Method for manufacturing a detection device comprising a packaging structure with an opaque thin layer placed on the peripheral wall of a mineral

Abstract

The invention relates to a method for manufacturing a detection device (1), comprising the steps of: o preparing thermal detectors distributed in a detection array (2p) and a compensation array (2s) by a mineral sacrificial layer (41, 42); o manufacturing a packaging structure (30s) comprising an opaque thin layer (33) extending over the compensation array (2s); o partially removing the mineral sacrificial layer (41, 42) by chemical etching to release the detection array (2p) and the compensation array (2s) and to obtain a peripheral wall (31s) formed by the non-etched parts of the mineral sacrificial layer (41, 42) and surrounding the compensation array (2s), the opaque thin layer (33) being suspended over the compensation array (2s) and placed on the peripheral wall.

Description

Technical Field

[0001] The present invention pertains to apparatus for detecting electromagnetic radiation (particularly infrared or terahertz radiation), the apparatus comprising an encapsulation structure in which an array of compensated thermal detectors is located, the encapsulation structure including a thin, opaque upper layer over the radiation to be detected. The invention is particularly applicable to the fields of infrared or terahertz imaging, thermal imaging, or even gas detection. Background Technology

[0002] A device for detecting electromagnetic radiation may include an array of sensitive pixels, each containing a thermal detector. The thermal detector is made of a readout substrate containing a readout integrated circuit (ROIC). The thermal detector may be of the type having an absorption film that is thermally insulated from the readout substrate. The absorption film includes an absorber associated with a temperature transducer that absorbs the electromagnetic radiation to be detected; the intensity of the electrical characteristics of the temperature transducer changes according to the heating of the temperature transducer.

[0003] However, the temperature of the temperature transducer is highly dependent on its environment, and the absorption film is typically thermally insulated from the substrate and the readout circuitry disposed within it. Therefore, the absorption film is usually suspended above the substrate by anchor posts and thermally insulated from it by retaining arms and insulating material. These anchor posts and insulating arms also serve an electrical function by ensuring the electrical connection between the suspended film and the readout circuitry disposed within the substrate.

[0004] However, during the reading of the electrical signal by a thermal detector during the absorption of electromagnetic radiation, the useful portion of the measured electrical signal associated with the heating of the temperature transducer (caused by the absorption of the detected electromagnetic radiation) remains relatively low relative to the strength of the measured electrical signal. Furthermore, the detection device typically includes a so-called compensated thermal detector, which is designed to measure the useless portion of the electrical signal associated with the environment of the thermal detector (also known as the common mode), and then subtract this useless portion from the response signal to derive the useful portion.

[0005] Specifically, when the detection device operates in rolling shutter mode, it may include an array of sensitive pixels, an array of compensating pixels, and a CTIA-type integrator. The array of compensating pixels is typically smaller than the array of sensitive pixels, and the CTIA-type integrator is positioned at the bottom of each column of pixels. During operation, the array of sensitive pixels is read line by line. The integrator receives the response signal I from the thermal detector. d And subtract the common-mode electrical signal I measured by the corresponding compensation detector from the response signal. c Therefore, it is included in the response signal I. d The useless part in is composed of common mode I cCompensation. Therefore, without requiring specific adjustment of the substrate temperature, a useful portion I associated with the absorption of the electromagnetic radiation to be detected is obtained. d -I c .

[0006] Document WO2012 / 056124A1 describes an example of a detection device comprising an array of sensitive pixels and an array of compensation pixels. Each pixel includes a thermal detector having an absorption film suspended above a readout substrate. The thermal detector is fabricated on and through a first polyimide sacrificial layer, and is covered by a second sacrificial layer. A compensation structure forms the chamber in which the array of compensation pixels is located. The compensation structure includes an opaque thin layer that allows the compensation pixels to be shielded, i.e., preventing the transmission of electromagnetic radiation to be detected. For this purpose, the opaque thin layer is fabricated by conformal deposition to continuously cover the upper surfaces and sidewalls of the two sacrificial layers. Furthermore, the opaque thin layer includes an upper wall extending above the compensation pixels and an outer peripheral wall placed on and extending around the readout substrate.

[0007] However, a method is needed to manufacture such a detection device that can improve the mechanical strength of the packaging structure of the compensation array without degrading the quality of the optical shielding and without complicating the fabrication process.

[0008] Furthermore, the known document US2009 / 0146059A1 describes a detection device including a thermal detector and a compensation element. However, this compensation element differs structurally from the thermal detector, which ensures the detection of electromagnetic radiation of interest, potentially compromising the quality of the compensation performed. Summary of the Invention

[0009] The object of this invention is to at least partially overcome the shortcomings of the prior art. To this end, the object of this invention is to provide a method for manufacturing an apparatus for detecting electromagnetic radiation, the method comprising the following steps:

[0010] o Prepare a detection array and at least one so-called compensation array located on and through the first sacrificial layer, the first sacrificial layer being placed on a readout substrate, the detection array being formed by a thermal detector intended to detect electromagnetic radiation, the compensation array being formed by a thermal detector not intended to detect electromagnetic radiation, and prepare a second sacrificial layer covering the thermal detector and the first sacrificial layer; the thermal detector (20s) of the compensation array (2s) is adapted to detect electromagnetic radiation and is structurally identical to the thermal detector (20p) of the detection array (2p);

[0011] o Prepare a so-called secondary packaging structure that defines a secondary chamber in which a compensation array is located. The secondary packaging structure includes an outer peripheral wall and an opaque upper wall, which is placed on the outer peripheral wall and is formed by at least one opaque thin layer.

[0012] According to the present invention, the first sacrificial layer and the second sacrificial layer are made of mineral materials. Furthermore, the steps for fabricating the secondary encapsulation structure include the following:

[0013] o Prepare an opaque thin layer such that the opaque thin layer extends only along the upper surface of the second mineral sacrificial layer in a continuous planar manner;

[0014] o. An aperture is fabricated in an opaque thin layer, with the aperture facing the compensation array;

[0015] o By means of chemical etching through the orifice, the first and second mineral sacrificial layers are partially removed to release the detection array and the compensation array, and the unetched portion of the mineral sacrificial layer is formed and surrounds the outer peripheral wall of the compensation array. An opaque thin layer is suspended above the compensation array and placed on the outer peripheral wall.

[0016] Some preferred, but non-limiting, aspects of this method are as follows.

[0017] The first and second sacrificial layers can be made from the same mineral material based on silicon nitride or silicon oxide.

[0018] The thermal detectors of the detection array and the thermal detectors of the compensation array both include an absorption film that absorbs the electromagnetic radiation to be detected. The absorption film includes a temperature transducer and is suspended above the readout substrate by anchoring posts and holding arms and is thermally insulated.

[0019] The thermal detectors of the detection array and / or the thermal detectors of the compensation array may both include a reflective layer, which is placed on the readout substrate below each absorption film.

[0020] The opaque upper wall may include an interference stack that can absorb the electromagnetic radiation to be detected.

[0021] An opaque thin layer can be a layer that can reflect or absorb the electromagnetic radiation to be detected.

[0022] Opaque thin layers can have a uniform thickness.

[0023] The opaque upper wall may also include at least one reinforcing thin layer covering the opaque thin layer, and the opaque upper wall may have an edge protruding relative to the outer peripheral wall in a plane parallel to the reading substrate, the protruding edge including the opaque thin layer and / or the reinforcing thin layer.

