Micro-electromechanical infrared light sensing device and method of manufacturing the same

Abstract

The present application provides a micro-electro-mechanical infrared light sensing device and a manufacturing method thereof. The micro-electro-mechanical infrared light sensing device includes a substrate and an infrared light sensing element disposed above the substrate. The infrared light sensing element has a sensing region and a light absorption region which do not overlap each other. The infrared light sensing element includes two infrared light absorption structures, an infrared light sensing layer, and a finger electrode structure. Each of the two infrared light absorption structures includes at least one infrared light absorption layer, and the two infrared light absorption structures are distributed in the sensing region and the light absorption region. The infrared light sensing layer is between the two infrared light absorption structures, and the infrared light sensing layer is located in the sensing region and does not extend to the light absorption region. The finger electrode structure is located in the sensing region, and the finger electrode structure is in electrical contact with the infrared light sensing layer.

Description

Technical Field

[0001] This invention relates to a microelectromechanical infrared light sensing device and a method for manufacturing the same. Background Technology

[0002] In recent years, microelectromechanical infrared (MEMS) sensors have been applied in various fields. In the future, the demand for MEMS infrared sensors in industrial production, environmental monitoring, home care, and temperature measurement will increase significantly. Generally, a MEMS infrared sensor mainly consists of an infrared absorption layer and an infrared sensing layer. The infrared absorption layer absorbs infrared radiation energy and converts it into heat energy. The heat energy converted from absorbed infrared light causes the infrared sensing layer to heat up. This temperature change causes a change in the resistance of the infrared sensing layer. Since the change in resistance can be reflected in a change in voltage or current, the temperature of the object being measured can be measured.

[0003] However, the materials used in infrared light sensing devices have the disadvantage of high resistivity, resulting in high overall component resistance and a large noise equivalent temperature difference (NETD). This not only reduces performance and increases circuit load but also affects the thermal sensitivity of the infrared light sensing device. On the other hand, the photoelectric conversion efficiency of an infrared light sensing device can be reflected by the fill factor, which is positively correlated with the ratio of the infrared light absorption area to the total component area. Therefore, the proportion of the infrared light absorption area is also one of the key factors for improving the efficiency of infrared light sensing devices.

[0004] In addition, existing MEMS infrared light sensing devices construct a suspended structure above the reflective layer. Because this suspended structure is suspended above the reflective layer, it is prone to uneven stress and warping. This results in inconsistent spacing between the suspended structure and the reflective layer, or even the suspended structure directly touching the reflective layer, affecting the heat insulation effect. Warping of the suspended structure not only affects the sensing performance of the MEMS infrared light sensing device, but may also pose a risk of complete failure. Summary of the Invention

[0005] An embodiment of the present invention discloses a microelectromechanical infrared (MEMS) light sensing device comprising a substrate and an infrared light sensing element. The infrared light sensing element is disposed above the substrate. The infrared light sensing element has a non-overlapping sensing region and a light absorption region. The infrared light sensing element includes two infrared light absorption structures, an infrared light sensing layer, and a finger electrode structure. Each of the two infrared light absorption structures includes at least one infrared light absorption layer, and the two infrared light absorption structures are distributed throughout the sensing region and the light absorption region. The infrared light sensing layer is located between the two infrared light absorption structures, situated within the sensing region and not extending into the light absorption region. The finger electrode structure is located within the sensing region and is in electrical contact with the infrared light sensing layer.

[0006] A method for manufacturing a microelectromechanical infrared light sensing device disclosed in an embodiment of the present invention includes: forming a sacrificial layer on a substrate; forming a lower infrared light absorption structure on the sacrificial layer; forming a forked electrode structure and an infrared light sensing layer on the lower infrared light absorption structure, wherein the infrared light sensing layer is located in the sensing region of the infrared light sensing element and does not extend to the light absorption region of the infrared light sensing element, the forked electrode structure is located in the sensing region and is electrically in contact with the infrared light sensing layer, and the sensing region and the light absorption region do not overlap; forming an upper infrared light absorption structure on the infrared light sensing layer; and removing the sacrificial layer.

[0007] According to the microelectromechanical infrared (MEMS) light sensing device and its manufacturing method disclosed in this invention, the infrared light absorption structure helps to improve the absorption rate, thereby increasing the fill factor value of the MEMS infrared light sensing device. Furthermore, it avoids warping of the infrared light sensing element or excessive thermal stress, thus contributing to improved manufacturing yield. The finger electrode structure can reduce the working area while meeting thermal sensitivity requirements, and the size of the infrared light sensing layer can also be reduced, increasing the working area of ​​the infrared light absorption layer and further increasing the fill factor of the MEMS infrared light sensing device. Through one or more of the above features, a MEMS infrared light sensing device with both low noise equivalent temperature difference and a large fill factor can be achieved.

