Thermal detector

Abstract

In accordance with an example aspect of the invention, there is provided a detector comprising: an optical absorbing film suspended over a cavity between the film and a substrate, the substrate included in the detector; and a thermoelectric converter attaching the optical absorbing film over the cavity, where the optical absorbing film forms a contact element between the n-type thermoelectric element and the p-type thermoelectric element of the thermoelectric converter.

Description

[0001] This patent application is a divisional application of application number 202080063009.0 (PCT / FI2020 / 050582) filed on September 11, 2020 and named “Thermal Detector”. Technical Field

[0002] The present disclosure relates to pyroelectric thermal detectors. Background Art

[0003] An optical detector is a light-sensitive sensor that determines the presence and / or intensity of incident electromagnetic radiation and outputs a measurement value according to a suitable electrical signal. Optical detectors are classified as quantum type detectors and thermal type detectors. Quantum detectors (or photovoltaic and photoconductive detectors) are typically faster and usually have higher sensitivity than thermal detectors, but are relatively complex. Quantum detectors operating in the infrared range are usually made of expensive and / or toxic materials and need to be operated at low temperatures to achieve high sensitivity (since lowering the temperature can suppress noise). A thermal sensor is a device configured to determine the power of electromagnetic radiation by converting the electromagnetic radiation into heat and determining the resulting temperature according to a suitable electrical signal.

[0004] Thermal sensors utilize a variety of technologies, but the most relevant commercial technologies are resistive thermal detectors and thermoelectric thermal detectors. A thermal detector consists of an absorber of incident radiation and a transducer that converts the temperature change of the absorber into an electrical signal. Resistive thermal detectors (sometimes called bolometers) use a temperature-dependent resistor as the transducer. Thermoelectric thermal detectors (usually thermopiles or thermocouples) use thermoelectric conversion based on the thermoelectric effect. Summary of the invention

[0005] According to some aspects, the subject matter of the independent claims is provided. Some embodiments are defined in the dependent claims.

[0006] According to a first aspect of the present disclosure, a detector is provided, comprising: an optical absorption film suspended above a cavity between the film and a substrate, the substrate being included in the detector; and a thermoelectric converter attaching the optical absorption film above the cavity, wherein the optical absorption film forms a contact element between an n-type thermoelectric element and a p-type thermoelectric element of the thermoelectric converter.

[0007] According to a second aspect of the present disclosure, a method for manufacturing a detector is provided, the method comprising: obtaining a substrate wafer and depositing an oxide layer on the substrate wafer; depositing a thermoelectric converter layer on the oxide layer; depositing an optical absorption layer on the oxide layer or on the thermoelectric converter layer; and etching a groove in the oxide layer to form a cavity, leaving an optical absorption film, the optical absorption film comprising the optical absorption layer and a portion of the thermoelectric converter layer suspended above the cavity by the thermoelectric converter layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A An example thermal detector according to at least some embodiments of the present invention is shown;

[0009] Figure 1B An example thermal detector according to at least some embodiments of the present invention is shown;

[0010] Figure 2A An example thermal detector according to at least some embodiments of the present invention is shown;

[0011] Figure 2B An example thermal detector having a patterned film according to at least some embodiments of the present invention is shown;

[0012] Figure 3A An example of a device configuration is shown;

[0013] Figure 3B An example of a device configuration is shown;

[0014] FIG. 4A to FIG. 4D The stages of the manufacturing method are shown;

[0015] FIG. 5A to FIG. 5D Various absorber film structures are shown, and

[0016] Figure 6 is a flow chart of a method according to at least some embodiments of the present invention. DETAILED DESCRIPTION

[0017] The detector of the structure disclosed herein includes an optical absorption film suspended by a thermoelectric converter, for example, suspended above a cavity. The cavity may have a reflector at its bottom to reflect back the incident light portion that is not absorbed by the film to improve the sensitivity of the detector. The cavity may have a resonance function. The film may be a nanofilm, whose thickness is nanometers. The nanoscale film is lightweight and can heat up faster as a response to incident radiation, thereby improving the response speed of the detector. The disclosed detector also does not have a separate support structure because the film is directly suspended and attached above the cavity by the thermoelectric converter itself. The fact that the detector does not have a separate support structure also improves the response time because in a system with a support structure, the support structure reduces the response time by increasing the heat capacity of the detector. Beneficially, the detector disclosed herein can be manufactured using safer (e.g., less toxic) materials. These materials can also be cheaper. In addition, the detector disclosed herein can be manufactured using micro-electromechanical, MEMS and other methods.

