MICROLENTIL MANUFACTURING PROCESS

Abstract

According to one aspect, a manufacturing process for an optical device on a support substrate (SUB) is proposed, comprising the formation of a plurality of microlenses including: - the formation of first microlens structures (LS1) by photolithography (PTH_LITO1) on the support substrate (SUB), then by deformation of the first microlens structures (LS1) so as to give a convex shape to the first microlens structures (LS1), the first microlens structures (LS1) being separated from each other by spacing regions (GP) after deformation,then - formation of second microlens structures (LS2) by photolithography (PTH_LITO2) followed by deformation of the second microlens structures (LS2) so that the second microlens structures (LS2) have a convex shape conforming to the convex shape of the first microlens structures (LS1) and extending partially into the spacing regions (GP) between the first microlens structures (LS1). Figure for the abstract: Fig 9,

Description

Title of the invention: METHOD FOR MANUFACTURING MICRO LENSES

[0001] Embodiments and implementation methods relate to optical sensors, and more particularly to manufacturing processes for microlenses for such optical sensors.

[0002] An optical sensor is a device that detects light intensity and converts it into a measurable quantity such as a current or a voltage. An optical sensor generally comprises an array of photosensitive areas and microlenses. In particular, each photosensitive area is covered by a microlens and generates a current from photons. For example, the photons can be used to reconstruct an image when collected by the optical sensor. Each pixel of the image then corresponds to the photons absorbed by a photosensitive area of ​​the array.

[0003] Microlenses are lenses generally having a diameter of less than 100 pm and can go down to dimensions on the order of pm, more typically between 1 and 10 pm.

[0004] A microlens focuses light onto a photosensitive area above which the microlens is positioned. A photosensitive area can then capture a greater quantity of photons when covered by a microlens, thereby increasing the quantum efficiency of the photosensitive area. Quantum efficiency (also known by the acronym 'QE') is the ratio between the number of incident photons and the number of photons absorbed by the photosensitive area. This ratio therefore depends on the number of photons that come into contact with the surface of the microlens and are redirected towards the photosensitive area.

[0005] In order to optimize quantum efficiency, i.e., to obtain a quantum efficiency close to 1, it is desirable to space the microlenses as close together as possible to collect all the incident photons and thus reduce light losses. Microlenses placed end to end also have the advantage of reducing optical interference by preventing photons from reaching neighboring photosensitive areas.

[0006] An example of a known microlens formation technique employs simple photolithography. Photolithography makes it possible to reproduce several microlens structures according to a given pattern using a mask on a support substrate. The microlens structures then exhibit an intermediate parallelepiped shape, and hereafter also referred to as "plots." These plots are then distributed across the substrate surface and spaced apart. The microlens structures then undergo thermal fining, meaning they become liquid under the influence of heat, to allow the structures to adhere to the substrate. Wetting corresponds to the natural deformation of a liquid in contact with the surface of a solid. A microlens structure in contact with the substrate surface then naturally takes on a final convex shape, thus forming a microlens.

[0007] During fining, the plot not only takes the form of a microlens, but also extends over the substrate so that the resulting microlens covers a larger surface area of ​​the substrate. When the structures formed by photolithography are too close together, they risk forming bridges ("bridging") between them, and thus connecting to each other.

[0008] A bridge formed between microlenses corresponds to the fusion between the ends of microlenses located side by side. A bridge between two microlenses does not allow the photons crossing this bridge to be properly directed towards the photosensitive areas located under these microlenses.

[0009] Furthermore, photons passing through a bridge are likely to create optical interference between the photosensitive areas of the matrix. Optical interference occurs, for example, when photons are redirected to a photosensitive area other than the one for which they were intended.

[0010] This therefore leads to a decrease in the performance of the optical sensor and a loss of information on the image to be reconstructed.

[0011] Moreover, current photolithography techniques do not allow the distances between each microlens structure to be sufficiently reduced without the risk of bridging between the microlenses and are not precise enough to completely reduce the distance between the microlenses.