[0008] The above description of the content of this invention and the following description of the embodiments are used to demonstrate and explain the principles of this invention, and to provide a further explanation of the claims of this invention. Attached Figure Description

[0009] Figure 1 This is a three-dimensional schematic diagram of a microelectromechanical infrared light sensing device according to an embodiment of the present invention;

[0010] Figure 2 for Figure 1 A top view schematic diagram of a microelectromechanical infrared light sensing device;

[0011] Figure 3 for Figure 1 An exploded view of the infrared light sensing element in a microelectromechanical infrared light sensing device;

[0012] Figure 4 for Figure 1 A cross-sectional schematic diagram of a microelectromechanical infrared light sensing device;

[0013] Figures 5 to 12 for Figure 1 Manufacturing process diagram of a microelectromechanical infrared light sensing device;

[0014] Figure 13 This is a cross-sectional schematic diagram of a microelectromechanical infrared light sensing device according to another embodiment of the present invention;

[0015] Figure 14 This is a cross-sectional schematic diagram of a microelectromechanical infrared light sensing device according to another embodiment of the present invention;

[0016] Figure 15 This is a cross-sectional schematic diagram of a microelectromechanical infrared light sensing device according to another embodiment of the present invention.

[0017] Symbol Explanation

[0018] 1, 2, 3, 4 Microelectromechanical infrared light sensing devices

[0019] 10 substrate

[0020] 20 Infrared light reflective layer

[0021] 30 Supporting elements

[0022] 40", 40", 40A, 40B Infrared light sensing elements

[0023] 410, 410", 410A, 410B Infrared light absorption structures

[0024] 411 Lower first infrared light absorption layer

[0025] 412 Lower Second Infrared Absorption Layer

[0026] 413, 414 Infrared light absorption layer

[0027] Infrared light absorption structure of 420, 420", 420A, 420B

[0028] 421 First infrared light absorption layer

[0029] 422 Second infrared light absorption layer

[0030] 423, 424 Infrared light absorption layer

[0031] 430 Infrared light sensing layer

[0032] 440 Sensing Electrode

[0033] 441 Finger-shaped electrode structure

[0034] 442 Connecting arm structure

[0035] 450 Flexible Arm

[0036] 50 Sacrificial Layers

[0037] 510 Through Hole

[0038] A1 Sensing Area

[0039] A2 light absorption region Detailed Implementation

[0040] The following embodiments describe in detail the features and advantages of the present invention, the content of which is sufficient to enable any person skilled in the art to understand the technical content of the present invention and implement it accordingly. Based on the disclosure of this specification, the claims, and the accompanying drawings, any person skilled in the art can easily understand the related objects and advantages of the present invention. The following embodiments further illustrate the viewpoints of the present invention in detail, but are not intended to limit the scope of the present invention in any way.

[0041] Please see Figure 1 and Figure 2 ,in Figure 1 This is a perspective view of a microelectromechanical infrared light sensing device according to an embodiment of the present invention. Figure 2 for Figure 1 The diagram is a top view of a microelectromechanical infrared light sensing device. In this embodiment, the microelectromechanical infrared light sensing device 1 includes a substrate 10, an infrared light reflective layer 20, a support element 30, and an infrared light sensing element 40.

[0042] The substrate 10 is, for example, but not limited to, a silicon substrate having a readout circuit. The infrared light reflective layer 20 is, for example, but not limited to, a metal film, disposed on the substrate 10.

[0043] The support element 30, for example but not limited to, is a metal pillar, which is disposed on the substrate 10 and is electrically connected to the reading circuit of the substrate 10. The infrared light sensing element 40 is suspended above the substrate 10 and the infrared light reflecting layer 20 by means of the support element 30. Figure 1 A plurality of support elements 30 are shown disposed on the substrate 10, wherein the number of support elements 30 is at least two.