[0018] Quantum detectors (or photovoltaic and photoconductive detectors) require cooling solutions for high sensitivity and are generally of high cost and require exotic and / or toxic materials, such as HgCdTe, required for long-wave infrared detection. The cooling system introduces complexity, power consumption and cost. The main limitation of uncooled optical detectors of both thermal and quantum types is the poor performance in terms of sensitivity described by a specific detectivity. State-of-the-art thermal detectors are typically slower than quantum detectors. Compared to resistive detectors that require active power, thermoelectric conversion offers the advantages of increased sensitivity and low power consumption. Thermoelectric conversion does not require an external power supply because it generates voltage itself. In addition, because no current is required for signal conversion in the case of thermoelectric elements, there are fewer noise sources, resulting in a higher signal-to-noise ratio (i.e., increased sensitivity).

[0019] Figure 1A An example detector according to at least some embodiments of the present invention is shown. The detector includes an optically absorbing film 110, which for simplicity is referred to as film 110 below. The film 110 heats up in response to incident electromagnetic radiation absorbed by it. An n-type semiconductor element 120 connects the film 110 to a short rod 122. A p-type semiconductor element 130 connects the film 110 to a short rod 132. The short rods 122, 132 may be disposed on a substrate having a Figure 1A The substrate may define a cavity below the membrane 110, as will be disclosed below. The detector may have more than one pair of semiconductor element 120, 130 legs, in which case the structure may be more robust. The membrane 110 may be thermally isolated by placing it in a vacuum.

[0020] Thermoelectric converters consist of two different thermoelectric materials that are joined together by contact elements. The different thermoelectric materials include an n-type semiconductor with negative charge carriers and a p-type semiconductor with positive charge carriers. Figure 1A In the embodiment of the present invention, the thermoelectric converter is thus composed of semiconductor elements 120 and 130. The membrane 110 is arranged to act as a contact element between the n-type thermoelectric element 120 and the p-type thermoelectric element 130 of the thermoelectric converter.

[0021] Figure 1B An example detector according to at least some embodiments of the present invention is shown. This figure shows different views of the detector, including Figure 1A Like parts, like reference numerals denote like structures. Here, it can be seen that the short rods 122, 132 are disposed on a substrate 140, which may include a suitable material. For example, the substrate 140 may include a silicon wafer. For example, the short rods 122, 132 may be composed of an oxide material (such as silicon oxide). Figure 1BThe detector also includes a reflector 150, which is arranged to reflect electromagnetic radiation that passes through the film 110 and is not absorbed by the film. The presence of the reflector therefore increases the sensitivity of the detector because a larger portion of the incident radiation is absorbed by the film 110. In fact, the radiation has two opportunities to be absorbed, one before reflecting from the reflector 150 and the other after reflecting from the reflector 150. In fact, an optical cavity is formed between the film 110 and the reflector 150. For example, for a distributed Bragg mirror, the reflector 150 can be composed of a metal, a semi-metal, a highly conductive semiconductor, a dielectric, or a semiconductor with poor conductivity. Alternatively, an N+ (high / degenerate N doping) or P+ (high / degenerate N doping) doped semiconductor mirror can be used with a fully doped substrate 140, a surface doped substrate 140 (e.g., using implantation or diffusion), or a deposition and doping layer. In some embodiments, the substrate 140 itself acts as a reflector, for example, when the substrate 140 is conductive, such as when it is a highly doped silicon or other semiconductor or metal substrate.

[0022] The stubs 122, 132 can provide electrical connections between the thermoelectric converters 120, 130 and readout electronics configured to process the signals from the detectors. For example, these electrical connections can be constructed using wire bonding, flip chip bonding, or wafer bonding techniques using metal pads. As another alternative, the substrate 140 can include CMOS circuits. In addition, the detectors can be interfaced with other optical devices, such as micro-spectrometer films (e.g., Fabry-Perot interferometers). For clarity, the following diagrams are used to illustrate the electrical connections between the thermoelectric converters 120, 130 and the readout electronics configured to process the signals from the detectors. For example, the electrical connections can be constructed using wire bonding, flip chip bonding, or wafer bonding techniques using metal pads. As another alternative, the substrate 140 can include CMOS circuits. In addition, the detectors can be interfaced with other optical devices, such as micro-spectrometer films (e.g., Fabry-Perot interferometers). Figure 1B The readout electronics are not shown. The stubs can be oxide materials or remnants of sacrificial layers etched during detector fabrication. For example, tetraethyl orthosilicate, TEOS, silicon oxide, plasma enhanced chemical vapor deposition, CVD, silicon oxide or low pressure CVD low temperature oxide, LTO, silicon oxide.