[0024] The secondary chamber can have a length and a width in a plane parallel to the read substrate, with the width being less than or equal to 200 μm. The width is less than the length.

[0025] The opaque upper wall may not include the following reinforcing pillars: reinforcing pillars that are integral with the thin layer of the opaque upper wall and made of the same material, located in the secondary chamber and placed on the read substrate.

[0026] The mineral sacrificial layer can be made of a material that can absorb the electromagnetic radiation to be detected.

[0027] The opaque thin layer can be made of degassing material.

[0028] The manufacturing method may include the following steps:

[0029] Prior to the partial removal step, an opaque upper wall is prepared, consisting of a stack including a protective thin layer made of inert amorphous carbon inert to the etchant used during the partial removal step. The protective thin layer is positioned to contact the second mineral sacrificial layer. The opaque thin layer extends only above and in contact with the protective thin layer, such that the opaque thin layer is protected by the protective thin layer during the partial removal step.

[0030] Following the partial removal step, at least a portion of the protective thin layer is removed by chemical etching to release the inner surface of the opaque thin layer.

[0031] The manufacturing method may include the step of fabricating a main package structure, the main package structure defining a main chamber, a detection array located in the main chamber, and the main package structure including a main upper wall, the main upper wall including a packaging thin layer disposed on a main outer peripheral wall, the step of fabricating the main package structure including:

[0032] o Deposit an encapsulation thin layer on the second mineral sacrificial layer, the encapsulation thin layer extending above the detection array and the compensation array;

[0033] o A main aperture is fabricated in the encapsulation thin layer, and the main aperture is arranged facing the detection array;

[0034] o Perform partial removal of the first and second mineral sacrificial layers to form an unetched portion of the mineral sacrificial layers surrounding the main outer peripheral wall of the detection array, with the encapsulation thin layer suspended above the detection array and placed on the main outer peripheral wall.

[0035] The manufacturing method may include the step of preparing a connecting cavity that connects a secondary chamber and a primary chamber, the connecting cavity being laterally defined by unetched portions of a first mineral sacrificial layer and a second mineral sacrificial layer.

[0036] The manufacturing method may include the step of preparing reinforcing pillars for the encapsulation thin layer, wherein the reinforcing pillars are preferably placed on the readout substrate by means of anchoring pillars of the thermal detector of the detection array.

[0037] Chemical etching in an acidic medium can be carried out using hydrofluoric acid in a vapor phase, and the first and second mineral sacrificial layers can be made of silicon-based (preferably silicon oxide-based) mineral materials. In particular, when the mineral sacrificial layers are made of silicon nitride, chemical etching in an acidic medium can be carried out using a fluorocarbon etchant in a vapor phase.

[0038] The present invention also relates to an apparatus for detecting electromagnetic radiation, the apparatus comprising:

[0039] o Read substrate;

[0040] o Detection array, which is formed by thermal detectors designed to detect electromagnetic radiation;

[0041] o At least one so-called compensation array, which is formed by thermal detectors not intended to detect electromagnetic radiation, the thermal detectors of the compensation array being adapted to detect electromagnetic radiation and structurally identical to the thermal detectors (20p) of the detection array (2p);

[0042] The so-called secondary packaging structure defines a secondary chamber, in which the compensation array is located. The secondary packaging structure includes an outer peripheral wall and an opaque upper wall, which is placed on the outer peripheral wall and is formed by at least one opaque thin layer.

[0043] The opaque thin layer extends in a continuous planar manner, and its outer wall is made of mineral material. Attached Figure Description

[0044] Other aspects, objects, and advantages of the present invention will be better appreciated by reading the following detailed description of preferred embodiments of the invention, which are given by way of non-limiting example and with reference to the accompanying drawings, wherein:

[0045] Figures 1A to 1F This is a schematic partial view illustrating the various steps of a method for manufacturing a detection device according to one embodiment;

[0046] Figure 2 It is based on Figure 1F A schematic partial top view of the detection device of an alternative embodiment is shown, wherein the detection device includes a plurality of secondary chambers;

[0047] Figures 3A to 3F This is a schematic partial view illustrating the various steps of a method for manufacturing a detection device according to an alternative embodiment, wherein the opaque thin layer is made of a material having a degassing effect;

[0048] Figures 4A to 4DThis is a schematic partial view illustrating various steps of a method for manufacturing a detection device according to another embodiment, wherein the packaging structure of the detection array includes a cover attached to and assembled to a reading substrate. Detailed Implementation

[0049] Throughout the accompanying drawings and the remainder of the specification, the same reference numerals denote the same or similar elements. Furthermore, various elements are not shown to scale to improve clarity. Moreover, different embodiments and variations are not mutually exclusive and can be combined together. Unless otherwise stated, the terms "generally," "about," and "approximately" mean within a range of 10%, preferably within a range of 5%. Furthermore, unless otherwise stated, the terms "between..." and equivalent expressions mean including the boundaries.

[0050] The present invention generally relates to a method for manufacturing an apparatus for detecting infrared electromagnetic radiation or terahertz electromagnetic radiation.

[0051] The detection device includes multiple thermal detectors, which are distributed to form at least one so-called sensitive array or detection array of thermal detectors intended to detect electromagnetic radiation, and at least one so-called compensation array of thermal detectors not intended to detect electromagnetic radiation.

[0052] The manufacturing method includes the step of fabricating an array of thermal detectors using so-called mineral sacrificial layers made of inorganic or mineral materials, which are intended to form the outer peripheral walls of the encapsulation structure. Here, this involves silicon-based dielectric materials, i.e., electrically insulating materials, which also enable the fabrication of intermetallic dielectric layers for the readout circuitry. These dielectric materials have a dielectric constant or relative permittivity, for example, less than or equal to 3.9, thereby limiting parasitic capacitance between interconnects. The mineral material does not include carbon chains and can be based on silicon oxide (e.g., silicon oxide SiO₂). x The mineral material can be optionally based on organosilicon (e.g., SiOC, SiOCH) or can be a fluorinated glass-type material (e.g., SiOF). It can also be based on silicon nitride, such as silicon nitride Si. x N y Preferably, the mineral material involves silicon dioxide (SiO₂). x .

[0053] The manufacturing method also includes a step of partially removing the mineral sacrificial layer by chemical etching (optionally performed in an acidic medium, particularly when the mineral material is based on silicon oxide, for example, using hydrofluoric acid (vapor HF) in a vapor phase). In the case of silicon nitride-based mineral materials, partial etching can be performed using gaseous fluorocarbons. In any case, other etchants may be used depending on the properties of the mineral material used.

[0054] The compensation array is located in a preferably sealed chamber, which is formed by an encapsulation structure extending above and around the compensation thermal detector. The encapsulation structure includes at least:

[0055] - A mineral peripheral wall extends around the compensation array and laterally defines the chamber. As explained laterally, the mineral peripheral wall is formed by the non-etched portion of the mineral sacrificial layer;

[0056] - An opaque upper wall extends above the compensation array and vertically defines the chamber. This opaque upper wall includes at least one opaque thin layer made of a material that is opaque to the electromagnetic radiation to be detected, i.e., the transmittance of the electromagnetic radiation to be detected is less than or equal to 5%.

[0057] Or even less than or equal to 1%.