[0044] An infrared light sensing element 40 is disposed above the substrate 10, and an infrared light reflecting layer 20 is located between the substrate 10 and the infrared light sensing element 40. The infrared light sensing element 40 has non-overlapping sensing regions A1 and light absorption regions A2, with the light absorption regions A2 surrounding the sensing regions A1. The infrared light sensing element 40 includes multiple infrared light absorption structures, an infrared light sensing layer 430, and sensing electrodes 440. Please refer to [the documentation / reference]. Figure 3 and Figure 4 ,in Figure 3 for Figure 1 An exploded view of the infrared light sensing element in a microelectromechanical infrared light sensing device. Figure 4 for Figure 1 A cross-sectional schematic diagram of a microelectromechanical infrared light sensing device. In this embodiment, the infrared light sensing element 40 includes a lower infrared light absorption structure 410 near the infrared light reflecting layer 20 and an upper infrared light absorption structure 420 away from the infrared light reflecting layer 20.

[0045] The lower infrared light absorption structure 410 is distributed across the sensing region A1 and the light absorption region A2, and includes multiple infrared light absorption layers stacked on top of each other. More specifically, the lower infrared light absorption structure 410 includes a lower first infrared light absorption layer 411 and a lower second infrared light absorption layer 412 located between the infrared light sensing layer 430 and the lower first infrared light absorption layer 411. The lower first infrared light absorption layer 411 and the lower second infrared light absorption layer 412 may be made of different materials, and the peak positions of the infrared light absorption rates of different materials are different, that is, their infrared light absorption rate peaks correspond to different infrared light wavelengths. For example, the lower first infrared light absorption layer 411 is made of silicon oxide, and the lower second infrared light absorption layer 412 is made of silicon nitride, and the infrared light absorption rate peaks of silicon oxide and silicon nitride are located at different infrared light wavelengths.

[0046] The upper infrared light absorption structure 420 is distributed across the sensing area A1 and the light absorption area A2, and includes multiple infrared light absorption layers stacked on top of each other. More specifically, the upper infrared light absorption structure 420 includes a first upper infrared light absorption layer 421 and a second upper infrared light absorption layer 422 located between the infrared light sensing layer 430 and the first upper infrared light absorption layer 421. The first upper infrared light absorption layer 421 and the second upper infrared light absorption layer 422 may be made of different materials, and the peak positions of the infrared light absorption rates of different materials are different, that is, their peak infrared light absorption rates correspond to different infrared light wavelengths. For example, the first upper infrared light absorption layer 421 is made of silicon oxide, and the second upper infrared light absorption layer 422 is made of silicon nitride, and the peak infrared light absorption rates of silicon oxide and silicon nitride are located at different infrared light wavelengths.

[0047] In this embodiment, the lower infrared light absorbing structure 410 and the upper infrared light absorbing structure 420 each contain multiple infrared light absorbing layers with the same composition. Specifically, "same composition" means that when both the lower infrared light absorbing structure 410 and the upper infrared light absorbing structure 420 contain multiple infrared light absorbing layers, the multiple infrared light absorbing layers of both have the same number of layers and the same type and quantity of materials, but the arrangement order may be different. Figure 4 The lower infrared light absorbing structure 410 and the upper infrared light absorbing structure 420 are exemplarily identical in composition, both consisting of two infrared light absorbing layers (the same number of layers), and each of their two infrared light absorbing layers is a combination of one layer of silicon oxide and one layer of silicon nitride (the same type and quantity of materials). In some other embodiments, the infrared light absorbing layers may be arranged from bottom to top in the following order: lower first infrared light absorbing layer 411, lower second infrared light absorbing layer 412, upper first infrared light absorbing layer 421, and upper second infrared light absorbing layer 422.

[0048] Furthermore, in this embodiment, the lower infrared light absorbing structure 410 and the upper infrared light absorbing structure 420 may have a stacked structure symmetrically arranged relative to the infrared light sensing layer 430. Specifically, the lower first infrared light absorbing layer 411 of the lower infrared light absorbing structure 410 and the upper first infrared light absorbing layer 421 of the upper infrared light absorbing structure 420 have the same material (silicon oxide), and the lower second infrared light absorbing layer 412 and the upper second infrared light absorbing layer 422 have the same material (silicon nitride). This embodiment uses silicon oxide or silicon nitride as an example to illustrate the infrared light absorbing layer material, and it is not intended to limit the invention. In other embodiments, the infrared light absorbing layer may be other materials (such as silicon oxide containing nitrogen) or composite materials, and each infrared light absorbing structure may contain more than two infrared light absorbing layers.

[0049] In this embodiment, the lower infrared light absorption structure 410 and the upper infrared light absorption structure 420 have the same thickness. More specifically, the lower first infrared light absorption layer 411 and the upper first infrared light absorption layer 421 have the same thickness, and the lower second infrared light absorption layer 412 and the upper second infrared light absorption layer 422 have the same thickness.