[0023] Figure 2A 2 shows an example detector according to at least some embodiments of the present invention. Figure 1A and Figure 1B A frame 160 is provided to provide stress tuning, allowing the use of thermoelectric materials with a wider range of stress characteristics. In the absence of frame 160, the thermoelectric materials used in semiconductor elements 120 and 130 can be made with low or medium tensile stress to properly suspend membrane 110. Figure 2AAs shown, the frame 160 can be placed on top of the semiconductor elements 120, 130, or additionally or alternatively, can be placed between the semiconductor elements 120, 130 and the short rods 122, 132, respectively. The frame can be composed of one of the following materials, for example: silicon nitride (SiNx) and aluminum oxide (Al2O3). For example, these materials can be deposited using plasma enhanced CVD, low pressure CVD, sputtering and / or atomic layer deposition (ALD) techniques. As described above, in some embodiments, the frame 160 is not present.

[0024] The optical absorption film 110 is as follows Figure 2A It is shown as being composed of thermoelectric converter layers 112a, 112b and an optical absorption layer 111. Physically, the thermoelectric converter layers 112a, 112b and the semiconductor elements 120, 130 may be the same manufacturing layer structure. In detail, the semiconductor element 120 and the thermoelectric converter layer 112a facing the thermoelectric element 120 may be the same semiconductor layer. The semiconductor element 130 and the thermoelectric converter layer 112b facing the thermoelectric element 130 may be the same semiconductor layer. In terms of manufacturing, the optical absorption layer 111 may be deposited on the thermoelectric converter layers 112a, 112b. In other words, the deposition of the optical absorption layer 111 defines the thermoelectric converter layers 112a, 112b as the portions of the thermoelectric elements 120, 130 covered by the optical absorption layer 111. In other embodiments, the optical absorption layer 111 may be located below the thermoelectric converter layers 112a, 112b, i.e., on the side of the cavity between the film 110 and the substrate 140. The gaps in the film 110 schematically indicate the patterning of the film, which is an optional feature. The patterning is discussed below. Figure 2B . The dimensions of the thermoelectric converter layers 112a, 112b may be equal or unequal. When the dimensions are unequal, the dimensions may be selected based on the specific thermoelectric material and absorber material used so that the overall contact and / or total resistance of the thermoelectric converter is minimized. The geometry of the thermoelectric elements 120, 130 may be selected, for example, as described in A. Varpula et al., Appl. Phys. Lett. 110, 262101 (2017) or in Thermoelectric Handbook: From Macro to Nano, edited by DM Rowe, Taylor & Francis, 2006 and H. Julian Goldsmid, Springer Series 121 in Materials Science: Introduction to Thermoelectrics, Springer, 2010.

[0025] In other embodiments, there may be two optical absorption layers, one on either side of the thermoelectric converter layers 112a, 112b. In other words, the optical absorption film may include two optical absorption layers and a thermoelectric converter layer, with the optical absorption layer disposed on either side of the thermoelectric converter layer. On the other hand, in some embodiments, the optical absorption film 110 includes one and only one optical absorption layer 111 and exactly one thermoelectric converter layer 112, with the optical absorption layer 111 disposed on one and only one side of the thermoelectric converter layer 112. FIG. 5A to FIG. 5D Specific examples of various film embodiments are discussed in more detail.

[0026] When there are two optical absorption layers in the optical absorption film 110, they can be the same material, or different materials. For example, the thickness of the optical absorption film 110 can be less than 800 nanometers, less than 200 nanometers, less than 180 nanometers, less than 160 nanometers, less than 100 nanometers, less than 60 nanometers, or less than 20 nanometers. As described above, the film has a low heat capacity. In addition, the film phonon thermal conductivity of the material in the film decreases as the thickness decreases to the nanometer level.

