Infrared thermopile sensor

Abstract

An infrared thermopile sensor includes a silicon cover with an infrared lens, an infrared sensing chip with dual thermopile sensing elements, and a microcontroller chip to calculate the temperature of an object, the elements using stacked 3D packaging to reduce volume. The infrared sensing chip and microcontroller chip can have metal layers to shield from thermal radiation. The non-contact infrared thermopile sensor of the invention can convert wrist temperature to body core temperature. Body core temperature is calculated from detected ambient temperature information, default or input water vapor pressure information, etc. There can be different conversion methods of wrist temperature to body core temperature at different temperature, gender, and relative humidity.

Description

Technical Field

[0001] This invention relates to a sensor, and more particularly to an infrared thermopile sensor. Background Technology

[0002] Wearable temperature sensors have proven effective in hospitals for the early detection of infections in patients, as infection is a major cause of morbidity and mortality in patients with kidney failure. Therefore, early identification and treatment of infections are used to reduce mortality, particularly in dialysis or immunosuppression during kidney transplantation and in the treatment of other immune-related diseases. Consequently, continuous monitoring of patients' body temperature can aid in the early detection and treatment of infections. Currently, in intensive care units, patients' body temperature is monitored by nurses every 2-4 hours; therefore, there is a need for continuous temperature monitoring.

[0003] Skin temperature monitoring is a convenient way to monitor body temperature over a long period of time. Wearable devices, such as watches, can measure wrist temperature using contact or non-contact sensors (e.g., thermopile sensors), and the readings can be transmitted to a control center via wireless communication (e.g., Bluetooth or Wi-Fi).

[0004] Traditional contact temperature sensors typically utilize silicon components, and their readings are proportional to the contact temperature. Due to thermal mass, contact temperature sensors have a relatively slow response time; for example, they must remain stable for 10 minutes to obtain a result. Furthermore, their accuracy can be affected by sweat, thermal resistance between the sensor and the package, and / or the tightness of the garment during wear.

[0005] Traditional non-contact temperature sensors detect infrared radiation from the human body, offering high accuracy and fast response times. However, their accuracy can vary due to changes in ambient temperature caused by the encapsulation radiation. Therefore, the use of non-contact temperature sensors requires compensation for the effects of ambient temperature variations caused by the encapsulation.

[0006] Furthermore, human skin temperature is not the same as core temperature. Wrist or skin temperature varies considerably from person to person and is related to ambient temperature, therefore it cannot be used directly to estimate body temperature. Generally speaking, skin temperature varies depending on ambient temperature, humidity, wind speed, core body temperature, clothing, gender, and metabolic rate, among other factors.

[0007] For wearable devices, wrist temperature monitoring is comfortable for users and suitable for long-term wear. Therefore, to solve the above problems, this invention considers an infrared thermopile sensor that can be used in wearable devices such as watches, and can provide core body temperature for personal health management. Summary of the Invention

[0008] The purpose of this invention is to provide an infrared thermopile sensor that can be used in wearable devices to accurately measure the body's core temperature.

[0009] To achieve the above objectives, this invention primarily discloses an infrared thermopile sensor, comprising an infrared sensing chip, a silicon cap, a microcontroller chip, a packaging substrate, and a sealing body. The infrared sensing chip includes a first substrate, a first thermopile sensing element, a second thermopile sensing element, and a front-end signal processing unit. The first substrate includes a wire bonding pad and two thin-film structures formed by front-side wet etching. The first thermopile sensing element is disposed on one of the thin-film structures and generates a temperature signal of a analyte. The second thermopile sensing element is disposed on the other thin-film structure, adjacent to the first thermopile sensing element, and generates a compensated temperature signal. The front-end signal processing unit is disposed on the first substrate and electrically connected to the first and second thermopile sensing elements, and includes an ambient temperature sensing element and a non-volatile memory. The ambient temperature sensing element generates ambient temperature information. The non-volatile memory stores the ambient temperature information. A silicon cap is connected to an infrared sensing chip via wafer-level bonding and includes an infrared Fresnel lens that focuses thermal radiation from the object under test onto a first thermopile sensing element. The size of the silicon cap is smaller than that of the infrared sensing chip, and wire bonding pads are exposed outside the silicon cap. A microcontroller chip is connected to the infrared sensing chip and receives temperature signals, compensated temperature signals, and ambient temperature information. Based on air temperature and water vapor pressure information, it calculates temperature correction information related to a default temperature and calculates the temperature of the object under test based on the temperature signals, compensated temperature signals, and temperature correction information. The microcontroller chip includes a second substrate, a first metal layer, and multiple through-silicon vias (TSVs). The first metal layer is disposed on an upper surface of the second substrate and includes a low-emissivity metallic material to reduce thermal interference from the microcontroller chip to the infrared sensing chip. The TSVs are disposed within the second substrate. The package substrate carries the microcontroller chip and receives input / output signals from the microcontroller chip through the TSVs. The packaging substrate includes multiple contacts disposed on a lower surface of the packaging substrate, and the through-silicon vias of the microcontroller chip are electrically connected to the contacts. A sealing body encapsulates the packaging substrate, the microcontroller chip, the infrared sensor chip, and a silicon cap, exposing an upper surface of the silicon cap.

[0010] In some embodiments of the present invention, the microcontroller chip subtracts a compensation temperature signal from the temperature signal and calculates the temperature of the object to be measured based on the ambient temperature information.

[0011] In some embodiments of the present invention, the microcontroller chip multiplies the compensated temperature signal by a first coefficient and then subtracts it from the temperature signal, and then calculates the temperature of the object to be measured based on the ambient temperature information.

[0012] In some embodiments of the present invention, the infrared sensing chip and the microcontroller chip are bonded together via a die-attach film.

[0013] In some embodiments of the present invention, the first substrate of the infrared sensing chip includes a second metal layer disposed on a lower surface of the first substrate.

