Heat detector

Abstract

According to one exemplary embodiment of the present invention, there is provided a detector comprising: a light-absorbing film suspended above a cavity between the light-absorbing film and a substrate, the substrate being included in the detector; and a thermoelectric transducer mounting the light-absorbing film above the cavity, the light-absorbing film forming a contact element between an n-type thermoelectric element and a p-type thermoelectric element of the thermoelectric transducer.

Description

[Technical field]

[0001] The present disclosure relates to thermoelectric heat detectors. [Background technology]

[0002] Photodetectors are light-sensitive sensors that measure the presence and / or intensity of incident electromagnetic radiation and convert the measurement into an appropriate electrical signal for output. Photodetectors are divided into quantum and thermal detectors. Quantum detectors (i.e. photovoltaic and photoconductive detectors) are typically fast and often more sensitive than thermal detectors, but are relatively complex. Quantum detectors operating in the infrared region are often made of expensive and / or toxic materials and must be operated at low temperatures to achieve high sensitivity (because lower temperatures reduce noise). Thermal sensors are devices configured to measure the power of electromagnetic radiation by converting it into heat and converting the generated temperature into an appropriate electrical signal.

[0003] Thermal sensors utilize a variety of technologies, but the most relevant commercial technologies are resistive and thermoelectric thermal detectors. Thermal detectors consist of an absorber of incident radiation and a transducer that converts the change in temperature of the absorber into an electrical signal. Resistive thermal detectors (sometimes called bolometers) use a temperature dependent resistance as the transducer. Thermoelectric thermal detectors (often thermopiles or thermocouples) use thermoelectric transduction based on the thermoelectric effect. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the problems in the prior art. [Means for solving the problem]

[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 there is provided a detector comprising: a light absorbing film, the light absorbing film suspended above a cavity between the light absorbing film and a substrate, the substrate being included in the detector; and a thermoelectric transducer mounting the light absorbing film above the cavity, the light absorbing film forming a contact element between an n-type thermoelectric element and a p-type thermoelectric element of the thermoelectric transducer.

[0007] According to a second aspect of the present disclosure, there is provided a method for manufacturing a detector, the method comprising the steps of obtaining a substrate wafer, depositing an oxide layer on the substrate wafer, depositing a thermoelectric transducer layer on the oxide layer, depositing a light absorbing layer on the oxide layer or on the thermoelectric transducer layer, and etching a recess down to the oxide layer to form a cavity leaving a light absorbing film including the light absorbing layer and a portion of the thermoelectric transducer layer suspended above the cavity by the thermoelectric transducer layer. [Brief description of the drawings]

[0008] [Figure 1A] 1 illustrates an example of a heat detector in accordance with at least some embodiments of the present invention. [Figure 1B] 1 illustrates an example of a heat detector in accordance with at least some embodiments of the present invention. [Figure 2A] 1 illustrates an example of a heat detector in accordance with at least some embodiments of the present invention. [Figure 2B] 1 illustrates an example of a thermal detector having a patterned membrane in accordance with at least some embodiments of the present invention. [Figure 3A] An example of a device configuration is shown. [Figure 3B] An example of a device configuration is shown. [Figure 4A] ~ [Figure 4D] 1 shows the phases of one manufacturing method. [Figure 5A] ~ [Figure 5D] 1 shows various structures of the absorbing membrane. [Figure 6] 1 is a flow graph of a method in accordance with at least some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A detector constructed as disclosed herein includes a light absorbing membrane suspended (for example) above a cavity by a thermoelectric transducer. The cavity may have a reflector at its bottom, which reflects back the portion of the incident light not absorbed by the membrane, enhancing the sensitivity of the detector. The cavity may have a resonant function. The membrane may be a nanomembrane, with a thickness on the nanometer scale. Nanoscale membranes are lightweight and therefore capable of heating up quickly in response to incident radiation, thereby increasing the response speed of the detector. The detector of the present disclosure further does not have a separate support structure. This is because the membrane is suspended and attached directly above the cavity by the thermoelectric transducer itself. The fact that the detector does not have a separate support structure also contributes to a faster response time. This is because if the system had a support structure, the support structure would increase the thermal capacity of the detector, slowing its response time. Advantageously, the detector disclosed herein can be manufactured from safer (e.g., less toxic) materials. Such materials may also be less expensive. Additionally, the detectors disclosed herein may be fabricated using Micro-Electro-Mechanical Systems (MEMS) techniques.

[0010] Quantum detectors (i.e. photovoltaic and photoconductive detectors) require cooling solutions to achieve high sensitivity, which are often expensive and require exotic and / or toxic materials (e.g. HgCdTe required for far infrared detection). Cooling systems are complex, power-hungry, and costly. The main limitation of uncooled photodetectors, both thermal and quantum, is their poor performance in terms of sensitivity, described by a specific detectivity. Even state-of-the-art thermal detectors are typically slower than quantum detectors. The advantage of thermoelectric transduction is high sensitivity and low power consumption compared to resistive detectors, which require active power. Thermoelectric transduction inherently generates a voltage, so no external power is required. Furthermore, no current is required for signal transduction in the case of thermoelectric elements, which reduces noise sources and results in a higher signal-to-noise ratio (i.e., higher sensitivity).

