An infrared filter for an integrated heating device and its manufacturing method

Abstract

This invention discloses an infrared filter with an integrated heating device and its fabrication method. The infrared filter with the integrated heating device includes a substrate, and a filter layer and a heating layer disposed on the substrate. The filter layer is used to filter light irradiating the surface of a thermopile chip; the heating layer is used to heat the cold end of the thermopile chip. By integrating the heating device onto the substrate of the infrared filter, compared with the prior art method of integrating the heating device onto the thermopile chip, the infrared filter with the integrated heating device in this invention has a simple structure, low manufacturing cost, and reduces the overall cost of the sensor. In use, the infrared filter only needs to be installed above the thermopile chip and connected to the control circuit. While filtering the light irradiating the thermopile chip, it can also heat its cold end, allowing the cold end temperature of the thermopile chip to reach the ambient temperature in a short time.

Description

Technical Field

[0001] This invention belongs to the field of thermopile sensor technology, specifically relating to an infrared filter for an integrated heating device and its manufacturing method. Background Technology

[0002] Thermopile sensors, based on the Seebeck effect, convert the acquired infrared energy into a voltage signal, which is then converted into measurable physical parameters such as temperature and gas concentration via signal circuitry. Since a thermopile chip consists of a hot junction and a cold junction, the cold junction temperature is typically the ambient temperature, while the hot junction temperature is the measured value. When the ambient temperature changes, it is necessary to wait for the cold junction temperature to reach the same temperature as the ambient temperature before obtaining an accurate measured value. Considering the packaging and application environment, this waiting time is usually quite long, sometimes exceeding 30 minutes.

[0003] To shorten waiting time, existing products generally place a separate heating device on the outside of the sensor, which results in inaccurate temperature control of the sensor and increases the cost of sensor application; or the heating device is integrated on the thermopile chip, resulting in a complex chip structure, increased chip size, and higher cost. Summary of the Invention

[0004] The main objective of this invention is to provide an infrared filter with an integrated heating device to solve the problems of complex structure and high cost of existing thermopile chips with integrated heating devices.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] An infrared filter for an integrated heating device includes a substrate, and a filter layer and a heating layer disposed on the substrate; the filter layer is used to filter light irradiated onto the surface of a thermopile chip; the heating layer is used to heat the cold end of the thermopile chip.

[0007] In one possible implementation, the filter layer includes a first optical film and a second optical film, the first optical film being disposed on the upper surface of the substrate, the second optical film and a heating layer being disposed on the lower surface of the substrate, and the heating layer being annular and surrounding the second optical film.

[0008] In one possible implementation, the second optical thin film and the heating layer are embedded in the substrate.

[0009] In one possible implementation, the first optical film and the second optical film are the same, and are one of the following: antireflection film, long-wavelength pass film, short-wavelength pass film, bandpass film, and narrowband film.

[0010] In one possible implementation, the heating layer material is one of Pt, W, Mo, Ta, Nb, SiC, MoSi2, or doped polycrystalline silicon.

[0011] In one possible implementation, the surface of the heating layer is covered with a connection layer for connection with the thermopile chip.

[0012] In one possible implementation, the bonding layer material is one or two of Si, SiO2, Au, Sn, Ti, and W.

[0013] In one possible implementation, the temperature detection module is a contact temperature sensor or a non-contact temperature sensor.

[0014] Based on the same inventive concept, the present invention also provides a method for manufacturing an infrared filter for an integrated heating device, comprising the following steps:

[0015] Clean the substrate and then evaporate a filter layer on the upper surface of the substrate.

[0016] A first photoresist is spin-coated onto the lower surface of the substrate. After removing the first photoresist at the corresponding position of the heating layer using a photolithography process, a groove for the heating layer is etched on the lower surface of the substrate.

[0017] A heating layer is deposited on the surface of the first photoresist and in the groove of the heating layer;

[0018] Remove the first photoresist and the heating layer on the surface of the first photoresist;

[0019] A second photoresist is spin-coated onto the lower surface of the substrate. After removing the second photoresist at the corresponding position of the filter layer on the lower surface of the substrate using a photolithography process, a filter layer groove is etched on the lower surface of the substrate.

[0020] A filter layer is deposited on the surface of the second photoresist and in the groove of the filter layer.

[0021] Remove the second photoresist and the filter layer on the surface of the second photoresist.