[0014] In some embodiments of the present invention, the front-end signal processing unit further includes a signal selection multiplexer and a communication interface electrically connected to the ambient temperature sensing element and the non-volatile memory, respectively.

[0015] In some embodiments of the present invention, the ambient temperature sensing element includes at least one thermal sensing diode.

[0016] In some embodiments of the present invention, the silicon cap includes a first cavity and a second cavity corresponding to the first thermopile sensing element and the second thermopile sensing element, respectively, and the silicon cap and the infrared sensing chip are connected in a wafer-level bonding manner by a co-metal bonding or a solder bonding.

[0017] When the silicon cap is connected to the infrared sensing chip, the first cavity and the second cavity are respectively sealed with a vacuum encapsulation method to the first thermopile sensing element and the second thermopile sensing element.

[0018] The depth of the first cavity is greater than or equal to about 40 micrometers and less than or equal to about 100 micrometers.

[0019] The silicon cap includes a fourth metal layer disposed on the upper surface of the silicon cap and corresponding to the second thermopile sensing element.

[0020] In some embodiments of the present invention, the metal material of the first metal layer includes aluminum.

[0021] In some embodiments of the present invention, the infrared sensing chip is a silicon-on-insulator (SOI) chip, and the package height of the infrared thermopile sensor is less than 1 cm.

[0022] In some embodiments of the present invention, the depth of the oxide insulating layer of the SOI chip is greater than 2 micrometers.

[0023] In some embodiments of the present invention, the ambient temperature information generated by the ambient temperature sensing element is offset from the air temperature of an external environment, and the microcontroller chip calculates the air temperature based on the ambient temperature information and the offset.

[0024] In some embodiments of the present invention, the microcontroller chip calculates a second temperature of the test object based on a first temperature of the test object.

[0025] In some embodiments of the present invention, the microcontroller chip converts the first temperature into the second temperature of the object to be measured according to a conversion curve.

[0026] In some embodiments of the present invention, the microcontroller chip converts the first temperature to a second temperature using different conversion curves based on different standard deviations of the first temperature relative to the air temperature.

[0027] In some embodiments of the present invention, the temperature of the object to be measured is a wrist temperature.

[0028] In some embodiments of the present invention, the microcontroller chip further calculates based on air temperature, water vapor pressure information and gender information to obtain temperature correction information related to the default temperature.

[0029] In summary, the infrared thermopile sensor of the present invention employs a stacked 3D package to reduce its size (e.g., approximately 2x2x1.0 mm). 3 The invention includes a silicon cap with a lens for limiting the receiving angle to less than 30 degrees (preferably less than 45 degrees), an infrared sensing chip with dual thermopile sensing elements, and a microcontroller chip for calculating the temperature of the object under test. The invention employs dual thermopile sensing elements, one of which acts as an active unit to measure the temperature of the object under test, while the other acts as a compensation unit (dumb unit) to compensate for the effects of the packaging structure. Therefore, the invention can accurately measure temperature even under drastically changing ambient temperatures.

[0030] Furthermore, the non-contact infrared thermopile sensor of the present invention can be used in wearable devices such as watches, and can be operated over a wide range of ambient temperatures to convert wrist temperature to core body temperature. By using the detected air temperature, the human wrist temperature sensed by the infrared thermopile sensor, default or input water vapor pressure information, and the gender information set on the watch, a compensated wrist temperature can be calculated and used to perform a non-linear conversion from wrist temperature to core body temperature.

[0031] Furthermore, the standard deviation of wrist temperature may differ from that of the default temperature (e.g., 25°C), therefore, standard deviation correction factors can also be incorporated into the standardized wrist temperature to core body temperature conversion curve. In other words, different air temperatures can result in different wrist temperature to core body temperature conversion curves.

[0032] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention. Attached Figure Description

[0033] Details of one or more embodiments of the subject matter described herein are set forth in the following drawings and description. Other features, aspects, and advantages of the subject matter of this specification will become apparent from the description, drawings, and claims, wherein:

[0034] Figure 1 This is a schematic diagram of an infrared thermopile sensor according to the present invention.

[0035] Figure 2 This is an exploded view of the infrared thermopile sensor of the present invention.

[0036] Figure 3A For along Figure 1 A cross-sectional view of line AA.

[0037] Figure 3B For along Figure 1 A cross-sectional view of the BB line.

[0038] Figure 4 This is a block diagram of the front-end signal processing unit of the infrared thermopile sensor of the present invention.

[0039] Figure 5 This is a graph showing the distribution of core body temperature and wrist temperature at room temperature.

[0040] Figure 6 A graph showing the nonlinear mapping of wrist temperature to core body temperature.

[0041] Figure 7 This is a distribution chart of wrist temperature correction values ​​for different genders at different air temperatures.

[0042] Figure 8A This is a schematic diagram of an embodiment of the present invention after bonding the silicon cap to the infrared sensing chip wafer. Figure 8B This is a schematic diagram of the silicon cap after cutting.

[0043] Figure 9A This is a schematic diagram of another embodiment of the present invention after bonding the silicon cap to the infrared sensing chip wafer. Figure 9B This is a schematic diagram of the silicon cap after cutting.