[0058] A thin layer refers to a layer formed by microelectronic material deposition technology, and the thickness of the thin layer is preferably less than or equal to 10 μm. Furthermore, when the transmittance of the thin layer to the center wavelength of the spectral range of the electromagnetic radiation to be detected is greater than or equal to 50%, preferably 75%, or even 90%, the thin layer is considered transparent. The absorptivity of the thin layer is preferably less than or equal to 50%, preferably 25%, and more preferably 10%.

[0059] Various embodiments are then shown, and these embodiments differ substantially in the packaging structure defining the main chamber in which the detection array resides. Thus, the various embodiments may involve a packaging structure made entirely by depositing a transparent thin layer on and through a mineral sacrificial layer; or a packaging structure in which at least a portion of the packaging structure is attached to and assembled to a readout substrate.

[0060] Figures 1A to 1F The various steps of a method for manufacturing a detection device 1 according to one embodiment are schematically and partially illustrated, wherein the encapsulation structure 30s of the compensation array 2s and the encapsulation structure 30p of the detection array 2p are formed by depositing thin layers on and through the mineral sacrificial layers 41, 42. For clarity, only a portion of the detection array 2p and the corresponding encapsulation structure 30p are shown in the figures. In this example, the detection device 1 includes the compensation array 2s located in a secondary chamber 3s; however, alternatively, the detection device may include multiple compensation arrays, each located in a dedicated secondary chamber 3s (see [link to documentation]). Figure 2 ).

[0061] Herein and for the remainder of the specification, a three-dimensional reference frame XYZ is defined, wherein the XY plane is generally parallel to the readout substrate 10, and the Z-axis is oriented in a direction generally orthogonal to the plane of the readout substrate 10 in the directions of the thermal detectors 20p and 20s. The terms “vertical” and “vertically located” are understood to refer to orientation generally parallel to the Z-axis, and the terms “horizontal” and “horizontally located” are understood to refer to orientation generally parallel to the XY plane. Furthermore, the terms “down” and “up” are understood to refer to increased positioning when moving away from the readout substrate 10 in the +Z direction.

[0062] Detection device 1 includes:

[0063] - A so-called sensitive array 2p of a thermal detector 20p designed to receive and detect electromagnetic radiation of interest, wherein the detection array 2p is preferably located in a main chamber 3p defined by a main package structure 30p;

[0064] - At least one so-called compensation array 2s of a thermal detector 20s not intended to receive electromagnetic radiation of interest, the compensation array 2s being located in a secondary chamber 3s defined by a secondary encapsulation structure 30s. The secondary encapsulation structure 30s includes an opaque upper wall 32s placed on a mineral peripheral wall 31s and including at least one opaque thin layer 33.

[0065] As an example, thermal detector 20p is here adapted to detect infrared radiation in the long-wavelength infrared (LWIR) range, where the wavelength of infrared radiation is between about 8 μm and about 14 μm. Thermal detectors 20p and 20s are connected to readout circuitry 14 located in substrate 10 (hence referred to as the readout substrate). Thus, the sensitive thermal detector 20p forms a sensitive pixel preferably arranged periodically, and the lateral dimension of the sensitive thermal detector in the plane of the readout substrate 10 can be about tens of micrometers, for example, equal to about 10 μm or even smaller.

[0066] In the sense that the compensating thermal detector 20s includes a suspended membrane 22 suspended by a holding arm (not shown) and an anchor post 21, the compensating thermal detector 20s is structurally similar to or identical to the sensitive thermal detector 20p. The suspended membrane 22 may also include a temperature-sensing transducer. Therefore, the compensating thermal detector can provide the readout circuit 14 with an electrical signal indicating the heating caused by the Joule effect during readout. Furthermore, it should be noted that some compensating thermal detectors can also provide the readout circuit 14 with an additional electrical signal (common mode) indicating the temperature of the readout substrate 10. For this purpose, these thermal detectors are thermally activated along with the readout substrate 10, provided that the holding arm does not ensure thermal insulation of the absorption membrane 22 relative to the readout substrate 10.

[0067] Reference Figure 1A The detection array 2p and compensation array 2s are fabricated on and through the first mineral sacrificial layer 41 from the readout substrate 10. The readout substrate 10 is made of silicon and is formed from a support substrate 11 containing a readout circuit 14 adapted to control and read the thermal detectors 20p and 20s. Here, the readout circuit 14 is in the form of a CMOS integrated circuit. The readout circuit specifically includes portions of conductive lines separated from each other by an intermetallic insulating layer made of a dielectric material, such as a silicon-based mineral material, like silicon oxide (SiO2). x Silicon nitride (SiN) x The conductive portion 12 is flush with the surface of the supporting substrate 11, ensuring electrical connection between the anchor posts 21 of the thermal detectors 20p and 20s and the readout circuit 14. Additionally, one or more portion or connecting studs 7 (see...) Figure 1F The readout circuit 14 is flush with the surface of the supporting substrate 11, enabling connection of the readout circuit 14 to an external electronic device (not shown). In this example, the readout circuit 14 is adapted to read an electrical signal emitted by the compensated thermal detector 20s, which represents the heating caused by the Joule effect during the readout (and optionally the temperature of the readout substrate 10). Therefore, by performing differential readout between the sensitive thermal detector 20p and the compensated thermal detector 20s, parasitic components related to the heating caused by the Joule effect (and optionally components related to the temperature of the substrate) can be subtracted from the "original" electrical signal to retain only the useful portion related to the detection of electromagnetic radiation of interest.

[0068] Each sensitive thermal detector 20s and preferably each compensated thermal detector 20p includes a reflective layer 23 (reflector) disposed on the readout substrate 10 and positioned facing each absorption film 22 (and thus below each absorption film). The reflector 23 may be formed from a portion of the conductive lines of the final interconnect layer, made of a material suitable for reflecting the electromagnetic radiation to be detected, or the reflector may be a layer deposited on the protective layer 13 described below. The reflector extends facing the absorption film 22 of the sensitive thermal detector 20p and is intended to form, together with the absorption film, a quarter-wavelength interference chamber associated with the electromagnetic radiation to be detected. Preferably, the reflector also extends facing the absorption film 22 of the compensated thermal detector 20s.

[0069] Finally, the read substrate 10 includes a protective layer 13 to specifically cover the intermetallic insulating layer. This protective layer 13 corresponds to an etch stop layer made of a substantially inert material that is inert to the chemical etchants (e.g., HF media in a vapor phase) used to subsequently remove the various mineral sacrificial layers. Therefore, the protective layer 13 forms a chemically inert sealing layer, and it is electrically insulating to prevent any short circuits between the anchor posts 21. Thus, the protective layer prevents the underlying intermetallic insulating layer from being etched during the step of removing the mineral sacrificial layers. The protective layer may be formed of aluminum nitride or aluminum oxide, or even aluminum trifluoride, or unintentionally doped amorphous silicon.

[0070] Subsequently, thermal detectors 20p and 20s are fabricated on the readout substrate 10. These fabrication steps are the same as or similar to those described in particular in document EP3239670A1. Here, the sensitive thermal detector 20p and the compensating thermal detector 20s advantageously have similar structures. Here, the sensitive thermal detector and the compensating thermal detector are microbolometers, each of which includes an absorption film 22, i.e., an absorption film capable of absorbing the electromagnetic radiation to be detected, which is suspended above the readout substrate 10 by anchoring posts 21 and holding arms (not shown). The holding arms also ensure that the absorption film is thermally insulated relative to the readout substrate 10. Of course, this is the case for the sensitive thermal detector 20p, but also for the compensating thermal detector 20s, which thus provides an electrical signal representing the heating caused by the Joule effect during readout.