[0011] FIG. 1A shows an example of a detector according to at least some embodiments of the present invention. The detector includes a light absorbing film 110, hereafter referred to as film 110 for brevity. The film 110 heats up in response to absorbing incident electromagnetic radiation. An n-type semiconductor element 120 connects the film 110 to a stub 122. A p-type semiconductor element 130 connects the film 110 to a stub 132. The stubs 122, 132 may be disposed on a substrate, not shown in FIG. 1A. As disclosed later in this specification, the substrate may define a cavity below the film 110. The detector may have more than one pair of legs of the semiconductor elements 120, 130, in which case the structure may be more robust. The film 110 may be thermally isolated by being placed in a vacuum.

[0012] The thermoelectric transducer is composed of two dissimilar thermoelectric materials joined together by a contact element. The dissimilar thermoelectric materials include an n-type semiconductor having negative charge carriers and a p-type semiconductor having positive charge carriers. Thus, in FIG. 1A, the thermoelectric transducer is composed of semiconductor elements 120 and 130. The film 110 is positioned to act as a contact element between the n-type thermoelectric element 120 and the p-type thermoelectric element 130 of the thermoelectric transducer.

[0013] FIG. 1B illustrates an example of a detector according to at least some embodiments of the present invention. This view shows the detector in a different view and includes the same elements as FIG. 1A, with similar numbering referring to similar structures. The stubs 122, 132 are shown here disposed on a substrate 140, which may include any suitable material. For example, the substrate 140 may include a silicon wafer. The stubs 122, 132 may be constructed of an oxide material (e.g., silicon oxide, etc.). The detector of FIG. 1B further includes a reflector 150, which is positioned to reflect back electromagnetic radiation that has passed through the film 110 without being absorbed by it. Thus, the presence of the reflector increases the sensitivity of the detector, since more of the incident radiation is absorbed by the film 110. In effect, radiation has two opportunities to be absorbed, one before it reflects off the reflector 150 and one after it reflects off the reflector 150. In effect, an optical cavity is formed between the film 110 and the reflector 150. The reflector 150 may be composed of, for example, a metal, a semimetal, a highly conductive semiconductor, a dielectric for a distributed Bragg reflector, or a low conductive semiconductor. Alternatively, an N+ (highly / degenerately N-doped) or P+ (highly / degenerately N-doped) doped semiconductor reflector may be used with a heavily doped substrate 140, a surface doped substrate 140 (e.g., by implantation or diffusion), or a deposited doped layer. In some embodiments, the substrate 140 itself acts as a reflector. This is the case, for example, when the substrate 140 is conductive, e.g., when the substrate 140 is highly doped silicon or other semiconductor, or a metallic substrate.

[0014] The stubs 122, 132 may provide electrical connections between the thermoelectric transducers 120, 130 and readout electronics configured to process signals from the detectors. For example, these electrical connections may be constructed using wire bonding, flip-chip bonding, or wafer bonding techniques using metal bond pads. As another alternative, the substrate 140 may include CMOS circuitry. Additionally, the detector may interface with other optical devices, such as microspectrometer films (e.g., Fabry-Perot interferometers). The readout electronics are not shown in FIG. 1B for simplicity. The stubs may be made of an oxide material, which may be a remnant of a sacrificial layer etched during the fabrication of the detector. For example, it may be tetraethyl orthosilicate (TEOS) silicon oxide, plasma-enhanced chemical vapor deposition (CVD) silicon oxide, or low pressure CVD low temperature oxide (LTO) silicon oxide.

[0015] FIG. 2A shows an example of a detector according to at least some embodiments of the present invention. Like numbering refers to similar structures as in FIGS. 1A and 1B. A frame 160 is provided to provide stress tuning, which allows the use of thermoelectric materials with a wider range of stress characteristics. In the absence of the frame 160, the thermoelectric materials used in the semiconductor elements 120 and 130 may be made to have low or moderate tensile stress to adequately suspend the membrane 110. The frame 160 may be placed over the semiconductor elements 120, 130 as shown in FIG. 2A, or may additionally or alternatively be placed between the semiconductor element 120 and the stub 122 and between the semiconductor element 130 and the stub 132. The frame may be made of, for example, the following materials, such as silicon nitride (SiN x ) and aluminum oxide (Al2O3). These materials may be deposited by techniques such as plasma enhanced CVD, low pressure CVD, sputtering, and / or atomic layer deposition (ALD). As mentioned above, in some embodiments, there is no frame 160.