[0012] In this regard, other conventional microlens manufacturing techniques make it possible to reduce the spacing between microlenses without forming bridges.

[0013] For example, a process involves performing a first photolithography to form first microlenses such that the first microlenses cover every other photosensitive area. After crosslinking the first microlenses, second microlenses are then formed by a second photolithography between each first microlens to cover the remaining photosensitive areas. Thus, such a process makes it possible to obtain first and second microlenses that are not, or only very slightly, spaced apart.

[0014] However, the alignment of the first and second microlenses remains relatively complex in this process and each of the photolithography steps Thography requires the use of a different mask, which represents a significant additional cost on the scale of microlens manufacturing.

[0015] Another example of a commonly used method for forming microlenses is based on the plasma transfer of microlenses onto an intermediate layer disposed on the substrate. Although the plasma makes it easier to adjust the spacing between the microlenses on the intermediate layer in order to reduce or eliminate the spacing between them, its radiation is likely to severely damage the photosensitive areas of the optical sensor and also affect the microlenses, making them rougher.

[0016] There is therefore a need to propose a solution that reduces the spacing between microlenses and increases quantum efficiency while avoiding high manufacturing costs and avoiding damage to the photosensitive areas of the optical sensor.

[0017] According to one aspect, a method for manufacturing an optical device on a support substrate is proposed, comprising the formation of a plurality of microlenses.

[0018] The formation of the plurality of microlenses involves the formation of first microlens structures by photolithography on the support substrate so that the first microlens structures are separated from each other, then by deformation of the first microlens structures so as to give a domed shape to the first microlens structures, the first microlens structures being separated from each other by spacing regions after deformation.

[0019] The formation of the plurality of microlenses also involves the formation of second microlens structures by photolithography such that the second microlens structures extend over the first microlens structures and then by deformation of the second microlens structures so that the second structures have a domed shape following the domed shape of said first microlens structures and extend partly into the spacing regions between the first microlens structures.

[0020] Each microlens is thus formed by the superposition of a first microlens structure and a second microlens structure.

[0021] The formation of microlenses by superimposing said second microlens structures on the first microlens structures makes it possible to reduce the spacing between the microlenses, or even to eliminate it in order to avoid the formation of bridges between each microlens.

[0022] Indeed, forming the second microlens structures on the first microlens structures allows for better control of the deformation of said second microlens structures so that the second structures of microlenses extend into the spacing regions to reduce the spacing between microlenses.

[0023] According to one embodiment, each second microlens structure has, after deformation, a curvature greater than or equal to a curvature of each first microlens structure.

[0024] The curvature of each second microlens structure can therefore be adjusted independently of the curvature of each first microlens structure. A higher microlens curvature makes it possible to reduce the focal length of the microlens so as to converge the light onto the photosensitive area when the latter is close to the microlens.

[0025] According to one embodiment, the process further comprises crosslinking the first microlens structures by heat treatment following their deformation, and crosslinking the second microlens structures by heat treatment, following the deformation of said second structures.

[0026] Crosslinking carried out after the deformation of the microlens structures makes it possible to eliminate the solvents in each of the microlens structures and to solidify the microlens structures in order to maintain their fixed position and stabilize them on the substrate

[0027] According to one embodiment, the photolithographies enabling the formation of said first microlens structures and said second microlens structures are carried out using the same mask.

[0028] The use of a single mask for both photolithographies reduces the cost of manufacturing the microlenses and allows a second photolithography to be carried out more quickly.

[0029] According to one embodiment, the deformation of said second microlens structures comprises a treatment by diffusion plasma at a suitable temperature. The second microlens structures are then deformed by fining, allowing the second microlens structures to be wetted onto the first microlens structures so as to conform to the shape of the first microlens structures and to extend partially into the spacing regions.

[0030] The temperature of the plasma diffusion treatment can be determined according to the nature of the material of the microlens structure to allow better control of the deformation of the second microlens structures and to obtain the desired microlens shape.