[0050] The infrared light sensing layer 430 is, for example but not limited to, amorphous silicon (a-Si) or a composite material with a high temperature coefficient of resistance (TCR), situated between the lower infrared light absorbing structure 410 and the upper infrared light absorbing structure 420. Furthermore, the infrared light sensing layer 430 is located in the sensing region A1 and does not extend into the light absorbing region A2.

[0051] The sensing electrode 440 is electrically contacted with the infrared light sensing layer 430. Specifically, the sensing electrode 440 is located between the lower infrared light absorbing structure 410 and the upper infrared light absorbing structure 420, and includes a forked electrode structure 441 located in the sensing region A1 and a connecting arm structure 442 located in the light absorption region A2. The forked electrode structure 441 may not extend into the light absorption region A2. The forked electrode structure 441 is electrically contacted with the infrared light sensing layer 430, and the forked electrode structure 441 is electrically contacted with the support element 30 via the connecting arm structure 442, thereby achieving electrical connection with the substrate. In this embodiment, the forked electrode structure 441 is located between the infrared light sensing layer 430 and the lower infrared light absorbing structure 410; in some other embodiments, the forked electrode structure may be located between the infrared light sensing layer and the upper infrared light absorbing structure 420.

[0052] The following describes the manufacturing method of the microelectromechanical infrared light sensing device 1. Please refer to the following instructions. Figures 5 to 12 ,for Figure 1 A flowchart illustrating the manufacturing process of a microelectromechanical infrared light sensing device is provided below. The detailed steps for manufacturing the microelectromechanical infrared light sensing device 1 are described below, but the specific implementation of each step is not intended to limit the invention.

[0053] like Figure 5 As shown, a substrate 10 with readout circuitry is provided, and an infrared light reflective layer 20 and a sacrificial layer 50 are sequentially formed on the substrate 10. Specifically, a metal layer (e.g., an aluminum layer with a thickness of approximately 300 nanometers) is deposited on the substrate 10, and patterned by etching to form the infrared light reflective layer 20. After forming the infrared light reflective layer 20, a sacrificial layer 50, such as an amorphous silicon material with a thickness of 1000–1500 nanometers, is deposited on the substrate 10 and the infrared light reflective layer 20. Optionally, a protective layer of silicon oxide (SiOx) can be formed on the infrared light reflective layer 20 before forming the sacrificial layer 50 to prevent the infrared light reflective layer 20 from being affected by the material of the sacrificial layer 50. The patterning can be performed by photolithography and / or etching processes.

[0054] like Figure 6 and Figure 7 As shown, a support element 30 is formed in the sacrificial layer 50. Specifically, a portion of the sacrificial layer 50 is etched away to form a through-hole 510, and then the support element 30 is formed in the through-hole 510. A conductive material (such as tungsten) can be deposited on the upper surface of the sacrificial layer 50 and in the through-hole 510, and a portion of the conductive material located on the upper surface of the sacrificial layer 50 is removed to form the support element 30. More specifically, a chemical-mechanical planarization (CMP) process can be used to remove a portion of the conductive material and a portion of the sacrificial layer 50 to form the support element 30, thereby ensuring that the upper surface of the sacrificial layer 50 is sufficiently flat.

[0055] like Figure 8 As shown, a lower infrared light absorption structure 410 is formed on the sacrificial layer 50. Specifically, a silicon oxide layer with a thickness of about 40 to 100 nanometers is first deposited to cover the support element 30 and the sacrificial layer 50. The silicon oxide layer and the silicon nitride layer serve as the lower first infrared light absorption layer 411 and the lower second infrared light absorption layer 412 of the lower infrared light absorption structure 410, respectively.

[0056] like Figure 9 As shown, a sensing electrode 440 is formed on the lower infrared light absorption structure 410. Specifically, after the aforementioned step of depositing silicon oxide and silicon nitride layers to form the lower infrared light absorption structure 410, a portion of the silicon oxide and silicon nitride layers is removed by etching to expose the support element 30; or, before the aforementioned step of depositing silicon oxide and silicon nitride layers, the support element 30 is covered with a mask before deposition, so that the support element 30 is exposed after deposition. Next, a conductive layer (such as titanium nitride with a thickness of about 50-100 nanometers) is deposited on the upper surface of the lower infrared light absorption structure 410 and the support element 30, and then the conductive layer is etched to pattern it to form the sensing electrode 440, and a portion of the conductive layer is selectively left around the sensing electrode 440 to form a signal transmission circuit in subsequent fabrication processes. The patterning can be performed by photolithography and / or etching processes.