[0027] Optical absorption layers, such as optical absorption layer 111, can be composed of metals, semi-metals, or highly doped semiconductors. Examples include TiW (titanium tungsten), Ti (titanium), W (tungsten), TiN (titanium nitride), NbN (niobium nitride), MoN (molybdenum nitride), Mo (molybdenum), thin Al, a-Si (amorphous silicon), Al:ZnO (aluminum-doped zinc oxide), highly doped single-crystalline silicon and polycrystalline silicon, and doped SrTiO3 (strontium titanate). Another example of an absorbing material is an infrared absorbing insulator, such as silicon nitride or aluminum oxide. These materials absorb well in the infrared band. In the absorption layer, the conductivity of the material can be selected so that it can be impedance matched to the vacuum impedance with low thermal mass, that is, the resistance should preferably not be too high, but should be high enough to obtain good absorptivity. For a plasmonic absorber, the dielectric constant of the selected material and the pattern feature size can be beneficially matched to the desired wavelength. With regard to electrical requirements, the selected absorber layer 111 material advantageously has a low contact resistance with the material of the semiconductor elements 120 and 130 (and therefore with the thermoelectric converter layers 112a, 112b). This contact resistance should be much lower than the total resistance of the thermoelectric legs 120, 130, otherwise the performance of the detector is degraded due to the contact resistance.

[0028] The thermoelectric materials used for thermoelectric elements 120, 130 and thermoelectric converter layers 112a, 112b can have a thickness of less than 200nm when applied to the detector. One is an N-type thermoelectric material, and the other is a P-type thermoelectric material. Suitable materials include highly doped N (P) type silicon, polycrystalline silicon and other semiconductors. Doping can be performed by ion implantation, diffusion or other suitable methods. Beneficially, the thermoelectric material has a high thermoelectric figure of merit ZT (for the definition of ZT, see, for example, A. Varpula et al., Appl. Phys. Lett. 110, 262101 (2017)). In order to maximize the sensitivity of the optical detector, the effective thermoelectric figure of merit (effective ZT) of the device should be maximized. As for the mechanical requirements of the thermoelectric materials of elements 120, 130 and thermoelectric converter layers 112a, 112b, they should have low or medium tensile stress in order to properly suspend the absorber. Less suitable stress conditions can be handled by using a frame 160 to tune the stress in the thermoelectric material.

[0029] Examples of suitable thermoelectric materials include Bi2Te3 (bismuth telluride), Bi2Se3 (bismuth selenide), HgCdTe (mercury cadmium telluride), ZnO2 (zinc peroxide), SrTiO3 (strontium titanate), silicon nanowires, thin single crystal silicon, thin polycrystalline silicon, Bi2Te3 (bismuth telluride), and Sb2Te3 (antimony telluride).

[0030] Optionally, the passivation layer ( Figure 2A The passivation layer (not shown) can be set as the top layer on top of the film 110, the elements 120, 130 and the frame 160 (when the frame 160 exists) to surround the other layers. For example, the passivation layer can be composed of Al2O3 or SiNx. For example, these materials can be deposited using plasma enhanced CVD, low pressure CVD, sputtering and atomic layer deposition (ALD) techniques. If necessary, the role of the passivation layer is to protect the absorbing material. The absorbing material side can be protected by patterning the passivation layer away from the edge of the absorbing material, by a spacer layer patterning technique, or they can be left unprotected by patterning the passivation layer and the thermoelectric material and the absorbing material at the same time. In some embodiments, one of the thermoelectric materials is used as a passivation layer, which is used for the absorbing layer of the optical absorption film.

[0031] Figure 2B An example detector having a patterned membrane in accordance with at least some embodiments of the present invention is shown. Figure 2A The cross section is obtained along the dashed line diagonally. Figure 2BIt can be seen that the optical absorption film 110 is patterned, in detail, patterned to have a plurality of holes that pass through the film. For example, the holes can be created by etching (such as wet etching or plasma etching). The benefit provided by the patterning of the film is that the film is therefore lighter, thereby reducing its heat capacity and thus causing it to heat faster in response to incident electromagnetic radiation. Patterning also allows tuning the effective sheet resistance of the patterned absorber film to achieve optical impedance matching of the absorber (in the case of a resistive impedance matching absorber), or to tune the optical properties of the absorber (in the case of a plasma absorber). Therefore, the response time of the detector can be improved. The holes can be designed to be smaller than the wavelength of the radiation that the detector is intended to detect, so that the absorbance is not adversely affected.

[0032] When the wavelength that the detector is intended to detect is known, the cavity may also be sized accordingly so that for a resistive absorber the height of the cavity is one quarter of the central wavelength that the thermal detector is arranged to detect. For a plasmonic absorber the cavity may be different than one quarter of the central wavelength.