[0016] The light absorbing film 110 is shown in FIG. 2A as being composed of thermoelectric transducer layers 112a, 112b and a light absorbing layer 111. Physically, the thermoelectric transducer layers 112a, 112b and the semiconductor elements 120, 130 may be part of the same fabricated layer structure. In particular, the semiconductor element 120 and the thermoelectric transducer layer 112a facing the thermoelectric element 120 may be part of the same semiconductor layer. The semiconductor element 130 and the thermoelectric transducer layer 112b facing the thermoelectric element 130 may be part of the same semiconductor layer. From a fabrication standpoint, the light absorbing layer 111 may be deposited on top of the thermoelectric transducer layers 112a, 112b. In other words, the deposition of the light absorbing layer 111 defines the thermoelectric transducer layers 112a, 112b as the portions of the thermoelectric elements 120, 130 that are covered by the light absorbing layer 111. In other embodiments, the light absorbing layer 111 may be below the thermoelectric transducer layers 112a, 112b, i.e., on the side of the cavity between the membrane 110 and the substrate 140. The gaps in the membrane 110 indicate the patterning of the membrane in schematic terms and are an optional feature. The patterning is shown in more detail in FIG. 2B and will be described below. The thermoelectric transducer layers 112a, 112b may be of equal or unequal size. If the sizes are unequal, the sizes may be selected to minimize the overall contact resistance and / or the total resistance of the thermoelectric transducer, depending on the particular thermoelectric and absorber materials used.The geometry of the thermoelectric elements 120, 130 may be selected, for example, as in A. Varpula et al., Appl. Phys. Lett. 110, 262101 (2017), or in "Thermoelectrics handbook: macro to nano", DM Rowe, Taylor & Francis (2006), and H. Julian Goldsmid, Springer series in materials science 121: "Introduction to Thermoelectricity", Springer (2010).

[0017] In yet another embodiment, there may be two light absorbing layers, one on each side of the thermoelectric transducer layers 112a, 112b. In other words, the light absorbing film may include two light absorbing layers and a thermoelectric transducer layer, with the light absorbing layers being disposed on both sides of the thermoelectric transducer layer. Meanwhile, in some embodiments, the light absorbing film 110 includes only one light absorbing layer 111 as well as one thermoelectric transducer layer 112, with the light absorbing layer 111 being disposed on only one side of the thermoelectric transducer layer 112. Specific examples of various embodiments of the film are detailed later with respect to FIGS. 5A-5D.

[0018] When there are two light absorbing layers in the light absorbing film 110, they may be made of the same material or different materials. The light absorbing film 110 may have a thickness of, for example, 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 previously disclosed, a thin film has a low heat capacity. Furthermore, as the thickness decreases to the nanoscale, the film phonon thermal conductivity of the material within the film decreases.

[0019] The light absorbing layer (e.g., light absorbing layer 111) may be composed of a metal, a semimetal, or a highly doped semiconductor. Examples include TiW (titanium tungsten), Ti (titanium), W (tungsten), TiN (titanium nitride), NbN (niobium nitride), MoN (molybdenum nitride), Mo (molybdenum), thin film Al, a-Si (amorphous silicon), Al:ZnO (aluminum doped zinc oxide), highly doped single crystal and polycrystalline silicon, and doped SrTiO3 (strontium titanate). Another example of an absorber material is an infrared absorbing insulator such as silicon nitride or aluminum oxide. These materials absorb well in the infrared band. In the absorber layer, the conductivity of the material may be selected to allow impedance matching with the low vacuum impedance of the thermal mass, i.e., high enough for good absorption without the resistance being too high optimally. In the case of a plasmonic absorber, the dielectric constant of the selected material and the pattern feature size may be advantageously matched to the desired wavelength. With regard to the electrical requirements, the material of the absorber layer 111 selected advantageously has a low contact resistance with the material of the semiconductor elements 120 and 130 (and thus with the thermoelectric transducer layers 112a, 112b). This contact resistance must be much lower than the total resistance of the thermoelectric legs 120, 130, since otherwise the contact resistance will degrade the performance of the detector.

[0020] The thermoelectric materials used for the thermoelectric elements 120, 130 and the thermoelectric transducer layers 112a, 112b may have a thickness of less than 200 nm when applied to the detector. One is an N-type thermoelectric material and the other is a P-type thermoelectric material. Suitable materials include semiconductors such as highly doped N(P)-type silicon, polysilicon, etc. Doping may be done by ion implantation, diffusion, or other suitable methods. Advantageously, the thermoelectric material has a high thermoelectric figure of merit (ZT) (see, for example, A. Varpula et al., Appl. Phys. Lett. 110, 262101 (2017) for a definition of ZT). To maximize the sensitivity of the photodetector, the effective thermoelectric figure of merit (effective ZT) of the device must be maximized. Regarding the mechanical requirements of the thermoelectric materials of the elements 120, 130 and the thermoelectric transducer layers 112a, 112b, these materials must have low or moderate tensile stress to properly suspend the membrane 110. If the stress conditions are not adequate enough, the frame 160 can be utilized to adjust the stress of the thermoelectric materials.