[0044] In the attached figures, the following labels are used:

[0045] 200 Infrared Thermopile Sensor

[0046] 300 Infrared Sensing Chip

[0047] 301 side

[0048] 310 First substrate

[0049] 311 Punch-in Pad

[0050] 312, 313 Thin Film Structures

[0051] 314, 315 concave part

[0052] 320 First thermopile sensing element

[0053] 320a Temperature Signal

[0054] 330 Second thermopile sensing element

[0055] 330a Compensated Temperature Signal

[0056] 340 Front-end signal processing unit

[0057] 341 Ambient temperature sensing element

[0058] 342 Non-volatile memory

[0059] 343 Low-noise, low-damping amplifier

[0060] 344, 345 signal selection multiplexer

[0061] 344a output signal

[0062] 344b digital signal

[0063] 346 Analog-to-Digital Converter

[0064] 347 Buffer

[0065] 348 Communication Interface

[0066] 350 Second metal layer

[0067] 400 Silicone Cap

[0068] 401 First cavity

[0069] 402 Second cavity

[0070] 403 metal bumps

[0071] 404 side

[0072] 405 upper surface

[0073] 410 Infrared Fresnel Lens

[0074] 420 photoresist

[0075] 430 adhesive

[0076] 440 Anti-reflective coating

[0077] 450 Third metal layer

[0078] 460 Fourth metal layer

[0079] 500 microcontroller chip

[0080] 510 Second substrate

[0081] 520 First Metal Layer

[0082] 530 Crystal Adhesion Thin Film

[0083] 540 Punch-in Pad

[0084] 550 Silicon Through-Hole

[0085] 600 package substrate

[0086] 610 Through Silicon Via (Through Silicon Via Pad)

[0087] 620 contacts

[0088] 630 solder paste

[0089] 700 sealing body

[0090] 900 Test Items

[0091] 910 thermal radiation

[0092] D1 Distance

[0093] D2 Depth

[0094] Test Self-Test Signals Detailed Implementation

[0095] As used herein, terms such as "first," "second," "third," and "fourth" describe various elements, components, regions, layers, and / or parts, which should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another. Unless the context clearly indicates otherwise, the use of terms such as "first," "second," "third," and "fourth" herein does not imply any order or sequence.

[0096] Figure 1 This is a schematic diagram of an infrared thermopile sensor according to the present invention. Figure 2 This is an exploded view of the infrared thermopile sensor of the present invention. Figure 3A For along Figure 1 A cross-sectional view of line AA. Figure 3B For along Figure 1 A cross-sectional view of the BB line.

[0097] It should be noted that the infrared thermopile sensor 200 of the present invention can be used in wearable devices (e.g., watches). The infrared thermopile sensor 200 of the present invention may have a silicon cap. The microstructure of the silicon cap can reduce the thermal effect of the encapsulation structure, and the silicon cap has a high thermal conductivity (e.g., about 148 W / m / K), thus it has high thermal conductivity and temperature uniformity, which can reduce the difference in thermal radiation received by the dual thermopile sensing elements from the encapsulation structure.

[0098] Please refer to Figure 1 , Figure 2 , Figure 3A and Figure 3B As shown, the infrared thermopile sensor 200 of the present invention includes an infrared sensing chip 300, a silicon cap 400, a microcontroller chip 500, a packaging substrate 600, and a sealing body 700.

[0099] In some embodiments, the infrared sensing chip 300 may include a first substrate 310, a first thermopile sensing element 320, a second thermopile sensing element 330, and a front-end signal processing unit 340. In some embodiments, the first substrate 310 includes a wire bonding pad 311 and two thin film structures (or floating plate structures) 312 and 313 formed by front-side wet etching. The wire bonding pad 311 is correspondingly disposed with respect to the thin film structures 312 and 313. In some embodiments, the wire bonding pad 311 is disposed on the side edge of the first substrate 310 for wire bonding with the microcontroller chip 500, while the thin film structures 312 and 313 are disposed away from the wire bonding pad 311 and corresponding to the silicon cap 400.

[0100] In some embodiments, the first substrate 310 further has two recesses 314 and 315 corresponding to thin film structures 312 and 313, respectively. That is, thin film structure 312 is located on the recess 314, and thin film structure 313 is located on the recess 315.

[0101] In some embodiments, a first thermopile sensing element 320 is disposed on the thin film structure 312 and corresponds to the recess 314. The hot end of the first thermopile sensing element 320 is located on the thin film structure 312, while the cold end is located at the periphery of the recess 314. The first thermopile sensing element 320 senses the temperature of the object 900 and generates a temperature signal. In this invention, the temperature of the object 900 is, for example, the temperature of a wrist, and the wrist temperature is converted to obtain the core temperature of the human body.

[0102] In some embodiments, a second thermopile sensing element 330 is disposed on the thin film structure 313 corresponding to the recess 315 and adjacent to the first thermopile sensing element 320. The hot end of the second thermopile sensing element 330 is located on the thin film structure 313, while the cold end is located at the periphery of the recess 315. The window portion of the second thermopile sensing element 330 is shielded, allowing it to sense only the thermal radiation from the silicon cap 400 to generate a compensation temperature signal.

[0103] In some embodiments, the front-end signal processing unit 340 is disposed on the first substrate 310 and electrically connected to the first thermopile sensing element 320 and the second thermopile sensing element 330.

[0104] Figure 4 This is a block diagram of the front-end signal processing unit of the infrared thermopile sensor of the present invention. Figure 4 As shown, in some embodiments, the front-end signal processing unit 340 may include at least an ambient temperature sensing element 341 and a non-volatile memory 342. During calibration, the ambient temperature sensing element 341 can generate ambient temperature information. The ambient temperature information is converted into a digital signal by an analog-to-digital converter 346, and then sent to the microcontroller chip 500 through the communication interface 348. After the microcontroller chip 500 calculates and corrects the parameters, the signal is stored in the non-volatile memory 342 through the communication interface 348.

[0105] In some embodiments, the ambient temperature sensing element 341 includes at least one thermal sensing diode, such as, but not limited to, a Schottky diode. In some embodiments, the ambient temperature sensing element 341 may be composed of, for example, multiple Schottky diodes connected in series.

[0106] In some embodiments, the front-end signal processing unit 340 may further include a low-noise low-compensation amplifier 343, multiple signal selection multiplexers 344 and 345, an analog-to-digital converter 346, a buffer 347, and a communication interface 348, wherein the components are electrically connected to the ambient temperature sensing element 341 and the non-volatile memory 342, respectively.