[0033] In general, a detector may be provided, comprising: an optical absorption film 110 suspended above a cavity between the film 110 and a substrate 140; and thermoelectric converters 120, 130 attaching the optical absorption film 110 above the cavity, wherein the optical absorption film 110 forms a contact element between the n-type thermoelectric material 120 and the p-type thermoelectric material 130 of the thermoelectric converters 120, 130. The film 110 may be patterned, for example by perforating it to have a plurality of holes. When the film 110 is patterned, both the thermoelectric converter layer 112 and the optical absorption layer 111 may have the same pattern, such that the holes of the pattern extend through the entire film 110, for example.

[0034] By being attached above the cavity by a thermoelectric converter, it can be meant that the legs 120, 130 connecting the membrane 110 to the rest of the detector (e.g., the stubs 122, 132) do not contain non-thermoelectric materials. The legs can be connected to or between other structures, such as the stubs 122, 132 and the frame 160, but the legs themselves can be composed only of thermoelectric materials.

[0035] The detector may include a back reflector attached to the inner edge of the cavity, arranged to reflect optical signals not absorbed by the membrane back to the membrane 110. Thus, the membrane 110 may have two opportunities to absorb energy from the optical signal.

[0036] The detector may be only passively cooled, meaning that the detector has no active cooling mechanism. In other words, the detector may be uncooled. In the case where the detector is actively cooled, it may be cooled using a Peltier chip, for example. Typically, uncooled detectors offer the benefit of slightly better sensitivity.

[0037] The detector may include a frame 160, either on top of the thermoelectric converters 120, 130, or between the thermoelectric converters 120, 130 and the stubs 122, 132 defining the cavity height. As described above, the presence of the frame 160 enables the use of a wider range of thermoelectric materials to construct the thermoelectric converters 120, 130 and the thermoelectric converter layer 112.

[0038] The optical absorption film 110 can be a resistive impedance matching absorber or a plasmonic absorber. For example, in the case where the film is a plasmonic absorber, it can be a broadband absorber. For a plasmonic absorber, the dielectric constant of the absorbing material and the characteristic size of the pattern can be matched to the wavelength desired to be detected with the detector. In the case where the optical absorption film is a resistive impedance matching absorber, the height of the cavity can be one quarter of the wavelength that the detector is arranged to detect.

[0039] Figure 3A An example of a device configuration is shown. Here, like reference numerals also refer to similar structures as in the previous figures. In these examples, the left absorber is pentagonal, while the middle and right absorbers are square. As can be seen from this figure, the thermoelectric converters 120, 130 can be arranged to suspend the membrane 110 in various ways. As described above, there can be Figure 3A The frame is not shown.

[0040] Figure 3B Examples of device configurations are shown. These configurations involve multiple detector arrays. Such arrays can be constructed from detectors of different shapes. For example, on the left is a square detector array, and on the right is a triangular detector array, as constructed as described herein. The detector arrays can be used in imaging applications, where the detector array forms a multi-pixel image sensor. The detector arrays can also be used in spectroscopy applications, such that the detectors included in the array are tuned to respond to incident electromagnetic radiation of different wavelengths. The absorber 110 will advantageously cover as much of the total detector area as possible. As described above, there can be Figure 3B The frame is not shown.

[0041] Figure 4 shows the stages of the manufacturing method. Figure 4A In the embodiment of the present invention, the process has started with a silicon wafer 140, which may be doped to create a reflector 150. Alternatively, a metal layer may be placed on the substrate 140 to construct the reflector 150. Subsequently, a sacrificial silicon oxide layer 130s is deposited on the reflector 150 (or the substrate 140, where the substrate 140 itself is reflective). Polysilicon deposition, doping and patterning are then performed to create the thermoelectric legs 120, 130 (on the Figure 1B , Figure 2B to achieve Figure 4A, where the thermoelectric elements 120 , 130 are present on a sacrificial layer 130 s.

[0042] Then, processing enters Figure 4B In order to achieve Figure 4B In the case of the thermoelectric material, the frame 160 material is deposited onto the thermoelectric material to construct the frame 160. Patterning can be used in the construction of the frame 160. For example, as described above in this article, the frame can be constructed of Al2O3 or silicon nitride.

