Electromagnetic radiation detection device comprising a pixelated filtering stage

Abstract

The invention relates to an electromagnetic radiation detection device comprising a readout substrate and a thermal detector array. Each thermal detector includes a filter, a micro-board, thermal insulation arms, and anchoring pillars, such that the micro-board is electrically connected to the readout substrate by the thermal insulation arms and anchoring pillars, and suspended above the readout substrate by the thermal insulation arms. The detection device further includes an encapsulation structure covering the thermal detector array on one side of the device opposite the readout substrate, such that each filter is arranged in and / or on the encapsulation structure.It comprises vertical walls, each made of a metal and extending between two adjacent micro-boards, from the encapsulation structure, towards a detection plane of the detection device defined by the set of micro-boards, without reaching it. Figure for the abbreviation: Figure 4H.

Description

Title of the invention: Electromagnetic radiation detection device comprising a pixelated filtering stage. Technical field

[0001] The field of the invention is that of devices for detecting electromagnetic radiation in the infrared, for example within the wavelength range of 3 pm to 20 pm, comprising a pixelated filtering stage, in particular detection devices for multispectral applications, such as absolute thermography or gas detection. PREVIOUS STATE OF THE ART

[0002] An infrared electromagnetic radiation detection device generally comprises an array of thermal detectors, for example, micrometer-sized bolometers, arranged in a matrix on a readout substrate. The detection device may be part of an infrared matrix sensor including an optical lens. If so, the bolometer matrix is ​​positioned in a focal plane of the lens, so that a thermal scene is imaged in the focal plane and each bolometer provides information for one pixel of the scene image.

[0003] A bolometer generally comprises a micro-board, two thermal insulation arms, and two anchoring pillars. The micro-board is suspended above a reading substrate by the anchoring pillars and thermally insulated from it by the thermal insulation arms. The anchoring pillars and the thermal insulation arms electrically connect the micro-board to a reading circuit located in and / or on the reading substrate. The entire micro-board assembly extends in a plane, hereinafter referred to as the detection plane.

[0004] The micro-board may include an absorber adapted to absorb the incident electromagnetic radiation, and a thermometer thermally coupled to the absorber. The thermometer may include a material with a resistivity that varies with temperature, for example vanadium oxide or amorphous silicon. Alternatively, the thermometer may include a measuring transistor, for example of the MOS type.

[0005] Infrared detection devices can, for example, detect electromagnetic radiation in the wavelength range extending from 3 pm to 20 pm, and more particularly in the range between 7 pm and 14 pm. They can be used for multispectral applications. For this type of application, particularly compact and fast detection devices include a A mosaic consisting of groups of thermal detectors sensitive to distinct wavelength ranges. The thermal detector groups are arranged and configured to simultaneously capture spectral information from the scene image. In the case of a bolometer array, for example, a bandpass optical filter for the thermal detector is placed upstream of each bolometer in the array, so as not to affect the bolometer's manufacturing and operation. The filters are arranged in a plane parallel to the detection plane, hereinafter referred to as the filtration stage. Because the filters are arranged in an array, the filtration stage is said to be pixelated.

[0006] By way of example, document FR3050526 describes a multispectral detection device comprising a thermal detector array and an encapsulation structure covering the thermal detector array. The detection device further comprises an interference filter array arranged opposite the detection array, with one filter per thermal detector. The interference filters consist of Fabry-Pérot cavities delimited by the encapsulation structure; that is, the encapsulation layer participates in the formation of each Fabry-Pérot cavity.

[0007] Document FR3040787 proposes using a frequency-selective surface as a bandpass filter. The frequency-selective surface (or FSS) consists of a metallic layer comprising regularly spaced and dimensioned through-holes. The through-holes contain a filling material. The metallic layer is mounted on a silicon cover over detectors of electromagnetic radiation.

[0008] However, the embodiments presented in these documents do not allow the step size of the thermal detector matrix to be reduced in order to increase the geometric and / or spectral resolution of the detection device. Description of the invention

[0009] The invention aims to remedy, at least in part, the drawbacks of the prior art, and more particularly to improve the resolution of prior art infrared electromagnetic radiation detection devices comprising a pixelated filtering stage upstream of a detection plane. The improved resolution may be geometric and / or spectral in nature.

[0010] To this end, the object of the invention is a device for detecting electromagnetic radiation, comprising a reading substrate and a matrix of thermal detectors. Each thermal detector comprises a filter, a micro-board, thermal insulation arms, and anchoring pillars, such that the micro-board is electrically connected to the reading substrate by the thermal insulation arms and the anchoring pillars, and suspended above the reading substrate by thermal insulation arms. The detection device further comprises an encapsulation structure covering the thermal detector array on one side of the detection device opposite the reading substrate, such that each filter is arranged in and / or on the encapsulation structure. It includes vertical walls, each comprising a metal and extending between two adjacent microboards, from the encapsulation structure, towards a detection plane of the detection device defined by the set of microboards, without reaching it.

[0011] Some preferred but not limiting aspects of this detection device are the following.

[0012] The encapsulation structure may include reinforcing pillars, each of which may rest on an anchoring pillar.

[0013] An anchoring pillar can be arranged between each group of four adjacent thermal detectors centered at the vertices of a rectangle. A reinforcing pillar can rest on each anchoring pillar. Each vertical wall can include a straight portion extending parallel to the detection plane along an axis passing through two adjacent reinforcing pillars.

[0014] The thermal insulation arms can extend into the detection plane. The detection device can include at least one vertical wall per thermal detector located directly above a region of the detection plane occupied by a thermal insulation arm.

[0015] The detection device may be a multispectral detection device. The set of filters may be divided into homogeneous subsets, the filters of a subset having a transmission band identical and distinct from the transmission bands of the filters of the other subsets. The subsets may form a regular tiling of the encapsulation structure.

[0016] Each filter can be a frequency-selective surface that can be based on the encapsulation structure.

[0017] The encapsulation structure may include a region opposite each filter having a thickness less than or equal to half a wavelength in the electromagnetic radiation encapsulation structure.

[0018] Each filter may include at least one hollow motif passing through the filter. The encapsulation structure may include a through-opening opposite each motif of the filter.

[0019] The vertical walls and filters can form parts of a common metallic layer of the detection device.

[0020] Each vertical wall may include an extension of the encapsulation structure and a metallic portion covering a lateral surface of the extension.

[0021] Each extension can be a single unit with an upper part of the encapsulation structure connecting all the extensions and on which the filters are based.

[0022] Each extension can be made of metal.

[0023] The vertical walls can form a continuous mesh comprising meshes. Each mesh can surround a micro-board or an anchor pillar in a view perpendicular to the detection plane.