[0107] In some embodiments, the signal selection multiplexer 344 selects based on the temperature signal 320a of the first thermopile sensing element 320, the compensated temperature signal 330a of the second thermopile sensing element 330, and the self-test signal Test, and generates an output signal 344a to the low-noise low-compensation amplifier 343. The low-noise low-compensation amplifier 343 amplifies the output signal 344a and outputs it to the signal selection multiplexer 345.

[0108] The signal selection multiplexer 345 can select either the ambient temperature information from the ambient temperature sensing element 341 or the amplified output signal 344a, and output it to the analog-to-digital converter 346 for analog-to-digital conversion. In some embodiments, the analog-to-digital converter 346 is, for example, a Sigma-Delta converter. The converted digital signal 344b is then output to the buffer 347 and can be output to the microcontroller chip 500 via the communication interface 348.

[0109] It is worth mentioning that when the infrared sensing chip 300 is subjected to spot measurement, the ambient temperature sensing element 341 can be calibrated simultaneously. The measured ambient temperature parameters can be stored in the non-volatile memory 342 via the buffer 347 and the communication interface 348. When the microcontroller chip 500 is started, it can read the ambient temperature parameters of the ambient temperature sensing element 341 stored in the non-volatile memory 342 via the buffer 347 and the communication interface 348. The microcontroller chip 500 can calculate and obtain the ambient temperature information based on the ambient temperature parameters. Therefore, the microcontroller chip 500 can perform calculations based on the air temperature and a water vapor pressure to obtain temperature correction information at a default temperature, and calculate the temperature of the object under test 900 based on the digital signal 344b and the temperature correction information. The specific calculation method of the microcontroller chip 500 is explained below.

[0110] Figure 5 This is a graph showing the distribution of core body temperature and wrist temperature at room temperature (e.g., 25°C). Figure 6 A graph showing the nonlinear mapping of wrist temperature to core body temperature. Figure 7 This is a distribution chart of wrist temperature correction values ​​for different genders at different air temperatures.

[0111] In order to obtain the body's core temperature (i.e., the second temperature) based on wrist temperature (i.e., the first temperature), certain calculations must be performed to overcome the effects of differences in air temperature, humidity, and skin temperature. Figure 5 The figure shows the average result of 1000 data points at room temperature (e.g., 25°C). The average wrist temperature is, for example, 33.7°C, and the standard deviation is, for example, 1.18°C. Specifically, the average wrist temperature is lower than the average core body temperature, and the standard deviation of wrist temperature is greater than that of core body temperature. Therefore, core body temperature cannot be directly estimated by translating wrist temperature.

[0112] Figure 6 The curve showing the nonlinear mapping of wrist temperature to core body temperature at room temperature (e.g., 25°C) can be approximated, for example, by a sixth-order polynomial function as shown in Equation (1).

[0113] T core=a1×Tw 6 +a2×Tw 5 +a3×Tw 4 +a4×Tw 3 +a5×Tw 2 +a6×Tw+a7 (1)

[0114] T core The body's core temperature is represented by Tw, which is the standardized wrist temperature at 25°C. a1 to a7 are coefficients derived from experimental data. 25°C can be considered a default temperature and is not intended to limit the invention.

[0115] As mentioned above, the wrist temperature of the same object being measured (i.e., the user) is not a fixed value under different environmental conditions (e.g., air temperature, humidity, clothing, etc.). Specifically, wrist (or skin) temperature is related to certain factors, such as air temperature, water vapor pressure, metabolic rate, wind speed, core body temperature, gender, and the amount of clothing worn. On the other hand, wearable devices cannot obtain all information. Therefore, in some embodiments, three main parameters, such as air temperature, water vapor pressure, and gender, can be considered as correction factors for wrist temperature, for example, using Equation (2) to correct wrist temperatures at different air temperatures to the wrist temperature at 25°C (i.e., the default temperature).

[0116] T wrist_adj =b1×Ta 2 +b2×Ta+c1×Wp 2 +c2×Wp+c3 (2)

[0117] T wrist_adj This is the correction value for wrist temperature adjusted to 25°C at air temperature (i.e., temperature correction information). Ta is the air temperature in °C. Wp is the water vapor pressure. b1, b2, c1, c2, and c3 are coefficients derived from experimental data.

[0118] It is worth noting that the ambient temperature information may deviate from the actual air temperature in the external environment. In other words, the ambient temperature information refers to the temperature around the sensing components in the wearable device, and therefore is not the exact air temperature of the external environment. This deviation can be measured experimentally and will vary with air temperature. The microcontroller chip 500 can use equation (3) based on the ambient temperature information T ambient and the measured offset T offset Calculate the ambient air temperature Ta. offset It can have a functional relationship with Ta or be a fixed constant.

[0119] Ta = T ambient +T offset (3)

[0120] In some embodiments, gender information may also need to be considered, that is, T wrist_adj It may be related to gender. In addition, the water vapor pressure can be obtained from the saturated water vapor pressure and relative humidity at air temperature Ta, and used in Equation (2). In some embodiments, the preset water vapor pressure can be estimated using the relative humidity of 60-70% (preferably 64%) at the air temperature.

[0121] The correlation between saturated water vapor pressure and room temperature in the range of 5°C to 45°C is shown in equation (4).

[0122] W ps = -3 × 10 -5 ×Ta 3 +0.0041×Ta 2 -0.0319×Ta+0.6482 (4)

[0123] W ps This is the saturated water vapor pressure, expressed in kPa.

[0124] Under a constant relative humidity, T in equation (2) wrist_adj It can be simplified as shown in equation (5).

[0125] T wrist _adj=b4×Ta 2 +b5×Ta+b6 (5)

[0126] b4, b5, and b6 are coefficients under a fixed relative humidity (e.g., 64% relative humidity).