[0043] Then, processing enters Figure 4C In order to achieve Figure 4C In the case of the optical absorption layer 110, the absorption material is deposited onto the thermoelectric material to form an absorption film. The portions of the thermoelectric elements 120, 130 covered by the absorption material become the thermoelectric converter layers 112a, 112b, while the absorption material itself constitutes the optical absorption layer 111. These two layers together are the optical absorption film 110. As described herein above, in this embodiment, the film is patterned. For example, the patterning may include perforations.

[0044] Then, finally enter Figure 4D At the stage shown, the sacrificial layer is removed, for example by releasing silicon via hydrofluoric acid, HF and water vapor, to construct a cavity between the optically absorbing film 110 and the reflector 150 (or substrate 140, where the substrate 140 itself is reflective). Alternatively, the release can occur during wet etching using an HF solution or a buffered HF solution. As remnants of the sacrificial layer, short rods 122 and 132 remain, for example to provide an electrical connection between the thermoelectric converter and the readout electronics.

[0045] FIG. 5A to FIG. 5D Various optical absorber film 110 structures are shown. In these figures, for clarity, only the thermoelectric layer and the absorber layer are shown, while the stubs, cavities, substrate and optional frame are not shown.

[0046] Figure 5A Shown with Figure 2A The film 110 of the embodiment of the present invention has a different film structure, wherein there is a gap 501 between the thermoelectric elements 120, 130 of the thermoelectric converter layers 112a, 112b. The gap can be made in place before depositing the absorber material. Therefore, in this case, the optical absorber layer 111 provides the only electrical connection between the thermoelectric elements 120 and 130. In fact, the absorber layer 111 can extend into the gap 501.

[0047] Figure 5AThe arrangement may be represented as an arrangement in which the optical absorption film forms a contact element between an n-type thermoelectric element and a p-type thermoelectric element of a thermoelectric converter, wherein the optical absorption film comprises an optical absorption layer overlying a thermoelectric converter layer, and a gap exists in the thermoelectric converter layer, separating the n-type thermoelectric element from the p-type thermoelectric element. The film may be patterned.

[0048] Figure 5B Shown with Figure 2A The film 110 has a different film structure in which one of the thermoelectric material groups covers another. In detail, in one part of the film, there is a three-layer section in which the thermoelectric elements overlap each other and are further covered by at least one absorption layer 111. In fact, there are two thermoelectric converter layers, one for each thermoelectric material type. They are illustrated as layer 112a and layer 112b.

[0049] Figure 5B The arrangement can be represented as an arrangement in which the optical absorption film forms a contact element between the n-type thermoelectric element and the p-type thermoelectric element of the thermoelectric converter, wherein the optical absorption film includes: a portion in which the n-type thermoelectric element and the p-type thermoelectric element overlap each other and are covered by the optical absorption layer. Therefore, in this portion, three layers overlap each other. The specific order in which the layers overlap each other may be different from that shown in the figure.

[0050] Figure 5C Shown with Figure 5B The film has a different film structure in which the overlap between the thermoelectric layers is more extensive. Another difference is that the thermoelectric material of the thermoelectric converter layer 112 is arranged on either side of the absorber layer 111. In fact, there are two thermoelectric converter layers, one for each thermoelectric material type. Figure 5C In FIG. 1 , they are illustrated as layer 112a and layer 112b.

[0051] Figure 5C The arrangement can be represented as an arrangement in which the optical absorption film forms a contact element between the n-type thermoelectric element and the p-type thermoelectric element of the thermoelectric converter, wherein the optical absorption film comprises: a portion in which the n-type thermoelectric element and the p-type thermoelectric element are arranged on either side of the optical absorption layer over the entire length of the optical absorption layer. Thus, the three layers overlap each other.

[0052] Figure 5D Shown with Figure 5C The film has a different film structure, in which the thermoelectric converter layer 112b corresponding to the thermoelectric element 130 surrounds the optical absorption layer 111 to be directly connected to the thermoelectric converter layer 112a corresponding to the thermoelectric element 120. In fact, there are two thermoelectric converter layers 112, one corresponding to each thermoelectric material type. They are illustrated as layer 112a and layer 112b.

[0053] Figure 5D The arrangement can be represented as an arrangement in which an optical absorption film forms a contact element between an n-type thermoelectric element and a p-type thermoelectric element of a thermoelectric converter, wherein the optical absorption film comprises: a portion in which the n-type thermoelectric element and the p-type thermoelectric element are arranged on either side of the optical absorption layer over the entire length of the optical absorption layer, and wherein the n-type thermoelectric element and the p-type thermoelectric element surround the optical absorption member by being directly connected to each other. Therefore, the three layers overlap each other. The benefit of this arrangement is that passivation of the absorption layer can be achieved using thermoelectric material without the need for a separate passivation layer. Alternatively, the separate passivation layer can cover FIG. 5A to FIG. 5D One or more optically absorbing films.