[0071] The absorption membrane 22 is typically fabricated using surface micromachining techniques, which include fabricating anchor posts 21 through the first mineral sacrificial layer 41 and fabricating the absorption membrane 22 and retaining arms on the upper surface of the mineral sacrificial layer 41. Each absorption membrane 22 also includes a temperature transducer, such as a thermistor material, which is connected to the reading circuit 14 via electrical connections disposed in the heat-insulating arms and anchor posts 21.

[0072] Sensitive thermal detectors 20p are located in the main region of the surface of the readout substrate 10, which corresponds to the main chamber 3p (detection chamber). Compensating thermal detectors 20s are located in a secondary region of this surface, which corresponds to the secondary chamber 3s (compensation chamber). It should be noted that the detection array 2p can contain a large number (e.g., 640 × 480) of thermal detectors 20p. As an example, the compensation array 2s can contain 4 × 480 thermal detectors 20s. Therefore, the surface area of ​​the main region is larger than the surface area of ​​the secondary region.

[0073] A second mineral sacrificial layer 42, preferably having the same properties as the mineral sacrificial layer 41, is subsequently deposited. Thus, the mineral sacrificial layer 42 covers the mineral sacrificial layer 41 as well as the sensitive thermal detector 20p and the compensating thermal detector 20s. The mineral sacrificial layer has a generally planar free upper surface. Typically, the various mineral sacrificial layers 41, 42 can be silicon dioxide obtained by PECVD deposition from a tetraethyl orthosilicate (TEOS) compound. The mineral sacrificial layers 41, 42 can be made from the same mineral material.

[0074] Reference Figure 1B An opaque thin layer 33 is prepared to shield the compensation array 2s, i.e., to prevent the transmission of the electromagnetic radiation to be detected in the direction of the compensation thermal detector 20s. The opaque thin layer 33 can be a layer that reflects or absorbs the electromagnetic radiation of interest. The opaque thin layer 33 is prepared such that it extends in a continuous planar manner on the upper surface (on a portion of the upper surface) of the mineral sacrificial layer 42.

[0075] In this example, an opaque thin layer 33 is deposited on and in contact with the second mineral sacrificial layer 42. Alternatively, one or more thin layers may be pre-deposited on the second mineral sacrificial layer 42. The opaque thin layer 33 is deposited to extend in a continuous plane above the compensation array 2s. A continuous plane means that the opaque thin layer 33 extends planarly in the XY plane over its entire surface area. The opaque thin layer is deposited such that it has a substantially constant thickness.

[0076] In the case of reflective materials, the opaque thin layer can involve aluminum, gold, tungsten, copper, or titanium, and has a constant thickness, for example, between 100 nm and several hundred nanometers (e.g., approximately 300 nm). Preferably, the thickness of the opaque thin layer 33 is less than or equal to 1 μm to avoid complicating the manufacturing process. Advantageously, these materials of the opaque thin layer 33 are substantially inert (or weakly reactive) to the chemical etching performed for the partial removal of the mineral sacrificial layers 41, 42. When the material is weakly reactive to the etchant used, the thickness of the deposited material will be slightly greater than the desired final thickness to account for slight partial etching (thinning) during the chemical etching step.

[0077] The opaque thin layer 33 can be deposited by a thin-layer deposition technique (e.g., by physical vapor deposition, which can be performed by cathode sputtering of a metal target or by vacuum evaporation of metal heated in a crucible) that ensures the uniformity of the thickness of the opaque thin layer.

[0078] The opaque thin layer 33 is then constructed by photolithography and local etching such that the opaque thin layer does not extend above the detection array 2p. Therefore, the opaque thin layer can extend anywhere on the second mineral sacrificial layer 42 (except above the detection array 2p - e.g.) Figure 4A (as shown), or it can extend only above the compensation array 2s and the secondary region (as shown). Figure 1F (As shown). In any case, the opaque thin layer 33 extends at least partially above the region where the mineral peripheral wall 31s of the secondary encapsulation structure 30s is located.

[0079] Preferably, considering the reinforcing pillars 35 of the encapsulation thin layer 34 for fabricating the main encapsulation structure 30p, recesses 43 and preferably insulating portions 44 are fabricated here. In a first step, a plurality of recesses 43 are fabricated, extending along the Z-axis from the upper surface of the second mineral sacrificial layer 42 to the anchoring pillar 21 of the sensitive thermal detector 20p. Then, a plurality of insulating portions 44 are fabricated in the recesses 43. These insulating portions 44 are thin film portions made of electrically insulating material. These insulating portions enable the prevention of electrical contact between the sensitive thermal detector 20p and the encapsulation thin layer 34 via the reinforcing pillars 35 of the encapsulation thin layer. For this purpose, an insulating thin layer is deposited on the free surface inside the recesses 43 of the anchoring pillar 21. Here, the insulating thin layer is advantageously partially etched above the sensitive thermal detector 20p to avoid interfering with or reducing the transmission of the electromagnetic radiation to be detected, but the insulating thin layer may not be etched. The insulating thin layer may have a thickness between about 10 nm and about 200 nm. The insulating thin layer is made of a material that is inert to the chemical etching performed during the removal of the mineral sacrificial layer, and the material may be selected from AlN, Al2O3, and HfO2.

[0080] Reference Figure 1CA packaging thin layer 34 is prepared for the main packaging structure 30p. This packaging thin layer 34 is formed by an upper portion extending above the detection array 2p, and includes reinforcing pillars 35 located in the main region. The reinforcing pillars are spaced apart from each other and placed on the readout substrate 10 via anchoring pillars 21 of the sensitive thermal detector 20p. For this purpose, the packaging thin layer 34 is conformally deposited. The packaging thin layer is made of a material that is transparent to the electromagnetic radiation of interest and inert to subsequent chemical etching (e.g., amorphous silicon, amorphous germanium, amorphous silicon-germanium, etc.). The thickness of the packaging thin layer is, for example, between 200 nm and 2 μm, for example, equal to about 800 nm or even less. The packaging thin layer 34 is deposited, for example, on the mineral sacrificial layer 42 and in the notch 43 by chemical vapor deposition (CVD). Preferably, the packaging thin layer is also covered with an opaque thin layer 33 to ensure enhanced mechanical strength of the packaging thin layer, which will be the opaque upper wall 32s of the secondary packaging structure 30s. Therefore, the encapsulation thin layer 34 includes an integral upper portion made of the same material and a reinforcing pillar 35, the upper portion being generally planar in the XY plane and extending along the Z-axis above the detection array 2p, the reinforcing pillar being indirectly placed on the readout substrate 10 via an anchoring pillar 21.

[0081] The encapsulation layer 34 forms a quarter-wavelength plate (lame) related to the electromagnetic radiation of interest. Therefore, in the case of amorphous silicon, for a spectral detection band in the range of 8 μm to 14 μm, the thickness of the encapsulation layer is advantageously about 800 nm. Thus, the opaque upper wall 32s, comprising the opaque layer 33 and the encapsulation layer 34 (quarter-wavelength plate), forms an interference stack that, while remaining opaque to the electromagnetic radiation of interest, allows for the reduction of reflection of the electromagnetic radiation of interest through absorption in the quarter-wavelength plate, which may form a parasitic image by the detection device 1. It should be noted that the opaque upper wall 32s may, of course, include supplementary layers to improve the interference characteristics of the stack.