[0127] Furthermore, as mentioned above, T wrist_adj It can also be related to gender. Figure 7 This displays the gender-corrected values ​​for wrist temperature at different air temperatures (Ta) and a relative humidity of 64%. Specifically, T... wrist_adj The correction value for the corresponding gender can be approximated as shown in equation (6).

[0128] T wrist_adj_sex_gender =d1×Ta 2 +d2×Ta+d3 (6)

[0129] T wrist_adj_sex_genderThe correction values ​​are for the corresponding gender (i.e., the temperature correction information after gender correction). d1 to d3 are coefficients for the correction values ​​of wrist temperatures corresponding to different genders. Water vapor pressure is already included in the correction values ​​due to the humidity assumption of 64% (as in Equation (5)). In some embodiments, if the gender is unknown, the average value can be used to obtain the coefficients d1 to d3. In some embodiments, gender information can be obtained from the settings of the wearable device (e.g., a watch) and can be transmitted to the infrared thermopile sensor 200 (e.g., ...). Figure 2 (as shown) and stored in non-volatile memory 342 (such as Figure 4 (As shown).

[0130] Furthermore, the standard deviation of wrist temperature may differ from that of the default temperature (e.g., 25°C), therefore, standard deviation correction factors can also be incorporated into the standardized wrist temperature to core body temperature conversion curve. In other words, different air temperatures can result in different wrist temperature to core body temperature conversion curves.

[0131] Based on the above, please refer to Figure 2 , Figures 4 to 7 As shown, the steps by which the microcontroller chip 500 calculates the core body temperature from the wrist temperature are as follows: Step 1, the ambient temperature sensing element 341 measures the ambient temperature information. The ambient temperature information may deviate from the external air temperature; this deviation can be measured experimentally and will change with the air temperature. The microcontroller chip 500 calculates the external air temperature Ta based on the ambient temperature information and the measured deviation.

[0132] Step 2: Calculate the corrected value T of wrist temperature using equation (6) based on a fixed (or known) relative humidity and a known gender. wrist_adj_sex_gender Step 3: Obtain the standardized wrist temperature at 25°C according to equation (7).

[0133] Tw = T wrist_measure +T wrist_adj_sex_gender (7)

[0134] Tw represents the standardized wrist temperature at 25°C. wrist_measure The wrist temperature is sensed by the infrared sensor chip (i.e., the digital signal 344b obtained by digitizing the temperature signal and the compensated temperature signal). It should be noted that, if gender information is not considered, the correction value T can be obtained according to equation (5). wrist_adj To obtain the standardized wrist temperature Tw at 25°C.

[0135] Step 4: Use the standardized wrist temperature Tw to obtain the body core temperature according to equation (1). In other words, the microcontroller chip 500 can convert the first temperature (i.e., wrist temperature) into the second temperature (i.e., body core temperature) of the object to be measured (i.e., the user) according to a conversion curve.

[0136] It is worth mentioning that, in some embodiments, if the standard deviation of wrist temperature is different from that of 25°C, a standard deviation correction element can be introduced into the conversion method from wrist temperature to core body temperature. That is, there can be different conversion methods from wrist temperature to core body temperature at different room temperatures.

[0137] Please refer to this again. Figure 1 , Figure 2 , Figure 3A and Figure 3B As shown, the silicon cap 400 is connected to the infrared sensing chip 300 via wafer bonding. The silicon cap 400 includes an infrared Fresnel lens 410, which focuses the thermal radiation 910 of the object under test 900 onto the first thermopile sensing element 320. One dimension of the silicon cap 400 is smaller than that of the infrared sensing chip 300, and the wire bonding pads 311 of the infrared sensing chip 300 are exposed outside the silicon cap 400. In some embodiments, the infrared Fresnel lens 410 of the silicon cap 400 can be fabricated using semiconductor processes. It is worth noting that the diameter of the first thermopile sensing element 320 is approximately 400 micrometers (μm), while the focal length of the lens is approximately 200 micrometers, which is difficult to achieve with conventional convex lenses. Therefore, this invention achieves the above requirements by using a semiconductor process to fabricate the infrared Fresnel lens 410.

[0138] Figure 8A This is a schematic diagram of an embodiment of the present invention after bonding the silicon cap to the infrared sensing chip wafer. Figure 8B This is a schematic diagram showing the silicon cap after cutting. Figure 8A As shown, in some embodiments, the silicon cap 400 and the infrared sensing chip 300 can be connected at the wafer level using a photoresist 420 and an adhesive 430. The thickness of the photoresist 420 can be, for example, greater than or equal to about 40 micrometers and less than or equal to about 100 micrometers. In other words, the silicon cap 400 can, for example, use the photoresist 420 (e.g., SU-8 photoresist) to raise its distance D1 from the infrared sensing chip 300 to at least 40 micrometers. In some embodiments, the distance D1 between the silicon cap 400 and the infrared sensing chip 300 can be 100 micrometers. This reduces the impact of gas thermal conductivity within the silicon cap 400 on the sensing of the first thermopile sensing element 320.

[0139] In some embodiments, the silicon cap 400 may further include an anti-reflection coating 440, a third metal layer 450, and a fourth metal layer 460. The anti-reflection coating 440 is disposed on the infrared Fresnel lens 410 to improve the focusing effect of the infrared Fresnel lens 410. The third metal layer 450 is disposed on the lower surface of the silicon cap 400 and corresponds to the second thermopile sensing element 330 to block the thermal radiation of the object under test from entering the second thermopile sensing element 330. The fourth metal layer 460 is disposed on the upper surface of the silicon cap 400 and corresponds to the second thermopile sensing element 330, with a notch allowing external thermal radiation to enter the light-receiving position of the first thermopile sensing element 320. In some embodiments, the fourth metal layer 460 may not be disposed on the upper surface of the silicon cap 400. Figure 8B As shown, after the silicon cap 400 is cut, the third metal layer 450 disposed on the lower surface of the silicon cap 400 can prevent oblique light from entering the second thermopile sensing element (dumb unit) 330 through the infrared Fresnel lens 410.