[0054] Figure 6 is a flow chart of a method according to at least some embodiments of the present invention. Stage 610 includes: obtaining a substrate wafer and depositing an oxide layer on the substrate wafer. Stage 620 includes: depositing a thermoelectric converter layer on the oxide layer. Stage 630 includes: depositing an optical absorption layer on the oxide layer or on the thermoelectric converter layer. Finally, stage 640 includes: etching a groove in the oxide layer to form a cavity, leaving an optical absorption film, the optical absorption film including the optical absorption layer and a portion of the thermoelectric converter layer suspended above the cavity by the thermoelectric converter layer. The thermoelectric converter layer may include two layers, one layer corresponding to an n-type thermoelectric element and the other layer corresponding to a p-type thermoelectric element. For example, the oxide may include silicon oxide.

[0055] The following combinations of materials may be used in the construction of the detector. A single combination of materials is disclosed on a single line:

[0056]

[0057]

[0058]

[0059] It should be understood that the disclosed embodiments of the present invention are not limited to the specific structures, process steps or materials disclosed herein, but are extended to equivalents thereof that will be recognized by those of ordinary skill in the relevant art. It should also be understood that the technical terms used herein are used only for the purpose of describing specific embodiments and are not intended to be limiting.

[0060] Reference to one embodiment or embodiments in this specification means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the invention. Thus, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout the specification do not necessarily all refer to the same embodiment. Where terms (such as, for example, approximately or substantially) are used to refer to values, the exact value is also disclosed.

[0061] As used herein, for convenience, multiple projects, structural elements, constituent elements and / or materials can be presented in a public list. However, these lists should be considered that each member in the list is individually determined as a separate, unique member. Therefore, any individual member on this list should not be considered as the de facto equivalent of any other member on the same list simply based on its performance in a common group, without an opposite indication. In addition, various embodiments of the present invention and examples and alternatives to its various components can be mentioned in this article. It should be understood that such embodiments, examples and alternatives should not be considered as de facto equivalents to each other, but should be considered as independent and autonomous representations of the present invention.

[0062] In addition, in one or more embodiments, the described features, structures or characteristics may be combined in any suitable manner. In the foregoing description, many specific details, such as examples of lengths, widths, shapes, etc., are provided to provide a thorough understanding of embodiments of the present invention. However, those skilled in the relevant art will recognize that the present invention may be implemented without one or more of the specific details, or with other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the present invention.

[0063] Although the above examples illustrate the principles of the present invention in one or more specific applications, it is obvious to those skilled in the art that a large number of modifications can be made in form, usage and implementation details without exercising creativity and without departing from the principles and concepts of the present invention. Therefore, the present invention is not limited except by the following claims.

[0064] The verbs "comprise" and "include" in this document are used as open limitations, neither excluding nor requiring the presence of unrecited features. Unless explicitly stated otherwise, the features recited in the dependent claims are freely combinable with each other. Furthermore, it should be understood that the use of "a" or "an" (i.e. the singular) in this document does not exclude the plural.

[0065] Industrial Applicability

[0066]

[01] At least some embodiments of the present invention have industrial applicability in the use and manufacture of detectors. Examples of potential detector applications include infrared imaging, infrared chemical analysis based on absorption spectroscopy (for example), and temperature measurement. These devices can also be used as calorimetric sensors.

[0067] List of abbreviations

[0068] ALD Atomic Layer Deposition

[0069] CVD Chemical Vapor Deposition

[0070] LPCVD Low Pressure CVD

[0071] LTO Low Temperature Oxide

[0072] PECVD Plasma Enhanced CVD

[0073] Reference numerals list

[0074]

[0075]

Claims

1. A detector, comprising: an optically absorbing film suspended over a cavity between the film and a substrate included in the detector, and A thermoelectric converter attaches the optical absorption film over the cavity, wherein the optical absorption film forms a contact element between an n-type thermoelectric element and a p-type thermoelectric element of the thermoelectric converter.

2. The detector according to claim 1, wherein: The optically absorptive film is attached to the cavity through the thermoelectric converter via legs that do not include non-thermoelectric material.