[0082] More generally, the opaque thin layer 33 can be an absorbing multilayer, such as a stack (multilayer) formed by alternating dielectric and metal element layers, thereby reducing parasitic reflections. The encapsulation thin layer 34 can also be a stack formed by alternating dielectric and metal layers; however, when the stack extends above the detection array 2p (see [reference needed]), [further details needed]. Figure 1E , Figure 3E The stack remains transparent to the electromagnetic radiation of interest, or when the stack does not extend above the detection array 2p (see [reference]). Figure 4CThe stacked portion can be opaque (absorbing multilayer portion). In any case, one or more multilayer portions of the opaque upper wall 32s can form an interference-absorbing stacked portion, thereby reducing parasitic reflections and thus improving the performance of the detection device 1. Furthermore, the opaque thin layer 33 and / or a portion of the encapsulation thin layer 34 located above the compensation array 2s, and more generally the opaque upper wall 32s can also have a lateral structure in the XY plane, thereby improving the opacity properties, particularly by absorbing the electromagnetic radiation of interest.

[0083] The reinforcing post 35 has a dimension in the XY plane that is approximately the same as that of the anchor post 21. Therefore, each anchor post 21 may include a vertical portion with a dimension of approximately 0.5 μm to 1 μm in the XY plane, and the top of the anchor post is an upper portion that protrudes laterally relative to the vertical portion by approximately 0.2 μm to 0.5 μm. Here, the reinforcing post 35 has a dimension in the XY plane that is approximately 0.5 μm to 2 μm.

[0084] Subsequently, apertures 36p and 36s are fabricated, enabling the fabrication of the main chamber 3p and the secondary chamber 3s. These apertures 36p and 36s open to the mineral sacrificial layer 42 and are designed to allow the various mineral sacrificial layers 41 and 42 to be discharged from the main chamber 3p and the secondary chamber 3s. A first aperture 36p is fabricated through the encapsulation layer 34, and this first aperture is intended to form the main chamber 3p. A second aperture 36s is fabricated through the encapsulation layer 34 and the opaque layer 33, and this second aperture is intended to form the secondary chamber 3s. The apertures 36p and 36s are arranged facing the main and secondary regions only, for example, at a ratio of one aperture per thermal detector. Therefore, the apertures will allow complete release of the surface of the read substrate 10 in the main and secondary regions and the formation of the mineral peripheral walls 31s. In this example, orifices 36p and 36s are positioned perpendicular to the suspension membrane of the sensitive thermal detector 20p and the suspension membrane of the compensating thermal detector 20s. However, the orifices can be arranged differently, specifically perpendicular to the anchor post 21 of the sensitive thermal detector and the anchor post of the compensating thermal detector 20s. Orifices 36p and 36s can have various shapes in the XY plane, such as circular shapes with a diameter of 0.4 μm or even smaller. Therefore, the first orifice 36p does not interfere with or minimally interferes with the transmission of the electromagnetic radiation of interest, and the second orifice 36s does not interfere with or minimally interferes with the shielding associated with the electromagnetic radiation of interest.

[0085] Reference Figure 1D A chemical etching suitable for partially removing the mineral sacrificial layers 41 and 42 is performed. Specifically, when the mineral sacrificial layers 41 and 42 are made of silicon oxide, the chemical etching is, for example, etching using hydrofluoric acid in its vapor phase. The products of the chemical reaction are discharged through orifices 36p and 36s.

[0086] Because the apertures 36p and 36s are positioned only facing the detection array 2p and the compensation array 2s, the etchant completely removes the mineral sacrificial layers 41 and 42 located in these areas. However, chemical etching is performed so that the etchant does not etch the peripheral portions of the mineral sacrificial layers 41 and 42 extending around the compensation array 2s (and here also around the detection array 2p). Therefore, the mineral peripheral wall 31s surrounds the compensation array 2s and laterally defines the secondary chamber 3s. The mineral peripheral wall also surrounds the detection array 2p and laterally defines the main chamber 3p (see...). Figure 1F The two mineral outer walls, 31s and 31p, are bonded between the main chamber 3p and the secondary chamber 3s.

[0087] Therefore, the opaque thin layer 33 and the encapsulation thin layer 34 together form an opaque upper wall 32s, which is suspended above the compensation array 2s and placed on the outer peripheral wall 31s of the mineral. The opaque thin layer helps to define the secondary chamber 3s together with the outer peripheral wall of the mineral. Furthermore, the encapsulation thin layer 34 is suspended above the detection array 2p and helps to define the main chamber 3p. The encapsulation thin layer is placed on the outer peripheral wall 31p of the mineral.

[0088] Unlike document WO2012 / 056124A1, the encapsulation structure 30s of the secondary chamber 3s does not include an outer peripheral wall formed by a thin layer that extends above and around the compensation array 2s and reaches the readout substrate 10. Within the scope of this invention, the encapsulation structure 30s of the secondary chamber 3s includes a mineral outer peripheral wall 31s and an opaque upper wall 32s, the opaque upper wall being disposed on the mineral outer peripheral wall and extending above the compensation array 2s in a continuous planar manner.

[0089] Reference Figure 1E A sealing layer 37 is deposited on the packaging thin layer 34 with sufficient thickness to ensure the sealing (i.e., blockage) of the orifices 36s and 36p. The sealing layer extends at least facing the main chamber 3p and the secondary chamber 3s. The sealing layer 37 is transparent to the electromagnetic radiation to be detected and can be made of germanium with a thickness of about 1.7 μm by vacuum deposition with a thermal detector arranged in a vacuum. An anti-reflective layer (not shown) can also be deposited to optimize the transmission of electromagnetic radiation through the main packaging structure 30p. This anti-reflective layer can be made of zinc sulfide with a thickness of about 1.2 μm.

[0090] Figure 1FThe detection device 1 is schematically and partially shown in a top view. A compensation array 2s is located in a secondary chamber 3s, which is laterally defined by a mineral outer peripheral wall 31s (the inner edge of the mineral outer peripheral wall is shown in dashed lines) and vertically defined by an opaque thin layer 33 (solid lines). The opaque thin layer extends with a constant thickness above the compensation array 2s in a continuous plane and rests on the mineral outer peripheral wall 31s. A detection array 2p is located in a main chamber 3p, which is laterally defined by the mineral outer peripheral wall 31p (dashed lines) and vertically defined by an encapsulation thin layer 34 (not shown). Here, a connecting stud 7 is located at the edge of the array of thermal detectors 20p and 20s, enabling the connection of the readout circuit 14 to an external electronic circuit (not shown). The connecting stud can be accessed from the outside through openings made in the non-etched portion of the mineral sacrificial layer (through layers 37, 34, 42 and then through layer 41). It should be noted that the lateral dimension of the secondary chamber 3s is smaller than that of the main chamber 3p. Therefore, the lateral dimension of the secondary chamber can be less than or equal to 200 μm. This width is limited such that the secondary packaging structure 30s differs from the main packaging structure 30p in that it does not require the reinforcing pillar 35, which will be integral with the thin layer (here, thin layer 34) of the opaque upper wall 32s and made of the same material.