[0140] Figure 9A This is a schematic diagram of another embodiment of the present invention after bonding the silicon cap to the infrared sensing chip wafer. Figure 9B This is a schematic diagram showing the silicon cap after cutting. Figure 9A As shown, in some embodiments, the silicon cap 400 may also include a first cavity 401 and a second cavity 402 (see reference). Figure 3B (As shown) These correspond to the first thermopile sensing element 320 and the second thermopile sensing element 330, respectively. The silicon cap 400 and the infrared sensing chip 300 are connected by a co-metal bond or a solder bond in a wafer-level bonding manner.

[0141] In some embodiments, a first cavity 401 and a second cavity 402 can be formed on the silicon cap 400 in regions corresponding to the first thermopile sensing element 320 and the second thermopile sensing element 330 using Silicon Deep Reactive Ion Etching (Silicon Deep RIE). The depth D2 of the first cavity 401 and the second cavity 402 can be greater than or equal to about 40 micrometers and less than or equal to about 100 micrometers. In some embodiments, the depth D2 of the first cavity 401 and the second cavity 402 can be 100 micrometers, but this is not limiting. It is worth mentioning that when the silicon cap 400 is wafer-level bonded to the infrared sensing chip 300, the first cavity 401 and the second cavity 402 can be sealed with a vacuum encapsulation method to the first thermopile sensing element 320 and the second thermopile sensing element 330, respectively, to improve the zero sensitivity of the sensing components. Furthermore, the silicon cap 400 can be connected to the infrared sensing chip 300 via metal bumps (solder pads) 403 using eutectic bonding or solder bonding. For example... Figure 9BAs shown, after the silicon cap 400 is cut, the fourth metal layer 460 disposed on the upper surface of the silicon cap 400 can prevent oblique light from entering the second thermopile sensing element (dumb unit) 330 through the infrared Fresnel lens 410. Additionally, a third metal layer 450 can also be disposed on the lower surface of the silicon cap 400 to shield the light-receiving position of the second thermopile sensing element 330 from external thermal radiation. Similarly, the lower surface of the silicon cap 400 may not have a third metal layer 450.

[0142] When the silicon cap 400 in the embodiment adopts a cavity structure and is vacuum wafer-level bonded to the infrared sensing chip 300, the infrared sensing chip 300 can be an SOI (Silicon Oxide Insulator) chip, and the depth (formation depth) of its oxide insulating layer is greater than 2 micrometers, preferably 10 micrometers, which can be used to reduce the thickness of the infrared sensing chip 300, and thus reduce the overall height of the infrared sensor 200 to less than 1 centimeter (mm).

[0143] Specifically, when the silicon cap 400 is too close to the thin film structures 312 and 313 on which the first thermopile sensing element 320 and the second thermopile sensing element 330 are disposed, gas thermal conduction will cause heat loss of the sensing components, thereby reducing the thermal sensing sensitivity. Therefore, the silicon cap 400 can be provided with a first cavity 401 and a second cavity 402 to increase the distance between the silicon cap 400 and the thin film structures 312 and 313. On the other hand, as Figure 8A and Figure 8B As shown, if the distance between the silicon cap 400 and the thin film structures 312 and 313 is increased by using photoresist 420, the cavity may not be provided on the silicon cap 400.

[0144] Please refer to this again. Figure 1 , Figure 2 , Figure 3A and Figure 3B As shown, in some embodiments, the length of the side 404 of the silicon cap 400 is approximately 200 to 400 micrometers smaller than the length of the side 301 of the infrared sensing chip 300. This allows the wire bonding pad 311 of the infrared sensing chip 300 to be exposed after the silicon cap 400 and the infrared sensing chip 300 are cut together.

[0145] In some embodiments, the microcontroller chip 500 is connected to the infrared sensing chip 300 and receives temperature signals and compensation temperature signals (i.e., digital signals 344b) digitized by the front-end signal processing unit 340. Based on ambient temperature information, water vapor pressure information, and gender information, it calculates temperature correction information at a default temperature and calculates the temperature of the object under test 900 based on the digital signal 344b and the temperature correction information. In some embodiments, the microcontroller chip 500 includes a second substrate 510 and a first metal layer 520. The infrared sensing chip 300 and the microcontroller chip 500 can be fixed together via a die-attach film (DAF) 530.

[0146] Because the microcontroller chip 500 operates at a high temperature, the thermal radiation generated on its surface can be received by the sensing components on the infrared sensing chip 300, affecting the accuracy of temperature measurement. Therefore, a first metal layer 520 can be disposed on the upper surface of the second substrate 510 and comprise a low-emissivity metal material to reduce the thermal interference of the microcontroller chip 500 on the infrared sensing chip 300. In some embodiments, the first metal layer 520 can be directly set as the uppermost metal layer of the microcontroller chip 500. The metal material of the first metal layer may include aluminum.

[0147] It should be noted that in some other embodiments, the first substrate 310 of the infrared sensing chip 300 may also include a second metal layer 350 disposed on the lower surface of the first substrate 310. That is, the metal layers 520 and 350 that isolate heat radiation can be disposed simultaneously on the upper surface of the microcontroller chip 500 and the lower surface of the infrared sensing chip 300, and the two are separated by a non-thermally conductive die-attach film 530, thereby increasing the heat shielding effect. Specifically, if the first metal layer 520 and the second metal layer 350 are used simultaneously, the low emissivity of the first metal layer 520 can reduce the impact of heat radiation from the microcontroller chip 500, the die-attach film 530 is a non-thermally conductive layer and can increase the thermal resistance from the microcontroller chip 500 to the infrared sensing chip 300, and the second metal layer 350 at the bottom of the infrared sensing chip 300 can further block the secondary heat radiation from the first metal layer 520 on top of the microcontroller chip 500.