[0024] The invention also relates to a method of manufacturing a detection device according to any one of the preceding characteristics, comprising a step of supplying a pre-treated substrate including the reading substrate, a lower sacrificial layer resting on the reading substrate, and a portion of each thermal detector including the micro-board, the thermal insulation arms and the anchoring pillars, such that each micro-board extends parallel to an upper face of the lower sacrificial layer opposite the reading substrate while intercepting or being flush with it,

[0025] The manufacturing process comprises depositing an upper sacrificial layer onto the lower sacrificial layer so as to cover the thermal insulation arms and the micro-boards of the thermal detectors in the matrix. It comprises etching trenches in an upper portion of the upper sacrificial layer opposite the lower sacrificial layer with respect to the detection plane defined by the set of micro-boards. It comprises forming the vertical walls, each in a trench, and forming the encapsulation structure, which includes a substep of depositing a dielectric layer onto the upper sacrificial layer, in which the encapsulation structure is formed. It comprises etching a through hole in the encapsulation structure and etching the lower and upper sacrificial layers through the through hole.

[0026] The substep of deposition of the dielectric layer may precede the etching of the trenches. The etching of the trenches may include etching of the dielectric layer so that the trenches can extend into the dielectric layer. The formation of the vertical walls may include conformal deposition of a metallic layer in the trenches. The manufacturing process may further include a step of forming filters in the metallic layer.

[0027] The etching of the trenches may precede the substep of deposition of the dielectric layer. The substep of deposition of the dielectric layer may further be a substep of the formation of the vertical walls. The dielectric layer may be deposited in the trenches and on an upper face of the upper sacrificial layer during the deposition substep. The manufacturing process may further include the formation of metallic portions on the internal walls of the trenches before the substep of deposition of the dielectric layer. Brief description of the drawings

[0028] Other aspects, objects, advantages and features of the invention will become more apparent upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0029] [Fig.1A] is a schematic top view of a first embodiment of a detection device according to the invention;

[0030] [Fig.1B] is a schematic view of the first embodiment along a horizontal section plane located between a filtration stage and a detection plane of the first embodiment;

[0031] [Fig.2A] is a schematic top view of a second embodiment of a detection device according to the invention;

[0032] [Fig.2B] is a schematic view of the second embodiment along a horizontal section plane located between a filtration stage and a detection plane of the second embodiment;

[0033] [Fig.3A] is a simulation result illustrating a technical problem solved by the invention;

[0034] [Fig.3B] is a simulation result obtained with a detection device conforming to the first embodiment;

[0035] Figures 4A to 4H are schematic cross-sectional views of a first manufacturing process for a detection device conforming to the first embodiment;

[0036] Figures 5A to 5G are schematic cross-sectional views of a second manufacturing process for a detection device according to the second embodiment.

[0037] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0038] In the figures and throughout the description, the same reference numerals represent identical or similar elements. Furthermore, the various elements are not drawn to scale in order to enhance the clarity of the figures. Moreover, the different embodiments and variants are not mutually exclusive and may be combined. Unless otherwise indicated, the terms "approximately," "about," and "in the order of" mean within 10%, and preferably within 5%. Furthermore, the terms "between ... and ..." and equivalents mean that the limits are inclusive, unless otherwise stated.

[0039] The invention relates to a device for detecting electromagnetic radiation comprising a readout substrate, a thermal detector array, and an encapsulation structure covering the thermal detectors. Each thermal detector includes a filter arranged in and / or on the encapsulation structure. The filter can be of any type, for example, a similar or identical Fabry-Pérot filter. to that described in document FR3050526, or as described below in particular embodiments of the invention, a frequency-selective surface. The set of filters constitutes a pixelated filtration stage. They are arranged in a matrix aligned with the matrix of thermal detectors.

[0040] It has been observed that reducing the spacing of the thermal detector array induces an increase in the overlap of spectral bands detected by adjacent thermal detectors in a multispectral detection device. Analysis has determined that the phenomenon is not due to a degradation of filter rejection, but results from optical crosstalk between adjacent pixels.

[0041] Indeed, when the filtering stage is upstream of the detection plane with respect to electromagnetic radiation—a configuration similar to that of documents FR3050526 and FR3040787—each filter acts as an optical window for a thermal detector directly above the filter. To avoid loss of resolution and / or sensitivity, the optical windows are contiguous. Thus, since the filtering stage is located at a distance from the detection plane, some of the light passing through a filter can reach a thermal detector adjacent to the one opposite it. This undesirable phenomenon is known as optical crosstalk. To increase the spatial and / or spectral resolution of the detection device, it is necessary to decrease the pixel matrix size by one step, which has the effect of increasing the impact of optical crosstalk.

[0042] By way of example, [Fig. 3A] shows a simulation result obtained for a filter matrix consisting of a contiguous tiling of four square filters, each having a transmission band distinct from the other three. The x-axis shows the wavelength in pm. The y-axis shows the absorption of electromagnetic radiation by a bolometer-type thermal detector, placed downstream of each filter and aligned with it, as a percentage of the energy of the portion of electromagnetic radiation incident on the filter at the corresponding wavelength. The bolometers are arranged in a matrix with a pitch of 12 pm along two orthogonal axes.

[0043] The filters are frequency-selective surfaces, each comprising hollow, through-hole patterns formed in a metallic layer common to all the filters. The metallic layer is of substantially constant thickness and rests on an upper face of the encapsulation structure. The encapsulation structure has a lower face opposite the upper face. The lower and upper faces are planar and parallel to each other. Curves C1, C2, C3, and C4 show the absorption as a function of wavelength for each of the four bolometers placed opposite one of the four separate filters.

[0044] Secondary absorption peaks are indicated by arrows on curves C3 and C4. This results in an increased overlap of the spectral bands. detected by the four bolometers. This can, for example, disrupt the reconstruction of a temperature map of a scene in the case of a thermography application, or the interpretation of the chemical content of a scene in the case of gas detection.

[0045] In a conventional infrared imaging context, document WO2019102121 proposes an electromagnetic radiation detection device comprising an array of filterless thermal detectors. Each thermal detector includes a micro-plate suspended above a reflective layer. The spacing between the micro-plate and the reflective layer is chosen to form a quarter-wave cavity resonant at a reference wavelength within the wavelength range of the electromagnetic radiation to be detected.

[0046] Vertical walls are formed before the micro-board is created. They are made of an opaque material. They are placed on and in contact with the reading substrate and extend longitudinally between two adjacent thermal detectors. The vertical walls block a portion of the electromagnetic radiation incident on an adjacent pixel that has been reflected by the reflective layer. They would have no effect on reducing spectral band overlap in a detection device comprising a pixelated filtering stage located upstream of a thermal detector array.