[0031] The use of a diffusion plasma makes it possible to obtain a deformation of the microlens structures without risking damage and affecting the roughness of the microlenses.

[0032] According to one embodiment, the diffusion plasma is a tetrafluoride plasma of carbon and dioxygen.

[0033] According to one embodiment, the first microlens structures and the second microlens structures are formed from different materials.

[0034] According to one embodiment, the first microlens structures and the second microlens structures are each formed of a novolac polymer resin.

[0035] According to one embodiment, the second microlens structures are formed from a material chosen so as to limit the reflection of light on the outer surface of the second microlens structures.

[0036] By limiting the reflection of light on the outer surface of the second microlens structures, a loss of photons is avoided and, consequently, a reduction in quantum efficiency.

[0037] According to one embodiment, the material forming said second microlens structures has a refractive index between 1.5 and 1.7.

[0038] According to one embodiment, the thickness of said second microlens structures is between 400nm and 4pm.

[0039] Thus, the process also makes it possible to use second microlens structures to smooth the surface of the first microlens structures which can sometimes be very rough.

[0040] According to one embodiment, the thickness of said second microlens structures is greater than 0.1 pm.

[0041] Second microlens structures having such a thickness value can be better distributed in the spacing regions between the first microlens structures. This yields a thickness sufficient to reduce, or even eliminate, the spacing between the microlenses.

[0042] According to one embodiment, the first microlens structures are formed so as to be spaced from each other by a distance greater than or equal to 300nm.

[0043] A minimum spacing between the first microlens structures makes it possible to reduce, or even avoid, the formation of bridges between the first microlens structures.

[0044] According to one embodiment, the second microlens structures are formed by photolithography so as to be spaced apart from each other, before said deformation, by a distance greater than or equal to 300nm.

[0045] According to one embodiment, the second microlens structures are spaced from each other, after the deformation of the second microlens structures, by a distance of at least substantially zero.

[0046] According to another aspect, a semiconductor device is proposed comprising a substrate support and a plurality of microlenses.

[0047] The plurality of microlenses comprises first microlens structures of convex shape arranged on the supporting substrate such that the first microlens structures are separated from each other by spacing regions.

[0048] The plurality of microlenses also includes second microlens structures extending over the first microlens structures and deformed so that the second structures have a domed shape conforming to the domed shape of said first microlens structures and extend partly into the spacing regions between the first microlens structures.

[0049] According to one embodiment, each second deformed microlens structure has a curvature greater than or equal to a curvature of each first microlens structure.

[0050] According to one embodiment, the materials of the first microlens structures and the second microlens structures are different.

[0051] According to one embodiment, the first microlens structures and the second microlens structures are made of novolac polymer resin.

[0052] According to one embodiment, the material of the second microlens structures is configured to limit the reflection of light on the outer surface of the second microlens structures.

[0053] According to one embodiment, the material of said second microlens structures has a refractive index between 1.5 and 1.7.

[0054] According to one embodiment, the thickness of said second microlens structures is between 400nm and 4pm.

[0055] According to one embodiment, the thickness of said second microlens structures is greater than 0.1 pm.

[0056] According to one embodiment, the first microlens structures are spaced from each other by a distance greater than or equal to 300nm.

[0057] According to one embodiment, the second microlens structures are spaced from each other by a distance that is at least substantially zero.

[0058] Other advantages and features of the invention will become apparent upon examination of the detailed description of embodiments and implementations, which are by no means limiting, and the accompanying drawings in which:

[0059] [Fig.1]

[0060] [Fig.2]

[0061] [Fig.3]

[0062] [Fig.4]

[0063] [Fig.5]

[0064] [Fig.6]

[0065] [Fig.7]

[0066] [Fig. 8]

[0067] [Fig.9]

[0068] [Fig. 10]

[0069] [Fig. 11], and

[0070] [Fig. 12] schematically illustrate methods of implementation and realization of the invention.

