein the deformation temperature T2 is at least 50°C and / or no more than 150°C.

17. The method of any of the preceding claims comprising, for hardening the film (16), heating the film (16) to a hardening temperature T3.

18. The method of claim 17 and of any of the claims 14 to 16 wherein the hardening temperature T3 is equal to or higher than the deformation temperature T2.

19. The method of any of the claims 14 to 16 and of any of the claims 17 or 18 comprising a heating phase during which the film (16) is heated while it is deformed and hardened.

20. The method of any of the preceding claims wherein the film (16), before hardening, is a prepolymer, and wherein hardening comprises curing the prepolymer.

21. The method of claim 20 wherein curing comprises at least one of thermo-curing and light-induced curing.

22. The method of any of the preceding claims further comprising the step of hardening the film (16) by irradiating the film (16), at each opening, in inhomogeneous manner before or while deforming the film (16).

23. The method of any of the preceding claims comprising the step of, after hardening, adding a filler layer (62) to the first film side (18).

24. The method of claim 23 wherein the filler layer (62) has a first filler side (36) facing away from the domes (26) and a second filler side (38) facing the domes (26), wherein the second filler side is shaped to fit the domes (26).

25. The method of claim 24 wherein the first filler side (36) is flat.

26. The method of any of the claims 23 to 25 wherein the filler layer (62) is transparent.

27. The method of any of the claims 23 to 26 wherein the filler layer (62) is added to the first film side (18) under vacuum conditions.

28. The method of any of the claims 23 to 27 comprising heating the filler layer (62), thereby at least partially liquefying it and making it fill recesses in the first film side (18).

29. The method of any of the preceding claims wherein the film (16) is transparent.

30. The method of any of the preceding claims wherein the carrier (2) comprises a plurality of chambers (6) separated by the lateral walls (8), and in particular wherein each opening (14) is connected to one chamber (6).

31. The method of any of the claims 1 to 29 wherein several of the openings (14) are connected to the same chamber (6), and in particular wherein the carrier (2) comprises a single chamber (6) only.

32. The method of any of the preceding claims wherein the lateral walls (8) extend from a substrate (4) of the carrier (2) to the first carrier side (10).

33. The method of claim 32 wherein the substrate (4) is a semiconductor substrate with integrated circuit elements, wherein the circuit elements are aligned with the lateral walls (8).

34. The method of any of the preceding claims comprising the step of, after hardening, separating the film (16) from the lateral walls (8).

35. The method of any of the preceding claims wherein the carrier (2) comprises, in at least some of the chambers (6), at least one of a light source (44), and a light detector (44).

36. The method of claim 35 comprising providing a substrate (4) with light sources and / or light detectors (44) integrated thereon, and forming the lateral walls (8) on the substrate (4).

37. The method of any of the preceding claims wherein a thickness (d) of the film (16) is at least 5 times smaller than a smallest diameter (D) of the openings (14).

38. The method of any of the preceding claims wherein a thickness (d) of the film (16) is smaller than 100 pm, in particular smaller than 10 pm.

39. The method of any of the preceding claims wherein the lateral walls (8) comprise fingers (46) or columns reaching into the openings (14), wherein the film (16) is laminated to the fingers (46) and columns, respectively.

40. The method of any of the preceding claims comprising manufacturing a first set (26a) of domes (26) and then, on a side of the first set (26a) of domes (26) that faces away from the carrier (2), at least a second set (26b) of domes (26), and in particular wherein the second set (26b) of domes (26) is at a distance from the first set (26a) of domes (26).

41. The method of any of the preceding claims comprising deforming the domes (26) to have apexes (56) facing away from the carrier and mounting a flat cover layer (52) to the domes (26) at the first side of the film (16) after hardening the film, wherein the cover layer (52) is connected to the apexes (56) only, and in particular adding at least one metal structure (54) to a side of the cover layer (52) that faces away from the domes (26).

42. The method of any of the preceding claims comprisingapplying at least one metal structure (54) to the first film side (18), and in particular applying the at least one metal structure (54) to the first film side (18) after hardening the film (16).

43. The method of any of the preceding claims wherein passages (30a, 30b, 30c) interconnecting at least some of the openings (14) are located in the lateral walls (8).

44. The method of claim 43 comprising after hardening the film (16), filling a liquid into the openings (14) using the passages (30a, 30b, 30c), and- hardening the liquid.

45. The method of claim 44 comprising using filling and / or degassing holes (58, 60), arranged in at least one of the film (16) and a substrate (4) of the carrier (2) for filling the liquid into the openings (14).

46. Use of the method of any of the preceding claims for manufacturing at least one of a plurality of lenses, a plurality of domed mirrors, an array of light sources or light detectors with lenses or mirrors.

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