[0047] For the sake of clarity, it is specified here that a "layer" is understood to mean an area consisting of one or more sublayers of a material whose thickness along a z-axis is less than, for example, ten times or even twenty times, its longitudinal dimensions of width and length in a plane (x, y) perpendicular to the z-axis. A layer may be structured, or a structure of substantially constant thickness extending mainly along a principal plane. When it consists of several sublayers, the sublayers may be made of different materials. The sublayer(s) extend in planes substantially parallel to the (x, y) plane. When a layer has a property, it is understood that when it consists of several sublayers, all the sublayers have the same property, unless explicitly stated otherwise.For example, in the absence of further details, a layer made of metal or a semiconductor or amorphous material may contain several sublayers, all respectively made of metal, a semiconductor material, or amorphous materials.

[0048] A matrix of thermal detectors (or pixels) is a regular arrangement of thermal detectors in which an elementary group of thermal detectors is periodically repeated along two axes, preferably orthogonal. The group comprises at least one thermal detector. Optionally, two neighboring groups of thermal detectors may be separated by a space. The space may be This can be used to insert electrical connection lines, electrical components, or optoelectronic components into the matrix. For example, it is possible to have a matrix of unfiltered thermal detectors interleaved with a matrix of thermal detectors consisting of an elementary group of three thermal detectors with filters.

[0049] In the description, an element or layer is said to be transparent if it transmits at least 80% of an electromagnetic radiation of interest, preferably at least 90%.

[0050] Specific embodiments will be described relating to an electromagnetic radiation detection device comprising a bolometer-type thermal detector array. However, these embodiments can be adapted to other array detection devices for infrared electromagnetic radiation, for example, detection devices implementing quantum photodetectors based on II-VI or III-V materials, or thermopile-based detection devices.

[0051] A first embodiment of a detection device 1 for electromagnetic radiation according to the invention will now be described with reference to Figures IA, IB and 4H. A view along section plane AA and along section plane BB of [Fig. 1A] are respectively shown at the top and bottom of [Fig. 4H].

[0052] The detection device 1 comprises a pixel matrix 5. Only one pixel 5 is shown in Figures IA and IB, surrounded by partial views of neighboring pixels. Each pixel 5 contains a thermal detector. The thermal detectors are therefore arranged in a matrix. Each thermal detector comprises a filter 140, a micro-board 120, two thermal insulation arms 122, and two anchoring pillars 115. The constituent elements of the thermal detectors are identical here, with the possible exception of the filters. The filters may be identical without departing from the scope of the invention. In the cross-sectional views of [Fig. 4H], inter-pixel separation planes 7 separating two neighboring pixels 5 are shown by dashed lines. The sectional plane BB is itself part of an inter-pixel separation plane 7.

[0053] Each filter 140 is a frequency-selective surface. It comprises one or more patterns 141 in the form of holes passing through a metallic layer 207 of the detection device 1, regularly distributed and sized to form a frequency-selective surface. Each filter 140 is here a transmission bandpass filter, centered on a wavelength X of electromagnetic radiation. The patterns 141 typically have one or more dimensions smaller than Xi. In this example, the patterns 141 are orthogonal crosses of different orientations.

[0054] The detection device 1 includes a readout substrate 100. The readout substrate 100 has a substantially flat upper face 100.1. It includes a circuit of Reading and powering the thermal detector array. The circuit can be a CMOS circuit. It can include a stack of interconnects of one or more levels. In [Fig. 4H], only one connection pad 103 of the last level of the stack is shown. The connection pad 103 is flush with the top face 100.1. The filter array 140 extends in a plane parallel to the top face 100.1, constituting a filtering stage of the detection device 1.

[0055] A three-dimensional orthogonal (X, Y, Z) direct coordinate system is defined herein and for the remainder of this description, where the X and Y axes form a plane parallel to the upper face 100.1 of the reading substrate 100, the X axis being oriented parallel to the cutting plane AA, and where the Z axis is oriented substantially orthogonally to the upper face 100.1, from the upper face 100.1 towards the filtration stage. In the remainder of this description, the terms "vertical" and "vertically" are understood to refer to an orientation substantially parallel to the Z axis, and the terms "horizontal" and "horizontally" to refer to an orientation substantially parallel to the (X, Y) plane. Furthermore, the terms "lower" and "upper" are understood to refer to an increasing positioning as one moves away from the reading substrate 100 along the +Z direction. A top view is a view along the -Z direction.

[0056] The detection device 1 further comprises an encapsulation structure 130 covering the thermal detector array. The encapsulation structure 130 extends mainly in a plane parallel to the upper face 100.1 and the filtration stage. It is made of an electrically insulating or poorly conductive material, for example, a dielectric material. Here, it is made of unintentionally undoped amorphous silicon.

[0057] The metallic layer 207 is in contact with the encapsulation structure 130, on one side of the encapsulation structure 130 opposite the reading substrate 100. The encapsulation structure 130 has two substantially parallel opposing surfaces facing each filter 140. In [Fig. 4H], it has optional through-holes 131 extending through the entire encapsulation structure 130 in the Z direction, at the level of the opposing surfaces. Each through-hole 131 is aligned with a corresponding motif 141. In top view, it has a geometry substantially identical to the geometry of the corresponding motif 141.

[0058] The encapsulation structure 130 has sufficient thickness to ensure mechanical stability, allowing a substantially constant and uniform distance to be maintained between each filter 140 and the upper face 100.1. Thus, each region of the metallic layer 207 located entirely opposite a micro-board 120 is substantially flat and parallel to the upper face 100.1 of the reading substrate 100. It is thin enough not to impact the bandwidth of each filter 140 and not to guide any of the electromagnetic radiation. The encapsulation structure 130 has, for example, a thickness less than or equal to the Half a wavelength in the encapsulation structure 130 of the electromagnetic radiation to be detected, preferably less than or equal to half the shortest wavelength in the encapsulation structure 130 of the electromagnetic radiation to be detected, for example, less than or equal to 400 nm when the encapsulation structure 130 is made of undoped amorphous silicon. The wavelength of radiation in a propagation medium, such as the encapsulation structure 130, is equal to the wavelength of the radiation in a vacuum, divided by the refractive index of the propagation medium.

[0059] In this embodiment, the metallic layer 207 extends continuously from one filter 140 to another. It comprises a vertical wall 145 arranged between each pair of filters 140. Each vertical wall 145 extends from the encapsulation structure 130 towards the upper face 100.1 over a substantially constant height. In this example, an extension of each vertical wall 145 covers an internal wall of a trench passing through the encapsulation structure 130. The extension is substantially parallel to the Z-axis. The trenches and the vertical walls 145 have identical rectangular cross-sections, with their long sides parallel to the X-axis or the Y-axis. They may, however, have other corresponding shapes.