[0071] Fig. 1 schematically illustrates a method of implementing a manufacturing process for a DISP optical sensor.

[0072] The manufacturing process includes obtaining 10 a support substrate SUB as shown in [Fig. 2] in a cross-sectional view. The support substrate SUB is formed from a material commonly used for manufacturing microlenses, such as polysilicon, and comprises photosensitive areas Z_PHT formed by various types of processes known per se, depending on the nature of the photosensitive area Z_PHT. The photosensitive area Z_PHT may be a junction photodiode or a buried photodiode, for example. The substrate may be p-type or n-type and may have a higher or lower resistivity. The doping of the transistors will differ depending on the substrate and the type of photodiode.

[0073] The process then comprises steps 11 to 18 for forming microlenses on the SUB substrate. The microlenses are not necessarily formed directly on the SUB substrate. In particular, layers, such as color filter layers, may be interposed between the SUB substrate and the microlenses.

[0074] More particularly, the formation of microlenses involves the formation of first domed microlens structures by steps 11 to 14 and then the formation of second domed microlens structures on the first microlens structures by steps 15 to 18.

[0075] The process thus comprises forming 11 a first layer of material Cl on the substrate support SUB. The first layer Cl can be formed from a photosensitive resin. The photosensitive resin can be a novolak polymer (usually referred to as "novolaks" in English). For example, the photosensitive resin can be MFR 400LL resin from the Japanese company JSR Corporation. Figure 3 illustrates a cross-sectional view of a result that can be obtained following this formation 11.

[0076] The process comprises forming 12 first LSI microlens structures by PHT_LITO1 photolithography on the SUB support substrate such that the first LSI microlens structures are separated from each other. Each first LS microlens structure then exhibits an intermediate dot shape.

[0077] More specifically, the PHT_LITHO1 photolithography is performed using an MSK mask previously placed over the first layer of Cl material. The MSK mask includes apertures so as to expose the surface of the first Cl layer to radiation and to form the first LSI microlens structures according to a pattern. Such a photolithography technique is known to those skilled in the art, who will be able to adapt the dimensions of the MSK mask apertures in order to form first LSI structures separated from one another from the first CL layer. The material of the first LSI microlens structures and the first Cl layer is identical and can be a novolac polymer, for example. [Fig. 4] and [Fig. 10] respectively illustrate a cross-sectional view and a top view of a result that can be obtained following the formation of first cubic LS1 microlens structures.

[0078] Advantageously, the first LSI microlens structures are formed above the photosensitive areas so as to be spaced from each other by a distance DI greater than or equal to 300 nm, for example a distance DI between 300 nm and 600 nm. Thus, the first LSI microlens structures have dimensions adapted so that the distance DI between the first LSI microlens structures prevents the formation of bridges after deformation 13 of the first LSI microlens structures.

[0079] In order to shape the first LSI microlens structures and give them a domed shape, the process includes the deformation 13 of the first LSI microlens structures.

[0080] Deformation 13 can be a deformation of the first LSI microlens structures by melting, i.e., under the action of heat. Melting is a classic technique well known to those skilled in the art, allowing the LS1 microlens structures to be liquefied so that they naturally take on a convex shape on the surface of the supporting substrate SUB. Figure 5 illustrates a cross-sectional view of a result that can be obtained following this deformation 13.

[0081] After deformation 13, the first LSI microlens structures are separated from each other by GP spacing regions. The GP spacing regions are the regions of the substrate SUB located between the first LSI microlens structures and are therefore not covered by the first LSI microlens structures. By adapting the dimensions of the MSK mask apertures during the first photolithography PHT_LITHO1 and the deformation of the first microlens structures, it is possible to precisely determine the width of the GP spacing regions between each first LSI microlens structure.