[0021] 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 film single crystal silicon, thin film polysilicon, Bi2Te3 (bismuth telluride), and Sb2Te3 (antimony telluride).

[0022] Optionally, a passivation layer, not shown in FIG. 2A, may be disposed as a top layer over the membrane 110, the elements 120, 130, and the frame 160 (if the frame 160 is present) to seal the other layers. The passivation layer may be, for example, Al2O3 or SiN xThese materials may be deposited by techniques such as plasma enhanced CVD, low pressure CVD, sputtering, and atomic layer deposition (ALD). The role of the passivation layer is to protect the absorbing material if necessary. The absorbing material surface may be protected by patterning the passivation layer away from the absorber edge (by spacer patterning techniques) or may be left unprotected by simultaneously patterning the passivation layer with the thermoelectric material and the absorber material. In some embodiments, one of the thermoelectric materials is used as a passivation layer for the absorbing layer of the light absorbing film.

[0023] FIG. 2B shows an example of a detector with a patterned film according to at least some embodiments of the present invention. The cross section of FIG. 2A is taken obliquely along the dotted line. As can be seen in FIG. 2B, the light absorbing film 110 is patterned, in particular with a number of holes drilled in the film. These holes may be made, for example, by etching (such as wet etching or plasma etching). Patterning the film has the advantage that it is lighter, which reduces its thermal mass and, as a result, heats up more quickly in response to incident electromagnetic radiation. Patterning also allows tuning the effective sheet resistance of the patterned absorber film for optical impedance matching of the absorber (in the case of a resistive impedance matched absorber) or tuning the optical properties of the absorber (in the case of a plasmonic absorber). This can improve the response time of the detector. The holes may be designed to be smaller than the wavelength of the radiation that the detector is intended to detect, so that there is no adverse effect on the absorption.

[0024] If the wavelength that the detector is intended to detect is known, the dimensions of the cavity may be determined accordingly, in the case of a resistive absorber the height of the cavity may be determined to be one quarter of the central wavelength that the thermal detector is configured to detect, in the case of a plasmonic absorber the cavity need not be one quarter of the central wavelength.

[0025] In general, a detector may be provided that includes a light absorbing film 110 suspended above a cavity between the light absorbing film 110 and a substrate 140, and thermoelectric transducers 120, 130 mounting the light absorbing film 110 above the cavity, the light absorbing film 110 forming contact elements between the n-type thermoelectric material 120 and the p-type thermoelectric material 130 of the thermoelectric transducers 120, 130. The film 110 may be patterned, for example, by drilling a number of holes in the film 110. When the film 110 is patterned, both the thermoelectric transducer layer 112 and the light absorbing layer 111 may have the same pattern, such that each hole in the pattern extends completely through the film 110, for example.

[0026] The legs 120, 130 connecting the membrane 110 to other parts of the detector (e.g., stubs 122, 132) may be mounted above the cavity by the thermoelectric transducer, meaning that they do not include non-thermoelectric material. The legs may be connected to or between other structures (e.g., stubs 122, 132 and frame 160), but the legs themselves may consist only of thermoelectric material.

[0027] The detector may include a back reflector attached to the inner edge of the cavity, positioned to reflect any optical signal not absorbed by the membrane 110 back towards the membrane 110. Thus, the membrane 110 has two opportunities to absorb energy from the optical signal.

[0028] The detector may only be passively cooled, i.e. the detector has no active cooling mechanism. In other words, the detector may not be cooled. If the detector is actively cooled, it may be cooled, for example, using a Peltier chip. Generally, not cooling the detector has the advantage of slightly better sensitivity.

[0029] The detector may include a frame 160 over the thermoelectric transducers 120, 130 or between the thermoelectric transducers 120, 130 and the stubs 122, 132, which determines the height of the cavity. As mentioned above, the pressure of the frame 160 allows the thermoelectric transducers 120, 130 and the thermoelectric transducer layer 112 to be constructed using a wider range of thermoelectric materials.

[0030] The light absorbing film 110 may be a resistive impedance matched absorber or a plasmonic absorber. If the film is a plasmonic absorber, it may be, for example, a broadband absorber. In the case of a plasmonic absorber, the dielectric constant of the absorbing material and the feature size of the pattern may be matched to the wavelength required to be detected by the detector. If the light absorbing film is a resistive impedance matched absorber, the height of the cavity may be one quarter of the wavelength that the detector is configured to detect.

[0031] Figure 3A shows examples of device configurations. Similar numbering again refers to similar structures in the preceding figures. In these examples, the absorber is a pentagon on the left and a square in the middle and right. As can be seen, the thermoelectric transducers 120, 130 may be positioned to suspend the membrane 110 in a variety of ways. A frame is not shown in Figure 3A but may be present, as described above.