[0060] The detection device 1 may be a multispectral detection device. In this case, the set of filters 140 is divided into homogeneous subsets. The filters 140 in a subset are identical, that is, their patterns 141 are identical and arranged relative to each other in the same way. The filters 140 in each subset therefore have the same transmission band. Two filters 140 belonging to distinct subsets have at least one different pattern 141, or one pattern arranged differently, or oriented differently, so that they have different transmission bands. The subsets of filters 140 form, for example, a regular tiling of the filtration stage, so that each thermal detector in the array has a neighboring thermal detector such that the filters 140 opposite these two thermal detectors belong to distinct subsets.As an example, the tiling could be a Bayer tiling transposed into the infrared.

[0061] Micro-plate 120 includes an absorber (not shown) adapted to absorb incident electromagnetic radiation, and a thermometer (also not shown) thermally coupled to the absorber. The thermometer can be a layer of vanadium oxide electrically connected to two electrodes.

[0062] The micro-board 120 is suspended above the reading substrate 100 by the two thermal insulation arms 122. In this example, the reading substrate 100 includes an optional reflective layer 105 opposite each micro-board. 120. The reflective layer 105 is arranged here within the reading substrate 100 and is flush with the upper face 100.1 of the reading substrate 100. It is capable of reflecting at least a portion of the electromagnetic radiation. It is positioned at an optical distance from the micro-board 120 that defines a quarter-wave cavity for a given wavelength of the electromagnetic radiation. It is, for example, made of a metal.

[0063] Each anchor pillar 115 includes an optional pad 115.1 having dimensions in the plane parallel to the upper face 100.1 strictly greater than the dimensions in the same directions of a lower portion of the anchor pillar 115 on which it rests. Each thermal insulation arm 122 is mechanically and electrically connected to an anchor pillar 115 by a first end of the thermal insulation arm 122, here via the pad 115.1. Each anchor pillar 115 extends vertically above the reading substrate 100 from a connecting pad 103. Each thermal insulation arm 122 is electrically connected to an electrode of the micro-board 120 by a second end of the thermal insulation arm 122 opposite to the first end.

[0064] In this example, the thermal insulation arms 122 and the micro-boards 120 extend in a detection plane of the detection device 1, parallel to the upper face 100.1 of the reading substrate 100. The filtration stage is typically positioned at a distance from the detection plane, less than a central wavelength of the electromagnetic radiation to be detected, preferably at a distance less than or equal to the central wavelength divided by 4.

[0065] The encapsulation structure 130 is sufficiently far from each micro-board 120 along the Z axis so as to limit a risk of physical contact between them and / or thermal conduction by convection between the encapsulation structure 130 and the micro-board 120 and / or electromagnetic coupling between on one side the encapsulation structure 130 or the filter 140, and on the other side the micro-board 120. The filtration stage and the detection plane are for example positioned at a distance greater than or equal to 1 pm, preferably between 1 pm and 2.5 pm, for example equal to 1.5 pm.

[0066] Figure [Fig. IB] is a cross-sectional and top view, along a horizontal cutting plane located between the filtration stage and the detection plane of the detection device 1. In this figure, the vertical walls 145 have been hatched.

[0067] The thermal insulation arms 122 are sufficiently long, narrow, and thin to ensure good thermal insulation of the micro-board 120. In this example, they occupy a region of the detection plane that is otherwise unavailable for electromagnetic radiation detection. For good thermal insulation of the micro-boards 120, it is also necessary to maintain them under vacuum. For example, the detection device 1 can be placed inside a hermetically sealed, vacuum-sealed enclosure. Alternatively, the encapsulation structure 130 is itself airtight and under vacuum. If necessary, it can extend continuously under each motif 141, or the motifs 141 can be sealed by a layer of plugging transparent to electromagnetic radiation.

[0068] Each vertical wall 145 does not reach the detection plane. For example, it is located at a sufficient distance from an opposing thermal insulation arm 122 to ensure that it does not come into contact with it, in order to preserve the thermal insulation of the micro-board 120. The thermal insulation arms 122 are susceptible to deformation under the effect of residual mechanical stress in a stack of their constituent layers, or under the effect of vibrations. The vertical walls 145 may, for example, be located at a distance d from the detection plane of between 100 nm and 500 nm, or between 200 nm and 500 nm, measured parallel to the Z-axis. They extend, for example, parallel to an inter-pixel separation plane 7 over a length greater than or equal to 80% of the size of the pixel 5 in the same direction. For example, they have a horizontal width between 100 nm and 500 nm.For example, their height, measured parallel to the Z-axis from the encapsulation structure 130, is between 500 nm and 2400 nm.

[0069] Preferably, a vertical wall 145 is located, at least partially, directly above a region of the detection plane occupied by one or more thermal insulation arms 122. When each thermal insulation arm 122 of a thermal detector extends along two axes of the pixel array, all the vertical walls 145 are preferably located, at least partially, directly above a region of the detection plane occupied by a thermal insulation arm 122, as is the case in [Fig. 1B]. Advantageously, each pair of neighboring pixels 5 shares a vertical wall 145. Here, each vertical wall 145 is further centered on an inter-pixel separation plane 7. In top view, each vertical wall 145 extends parallel to the detection plane along a straight axis passing through two anchoring pillars 115.

[0070] The vertical wall 145 of [Fig. 4H] is shown with a recess. However, this is only one special case. The vertical wall 145 can also be solid.

[0071] The metallic layer 207 is made of a metal, for example tungsten (W), tungsten silicide (WSi), copper (Cu), gold (Au), titanium (Ti), or titanium nitride (TiN). Its thickness, measured parallel to the Z-axis at each filter, is substantially constant and strictly greater than its skin thickness at the longest wavelength of the electromagnetic radiation to be detected. Preferably, its thickness at the vertical walls 145 is greater than or equal to three times this skin thickness, the thickness being measured parallel to the (X, Y) plane. The metallic layer 207, for example, has a thickness between 150 nm and 500 nm. As an example, the skin thicknesses of WSi, W, Ti and TiN are respectively equal to 150 nm, 60 nm, 120 nm and 125 nm for a wavelength of 10 pm.

[0072] The detection device 1 includes an optional protective layer 110, useful for the first and second manufacturing processes described below. The protective layer 110 is in contact with the upper face 100.1 and encloses the anchoring pillars 115.

[0073] The encapsulation structure 130 can rest on the reading substrate 100 by means of a peripheral wall (not shown) surrounding the pixel matrix 5 and serving as a spacer between the encapsulation structure 130 and the reading substrate 100. The encapsulation structure 130 advantageously comprises one or more reinforcing pillars 155. Each reinforcing pillar 155 rests on an anchoring pillar 115, here on the pad 115.1. It is entirely covered with an optional insulating portion 153. The insulating portion 153 is in contact with the reinforcing pillar 155 and the pad 115.1. The insulating portion 153 is made of an electrically insulating material, for example, AIN or Al2O3. The reinforcing pillars 155 contribute to the maintenance and mechanical stability of the encapsulation structure 130. Advantageously, each anchoring pillar 115 is surmounted by a reinforcing pillar 155.The encapsulation structure 130 preferably extends continuously over the entire thermal detector matrix except for areas opposite the vertical walls 145 and, possibly, areas opposite the patterns 141.