[0082] Next, the process includes a crosslinking 14 (known as the term "cross-link" in English) of the first LSI microlens structures by heat treatment following deformation 13. A cross-linking 14 allows the solvents to be removed from each of the first LS 1 microlens structures and the first LSI microlens structures to be solidified in order to maintain their fixed position and stabilize them on the SUB support substrate.

[0083] The process also includes the formation 15 of a second layer of material C2 on the first LSI microlens structures and on the SUB support substrate in the GP spacing regions. The second layer C2 can be formed from a photosensitive resin identical to the resin used for the first layer C1, or from a different material such as poly(hydroxystyrene) (PHS). The resin can, for example, be the same as that used for the first layer C1 and the first LSI microlens structures, i.e., MFR 400LL novolac polymer resin. Figure 6 illustrates a cross-sectional view of a result that can be obtained following this formation 15.

[0084] The process includes forming 16 of the second microlens structures LS2 by PHT_LITO2 photolithography such that the second microlens structures LS2 extend over the first microlens structures LSI. Each second microlens structure LS2 then has an intermediate dot shape.

[0085] The PHT_LITHO2 photolithography is performed using an MSK mask previously placed above the second layer of material C2. Advantageously, the PHT_LITHO1 and PHT_LITHO2 photolithographies, which form the first LSI microlens structures and the second LS2 microlens structures, are performed using the same MSK mask. Using a single MSK mask for both PHT_LITHO1 and PHT_LITHO2 photolithographies reduces the manufacturing cost of the microlenses and allows for a faster second PHT_LITHO2 photolithography.

[0086] The material of the second microlens structure LS2 and the second layer C2 is identical and can be, for example, MFR 400LL resin, the base of which is a novolac polymer. Figures 7 and 11 illustrate, respectively, a cross-sectional view and a top view of a result that can be obtained following the formation of cubic second microlens structures LS2.

[0087] Advantageously, the second microlens structures LS2 are formed so as to be spaced apart from each other before deformation 17 by a distance D2 greater than 300 nm, for example a distance D2 between 300 nm and 400 nm. The distance D2 can be equal to the distance DI corresponding to the spacing between the first microlens structures LSI.

[0088] Advantageously, the thickness of the second microlens structures is su greater than 0.1 pm. The second microlens structures LS2 then have a thickness E2 sufficient to be better distributed in the GP spacing regions between the first microlens structures LSI following a deformation 17, described below, of the second microlens structures LS2 and to allow to reduce, or even cancel the spacing between the microlenses.

[0089] Furthermore, the thickness E2 of the second microlens structures LS2 is between 400 nm and 4 pm. The process also allows, after deformation 17 of the second microlens structures LS2, the use of these second microlens structures LS2 to smooth the surface of the first microlens structures LS2, which can be relatively rough. Thus, the surface finish of the microlenses can be improved.

[0090] The process includes deforming 17 of the second microlens structures LS2 so that the second microlens structures LS2 have a domed shape following the domed shape of the first microlens structures LSI and extend partly into the GAP spacing regions between the first microlens structures LSI.

[0091] Deformation 17 can be a deformation of the second microlens structures LS2 by thinning, i.e., under the action of heat. The process thus makes it possible to adapt the thinning technique described above to allow the second microlens structures LS2 to naturally assume a convex shape on the surface of the first microlens structures LSI. Figure 8 illustrates a cross-sectional view of a result that can be obtained following this deformation 17.

[0092] Advantageously, the deformation 17 of the second microlens structures LS2 includes a diffusion plasma treatment at a suitable temperature. The diffusion plasma treatment temperature can be determined according to the nature of the material of the second microlens structures LS2 to allow for better control of the deformation 17 of the second microlens structures LS2 and to obtain the desired microlens shape. The diffusion plasma treatment temperature is typically between 150°C and 180°C.

[0093] In particular, the diffusion plasma is a carbon and dioxygen tetrafluoride plasma with the chemical formula CF4O2. Unlike other types of plasma, the carbon and dioxygen tetrafluoride plasma has the advantage of allowing deformation of the microlens structures without risking damage to the photosensitive areas of the DISP optical sensor and without affecting the roughness of the microlenses.