[0032] FIG. 3B shows examples of device configurations. These configurations concern multi-detector arrays. Such arrays may be constructed with detectors of various shapes. For example, on the left is an array of square detectors, and on the right is an array of triangular detectors constructed as disclosed herein. Detector arrays may be used in imaging applications where the detector array forms a multi-pixel image sensor. Detector arrays may also be used in spectroscopy applications, where each detector constituting the array is tuned to respond to different wavelengths of incident electromagnetic radiation. The absorber 110 advantageously covers as much of the total detector area as possible. A frame is not shown in FIG. 3B, but may be present, as described above.

[0033] Figure 4 shows the phases of the manufacturing method. In Figure 4A, the process starts with a silicon wafer 140, which may be doped to create a reflector 150. As an alternative, a metal layer may be placed on the substrate 140 to build the reflector 150. A sacrificial silicon oxide layer 130 is then deposited on the reflector 150 (or on the substrate 140, if the substrate 140 is itself reflective). Polysilicon is then deposited, doped, and patterned to create the thermoelectric legs 120, 130 (visible in Figures 1B, 2B), resulting in the state shown in Figure 4A, where the thermoelectric elements 120, 130 are present on the sacrificial layer 130.

[0034] The process then proceeds to the phase shown in Figure 4B. The material of frame 160 is deposited on the thermoelectric material to construct frame 160, as shown in Figure 4B. Patterning may be used in the construction of frame 160. As previously disclosed herein, the frame may be constructed of, for example, Al2O3 or silicon nitride.

[0035] The process then proceeds to the phase shown in Figure 4C. An absorbing material is deposited on top of the thermoelectric material to form an absorbing film, as shown in Figure 4C. The portions of the thermoelectric elements 120, 130 over which the absorbing material is deposited become the thermoelectric transducer layers 112a, 112b, while the absorbing material itself constitutes the light absorbing layer 111. These two layers together become the light absorbing film 110. The film is patterned, in this embodiment, as previously disclosed herein. Patterning may include, for example, drilling holes.

[0036] Finally, going to the phase shown in Fig. 4D, the sacrificial layer is removed to create a cavity between the light absorbing film 110 and the reflector 150 (or the substrate 140, if the substrate 140 is itself reflective). This is done, for example, by stripping the silicon with hydrogen fluoride (HF) vapor. Alternatively, the removal can be done as a wet etch using a HF solution or a buffered HF solution. The remainder of the sacrificial layer are the stubs 122 and 132, which provide, for example, an electrical connection between the thermoelectric transducer and the readout electronics.

[0037] 5A-5D show various structures of the light absorbing film 110. For clarity, these figures show only the thermoelectric and absorbing layers, not the stubs, cavities, substrate, and optional frame.

[0038] 5A shows a different membrane structure from the membrane 110 of FIG. 2A, with the difference being that there is a gap 501 between the thermoelectric elements 120, 130 of the thermoelectric transducer layers 112a, 112b. The gap may be fabricated in place before the absorbing material is deposited. Thus, in this case, the light absorbing layer 111 only provides an electrical connection between the thermoelectric elements 120, 130. In fact, the absorbing layer 111 may extend into the gap 501.

[0039] 5A may be represented as an arrangement in which the light absorbing film forms a contact element between an n-type thermoelectric element and a p-type thermoelectric element of a thermoelectric transducer, the light absorbing film including a light absorbing layer overlying a thermoelectric transducer layer, where there is a gap in the thermoelectric transducer layer separating the n-type thermoelectric element from the p-type thermoelectric element. The film may be patterned.

[0040] Figure 5B shows a different membrane structure than membrane 110 of Figure 2A, except that one of the thermoelectric materials partially overlaps the other. In particular, in one part of the membrane there is a three-layer section where the thermoelectric elements overlap each other and are further overlapped by at least one absorber layer 111. There are essentially two thermoelectric transducer layers, one for each type of thermoelectric material. These are shown as layers 112a and 112b.

[0041] The arrangement of Figure 5B may be expressed as an arrangement in which the light absorbing film forms a contact element between the n-type and p-type thermoelectric elements of the thermoelectric transducer, and the light absorbing film includes a section in which the n-type and p-type thermoelectric elements overlap one another and are covered by the light absorbing layer. Thus, in this section, three layers overlap one another. The particular order in which these layers overlap one another may be different than that shown.

[0042] Figure 5C shows a different membrane structure than that of Figure 5B, with a more extensive overlap between the thermoelectric layers. A further difference is that the thermoelectric material of the thermoelectric transducer layer 112 is disposed on either side of the absorbing layer 111. In effect, there are two thermoelectric transducer layers, one for each type of thermoelectric material. These are shown in Figure 5C as layers 112a and 112b.

[0043] 5C may be expressed as an arrangement in which the light absorbing film forms a contact element between the n-type and p-type thermoelectric elements of the thermoelectric transducer, and the light absorbing film includes sections in which the n-type and p-type thermoelectric elements are disposed on either side of the light absorbing layer over the entire length of the light absorbing layer, thus resulting in three layers overlapping each other.