[0148] In some embodiments, a wire bonding pad 540 may be provided on one side of the microcontroller chip 500 for wire bonding connection with the infrared sensing chip 300, while the other three sides of the microcontroller chip 500 may be electrically connected to the packaging substrate 600 by through silicon vias 550 (TSVs) disposed in the second substrate 510.

[0149] In some embodiments, the package substrate 600 carries the microcontroller chip 500 and receives input / output signals from the microcontroller chip 500 via through-silicon vias 550. The package substrate 600 may include a plurality of through-silicon vias 610. Figure 2 The diagram shows a through-silicon via (TSV) pad and a plurality of contacts 620 disposed on the lower surface of the package substrate 600. The TSV 550 of the microcontroller chip 500 is electrically connected to the TSV 610 and contacts 620 of the package substrate 600. In some embodiments, the package substrate 600 and the microcontroller chip 500 can be connected by solder paste 630. This allows the package substrate 600 to transmit signals from the microcontroller chip 500 to the plurality of contacts 620 on the lower surface via the TSV 610. The contacts 620 can then be formed as pins for surface mount assembly (SMA) components.

[0150] In some embodiments, the seal 700 covers the package substrate 600, the microcontroller chip 500, the infrared sensing chip 300, and the silicon cap 400, and exposes an upper surface 405 of the silicon cap 400.

[0151] Please refer to Figure 3A and Figure 3B As shown, the first thermopile sensing element 320 is an active unit that receives the thermal radiation 910 of the object under test 900 through the infrared Fresnel lens 410 on the silicon cap 400. The second thermopile sensing element 330 is a compensation unit (dumb unit) that is shielded by the fourth metal layer 460 of the silicon cap 400, and therefore can only receive the thermal radiation within the second cavity 402 of the silicon cap 400. Since the structures of the first thermopile sensing element 320 and the second thermopile sensing element 330 are symmetrical, and the silicon cap 400 has good thermal conductivity, the second thermopile sensing element 330 can be used to compensate for the thermal radiation effect of the silicon cap 400 to make the temperature measurement more accurate.

[0152] In some embodiments, the second thermopile sensing element 330 is connected in series with the first thermopile sensing element 320 in reverse order. This allows the temperature signal of the first thermopile sensing element 320 to be directly subtracted from the compensated temperature signal of the second thermopile sensing element 330, and the temperature of the object to be measured 900 can be calculated using the ambient temperature information.

[0153] In other embodiments, when there is a difference in sensitivity between the first thermopile sensing element 320 and the second thermopile sensing element 330, and directly subtracting the second thermopile sensing element 330 still cannot fully compensate for the thermal radiation effect of the silicon cap 400, the output of the second thermopile sensing element 330 can be multiplied by a first coefficient Ktp before being subtracted from the temperature signal. The steps for obtaining the first coefficient Ktp are as follows:

[0154] Assuming VTP1 is the value of the temperature signal received by the first thermopile sensing element 320, and VTP2 is the value of the compensated temperature signal received by the second thermopile sensing element 330, then the compensated thermal sensing output Vdet is:

[0155] Vdet = VTP1 – Ktp x VTP2

[0156] That is, the first coefficient Ktp is the coefficient that the first thermopile sensing element 320 wants to obtain when the Vdet output is zero under a uniform temperature environment (e.g., 25°C) and the thermal radiation input is blocked. Ktp = VTP2 / VTP1.

[0157] In summary, the infrared thermopile sensor 200 of the present invention integrates an infrared Fresnel lens 410 to control the angle at which the first thermopile sensing element 320 (active unit) receives thermal radiation. Furthermore, the infrared thermopile sensor 200 of the present invention further reduces the thermal effect of the packaging structure through the microstructure of the silicon cap 400, and the silicon cap 400 has a high thermal conductivity (e.g., approximately 148 W / m / K), thus exhibiting high thermal conductivity and temperature uniformity, thereby reducing the difference in thermal radiation received by the dual thermopile sensing elements 320 and 330 from the packaging structure.

[0158] In summary, the infrared thermopile sensor of the present invention employs a stacked 3D package to reduce its size (e.g., approximately 2x2x1.0 mm). 3 The invention includes a silicon cap with a lens for limiting the receiving angle to less than 30 degrees (preferably less than 45 degrees), an infrared sensing chip with dual thermopile sensing elements, and a microcontroller chip for calculating the temperature of the object under test. The invention employs dual thermopile sensing elements, where the first thermopile sensing element acts as an active unit to measure the temperature of the object under test, and the second thermopile sensing element acts as a compensation unit (dumb unit) to compensate for the effects of the packaging structure. Therefore, the invention can accurately measure temperature even under drastically changing ambient temperatures.

[0159] Furthermore, the non-contact infrared thermopile sensor of the present invention can be used in wearable devices such as watches, and can be operated over a wide range of ambient temperatures to convert wrist temperature to core body temperature. By using the detected air temperature, the human wrist temperature sensed by the infrared thermopile sensor, default or input water vapor pressure information, and the gender information set on the watch, a compensated wrist temperature can be calculated and used to perform a non-linear conversion from wrist temperature to core body temperature.

[0160] Furthermore, the standard deviation of wrist temperature may differ from that of the default temperature (e.g., 25°C), therefore, standard deviation correction factors can also be incorporated into the standardized wrist temperature to core body temperature conversion curve. In other words, different air temperatures can result in different wrist temperature to core body temperature conversion curves.