[0022] In one possible implementation, after removing the second photoresist and the filter layer on the surface of the second photoresist, the method further includes depositing a bonding layer on the heating layer on the lower surface of the substrate.

[0023] Based on the same inventive concept, the present invention also provides a thermopile sensor that uses an infrared filter with the above-mentioned integrated heating device.

[0024] The beneficial effects of adopting the above technical solution are as follows: By integrating the heating device on the substrate of the infrared filter, compared with the prior art of integrating the heating device on the thermopile chip, the infrared filter structure of the present invention is simple and the manufacturing process cost is low. At the same time, when integrated with the thermopile chip, the heating device is located above the cold end of the thermopile and overlaps with the hot end circuit in the vertical direction, which reduces the sensor size and lowers the overall cost of the sensor. In use, the infrared filter only needs to be installed above the thermopile chip and connected to the control circuit. While filtering the light irradiating the thermopile chip, it can also heat its cold end, so that the cold end temperature of the thermopile chip can reach the ambient temperature in a short time. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 This is a schematic diagram of the structure of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention;

[0027] Figure 2 This is a cross-sectional view (excluding the connecting layer) of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention;

[0028] Figure 3 This is a cross-sectional view (including the connecting layer) of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention;

[0029] Figure 4 This is a cross-sectional view of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention;

[0030] Figure 5 This is a cross-sectional view of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention;

[0031] Figure 6 This is a cross-sectional view of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention;

[0032] Figure 7 This is a cross-sectional view of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention;

[0033] Figure 8 This is a schematic diagram of the infrared filter of the integrated heating device provided in Embodiment 1 of the present invention mounted on a thermopile chip;

[0034] Figure 9 This is a flowchart of the method for manufacturing the infrared filter of the integrated heating device provided in Embodiment 2 of the present invention;

[0035] Figure 10 This is a process flow diagram of the manufacturing process of the infrared filter of the integrated heating device provided in Embodiment 2 of the present invention.

[0036] in:

[0037] 1. Substrate; 11. Heating layer groove; 12. Filter layer groove; 2. Filter layer; 21. First optical thin film; 22. Second optical thin film; 3. Heating layer; 4. Connecting layer; 5. First photoresist; 6. Second photoresist; 7. Thermopile chip substrate; 71. Wire; 72. First solder ball; 73. Second solder ball; 74. Third solder ball; 75. Fourth solder ball; 8. Passivation layer. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] In the description of this invention, it should be clearly stated that the terms "vertical," "lateral," "longitudinal," "front," "rear," "left," "right," "up," "down," and "horizontal," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are merely for the convenience of describing this invention. They do not imply that the device or element referred to must have a specific orientation or position, and therefore should not be construed as a limitation of this invention. The term "quantity" should also not be construed as a limitation of this invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] It should be understood that each element of the apparatus or each step of the method can be described using apparatus terminology or method terminology. Such terms can be replaced where necessary to clarify the implicit broad scope of the invention. By way of example only, it should be understood that all steps of a method can be disclosed as actions, means of taking said actions, or elements causing said actions. Similarly, each element of the apparatus can be disclosed as a physical element or an action facilitated by said physical element. By way of example only, the disclosure of "connector" should be understood to cover the disclosure of the "connection" action, whether or not it is explicitly discussed—and conversely, if the "connection" action is disclosed, this disclosure should be understood to cover the disclosure of "connector" and even "means for connection." These alternative terms used for each element or step should be understood to be explicitly included in the specification.

[0042] Example 1

[0043] Embodiment 1 of the present invention provides an infrared filter for an integrated heating device, such as... Figure 1-3 As shown, it includes a substrate 1, a filter layer 2, and a heating layer 3; the filter layer 2 is disposed on the substrate 1 and is used to filter the light irradiated onto the surface of the thermopile chip; the heating layer 3 is also disposed on the substrate 1 and is used to heat the cold end of the thermopile chip.

[0044] By adopting the above technical solution, the present invention integrates the heating device on the substrate 1 of the infrared filter. Compared with the prior art of integrating the heating device on the thermopile chip, the infrared filter structure with integrated heating device in the present invention is simple, the manufacturing process cost is low, and the overall cost of the sensor is reduced. In use, the infrared filter only needs to be installed on the top of the thermopile chip and connected to the control circuit. While filtering the light irradiating the thermopile chip, it can also heat its cold end, so that the cold end temperature of the thermopile chip can reach the ambient temperature in a short time.