[0091] Therefore, a secondary sealed chamber 3s is obtained, which is preferably arranged in a vacuum or reduced pressure, and the compensating thermal detector 20s is housed in the secondary sealed chamber. Thus, the secondary encapsulation structure 30s includes an opaque upper wall 32s, which is formed by an opaque thin layer 33, an encapsulation thin layer 34, and a sealing thin layer 37, and is positioned on the outer peripheral wall 31s of the mineral.

[0092] Therefore, the secondary packaging structure 30s, apart from the mineral peripheral wall 31s, does not include any supporting structure for the opaque upper wall 32s used for the readout substrate 10. The mineral peripheral wall is derived from the mineral sacrificial layers 41 and 42 necessary for fabricating the thermal detectors 20p and 20s. Thus, the mineral peripheral wall does not include the thin peripheral wall fabricated through the mineral sacrificial layers 41 and 42 and placed directly on the readout substrate 10, as described in document WO2012 / 056124A1. Furthermore, the mineral peripheral wall 31s is not reflective, which prevents parasitic light from being reflected towards the sensitive thermal detector 20p.

[0093] In addition to enabling a reduction in the complexity of the manufacturing process (particularly in terms of the number of preparation steps), it also prevents localized etching of the mineral sacrificial layers 41, 42 that will lead to the read substrate 10. Therefore, any risk of degradation of the protective layer 13, particularly in terms of sealing, is prevented, which eliminates the risk of degradation of the read substrate 10 during chemical etching with HF vapor. Furthermore, since the opaque upper wall 32s is assembled with the read substrate 10 via the mineral outer peripheral wall 31s, the mechanical strength of the package structure 30s is improved, as the surface area of ​​the interface between the mineral outer peripheral wall 31s and the read substrate 10 is larger than the surface area of ​​the interface between the thin outer peripheral wall and the read substrate 10.

[0094] Furthermore, the absence of reinforcing pillars 35 in the secondary chamber 3s prevents topological changes in the opaque thin layer 33 in the XY plane, and even prevents changes in its thickness. Such changes could lead to a degradation of the optical properties of the opacity of the opaque thin layer 33. Additionally, these reinforcing pillars would extend through openings formed in the opaque thin layer 33; these openings would degrade the shielding of the compensation array 2s. Moreover, since there are no reinforcing pillars 35 in the secondary chamber 3s, the opaque thin layer 33 can maintain a continuous plane and a constant thickness, thereby preserving good uniformity of the opaque optical properties of the opaque thin layer.

[0095] Furthermore, compared to the case where the opaque thin layer 33 forms the outer peripheral wall of the thin layer, as in WO2012 / 056124A1, the preparation of the opaque thin layer 33 by PVD opens up a wider selection of possible materials (especially metals). In practice, in this case, it is necessary to use specific deposition techniques, such as Chemical Vapor Deposition (CVD), which limits the selection of possible materials. Moreover, the wider selection of possible materials allows for the selection of opaque materials with complementary functions (e.g., degassing functions), as referred to below. Figures 3A to 3F As described.

[0096] Furthermore, the opaque thin layer 33, by being placed on the outer peripheral wall 31s of the mineral, can bulge laterally relative to the compensation array 2s, which enables good shielding efficiency. Since the material of the outer peripheral wall 31s of the mineral can contribute to lateral shielding of the electromagnetic radiation of interest, the shielding efficiency is even more important. In fact, as an example, silicon oxide exhibits high absorption in the spectral band between 8 μm and 14 μm.

[0097] Finally, for illustrative purposes, an opaque upper wall 32s is described in this example. Of course, other configurations are possible. Therefore, the opaque upper wall 32s may include other thin layers located below or above the opaque thin layer 33. Furthermore, the arrangement of the thin layers in the opaque upper wall 32s can be chosen to take into account the differences in mechanical stress within each of the thin layers.

[0098] Figure 2 It is based on Figure 1F A schematic partial top view of the modified detection device 1 is shown. In this example, the detection device 1 is... Figure 1F The difference in the detection device described herein is essentially that it includes multiple secondary chambers, specifically two secondary chambers, each housing a compensation array 2s. The two secondary chambers are adjacent and separated by the same mineral peripheral wall 31s. Here, an opaque thin layer 33 extends continuously above the two compensation arrays 2s. Thus, the opaque thin layer is positioned on the mineral peripheral wall 31s between the two secondary chambers. Alternatively, the secondary encapsulation structure 30 may each include a dedicated opaque thin layer 33. In any case, it is advantageous to provide multiple secondary chambers when the required number of compensation thermal detectors 20s makes it impossible to house all the compensation thermal detectors in the same secondary chamber without having to fabricate a reinforcing column 35 similar to the reinforcing column of the main chamber. In other words, it is advantageous to house the compensation thermal detectors 20s in multiple secondary chambers with significantly reduced lateral dimensions to prevent the need to fabricate reinforcing columns 35, for example, less than or equal to about 200 μm.

[0099] Figures 3A to 3F The diagram illustrates, schematically and partially, according to Figures 1A to 1F The various steps of the manufacturing method shown in the alternative embodiment. In this example, the opaque thin layer 33 is made of a material with degassing capabilities. Typically, materials with degassing capabilities are those intended to be exposed to the atmosphere of a sealed chamber and capable of performing gas pumping by absorption and / or adsorption. This may involve metallic materials that can reflect electromagnetic radiation of interest, such as titanium.

[0100] In this example, the metallic material is sensitive to the etchant used during the chemical etching process for partially removing the mineral sacrificial layers 41 and 42. Furthermore, a protective sacrificial layer 38 made of amorphous carbon protects the metallic material from the etchant.

[0101] Alternatively, the amorphous carbon can be of the diamond-like carbon (DLC) type, meaning that the amorphous carbon is effective against sp... 3The carbon exhibits a high level of hybridization. This amorphous carbon is substantially inert relative to the chemical etching performed for the partial removal of the mineral sacrificial layers 41, 42; that is, the amorphous carbon reacts little or not at all with the chemical etchant. Furthermore, the amorphous carbon still protects the degassing material at the end of the partial removal step. The protective sacrificial layer 38 is suitable for removal by a second chemical etching (e.g., dry chemical etching), the etchant of which is, for example, oxygen contained in plasma.

[0102] Reference Figure 3A The detection array 2p and the compensation array 2s are fabricated on and through the first mineral sacrificial layer 41. A second mineral sacrificial layer 42 covers both arrays of thermal detectors 20p and 20s, as well as the first mineral sacrificial layer 41. The second mineral sacrificial layer has a planar upper surface. This step is the same as the steps described above.

[0103] Reference Figure 3B An opaque stacked portion is prepared, consisting of a protective thin layer 38 and an opaque thin layer 33. This stacked portion extends continuously and planarly above the compensation array 2s, but not above the detection array 2p. The stacked portion is intended to be placed on the outer peripheral wall 31s of the mineral.

[0104] A protective thin layer 38 is disposed on and in contact with the second mineral sacrificial layer 42. The protective thin layer is intended to protect the opaque thin layer 33 during chemical etching performed during the partial removal of the mineral sacrificial layers 41 and 42. The protective thin layer is intended to be removed during the second chemical etching, for example by dry chemical etching, and the opaque thin layer 33 is substantially inert to this second chemical etching. The protective thin layer is made of amorphous carbon and has a thickness between 50 nm and 500 nm.