[0074] A reinforcing pillar 155 may have horizontal dimensions on the order of those of the lower part of the anchor pillar 115 that it surmounts. Preferably, all the reinforcing pillars 155 are identical; all the lower parts of the anchor pillars 115 are identical, for example, cylindrical in shape with an axis parallel to the Z-axis; all the pads 115.1 are identical. In [Fig. 4H], the reinforcing pillar 155 is shown with a central recess. This is, however, only a specific example. Each reinforcing pillar 155 may also be solid. The metal layer 207 may extend continuously above the reinforcing pillars 155, whether or not they have a central recess, or, as shown here, include an opening opposite the reinforcing pillar 155, whether it is solid or not.

[0075] In [Fig. 3B], a simulation result obtained with a detection device 1 according to the first embodiment is given, under the same conditions as the result of [Fig. 2A], with the sole difference that the detection device 1 comprises four vertical walls 145 per pixel 5 arranged in each of the inter-pixel separation planes 7, as shown in [Fig. 1A]. The filtration stage is notably identical to that of [Fig. 2A]. The trenches 132 and the vertical walls 145 have here a horizontal width equal to 300 nm and a length equal to 9,000 nm. Each vertical wall 145 has a height equal to 1,000 nm.

[0076] As in [Fig. 3A], the encapsulation structure 130 has a thickness of 400 nm at each filter 140. The distance between the encapsulation structure 130 and the micro-board 120 is 1500 nm, measured along the Z-axis. The metallic layer 207 is made of WSi. The encapsulation structure 130 is made of amorphous silicon. The values ​​along the axes are given in the same units as in [Fig. 3A]. It should be noted that the peaks observed in [Fig. 3A] in the absence of the vertical wall 145 have disappeared in [Fig. 3B] due to the presence of the vertical walls 145.

[0077] A second embodiment of an electromagnetic radiation detection device 1 according to the invention will now be described with reference to Figures 2A, 2B, and 5G. A view along section plane AA and section plane BB of Figure 2A are shown at the top and bottom of Figure 5G, respectively. Figure 2B is a cross-sectional top view along a horizontal section plane located between the filtration stage and the detection plane of the detection device 1. Only the differences with the first embodiment are explicitly described.

[0078] In this second embodiment, each vertical wall 145 comprises an extension 145.2 of the encapsulation structure 130 and a metallic portion 145.1 in contact with the extension 145.2. The encapsulation structure 130 comprises a lower flat surface and an upper flat surface opposite each filter 140, both substantially parallel to the upper face 100.1 of the reading substrate 100. The lower flat surfaces are substantially coplanar. The upper flat surfaces are also substantially coplanar.

[0079] The extension 145.2 extends parallel to the Z-axis from a lower flat surface towards the upper face 100.1. It may be solid, as shown here, or have a central recess. It has a distal face located on one side of the extension 145.2 opposite the lower flat surfaces. The distal face is substantially parallel to the upper face 100.1. It is connected to a lower flat surface by a lateral surface of the extension 145.2. Each lateral surface of each extension 145.2 is covered by a metallic portion 145.1 over a substantial part of its surface, preferably over the entire lateral surface. The lateral surfaces are here substantially parallel to the Z-axis.

[0080] The extensions 145.2 are made of metal, a dielectric material, or a semiconductor material. Here, they are formed as a single unit with the rest of the encapsulation structure 130. They are made of a dielectric or semiconductor material, for example, amorphous silicon. The distal face is metal-free. The metallic portions 145.1 are made of metal. A metallic portion 145.1 may cover the distal face.

[0081] The encapsulation structure 130 comprises an upper portion connecting all the extensions 145.2, on which the filters 140 rest entirely. The upper portion includes the reinforcing pillars 155 when present. The reinforcing pillars 155 are integral with the upper portion. The upper portion of the encapsulation structure 130 is made of a material transparent to the electromagnetic radiation to be detected. In this example, it is made of a material identical to that of the extensions 145.2, for example, amorphous silicon.

[0082] The vertical walls 145 can be arranged in a similar or identical manner to one of those described in connection with the first embodiment. Advantageously, as shown in Figures 2A and 2B, a vertical wall 145 continuously surrounds a micro-board 120 in top view, thereby further reducing optical crosstalk. The vertical walls 145 form, for example, a continuous mesh extending parallel to the upper face 100.1, each mesh surrounding, in top view, either a micro-board 120 or an anchor pillar 115. In this case, each metallic portion 145.1 forms a closed loop in top view, surrounding a micro-board 120 or an anchor pillar 115. As shown here, the mesh may include a straight section centered on an axis passing through two adjacent reinforcing pillars 155.Two neighboring pixels of the detection device (1) therefore share a part of their respective vertical walls 145.

[0083] In this second embodiment, the metallic layer 207 extends over and is in contact with an upper surface of the encapsulation structure 130, which is flat and parallel to the upper face 100.1 of the reading substrate 100. It may be made of a different or the same metal as the metallic portion 145.1. It is therefore possible to decouple a property of the metal of the metallic layer 207, useful for obtaining an FSS filter 140 with good rejection and / or transmission, from a property of the metal of the metallic portions 145.1, useful for their manufacture. The first could, for example, be an electrical conductivity greater than or equal to 7 MS / m. The second could, for example, be the ability to deposit the metal conformally.

[0084] The metal layer 207 and the metal portions 145.1 can be, independently of each other, made of tungsten (W), tungsten silicide (WSi), copper (Cu), gold (Au), titanium (Ti), or titanium nitride (TiN). Advantageously, the metal portions 145.1 can be made of titanium nitride, and the metal layer 207 of aluminum.

[0085] These examples according to the first and second embodiments have been described with respect to matrices of thermal detectors comprising an elementary group of four thermal detectors centered at the vertices of a square, repeated periodically along two orthogonal axes. The elementary group may, however, comprise any number of thermal detectors without departing from the scope of the invention. The thermal detector array may thus comprise an elementary group of three pixels, consisting, for example, of pixel 5 and the pixels immediately above and to the right of pixel 5 in Figures IA and 2A. In this alternative embodiment of the first or second embodiment, an array of unfiltered pixels may be interlaced with the thermal detector array, for example, for acquiring an unfiltered image of the scene.