[0045] Furthermore, such as Figure 4 As shown, the filter layer 2 includes a first optical film 21 and a second optical film 22. The first optical film 21 is disposed on the upper surface of the substrate 1, and the second optical film 22 and the heating layer 3 are disposed on the lower surface of the substrate 1. The heating layer 3 is annular and surrounds the second optical film 22. In this invention, the heating layer 3 is disposed as close as possible to the edge of the substrate 1, and the second optical film 22 is disposed in the central region of the heating layer 3. This not only reduces the influence of the heating layer 3 on the light transmission of the infrared filter, but also ensures that the cold end of the thermopile chip is heated uniformly.

[0046] The substrate 1 is made of one of the following materials: Si, Ge, sapphire, and glass, preferably Si.

[0047] The heating layer 3 is made of one of the following materials: Pt, W, Mo, Ta, Nb, SiC, MoSi2, or doped polycrystalline silicon.

[0048] The first optical film 21 and the second optical film 22 are identical, and are one of the following: antireflection film, long-wavelength pass film, short-wavelength pass film, bandpass film, and narrowband film. For example, in the field of human body temperature measurement, a 5.5um to 14um bandpass optical film is used to select light.

[0049] In one possible implementation, both the second optical thin film 22 and the heating layer 3 are embedded in the substrate 1 to reduce the overall thickness of the infrared filter. The second optical thin film 22 may be flush with the lower surface of the substrate 1 (e.g., Figure 4 As shown), it can also be lower than the lower surface of the substrate 1 (e.g. Figure 5 (As shown).

[0050] Furthermore, such as Figure 3 As shown, the surface of the heating layer 3 is covered with a connecting layer 4 for connection with the thermopile chip. The material of the connecting layer 4 is one or two of Si, SiO2, Au, Sn, Ti, and W. When the material of the connecting layer 4 is the same as that of the substrate 1 (both are Si), it can also be regarded as part of the substrate 1.

[0051] If the surface of the thermopile chip already has a passivation layer 8, such as Figure 2 As shown, the connecting layer 4 on the infrared filter can then be removed.

[0052] Of course, the heating layer 3 can also float on the lower surface of the substrate 1. If a connecting layer 4 is provided, the connecting layer 4 wraps around the outside of the heating layer 3. In this case, the second optical thin film 22 can float on the lower surface of the substrate 1 and be located in the area enclosed by the heating layer 3 (e.g., Figure 6 (as shown); the second optical thin film 22 may also be lower than the lower surface of the substrate 1 (e.g., Figure 7 (As shown).

[0053] Example 2

[0054] Embodiment 2 of the present invention provides an infrared filter for an integrated heating device, such as... Figure 9-10 As shown, it includes the following steps:

[0055] S1. Clean substrate 1, and deposit a filter layer 2 on the upper surface of substrate 1 by vapor deposition;

[0056] S2. Spin-coat the first photoresist 5 on the lower surface of the substrate 1. After removing the first photoresist 5 at the corresponding position of the heating layer 3 using photolithography, etch the heating layer groove 11 on the lower surface of the substrate 1.

[0057] S3. Deposit heating layer 3 on the surface of the first photoresist 5 and in the heating layer groove 11;

[0058] S4. Remove the first photoresist 5 and the heating layer 3 on the surface of the first photoresist 5;

[0059] S5. Spin-coat the second photoresist 6 on the lower surface of the substrate 1. After removing the second photoresist 6 at the corresponding position of the filter layer 2 on the lower surface of the substrate 1 using photolithography, etch the filter layer groove 12 on the lower surface of the substrate 1.

[0060] S6. A filter layer 2 is deposited on the surface of the second photoresist 6 and in the filter layer groove 12.

[0061] S7. Remove the second photoresist 6 and the filter layer 2 on the surface of the second photoresist 6;

[0062] In steps S1 and S6, the filter layer 2 can be deposited using a vacuum evaporation process.

[0063] In step S3, a physical vapor deposition or chemical vapor deposition filter layer 2 can be used.

[0064] In steps S2 and S5, the heating layer groove 11 or the filter layer groove 12 can be etched using dry or wet etching processes.

[0065] In steps S4 and S7, the lift-off process can be used to remove the first photoresist 5 and the heating layer 3 on the surface of the first photoresist 5, or the filter layer 2 on the surface of the second photoresist 6 and the second photoresist 6.