[0105] An opaque thin layer 33 is placed on and in contact with the protective thin layer 38, so that the opaque thin layer does not come into contact with the second mineral sacrificial layer 42. The opaque thin layer is made of a metallic material (e.g., titanium) that can reflect the electromagnetic radiation to be detected and has a degassing effect.

[0106] The notch 43 and the insulating portion 44 are also prepared in the same manner as described above, and the notch and the insulating portion are intended to prepare the reinforcing pillar 35 of the encapsulation thin layer 34 of the main encapsulation structure 30p.

[0107] Reference Figure 3C Subsequently, an encapsulation thin layer 34 is deposited to cover the opaque stack and extend over the detection array 2p. The encapsulation thin layer fills the notch 43 and forms a reinforcing pillar 35. A first aperture 36p and a second aperture 36s are also fabricated.

[0108] Reference Figure 3DChemical etching was performed to partially remove the mineral sacrificial layers 41 and 42, thereby forming the main chamber 3p and the secondary chamber 3s defined by the mineral peripheral walls 31s and 31p (see...). Figure 3F Therefore, the opaque upper wall 32s is suspended above the compensation array 2s and placed on the outer peripheral wall 31s of the mineral. A portion of the lower surface of the protective layer 38 has been released. However, the protective layer protects the opaque layer 33 from the etchant used. Therefore, the structural integrity of the opaque layer 33 is preserved, and thus its optical properties and degassing function are also preserved.

[0109] Reference Figure 3E A second chemical etching (e.g., dry chemical etching) is performed to remove the portion of the protective layer 38 with a free lower surface, which is sensitive to the second chemical etching. Lateral over-etching may also occur. As a result, a portion of the lower surface of the opaque layer 33 is released. A sealing layer is then deposited to seal the orifices 36p and 36s. Subsequently, the chemical adsorption of the degassing material in the opaque layer 33 is activated by appropriate heat treatment of the detection device 1, for example, in a furnace or oven.

[0110] Figure 3F This is a schematic partial top view of the detection device 1 obtained in this way. To ensure gas pumping between the primary and secondary chambers by the degassing material of the opaque thin layer 33, a connecting cavity 6 is prepared, ensuring gas communication between the two chambers. The connecting cavity is laterally defined by the unetched portion of the mineral sacrificial layer and vertically defined by the opaque upper wall 32s. To obtain the connecting cavity 6 during the step of partially removing the mineral sacrificial layer, orifices 36s and 36p are pre-prepared through the opaque upper wall 32s, and the orifices are positioned above the area intended to form the connecting cavity 6. Here, orifice 36s passes through layers 34, 33, and 38, while orifice 36p only passes through layer 34.

[0111] Figures 4A to 4D The various steps of a manufacturing method according to another embodiment are illustrated schematically and partially. The difference between this other embodiment and the one described above is essentially that the main package structure 30p does not include the package thin layer 34, but instead includes an attachment rigid cover 9 (i.e., a cover pre-prepared and then attached and assembled to the readout substrate 10) to package the detection array 2p (here, the cover 9 also packages the compensation array 2s). The main package structure 30p here is similar to or identical to the main package structure described in document EP3239670A1.

[0112] The cover 9 may be made of a silicon substrate and is configured to include an outer peripheral wall intended for assembly to the read substrate 10. The outer peripheral wall is secured to the read substrate 10 by a vacuum seal 8, preferably in contact with a junction of a metal layer. The vacuum seal 8 may be obtained by remelting a fusible metal or by forming an intermetallic alloy.

[0113] The method then includes fabricating on the readout substrate 10 as described above. Figure 4A The steps of the detection array 2p and the compensation array are described above. The opaque upper wall 32s is formed here by a stack comprising an opaque thin layer 33 and a reinforcing thin layer 39. As described above, the reinforcing thin layer 39 can be formed as a quarter-wavelength plate. Here, the reinforcing thin layer helps to enhance the mechanical strength of the opaque upper wall 32s. The opaque upper wall 32s extends in the secondary region and optionally around the main region, but does not extend above the detection array 2p. In this example, the opaque upper wall is intended to extend beyond the mineral peripheral wall 31s to form an overhang (a portion that laterally protrudes beyond the mineral peripheral wall 31s in the direction opposite to the secondary chamber 3s).

[0114] Subsequently, partial removal of the mineral sacrificial layers 41 and 42 was performed by chemical etching. Figure 4B Therefore, the detection array 2p and the compensation array 2s surrounded by the mineral peripheral wall 31s are released. Thus, the opaque upper wall 32s has an overhang between the compensation array 2s and the detection array 2p. In this example, the overhang is formed by two thin layers 33, 39; however, alternatively, the overhang can be formed solely by the reinforcing thin layer 39 (the opaque thin layer 33 blocking the mineral peripheral wall 31s). The choice between these two configurations can depend on the difference in mechanical stress between these thin layers 33, 39. Therefore, the configuration where the overhang is formed solely by the reinforcing thin layer 39 is advantageous in preventing an imbalance of mechanical stress between the two layers 33, 39 and correcting for possible deflection of the overhang. It should be noted that in a confined environment (i.e., below the opaque upper wall 32s), the transverse etching rate (in the XY plane) of the mineral sacrificial layers 41, 42 in an acidic medium appears to be faster than the vertical etching rate (along the Z-axis). Furthermore, the release of the detection array 2p and the formation of the secondary chamber 3s (etching of layers 41 and 42 and discharge through the orifice 36s) are achieved over time.

[0115] Subsequently, a line portion made of sealing material is deposited to form a vacuum seal 8, the line portion made of sealing material being placed on the readout substrate 10 and surrounding the detection array 2p. Figure 4CHere, a line portion made of sealing material also surrounds the compensation array 2s. This line portion made of sealing material is deposited, for example, in a peripheral trench passing through the mineral sacrificial layers 41, 42 and surrounding the detection array 2p before partial removal of the mineral sacrificial layers. The cover 9 is then attached to the vacuum seal 8, and the readout substrate 10 is assembled. It should be noted that the cover 9 ensures the closure of the orifice 36s. Therefore, the chamber 3s is contained within the chamber 3p.

[0116] Figure 4D This is a schematic partial top view of the detection device 1 obtained after the step of preparing the vacuum seal 8 and before attaching the cover 9. Here, the width of the mineral peripheral wall 31s of the secondary encapsulation structure 30s is less than the length of the mineral peripheral wall, and this mineral peripheral wall extends longitudinally around the compensation array 2s. An opaque thin layer 33 extends above the compensation array 2s, rests on the mineral peripheral wall 31s, and has an overhang here. Therefore, the remaining portion of the surface of the read substrate 10 is not covered by the unetched portion of the mineral sacrificial layer.

[0117] Specific embodiments have already been described. Various variations and modifications are possible while remaining within the scope of this invention.

[0118] Therefore, alternatively, the main package structure 30p can be similar to or the same as the main package structure described in document EP3399290A1. This package structure includes an outer peripheral wall surrounding the detection array 2p, fabricated using a thin-layer deposition technique. An upper wall can be attached and assembled to the outer peripheral wall via a temporary shank.