3. The detector according to claim 1 or 2, wherein: The film has a thickness of less than 800 nanometers, less than 200 nanometers, less than 180 nanometers, less than 160 nanometers, less than 100 nanometers, less than 60 nanometers, or less than 20 nanometers.

4. The detector according to any one of claims 1 to 3, wherein: The detector further comprises a back reflector attached in an inner edge of the cavity, the back reflector being arranged to reflect optical signals not absorbed by the membrane back to the membrane.

5. The detector according to any one of claims 1 to 4, wherein: The detector is only passively cooled.

6. The detector according to any one of claims 1 to 5, further comprising a frame, the frame being either on top of the thermoelectric converter or between the thermoelectric converter and a short rod defining the height of the cavity.

7. The detector according to claim 6, wherein: The frame consists of aluminum oxide.

8. The detector according to any one of claims 1 to 7, wherein: The thermoelectric converter comprises in part silicon.

9. The detector according to any one of claims 1 to 8, wherein: The thermoelectric converter includes, in part, bismuth telluride.

10. The detector according to any one of claims 1 to 9, wherein: The thermoelectric converter includes, in part, antimony telluride.

11. The detector according to any one of claims 1 to 10, wherein: The optical absorption film includes titanium nitride.

12. The detector according to any one of claims 1 to 11, wherein: The optically absorptive film includes titanium tungsten.

13. The detector according to any one of claims 1 to 12, wherein: The optically absorptive film includes titanium.

14. The detector according to any one of claims 1 to 13, wherein: The optically absorbing film includes aluminum-doped zinc oxide.

15. The detector according to any one of claims 1 to 14, wherein: The optically absorptive film includes aluminum.

16. The detector according to claim 6, wherein: The stub includes an electrical connection between the thermoelectric converter and readout electronics configured to process signals from the detector.

17. The detector according to claim 16, wherein: The short rods are composed of silicon oxide.

18. The detector according to any one of claims 1 to 17, wherein: The optical absorption film is a resistive impedance matching absorber or a plasmonic absorber.

19. The detector according to claim 18, wherein: The optically absorptive film is the resistive impedance matched absorber and wherein the height of the cavity is one quarter of the wavelength that the detector is arranged to detect.

20. The detector according to any one of claims 1 to 19, wherein: The substrate includes a silicon layer.

21. The detector according to any one of claims 1 to 20, wherein: The optically absorptive film is patterned to have a pattern including a plurality of holes piercing the film.

22. The detector according to any one of claims 1 to 21, wherein: The optical absorption film includes two optical absorption layers and a thermoelectric converter layer, the optical absorption layers being disposed on either side of the thermoelectric converter layer.

23. The detector according to any one of claims 1 to 22, wherein: The optical absorption film includes: one and only one optical absorption layer and a thermoelectric converter layer, wherein the optical absorption layer is disposed on one and only one side of the thermoelectric converter layer.

24. The detector according to any one of claims 1 to 23, wherein: One and only one of the following applies: The optical absorption film includes an optical absorption layer covering a thermoelectric converter layer, wherein a gap exists in the thermoelectric converter layer, and the gap separates the n-type thermoelectric element from the p-type thermoelectric element; The optical absorption film includes a portion in which the n-type thermoelectric element and the p-type thermoelectric element overlap each other and are covered by an optical absorption layer; The optical absorption film includes a portion in which the n-type thermoelectric element and the p-type thermoelectric element are disposed on either side of the optical absorption layer over the entire length of the optical absorption layer, and The optical absorption film includes a portion wherein the n-type thermoelectric element and the p-type thermoelectric element are disposed on either side of the optical absorption layer over the entire length of the optical absorption layer, and wherein the n-type thermoelectric element and the p-type thermoelectric element surround the optical absorption member by being directly connected to each other.

25. A method of manufacturing a detector, comprising: obtaining a substrate wafer and depositing an oxide layer on the substrate wafer; depositing a thermoelectric converter layer on the oxide layer; depositing an optical absorption layer on the oxide layer or on the thermoelectric converter layer, and A recess is etched in the oxide layer to form a cavity, leaving an optically absorbing film including the optically absorbing layer and a portion of the thermoelectric converter layer suspended by the thermoelectric converter layer over the cavity.

26. The method according to claim 25, wherein: The optically absorptive film is attached to the cavity through the thermoelectric converter via legs that do not include non-thermoelectric material.

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