[0086] A first manufacturing process for a detection device 1 according to the first embodiment will now be described with reference to Figures 4A to 4H. In each of these figures, a view along section plane AA and along section plane BB of [Fig. 1A] at a particular stage of the first manufacturing process is shown at the top and bottom, respectively. [Fig. 4H] represents a final stage of the first manufacturing process at the end of which the detection device 1 is obtained. The manufacturing of the elements visible in the figures is described, it being understood that the equivalent elements of the thermal detectors of the matrix are produced simultaneously by the same sequence of process steps. The inter-pixel separation planes 7 are shown in all the sectional views.

[0087] In [Fig. 4A], the reading substrate 100 is provided, comprising the upper face 100.1, the reflective layers 105, and the connecting pads 103. The protective layer 110 is deposited on the upper face 100.1. A lower sacrificial layer 201 is deposited on the protective layer 110. The materials of the protective layer 110 and the lower sacrificial layer 201 are such that the lower sacrificial layer 201 can be selectively etched with respect to the protective layer 110. The lower sacrificial layer 201 can be made of polyimide, or, as shown here, of silicon dioxide. The protective layer 110 can be a bilayer of alumina (Al₂O₃) and silicon nitride (SiN), or a bilayer of aluminum nitride (Al₂O₃) and silicon nitride (SiN).

[0088] An opening is then formed passing through the lower sacrificial layer 201 and the protective layer 110 until reaching the connection pad 103. The through opening is filled with one or more metals to create the lower part of the anchor pillar 115. The lower part of the anchor pillar 115 is flush with an upper face of the lower sacrificial layer 201. It has horizontal dimensions smaller than the horizontal dimensions of the connection pad 103 measured along the same directions.

[0089] Next, the pad 115.1, the thermal insulation arm 122 and the micro-board 120 are formed. These three elements extend over the upper face of the sacrificial layer. lower 201. Alternatively, the studs 115.1, the thermal insulation arms 122 and the micro-boards 120 can be embedded in the lower sacrificial layer 201; if so, they can be flush with the upper surface of the lower sacrificial layer 201.

[0090] In [Fig. 4B], an upper sacrificial layer 202 is deposited on and in contact with the lower sacrificial layer 201, the thermal insulation arm 122, the stud 115.1, and the micro-board 120. The upper sacrificial layer 202 is preferably made of the same material as the lower sacrificial layer 201, as is the case here. It has a thickness between 500 nm and 2.5 pm, for example, 1.5 pm.

[0091] In the case where the detection device 1 includes one or more reinforcing pillars 155, a via 211 is then engraved opposite the stud 115.1, until the stud 115.1 is reached. The via has horizontal dimensions strictly smaller than the horizontal dimensions of the stud 115.1 measured in the same directions. Thus, the via has a base consisting of a portion of the stud 115.1, and an internal wall extending from an upper face of the upper sacrificial layer 202 to the base. Here, the internal wall is substantially perpendicular to the base and to the upper face of the upper sacrificial layer 202.

[0092] In [Fig. 4C], an insulating portion 153 is advantageously provided in the via 211 opening onto the stud 115.1. To achieve this, a conformal thin layer of an electrically insulating material is deposited on the bottom and the inner wall of the via 211, as well as on the upper face of the upper sacrificial layer 202. Preferably, the conformal thin layer is etched locally opposite the micro-board 120 so as not to reduce the transmission of electromagnetic radiation to the micro-board 120. Preferably, the thin layer is completely removed in a region opposite the micro-board 120.

[0093] The conforming thin film is made of a material resistant to etching of the lower and upper sacrificial layers 201, 202, for example, AlN or, advantageously, Al2O3. The insulating portion 153 has, for example, a thickness between 5 nm and 200 nm, preferably between 20 nm and 40 nm. Preferably, the conforming thin film is deposited by Atomic Layer Deposition (ALD). The insulating portion 153 prevents electrical conduction through the encapsulation structure 130 and / or the filter 140, and may also promote the adhesion of the reinforcing pillar 155 to the pad 115.1, as is the case with AlN or Al2O3.

[0094] In [Fig. 4D], a dielectric layer 205 is conformally deposited on the upper face of the upper sacrificial layer 202 and on the insulating portion 153. The dielectric layer 205 is made of any electrically insulating material that is transparent to the electromagnetic radiation to be detected. Here, it is made of amorphous silicon. intrinsic. Alternatively, the deposition may be non-conforming and followed by chemical mechanical polishing (CMP) to obtain the dielectric layer 205. The dielectric layer 205 has, for example, a thickness less than or equal to 400 nm. A portion of the dielectric layer 205 located entirely within the via 211 constitutes the reinforcing pillar 155. The reinforcing pillar 155 is shown with a central recess in [Fig. 4D], but depending on one or more dimensions of the via 211, and / or the deposition technique used, the reinforcing pillar 155 could be solid, without a central recess.

[0095] In [Fig. 4E], trenches 132 are locally etched through the dielectric layer 205 and part of the upper sacrificial layer 202. The trenches 132 define the positions and dimensions of the vertical walls 145. Preferably, they are not aligned with the micro-plate 120. Here, each trench is centered on an inter-pixel separation plane 7. In top view, they extend from one reinforcing pillar 155 to another, without, however, reaching them. The trenches 132 are separated from the thermal insulation arms 122 by a distance d along the Z-axis.

[0096] For example, it is possible to locally etch the dielectric layer 205 through a mask by a dry etch selective with respect to the upper sacrificial layer 202, until the upper sacrificial layer 202 is reached. The upper sacrificial layer 202 is then partially etched by a dry etch using a plasma of different species.

[0097] In [Fig. 4F], the metal layer 207 is conformally deposited on an upper face of the dielectric layer 205 and in the trenches 132. The metal layer 207 is made of a conformally depositable metal with an electrical conductivity greater than or equal to 0.3 MS / m„, sufficient to achieve good transmission and / or rejection of the filters 140 to be produced in a subsequent step of the manufacturing process. The metal layer 207 may be made of tungsten (W), titanium (Ti), titanium nitride (TiN), or advantageously, tungsten silicide (WSi). It may, for example, be deposited by chemical vapor deposition (CVD).

[0098] In [Fig. 4G], at least one through-hole is locally etched through the metal layer 207 and the dielectric layer 205 used to etch the lower and upper sacrificial layers 201, 202 through the through-hole created in the step of [Fig. 4H]. Here, each motif 141 is a through-hole portion of such a through-hole through the metal layer 207, and there are as many through-holes as there are motifs 141. The step of [Fig. 4G] involves one or more photolithography and dry etching substeps.

[0099] The patterns 141 of a filter 140 are engraved in the metallic layer 207 at a region of the metallic layer 207 located between the inter-partition planes pixel 7 of pixel 5 to which filter 140 belongs. The patterns 141 are then transferred by etching into the dielectric layer 205 to create through-holes 131, each coinciding with a pattern 141. The through-holes 131 pass completely through the dielectric layer 205. At the end of the step in [Fig. 4G], the filter 140 and the encapsulation structure 130 are obtained.