[0094] After deformation 17, each second microlens structure LS2 exhibits a curvature greater than or equal to the curvature of each first microlens structure LSI. By way of example, the radius of curvature RI of the first microlenses LS1 can be between 20° and 40° and the radius of curvature R2 of the second LS2 microlens structures can be between 40° and 60°.

[0095] The curvature of each second microlens structure LS2 can therefore be adjusted independently of the curvature of each first microlens structure LSI. A higher microlens curvature makes it possible to reduce the focal length of the microlens so as to converge the light onto the photosensitive area when the latter is close to the microlens.

[0096] Next, the process includes a crosslinking 18 of the second microlens structures LS2 by heat treatment following the deformation 17 of the second microlens structures LS2. A crosslinking 18 makes it possible to solidify the second microlens structures LS2 in order to maintain their fixed position and stabilize them on the support substrate SUB.

[0097] The two-step formation of microlenses, by first forming primary microlens structures and then secondary microlens structures on top of the primary microlens structures, allows for the formation of microlenses without the formation of bridges that can cause light loss and optical interference between the photosensitive areas of the DISP optical sensor. Consequently, the DISP optical sensor benefits from improved quantum efficiency and increased performance. Figure 12 illustrates a top view of a result that can be obtained following this deformation.

[0098] Fig. 9 illustrates a cross-sectional view of a DISP optical sensor made from the process described above and which includes photosensitive areas Z_PHT located under each second microlens structure LS2.

[0099] The microlenses formed from the first microlens structures LSI and the second microlens structures LS2 of a DISP optical sensor have no spacing between them, or very little spacing, and thus allow the incident light LUM to be focused onto the photosensitive area Z_PHT covered by each microlens. Preferably, the second microlens structures LS2 are spaced from each other, after deformation 17, by a distance that is at least substantially zero. Consequently, such a DISP optical sensor has the advantage of increasing the quantity of photons collected by the photosensitive areas Z_PHT as well as the overall quantum efficiency without light loss or optical interference between the photosensitive areas.

[0100] Of course, the present invention is susceptible to various variations and modifications which will become apparent to those skilled in the art. For example, the first microlens structures LS1 and the second microlens structures LS2 can be formed from different materials. Preferably, the second microlens structures LS2 are formed from a material configured to limit the reflection of LUM light on the outer surface of the second microlens structures. LS2. This material can be, for example, siloxane (cyclic or bicyclic), PET (polyester), or acrylic, acting as an anti-reflective coating depending on the environment outside the lens. Specifically, the material forming the second LS2 microlens structures has a refractive index between 1.5 and 1.7. By limiting the reflection of LUM light on the outer surface of the second LS2 microlens structures, photon loss is prevented. The quantum efficiency of the photosensitive areas is thus increased.

Claims

Demands

1. A method for manufacturing an optical device on a support substrate (SUB), comprising the formation of a plurality of microlenses including: - the formation of first microlens structures (LSI) by photolithography (PTH_LIT01) on the support substrate (SUB) such that the first microlens structures (LSI) are separated from each other, then by deformation of the first microlens structures (LSI) so as to give a convex shape to the first microlens structures (LSI), the first microlens structures (LSI) being separated from each other by spacing regions (GP) after deformation,then - the formation of second microlens structures (LS2) by photolithography (PTH_LIT02) such that the second microlens structures (LS2) extend over the first microlens structures (LSI), then by deformation of the second microlens structures (LS2) so that the second microlens structures (LS2) have a convex shape conforming to the convex shape of said first microlens structures (LSI) and extend partly into the spacing regions (GP) between the first microlens structures (LSI).

2. A method according to claim 1, wherein, after deformation, each second microlens structure (LS2) has a curvature greater than or equal to a curvature of each first microlens structure (LSI).