[0161] The foregoing outlines components of several embodiments to enable those skilled in the art to better understand the concepts of the embodiments of the present invention. Those skilled in the art should understand that the embodiments of the present invention can be used as a basis to design or modify other processes and structures to achieve the same purpose and / or benefits as the embodiments described herein. Those skilled in the art should also understand that these equivalent structures do not depart from the spirit and scope of the present invention, and various changes, substitutions, and other options can be made therein without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0162] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. An infrared thermopile sensor, characterized in that, include: An infrared sensing chip, comprising: A first substrate includes a wire bonding pad and two thin film structures formed by front wet etching. A first thermopile sensing element is disposed on one of the two thin film structures and generates a temperature signal of a test object, wherein the temperature signal indicates the surface temperature of the test object in a current environment, the current environment being maintained at an air temperature; A second thermopile sensing element is disposed on the other of the two thin-film structures and adjacent to the first thermopile sensing element, and generates a compensation temperature signal; A front-end signal processing unit is disposed on the first substrate and electrically connected to the first thermopile sensing element and the second thermopile sensing element, comprising: An ambient temperature sensing element generates ambient temperature information, wherein the ambient temperature information is the temperature of a surrounding area adjacent to the infrared sensing chip, and the surrounding temperature is different from the air temperature; A non-volatile memory that stores the ambient temperature information; A silicon cap is connected to the infrared sensing chip via wafer-level bonding and includes an infrared Fresnel lens that focuses thermal radiation from the test object onto the first thermopile sensing element. The size of the silicon cap is smaller than that of the infrared sensing chip, and the wire bonding pad is exposed outside the silicon cap. A microcontroller chip is connected to the infrared sensing chip and receives the temperature signal, the compensated temperature signal, and the ambient temperature information. The microcontroller chip calculates the air temperature based on the ambient temperature, calculates temperature correction information related to a default temperature based on the air temperature and a water vapor pressure, and calculates a first temperature of the object under test in a target environment based on the temperature signal, the compensated temperature signal, and the temperature correction information. The target environment is maintained at the default temperature, which is different from the air temperature and the ambient temperature. The microcontroller chip includes: A second substrate; and A first metal layer is disposed on an upper surface of the second substrate and includes a low-emissivity metallic material to reduce thermal interference from the microcontroller chip to the infrared sensing chip; and Multiple silicon vias are disposed within the second substrate; A packaging substrate, carrying the microcontroller chip and receiving an input / output signal from the microcontroller chip via a plurality of through-silicon vias (TSVs), includes a plurality of contacts disposed on a lower surface of the packaging substrate, wherein the plurality of TSVs of the microcontroller chip are electrically connected to the plurality of contacts; and A sealed body covers the packaging substrate, the microcontroller chip, the infrared sensing chip, and the silicon cap, and exposes an upper surface of the silicon cap.

2. The infrared thermopile sensor according to claim 1, characterized in that, The microcontroller chip subtracts the compensation temperature signal from the temperature signal and calculates the first temperature of the object under test based on the ambient temperature information.

3. The infrared thermopile sensor according to claim 2, characterized in that, The microcontroller chip multiplies the compensated temperature signal by a first coefficient and then subtracts it from the temperature signal, and then calculates the first temperature of the object to be measured based on the ambient temperature information.

4. The infrared thermopile sensor according to claim 1, characterized in that, The infrared sensing chip and the microcontroller chip are bonded together via a die-attach film.

5. The infrared thermopile sensor according to claim 1, characterized in that, The first substrate of the infrared sensing chip includes a second metal layer disposed on a lower surface of the first substrate.

6. The infrared thermopile sensor according to claim 1, characterized in that, The front-end signal processing unit further includes a signal selection multiplexer and a communication interface that are electrically connected to the ambient temperature sensing element and the non-volatile memory, respectively.

7. The infrared thermopile sensor according to claim 1, characterized in that, The ambient temperature sensing element includes at least one thermal sensing diode.

8. The infrared thermopile sensor according to claim 1, characterized in that, The silicon cap includes a first cavity and a second cavity corresponding to the first thermopile sensing element and the second thermopile sensing element, respectively, and the silicon cap and the infrared sensing chip are connected in a wafer-level bonding manner by a co-gold bonding or a solder bonding.

9. The infrared thermopile sensor according to claim 8, characterized in that, When the silicon cap is connected to the infrared sensing chip, the first cavity and the second cavity respectively seal the first thermopile sensing element and the second thermopile sensing element in a vacuum sealing manner.

10. The infrared thermopile sensor according to claim 8, characterized in that, The depth of the first cavity is greater than or equal to 40 micrometers and less than or equal to 100 micrometers.

11. The infrared thermopile sensor according to claim 1, characterized in that, The silicon cap includes a fourth metal layer disposed on the upper surface of the silicon cap and corresponding to the second thermopile sensing element.

12. The infrared thermopile sensor according to claim 1, characterized in that, The metal material of the first metal layer includes aluminum.

13. The infrared thermopile sensor according to claim 1, characterized in that, The infrared sensing chip is a silicon-on-insulator chip, and the package height of the infrared thermopile sensor is less than 1 cm.

14. The infrared thermopile sensor according to claim 13, characterized in that, The insulating layer on which the silicon chip is covered has an oxide insulating layer with a depth greater than 2 micrometers.

15. The infrared thermopile sensor according to claim 1, characterized in that, The ambient temperature information generated by the ambient temperature sensing element has an offset from the air temperature of an external environment. The microcontroller chip calculates the air temperature based on the ambient temperature information and the offset.

16. The infrared thermopile sensor according to claim 1, characterized in that, The microcontroller chip calculates a second temperature of the test object based on the first temperature of the test object.

17. The infrared thermopile sensor according to claim 16, characterized in that, The microcontroller chip converts the first temperature into the second temperature of the object under test based on a conversion curve.

18. The infrared thermopile sensor according to claim 17, characterized in that, The microcontroller chip uses different conversion curves to convert the first temperature to the second temperature based on different standard deviations of the first temperature relative to the air temperature.

19. The infrared thermopile sensor according to claim 1, characterized in that, The first temperature of the object to be tested is the temperature of a wrist.

20. The infrared thermopile sensor according to claim 1, characterized in that, The microcontroller chip further calculates based on the air temperature, the water vapor pressure information, and gender information to obtain the temperature correction information related to the default temperature.

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