[0044] Figure 5D shows a different film structure than that of Figure 5C, except that the thermoelectric transducer layer 112b corresponding to the thermoelectric element 130 seals the light absorbing layer 111 and directly connects to the thermoelectric transducer layer 112a corresponding to the thermoelectric element 120. There are essentially two thermoelectric transducer layers 112, one for each type of thermoelectric material, shown as layer 112a and layer 112b.

[0045] The arrangement of FIG. 5D may be expressed as an arrangement in which the light absorbing film forms a contact element between the n-type thermoelectric element and the p-type thermoelectric element of the thermoelectric transducer, the light absorbing film including a section in which the n-type thermoelectric element and the p-type thermoelectric element are arranged on either side of the light absorbing layer over the entire length of the light absorbing layer, the n-type thermoelectric element and the p-type thermoelectric element directly connect to each other, thereby sealing the light absorbing member. Thus, the three layers overlap each other. The advantage of this arrangement is that the passivation of the absorbing layer can be achieved with the thermoelectric material without using a separate passivation layer. Alternatively, a separate passivation layer may be coated on the light absorbing film in one or more of FIGS. 5A-5D.

[0046] 6 is a flow graph of a method according to at least some embodiments of the present invention. In phase 610, a substrate wafer is obtained and an oxide layer is deposited on the substrate wafer. In phase 620, a thermoelectric transducer layer is deposited on the oxide layer. In phase 630, a light absorbing layer is deposited on the oxide layer or on the thermoelectric transducer layer. Finally, in phase 640, a recess is etched down to the oxide layer to form a cavity, leaving a light absorbing film including the light absorbing layer and a portion of the thermoelectric transducer layer suspended above the cavity by the thermoelectric transducer layer. The thermoelectric transducer layer may include two layers, one corresponding to the n-type thermoelectric element and one corresponding to the p-type thermoelectric element. The oxide may include, for example, silicon oxide.

[0047] The following combinations of materials may be used in constructing the detector: One combination of materials is disclosed in one line. [Table 1]

[0048] It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures, process steps, or materials disclosed herein, but extend to equivalents thereof as would be recognized by one of ordinary skill in the art. It is also to be understood that the terminology used herein is used only for the purpose of describing particular embodiments, and is not intended to be limiting.

[0049] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. For example, when a numerical value is referenced using a phrase such as about or substantially, the exact numerical value is also disclosed.

[0050] As used herein, a number of items, structural elements, compositional elements, and / or materials may be present in common lists for convenience. However, these lists should be construed as if each element of the list were individually identified as a separate and unique element. Thus, the individual elements of such lists should be construed as de facto equivalents of any other elements of the same list solely based on their presence in a common grouping, unless otherwise indicated. Furthermore, various embodiments and examples of the invention may be referenced herein in conjunction with alternatives with respect to their various components. It should be understood that such embodiments, examples, and alternatives should not be construed as de facto equivalents of each other, but should be considered as separate and independent manifestations of the invention.

[0051] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the above description, various specific details are set forth, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the present invention. However, one of ordinary skill in the art will recognize that the present invention may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the present invention.

[0052] While the above-described embodiments illustrate the principles of the present invention in one or more specific applications, it will be apparent to those skilled in the art that various changes in form, usage, and details of the embodiments may be made without the exercise of the inventive faculty and without departing from the principles and concepts of the present invention. Accordingly, the present invention is not intended to be limited except as by the claims that follow.