3. A method according to any one of claims 1 or 2, further comprising: - crosslinking of the first microlens structures (LS1) by heat treatment following their deformation, and - crosslinking of the second microlens structures (LS2) by heat treatment following the deformation of said second microlens structures (LS2).

4. A method according to any one of claims 1 to 3, wherein the photolithographies (PTH_LITO1, PTH_LITO2) enabling the formation of said first microlens structures (LSI) and said second microlens structures (LS2) are carried out using the same mask (MSK).

5. A method according to any one of claims 1 to 4, wherein the deformation of said second microlens structures (LS2) comprises a plasma diffusion treatment at a suitable temperature.

6. A method according to claim 5, wherein the diffusion plasma is a carbon tetrafluoride and dioxygen plasma.

7. A method according to any one of claims 1 to 6, wherein the first microlens structures (LS1) and the second microlens structures (LS2) are formed from different materials.

8. A method according to any one of claims 1 to 6, wherein the first microlens structures (LS1) and the second microlens structures (LS2) are each formed of a novolac polymer resin.

9. A method according to any one of claims 1 to 7, wherein the second microlens structures (LS2) are formed from a material chosen to limit the reflection of light on the outer surface of the second microlens structures (LS2).

10. A method according to claim 9, wherein the material forming said second microlens structures (LS2) has a refractive index between 1.5 and 1.

7.

11. A method according to any one of the preceding claims, wherein the thickness (E2) of said second microlens structures (LS2) is between 400nm and 4pm.

12. A method according to any one of the preceding claims, wherein the thickness (E2) of said second microlens structures (LS2) is greater than 0.1 pm.

13. A method according to any one of the preceding claims, wherein the first microlens structures (LSI) are formed so as to be spaced apart from each other by a distance greater than or equal to 300nm.

14. A method according to any one of the preceding claims, wherein the second microlens structures (LS2) are formed by photolithography so as to be spaced apart from each other, before said deformation, by a distance greater than or equal to 300nm.

15. A method according to any one of the preceding claims, wherein the second microlens structures (LS2) are spaced apart from each other, after deformation of the second microlens structures (LS2), by a distance of at least substantially zero.

16. Optical sensor (DISP) comprising a support substrate (SUB) and a plurality of microlenses comprising: - First microlens structures (LSI) of convex shape arranged on the support substrate (SUB) such that the first microlens structures (LSI) are separated from each other by spacing regions (GP), - Second microlens structures (LS2) extending over the first microlens structures (LSI) and deformed so that the second microlens structures (LS2) have a convex shape following the convex shape of said first microlens structures (LSI) and extend partly into the spacing regions (GP) between the first microlens structures (LSI).

17. Optical sensor according to claim 16, wherein each second deformed microlens structure (LS2) has a curvature greater than or equal to a curvature of each first microlens structure (LSI).

18. Optical sensor according to any one of claims 16 or 17, wherein the materials of the first microlens structures (LSI) and the second microlens structures (LS2) are different.

19. Optical sensor according to any one of claims 16 or 17, wherein the first microlens structures (LS1) and the second microlens structures (LS2) are made of novolac polymer resin.

20. Optical sensor according to any one of claims 16 to 18, wherein the material of the second microlens structures (LS2) is configured to limit the reflection of light (LUM) on the outer surface of the second microlens structures (LS2).

21. Optical sensor according to claim 20, wherein the material of said second microlens structures (LS2) has a refractive index between 1.5 and 1.

7.

22. Optical sensor according to any one of the preceding claims, wherein the thickness (E2) of said second microlens structures (LS2) is between 400nm and 4pm.

23. Optical sensor according to any one of the preceding claims, wherein the thickness (E2) of said second microlens structures is greater than 0.1 pm.

24. Optical sensor according to any one of the preceding claims, wherein the first microlens structures (LSI) are spaced apart from each other by a distance greater than or equal to 300nm.

25. Optical sensor according to any one of the preceding claims, in which the second microlens structures (LS2) are spaced from each other by a distance that is at least substantially zero.

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