[0100] In [Fig. 4H], the lower and upper sacrificial layers 201, 202 are etched through the through hole, here through the patterns 141 and the through openings 131. This step implements selective etching with respect to the metallic layer 207, the dielectric layer 205, the protective layer 110 and one or more materials of the thermal insulation arms 122 and the micro-board 120 in contact with the lower and upper sacrificial layers 201, 202. The lower and upper sacrificial layers 201, 202 are completely etched in a region opposite the filter matrix 140. In this example, since the lower and upper sacrificial layers 201, 202 are made of silicon oxide, it is possible to etch them with hydrofluoric acid (HF) in the vapor phase. At the end of the step in [Fig.4H], we obtain a detection device 1 according to the first embodiment.

[0101] A second manufacturing method for a detection device 1 according to the second embodiment will now be described with reference to Figures 5A to 5G. In each of these figures, a view along section plane AA and along section plane BB of [Fig. 2A] at a particular step of the second manufacturing method is shown at the top and bottom, respectively. [Fig. 5G] represents a final step of the second manufacturing method at the end of which the detection device 1 is obtained. The manufacturing of the elements visible in the figures is described, it being understood that the equivalent elements of the thermal detectors are produced simultaneously by the same sequence of process steps. The inter-pixel separation planes 7 are shown in all the sectional views. Only the differences with the first manufacturing method are explicitly described.

[0102] For this second process, the step in [Fig.4A] is carried out beforehand.

[0103] Next, in [Fig. 5A], one or more trenches 232 are locally etched through a portion of the upper sacrificial layer 202. Each trench 232 defines the position and dimensions of a vertical wall 145. Preferably, it is not opposite the micro-plate 120. Here, it is centered, at least partially, on an inter-pixel separation plane 7. It is separated from the thermal insulation arms 122 by a distance d along the Z-axis. It comprises a bottom and one or more internal walls connecting the bottom to an upper face of the upper sacrificial layer 202. Each internal wall is substantially perpendicular to the upper face of the upper sacrificial layer 202 and to the bottom of the corresponding trench 232. The bottom is substantially parallel to the upper face 100.1 of the reading substrate 100.

[0104] Advantageously, as is the case here, a trench 232 is engraved, forming in top view a closed loop surrounding the micro-board 120. Advantageously, when the detection device 1 comprises several pixels 5, the trenches 232 surrounding two neighboring pixels 5 have one or more common parts. Here, the trenches 232 form a continuous mesh extending parallel to the upper face 100.1, each mesh surrounding, in top view, a micro-board 120 or an anchor pillar 115.

[0105] In [Fig. 5B], the metallic portions 145.1 are formed on the inner walls of the trenches 232. To do this, a metallic layer is deposited conformally on the upper sacrificial layer 202 and inside the trenches 232. The metallic layer is in contact with each inner wall of a trench 232. The metallic layer has a substantially constant thickness, for example within 10%, greater than or equal to 3 times its skin thickness at the longest wavelength of the electromagnetic radiation to be detected. For example, its thickness is between 100 nm and 300 nm.

[0106] The metallic layer is then etched by a predominantly anisotropic dry etching in the Z direction, so as to expose the upper face of the upper sacrificial layer 202 and the bottom of each trench 232. Unetched parts of the metallic layer in contact with the internal walls of the trench 232 constitute the metallic portions 145.1.

[0107] In the case where the detection device 1 includes one or more reinforcing pillars 155, the sequence of steps in [Fig. 5C] is carried out. A via 211 is engraved in accordance with the explanations in [Fig. 4B]. The insulating portion 153 can then be formed in the same way as in [Fig. 4C], except that the topology of the upper sacrificial layer 202 is not the same. Thus, the conforming thin layer also follows the contours of the trenches 232 and covers the metallic portions 145.1.

[0108] In [Fig. 5D], a dielectric layer 205 is deposited conformally or non-conformally on the upper face of the upper sacrificial layer 202, on the insulating portion 153, on the metallic portion 145.1, and inside the trenches 232. The dielectric layer 205 is made of any dielectric material and is transparent to the electromagnetic radiation to be detected. Here, it is made of intrinsic amorphous silicon. The deposition can be followed by chemical mechanical polishing (CMP) to obtain the dielectric layer 205. The dielectric layer 205, for example, has a thickness less than or equal to 400 nm at the top face of the upper sacrificial layer 202. In the case of a conformal deposition and a trench depth 232 greater than or equal to the thickness of the dielectric layer 205, the trenches 232 can have a sufficiently small horizontal width to allow complete filling of the trenches 232 by the dielectric layer 205. A portion of the dielectric layer 205 entirely located within the via 211 constitutes the reinforcing pillar 155. A portion of the dielectric layer 205 entirely located within a trench 232 constitutes the extension 145.2 of the encapsulation structure 130 and a vertical wall 145. At the end of [Fig. 5D], the dielectric layer 205 has a flat upper face parallel to the upper face 100.1 of the reading substrate 100.

[0109] In [Fig. 5E], the metal layer 207 is deposited on the upper surface of the dielectric layer 205, and in contact with it. Since the upper surface of the dielectric layer 205 is flat, the deposition of the metal layer 207 may not be perfectly conformal. The metal layer 207 may be made of tungsten (W), titanium (Ti), titanium nitride (TiN), tungsten silicide (WSi), or advantageously aluminum (Al).

[0110] In [Fig.5F], the step of [Fig.4G] is carried out to obtain the filter 140 and the encapsulation structure 130. Since the upper face of the dielectric layer 205 is flat, the photolithography step(s) are facilitated.

[0111] In [Fig. 5G], the lower and upper sacrificial layers 201, 202 are etched through the through hole, here through the patterns 141 and the through openings 131. This step implements selective etching with respect to the metallic portions 145.1, the dielectric layer 205, the metallic layer 207, the protective layer 110, and one or more materials of the thermal insulation arms 122 and the micro-board 120 in contact with the lower and upper sacrificial layers 201, 202. The lower and upper sacrificial layers 201, 202 are completely etched in a region opposite the filter matrix 140. In this example, since the lower and upper sacrificial layers 201, 202 are made of silicon oxide, it is possible to use etching with hydrofluoric acid (HF) in the vapor phase. At the end of the step in [Fig.5G], we obtain a detection device 1 according to the second embodiment.

[0112] A variant of the second manufacturing process will now be described. This leads to the production of a detection device 1 according to a variant of the second embodiment in which the extensions 145.2 are made of metal. Only the differences with the second manufacturing process are expressly described.