Claims

1. A method for manufacturing a device (1) for detecting electromagnetic radiation, the method comprising the following steps: o Prepare a detection array (2p) and at least one so-called compensation array (2s) located on and through a first sacrificial layer (41), the first sacrificial layer being placed on a readout substrate (10). The detection array is formed by thermal detectors (20p) designed to detect the electromagnetic radiation, and the compensation array is formed by thermal detectors (20s) not designed to detect the electromagnetic radiation. The thermal detector (20s) of the compensation array (2s) is adapted to detect the electromagnetic radiation and is structurally identical to the thermal detector (20p) of the detection array (2p); o Prepare a second sacrificial layer (42) covering the thermal detector (20s, 20p) and the first sacrificial layer (41); o Prepare a so-called secondary packaging structure (30s) that defines a secondary chamber (3s) in which the compensation array (2s) is located. The secondary packaging structure includes an outer peripheral wall (31s) and an opaque upper wall (32s) placed on the outer peripheral wall (31s) and formed by at least one opaque thin layer (33). o Features: o The first sacrificial layer (41) and the second sacrificial layer (42) are made of mineral materials; The steps for preparing the secondary packaging structure (30s) include the following: Prepare the opaque thin layer (33) such that the opaque thin layer extends in a continuous plane only along the upper surface of the second mineral sacrificial layer (42); An aperture (36s) is prepared in the opaque thin layer (33), and the aperture is arranged facing the compensation array (2s); The first mineral sacrificial layer (41) and the second mineral sacrificial layer (42) are partially removed by chemical etching through the orifice (36s) to release the detection array (2p) and the compensation array (2s), and to obtain the outer peripheral wall (31s) formed by the unetched portions of the first mineral sacrificial layer (41) and the second mineral sacrificial layer (42) and surrounding the compensation array (2s), with the opaque thin layer (33) suspended above the compensation array (2s) and placed on the outer peripheral wall (31s).

2. The manufacturing method according to claim 1, wherein, The first sacrificial layer (41) and the second sacrificial layer (42) are made of the same mineral material based on silicon nitride or silicon oxide.

3. The manufacturing method according to claim 1, wherein, The thermal detector (20p) of the detection array (2p) and the thermal detector (20s) of the compensation array (2s) both include an absorption film (22) capable of absorbing the electromagnetic radiation to be detected, and the absorption film includes a temperature transducer. The absorption film is suspended above the reading substrate (10) by anchoring posts (21) and holding arms and is thermally insulated.

4. The manufacturing method according to claim 3, wherein, The thermal detector (20p) of the detection array (2p) and / or the thermal detector (20s) of the compensation array (2s) both include a reflective layer (23) placed on the readout substrate (10) below each absorption film (22).

5. The manufacturing method according to claim 1, wherein, The opaque upper wall (32s) includes an interference stack that can absorb the electromagnetic radiation to be detected.

6. The manufacturing method according to claim 1, wherein, The opaque upper wall (32s) further includes at least one reinforcing thin layer (39) covering the opaque thin layer (33), and the opaque upper wall has an edge protruding relative to the outer peripheral wall (31s) in a plane parallel to the reading substrate (10), the protruding edge including the opaque thin layer (33) and / or the reinforcing thin layer (39).

7. The manufacturing method according to claim 1, wherein, The secondary chamber (3s) has a length and a width in a plane parallel to the read substrate (10), the width being less than or equal to 200 μm, and the opaque upper wall (32s) does not include a reinforcing pillar that is integral with the thin layer of the opaque upper wall (32s) and made of the same material, located in the secondary chamber (3s) and placed on the read substrate (10).

8. The manufacturing method according to claim 1, wherein, The first mineral sacrificial layer (41) and the second mineral sacrificial layer (42) are made of materials capable of absorbing the electromagnetic radiation to be detected.

9. The manufacturing method according to claim 1, wherein, The opaque thin layer (33) is made of a material that has a degassing effect.

10. The manufacturing method according to claim 9, wherein the manufacturing method comprises the following steps: o Prior to the partial removal step, the opaque upper wall (32s) is prepared by a stack of portions including a protective thin layer (38) made of inert amorphous carbon that is inert to the etchant used during the partial removal step. The protective thin layer is positioned to contact the second mineral sacrificial layer (42). The opaque thin layer (33) extends only above and in contact with the protective thin layer (38). This ensures that during the partial removal step, the opaque thin layer (33) is protected by the protective thin layer (38). o After the partial removal step, at least a portion of the protective thin layer (38) is removed by chemical etching to release the inner surface of the opaque thin layer (33).

11. The manufacturing method according to claim 1, the manufacturing method comprising the step of preparing a main package structure (30p), the main package structure defining a main chamber (3p), the detection array (2p) being located in the main chamber, and the main package structure including a main upper wall (32p), the main upper wall including a packaging thin layer (34) disposed on a main outer peripheral wall (31p), the step of preparing the main package structure comprising: o Deposit the encapsulation thin layer (34) on the second mineral sacrificial layer (42), the encapsulation thin layer extending above the detection array (2p) and the compensation array (2s); o A main aperture (36p) is prepared in the encapsulation thin layer (34), the main aperture being arranged facing the detection array (2p); o Perform partial removal of the first mineral sacrificial layer (41) and the second mineral sacrificial layer (42) to form the main outer peripheral wall (31p) formed by the unetched portions of the first mineral sacrificial layer (41) and the second mineral sacrificial layer (42) and surrounding the detection array (2p), the encapsulation thin layer (34) is suspended above the detection array (2p) and placed on the main outer peripheral wall (31p).

12. According to the manufacturing method of claim 11, the opaque thin layer (33) is made of a material having a degassing effect, the manufacturing method comprising the step of preparing a connecting cavity (6) connecting the secondary chamber (3s) and the main chamber (3p), the connecting cavity (6) being laterally defined by unetched portions of the first mineral sacrificial layer (41) and the second mineral sacrificial layer (42).

13. The manufacturing method according to claim 11, the manufacturing method comprising the step of preparing a reinforcing post (35) of the encapsulation thin layer (34), the reinforcing post preferably being placed on the readout substrate (10) by means of an anchor post (21) of a thermal detector (20p) of the detection array (2p).

14. The manufacturing method according to claim 1, wherein, The chemical etching is carried out using hydrofluoric acid in a vapor phase, and the first mineral sacrificial layer (41) and the second mineral sacrificial layer (42) are made of silicon oxide-based mineral materials.

15. An apparatus for detecting electromagnetic radiation manufactured by the manufacturing method according to any one of claims 1 to 14, the apparatus comprising: o Read substrate (10); o Detection array (2p), the detection array being formed by thermal detectors (20p) designed to detect the electromagnetic radiation; o At least one so-called compensation array (2s) formed by thermal detectors (20s) not intended to detect the electromagnetic radiation, the thermal detectors of the compensation array being adapted to detect the electromagnetic radiation and structurally identical to the thermal detectors (20p) of the detection array (2p); o The so-called secondary packaging structure (30s) defines a secondary chamber (3s) in which the compensation array (2s) is located. The secondary packaging structure includes an outer peripheral wall (31s) and an opaque upper wall (32s), the opaque upper wall being placed on the outer peripheral wall (31s) and formed by at least one opaque thin layer (33). o Features: The opaque thin layer (33) extends in a continuous planar manner; The outer peripheral wall (31s) is made of mineral material.

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