[0066] In step S5, the corresponding positions of the filter layer 2 on the substrate 1 can be deeply etched, so that the filter layer 2 deposited in the groove of the filter layer 2 in step S6 is lower than the lower surface of the substrate 1, such as... Figure 5 , Figure 7 As shown.

[0067] The first photoresist 5 and the second photoresist 6 are the same.

[0068] Furthermore, the manufacturing method also includes: S8, depositing a connecting layer 4 on the heating layer 3 on the lower surface of the substrate 1.

[0069] Example 3

[0070] Embodiment 3 of the present invention provides a thermopile sensor that utilizes the infrared filter of the above-mentioned integrated heating device, such as... Figure 8As shown, the infrared filter of the integrated heating device in Embodiment 1 (where the second optical film 22 and the heating layer 3 are both embedded in the substrate 1, and the second optical film 22 is lower than the lower surface of the substrate 1) is mounted above the thermopile chip in the thermopile sensor. The substrate 1 of the infrared filter and the passivation layer 8 (preferably made of SiO2 material) on the top surface of the thermopile chip substrate 7 are connected by silicon-glass bonding. There is a gap (preferably a vacuum gap) between the second optical film 22 and the passivation layer 8 on the top surface of the thermopile chip substrate 7. The thermopile chip substrate 7 has a through hole inside, and a wire 71 is provided in the through hole. One end of the wire 71 is connected to the heating layer 3 of the infrared filter, and the other end is connected to the first solder ball 72 and the fourth solder ball 75 located on the bottom surface of the thermopile chip substrate 7. The control circuit controls the current and voltage of the heating layer 3 in the infrared filter through the first solder ball 72 and the fourth solder ball 75. The bottom surface of the thermopile chip substrate 7 is also provided with a second solder ball 73 and a third solder ball 74 for thermopile signal transmission.

[0071] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An infrared filter integrated with a heating device, characterized in that, The application relates to an integrated heating device for a thermoelectric sensor. The application comprises: a substrate; a filter layer arranged on the substrate for filtering light irradiated to the surface of a thermoelectric chip; the filter layer comprises: a first optical film arranged on the upper surface of the substrate; a second optical film arranged on the lower surface of the substrate together with a heating layer, wherein the heating layer is annular and arranged around the second optical film; 2. The integrated heating device's infrared filter according to claim 1, characterized in that, a heating layer arranged on the substrate for heating the cold end of the thermoelectric chip.

3. The integrated heating device's infrared filter according to claim 1, wherein, The second optical film and the heating layer are embedded in the substrate.

4. The integrated heating device's infrared filter according to claim 1, wherein, The first optical film and the second optical film are the same and one of an anti-reflection film, a long-wave pass film, a short-wave pass film, a band pass film and a narrow band film.

5. The integrated heating device's infrared filter according to any one of claims 1-4, characterized in that, The material of the heating layer is one of Pt, W, Mo, Ta, Nb, SiC, MoSi2 and doped polysilicon. The application further comprises:

6. The integrated heating device's infrared filter according to claim 5, characterized in that, a connecting layer arranged on the heating layer for connecting the thermoelectric chip.

7. A method of fabricating an integrated heating device infrared filter according to any one of claims 1 to 6, characterized in that, The material of the connecting layer is one or two of Si, SiO2, Au, Sn, Ti and W. The application comprises the following steps: cleaning the substrate and evaporating a filter layer on the upper surface of the substrate; spinning a first photoresist on the lower surface of the substrate, etching a heating layer groove on the lower surface of the substrate after removing the first photoresist corresponding to the position of the heating layer by using a photoetching process; depositing a heating layer on the surface of the first photoresist and in the heating layer groove; removing the first photoresist and the heating layer on the surface of the first photoresist; spinning a second photoresist on the lower surface of the substrate, etching a filter layer groove on the lower surface of the substrate after removing the second photoresist corresponding to the position of the filter layer on the lower surface of the substrate by using a photoetching process; evaporating a filter layer on the surface of the second photoresist and in the filter layer groove; 8. The method of claim 7, wherein the integrated heating device is an infrared filter. removing the second photoresist and the filter layer on the surface of the second photoresist.

9. A thermopile sensor, characterized by After removing the second photoresist and the filter layer on the surface of the second photoresist, the application further comprises depositing a connecting layer on the heating layer on the lower surface of the substrate. The thermoelectric sensor applies the integrated heating device of the infrared filter according to any one of claims 1-6.

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