[0053] In this document, the verbs "to comprise" and "to include" are used as open limitations that do not exclude or require the presence of unrecited features. Features recited in the dependent claims may be freely combined with each other, unless expressly stated otherwise. Furthermore, it is to be understood that the use of "a" or "an", i.e. the singular, does not exclude a plurality throughout this document. [Appendix 1] A detector comprising: a light absorbing film suspended above a cavity between the light absorbing film and a substrate, the substrate being included in the detector; and a thermoelectric transducer having the light absorbing film mounted above the cavity, the light absorbing film forming a contact element between an n-type thermoelectric element and a p-type thermoelectric element of the thermoelectric transducer; A detector including: [Appendix 2] 2. The detector of claim 1, wherein the attachment of the light absorbing film above the cavity by the thermoelectric transducer is by legs that do not include non-thermoelectric material. [Appendix 3] 3. The detector of 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. [Appendix 4] 4. The detector of any one of claims 1 to 3, further comprising a back reflector attached to an inner edge of the cavity, the back reflector positioned to reflect optical signals not absorbed by the membrane back towards the membrane. [Appendix 5] 5. The detector of any one of claims 1 to 4, wherein the detector is cooled only by passive cooling. [Appendix 6] 6. The detector of any one of claims 1 to 5, further comprising a frame on top of the thermoelectric transducer or between the thermoelectric transducer and the stub, which frame determines the height of the cavity. [Appendix 7] 7. The detector of claim 6, wherein the frame is made of aluminum oxide. [Appendix 8] The detector according to any one of claims 1 to 7, wherein the thermoelectric transducer is partially made of silicon. [Appendix 9] 9. The detector according to any one of claims 1 to 8, wherein the thermoelectric transducer is partially made of bismuth telluride. [Appendix 10] 10. The detector according to any one of claims 1 to 9, wherein the thermoelectric transducer is partially made of antimony telluride. [Appendix 11] 11. The detector according to any one of claims 1 to 10, wherein the light absorbing film is made of titanium nitride. [Appendix 12] 12. The detector according to any one of claims 1 to 11, wherein the light absorbing film is made of titanium tungsten. [Appendix 13] 13. The detector according to any one of claims 1 to 12, wherein the light absorbing film is made of titanium. [Appendix 14] 14. The detector according to any one of claims 1 to 13, wherein the light absorbing film is made of aluminum-doped zinc oxide. [Appendix 15] 15. The detector according to any one of claims 1 to 14, wherein the light absorbing film is made of aluminum. [Appendix 16] 7. The detector of claim 6, wherein the stub comprises an electrical connection between the thermoelectric transducer and readout electronics configured to process signals from the detector. [Appendix 17] 17. The detector of claim 16, wherein the stub is comprised of silicon oxide. [Appendix 18] 18. The detector according to any one of claims 1 to 17, wherein the light absorbing film is a resistive impedance matched absorber or a plasmonic absorber. [Appendix 19] 19. The detector of claim 18, wherein the light absorbing film is a resistive impedance matched absorber and the height of the cavity is one quarter of a wavelength the detector is configured to detect. [Appendix 20] 20. The detector of any one of claims 1 to 19, wherein the substrate comprises a silicon layer. [Appendix 21] 21. The detector according to any one of claims 1 to 20, wherein the light absorbing film is patterned with a pattern that includes drilling a plurality of holes in the film. [Appendix 22] 22. The detector of any one of claims 1 to 21, wherein the light absorbing film includes two light absorbing layers and a thermoelectric transducer layer, the light absorbing layers being disposed on both sides of the thermoelectric transducer layer. [Appendix 23] 23. The detector of any one of claims 1 to 22, wherein the light absorbing film includes a single light absorbing layer and a thermoelectric transducer layer, the light absorbing layer being disposed on only one side of the thermoelectric transducer layer. [Appendix 24] the light absorbing film includes a light absorbing layer overlying a thermoelectric transducer layer, a gap being present in the thermoelectric transducer layer separating the n-type thermoelectric element from the p-type thermoelectric element; The light absorbing film includes a section in which the n-type thermoelectric element and the p-type thermoelectric element overlap each other and are covered with a light absorbing layer; the light absorbing film includes a section in which the n-type thermoelectric element and the p-type thermoelectric element are disposed on either side of the light absorbing layer over the entire length of the light absorbing layer; The light absorbing film includes a section in which the n-type thermoelectric element and the p-type thermoelectric element are disposed on both sides of the light absorbing layer over the entire length of the light absorbing layer, and the n-type thermoelectric element and the p-type thermoelectric element are directly connected to each other to seal the light absorbing member; 24. A detector according to any one of appendix 1 to 23, wherein only one of the following applies. [Appendix 25] obtaining a substrate wafer and depositing an oxide layer on the substrate wafer; depositing a thermoelectric transducer layer on the oxide layer; depositing a light absorbing layer on the oxide layer or on the thermoelectric transducer layer; etching a recess down to the oxide layer to form a cavity leaving a light absorbing film including the light absorbing layer and a portion of the thermoelectric transducer layer suspended above the cavity by the thermoelectric transducer layer; A method for manufacturing a detector comprising: [Appendix 26] 26. The method of claim 25, wherein the attachment of the light absorbing film above the cavity by the thermoelectric transducer is by legs that do not include non-thermoelectric material. [Industrial Applicability]

[0054] At least some embodiments of the present invention have industrial applicability in the use and manufacture of detectors. Examples of potential applications of detectors include infrared imaging (e.g., infrared chemical analysis based on absorption spectroscopy) and temperature measurement. These devices can also be used as calorimetric sensors. Acronym List ALD atomic layer deposition CVD Chemical vapor deposition LPCVD low-pressure CVD LTO low temperature oxide PECVD Plasma-enhanced CVD Reference List 110 Light absorbing film ("film") 111 Light absorbing layer 112a, 112b Thermoelectric transducer layer 120, 130 Thermoelectric element 122, 132 stub 140 Substrate 150 Reflector 160 frames 501 Gap 610~640 Phases of the process in Figure 6