[0113] Step [Fig. 5B] is omitted. Following step [Fig. 5A], an electrically conductive nucleation layer for an electrolysis process is conformably deposited on the upper surface of the upper sacrificial layer 202 and in the trenches 232. A thick metal layer is then deposited by electrolysis. The nucleation layer can, for example, be a bilayer of titanium and titanium nitride. The thick layer can, for example, be copper. The thick layer is then polished by chemical-mechanical polishing, stopping at the upper sacrificial layer 202. The upper sacrificial layer 202 can, for example, be oxide of silicon. This yields the metallic portions 145.1 and the extensions 145.2, here respectively in Ti / TiN and copper. The distal face of each extension 145.2 is covered by a metallic portion 145.1 which is part of the nucleation layer.

[0114] The steps shown in Figures 5C and following are then carried out. In step [Fig. 5C], the conformal thin film rests on the extensions 145.2. In step [Fig. 5D], the upper part of the encapsulation structure 130 is formed.

[0115] Specific embodiments have just been described. Various variations and modifications will be apparent to those skilled in the art. For example, it is possible to remove the metallic layer 207 before the sacrificial layer removal step of the first process on a surface of the encapsulation structure 130 opposite a microboard 120, to produce a filter 140 having a Fabry-Pérot cavity delimited by the encapsulation structure 130 similar or identical to one of the filters described in document FR3050526. It is also possible to produce such a filter by omitting the deposition of the metallic layer 207 in the second manufacturing process or its variant and to carry out the process steps leading to the production of an interference filter described in document FR3050526.

Claims

Demands

1. A detection device (1) for electromagnetic radiation, comprising: • a reading substrate (100), • a thermal detector array, each comprising a filter (140), a micro-board (120), thermal insulation arms (122), and anchoring pillars (115), such that the micro-board (120) is electrically connected to the reading substrate (100) by the thermal insulation arms (122) and the anchoring pillars (115), and suspended above the reading substrate (100) by the thermal insulation arms (122), • an encapsulation structure (130) covering the thermal detector array on one side of the detection device (1) opposite the reading substrate (100), such that each filter (140) is arranged in and / or on the encapsulation structure (130), the detection device (1) being characterized in that it comprises • vertical walls (145),each comprising a metal and extending between two adjacent micro-plates (120), from the encapsulation structure (130), towards a detection plane of the detection device (1) defined by the set of micro-plates (120), without reaching it.

2. Detection device (1) according to claim 1, wherein the encapsulation structure (130) comprises reinforcing pillars (155), each resting on an anchoring pillar (115).

3. Detection device (1) according to claim 2, wherein an anchoring pillar (115) is arranged between each group of four neighboring thermal detectors centered at the vertices of a rectangle, a reinforcing pillar (155) rests on each anchoring pillar (115), and wherein each vertical wall (145) has a straight portion extending parallel to the detection plane along an axis passing through two neighboring reinforcing pillars (155).

4. A detection device (1) according to any one of claims 1 to 3, wherein the thermal insulation arms (122) extend in the detection plane and the detection device (1) comprises at least one vertical wall (145) per thermal detector located directly above a region of the detection plane occupied by a thermal insulation arm (122).

5. Detection device (1) according to any one of claims 1 to 4, wherein the detection device (1) is a multispectral detection device and the set of filters (140) is divided into homogeneous subsets, the filters (140) of a subset having an identical transmission band distinct from the transmission bands of the filters of the other subsets, so that the subsets form a regular tiling of the encapsulation structure (130).

6. Detection device (1) according to claim 5, wherein each filter (140) is a frequency-selective surface based on the encapsulation structure (130).

7. Detection device (1) according to claim 6, wherein the encapsulation structure (130) has a region opposite each filter (140) having a thickness less than or equal to half a wavelength in the encapsulation structure (130) of the electromagnetic radiation.

8. Detection device (1) according to claim 6 or 7, wherein each filter (140) has at least one hollow pattern (141) passing through the filter (140), and wherein the encapsulation structure (130) has a through opening (131) opposite each pattern (141) of the filter (140).

9. Detection device (1) according to any one of claims 6 to 8, wherein the vertical walls (145) and the filters (140) constitute parts of a common metallic layer (207) of the detection device (1).

10. Detection device (1) according to any one of claims 6 to 8, wherein each vertical wall (145) comprises an extension (145.2) of the encapsulation structure (130) and a metallic portion (145.1) of metal covering a lateral surface of the extension (145.2).

11. Detection device (1) according to claim 10, wherein each extension (145.2) is a single piece with an upper part of the encapsulation structure (130) connecting all the extensions (145.2) and on which the filters (140) rest.

12. Detection device (1) according to claim 10, wherein each extension (145.2) is made of metal.

13. Detection device (1) according to any one of claims 10 to 12, wherein the vertical walls (145) form a continuous mesh comprising meshes such that each mesh surrounds a micro-board (120) or an anchor pillar (115) on a view perpendicular to the detection plane.

14. A method for manufacturing a detection device (1) according to any one of claims 1 to 13, comprising the following steps: • providing a pre-treated substrate comprising the reading substrate (100), a lower sacrificial layer (201) resting on the reading substrate (100), and a portion of each thermal detector comprising the micro-board (120), the thermal insulation arms (122), and the anchoring pillars (115), such that each micro-board (120) extends parallel to an upper face of the lower sacrificial layer (201) opposite the reading substrate (100) while intercepting or being flush with it, • depositing an upper sacrificial layer (202) on the lower sacrificial layer (201) so as to cover the thermal insulation arms (122) and the micro-boards (120) of the thermal detectors of the matrix, • etching trenches (132,232) in an upper part of the upper sacrificial layer (202) opposite the lower sacrificial layer (201) with respect to the detection plane defined by the set of micro-boards (120), • formation of the vertical walls (145), each in a trench (132, 232), • formation of the encapsulation structure (130) comprising a sub-step of deposition on the upper sacrificial layer (202), of a dielectric layer (205) in which the encapsulation structure (130) is formed, • etching of a through hole in the encapsulation structure (130), • etching of the lower and upper sacrificial layers (201, 202) through the through hole.

15. A manufacturing process according to claim 14, wherein: • the substep of deposition of the dielectric layer (205) precedes the etching of the trenches (132), • the etching of the trenches (132) includes an etching of the dielectric layer (205) such that the trenches (132) extend into the dielectric layer (205), • the formation of the vertical walls (145) includes a conformal deposition of a metallic layer (207) in the trenches (132), and wherein the manufacturing process further comprises a step of forming the filters (140) in the metallic layer (207).

16. A manufacturing method according to claim 14, wherein • the engraving of the trenches (232) precedes the substep of deposition of the dielectric layer (205), • the substep of deposition of the dielectric layer (205) is further a substep of the formation of the vertical walls (145), • the dielectric layer (205) is deposited in the trenches (232) and on an upper face of the upper sacrificial layer (202) during the deposition substep, and wherein the manufacturing method further comprises the formation of metallic portions (145.1) on internal walls of the trenches (232) before the substep of deposition of the dielectric layer (205).

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