Claims

1. A detector comprising: a light absorbing film, the light absorbing film being suspended over a cavity between the light absorbing film and a substrate, the substrate being included in the detector, the light absorbing film comprising a thermoelectric transducer layer and a light absorbing layer, the thermoelectric transducer layer comprising a first portion and a second portion, and the light absorbing layer being perforated; a thermoelectric transducer mounting the light absorbing film above the cavity, the light absorbing film forming a contact element between an n-type thermoelectric element and a p-type thermoelectric element of the thermoelectric transducer; the attachment of the light absorbing film over the cavity by the thermoelectric transducer is by a first leg and a second leg that do not include a non-thermoelectric material, the first leg and the first portion being formed from a first semiconductor layer, and the second leg and the second portion being formed from a second semiconductor layer; The detector, the light absorbing film includes a section in which the n-type thermoelectric element and the p-type thermoelectric element are disposed on either side of the light absorbing layer over the entire length of the light absorbing layer; The n-type thermoelectric element and the p-type thermoelectric element are directly connected to each other to seal the light absorbing layer; The light absorbing film includes a section in which the n-type thermoelectric element and the p-type thermoelectric element overlap each other and are covered with the light absorbing layer; Only one of the following applies: Detector.

2. 10. The detector of claim 1, wherein the light absorbing film has a thickness 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.

3. 3. The detector of claim 1 or 2, further comprising a back reflector attached to an inner edge of the cavity, the back reflector being positioned to reflect optical signals not absorbed by the light absorbing film back towards the light absorbing film.

4. Detector according to any one of claims 1 to 3, wherein the detector is cooled only by passive cooling.

5. A detector according to any one of claims 1 to 4, further comprising a frame over the thermoelectric transducer or between the thermoelectric transducer and a stub, which defines the height of the cavity.

6. The detector of claim 5 , wherein the frame is constructed from aluminum oxide.

7. A detector as claimed in any preceding claim, wherein the thermoelectric transducer is constructed in part from silicon.

8. A detector as claimed in any preceding claim, wherein the thermoelectric transducer is constructed in part from bismuth telluride.

9. A detector as claimed in any preceding claim, wherein the thermoelectric transducer is constructed in part from antimony telluride.

10. The detector according to any one of claims 1 to 9, wherein the light absorbing film is made of titanium nitride.

11. A detector as claimed in any one of claims 1 to 10, wherein the light absorbing film is made of titanium tungsten.

12. A detector as claimed in any one of claims 1 to 11, wherein the light absorbing film is made of titanium.

13. A detector as claimed in any one of claims 1 to 12, wherein the light absorbing film consists of aluminium doped zinc oxide.

14. The detector according to any one of claims 1 to 13, wherein the light absorbing film is made of aluminum.

15. The detector of claim 5 , wherein the stub comprises an electrical connection between the thermoelectric transducer and readout electronics configured to process signals from the detector.

16. The detector of claim 15 , wherein the stub is comprised of silicon oxide.

17. A detector according to any preceding claim, wherein the light absorbing film is a resistive impedance matched absorber or a plasmonic absorber.

18. 20. The detector of claim 17, wherein the light absorbing film is a resistive impedance matched absorber and the height of the cavity is one quarter of a wavelength the detector is configured to detect.

19. A detector according to any preceding claim, wherein the substrate comprises a silicon layer.

20. The detector of any one of claims 1 to 19, wherein the light absorbing film is patterned with a pattern that includes drilling a plurality of holes in the light absorbing film.

21. The detector of any one of claims 1 to 20, wherein the light absorbing film comprises two light absorbing layers and a thermoelectric transducer layer, the light absorbing layers being disposed on both sides of the thermoelectric transducer layer.

22. 22. The detector of claim 1, wherein the light absorbing film comprises only one light absorbing layer and a thermoelectric transducer layer, the light absorbing layer being disposed on only one side of the thermoelectric transducer layer.

23. obtaining a substrate wafer and depositing an oxide layer on the substrate wafer; depositing a thermoelectric transducer layer on the oxide layer; depositing a light absorbing layer on the oxide layer or on the thermoelectric transducer layer; etching a recess down to the oxide layer to form a cavity leaving a light absorbing film including the light absorbing layer and a portion of the thermoelectric transducer layer suspended above the cavity by the thermoelectric transducer layer; the light absorbing film is attached above the cavity by a thermoelectric transducer via a first leg and a second leg that do not include a non-thermoelectric material; the thermoelectric transducer layer having a first portion and a second portion; the light absorbing layer is perforated; the first leg and the first portion are formed from a first semiconductor layer, and the second leg and the second portion are formed from a second semiconductor layer; the light absorbing film forms a contact element between the n-type thermoelectric element and the p-type thermoelectric element of the thermoelectric transducer; A method for manufacturing a detector, comprising the steps of: the light absorbing film includes a section in which the n-type thermoelectric element and the p-type thermoelectric element are disposed on either side of the light absorbing layer over the entire length of the light absorbing layer; The n-type thermoelectric element and the p-type thermoelectric element are directly connected to each other to seal the light absorbing layer; The light absorbing film includes a section in which the n-type thermoelectric element and the p-type thermoelectric element overlap each other and are covered with the light absorbing layer; Only one of the following applies: A method for manufacturing a detector.

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