[0057] like Figure 10 As shown, an infrared light sensing layer 430 is formed on the sensing electrode 440. Specifically, a material layer with a high temperature coefficient of resistance (such as amorphous silicon with a thickness of about 50 to 100 nanometers) is deposited on the sensing electrode 440, and then the material layer is etched to pattern it to form the infrared light sensing layer 430 above the finger electrode structure 441 of the sensing electrode 440. The area where the material layer is removed by etching can be defined as... Figure 4 The locations of the light absorption region A2 of the infrared light sensing element 40, the infrared light sensing layer 430, and the finger electrode structure 441 can be defined as follows: Figure 4 The sensing area A1 is described. The patterning may be performed using photolithography and / or etching processes. Figure 9 and Figure 10 The illustration shows the formation of the sensing electrode 440 first and then the infrared light sensing layer 430, but the present invention is not limited thereto. In other embodiments, the infrared light sensing layer may be formed first and then the sensing electrode may be formed.

[0058] like Figure 11As shown, an upper infrared light absorption structure 420 is formed on the infrared light sensing layer 430. Specifically, a silicon nitride layer with a thickness of approximately 100–170 nanometers is first deposited to cover the infrared light sensing layer 430 and the sensing electrode 440. Next, a silicon oxide layer with a thickness of approximately 40–100 nanometers is deposited on this silicon nitride layer. Then, the silicon oxide layer and the silicon nitride layer are patterned by etching to form the upper first infrared light absorption layer 421 and the upper second infrared light absorption layer 422 of the upper infrared light absorption structure 420. The upper infrared light absorption structure 420 covers the upper surface and sides of the infrared light sensing layer 430. The patterning can be performed using photolithography and / or etching processes.

[0059] like Figure 12 As shown, a portion of the lower infrared light absorbing structure 410 and a portion of the upper infrared light absorbing structure 420 are removed to form the elastic support arm 450 of the infrared light sensing element 40. Next, the sacrificial layer 50 is removed by etching, forming a gap between the lower infrared light absorbing structure 410 and the infrared light reflecting layer 20. Furthermore, in addition to the partial removal of the lower infrared light absorbing structure 410 and a portion of the upper infrared light absorbing structure 420, a portion of the conductive layer remaining around the sensing electrode 440 is also partially removed to form a signal transmission circuit.

[0060] When infrared light is incident on the microelectromechanical infrared light sensing device 1 from the outside, the radiant energy of the infrared light passing through the infrared light sensing element 40 is absorbed by the lower infrared light absorption structure 410 and the upper infrared light absorption structure 420. Consequently, the temperature of the infrared light sensing layer 430, which is in contact with the lower and upper infrared light absorption structures 410 and 420, also rises. The increase in temperature of the infrared light sensing layer 430 causes a change in its resistance value, which in turn changes the overall resistance value of the infrared light sensing layer 430 and the sensing electrode 440, which are in electrical contact with each other. Therefore, the reading circuit of the substrate 10 can obtain an electrical signal (such as a change in voltage or current).

[0061] In this embodiment, each infrared light absorption structure (lower infrared light absorption structure 410 and upper infrared light absorption structure 420) includes multiple infrared light absorption layers for absorbing infrared light energy of different wavelengths. Since infrared light from the external environment typically includes multiple wavelengths, the infrared light absorption structure helps to increase the absorption rate, thereby increasing the fill factor value of the microelectromechanical infrared light sensing device 1. Furthermore, the symmetrically distributed lower infrared light absorption structure 410 and upper infrared light absorption structure 420 can have the same or similar material properties (such as coefficient of thermal expansion or Young's coefficient), structure, and size. Therefore, during the manufacturing process of the microelectromechanical infrared light sensing device 1, warpage of the infrared light sensing element 40 or excessive thermal stress can be avoided, which helps to improve the manufacturing yield of the microelectromechanical infrared light sensing device 1.

[0062] Furthermore, in this embodiment, the sensing electrode 440 includes a forked electrode structure 441. Compared to conventional electrode structures, the forked electrode structure 441 has the advantages of shorter electrode spacing and lower resistance. Therefore, the forked electrode structure 441 can provide a smaller working area than conventional electrode structures while still having a sufficiently small noise equivalent temperature difference to meet the thermal sensitivity requirements of the microelectromechanical infrared light sensing device 1, which is in line with the miniaturization trend. At the same time, due to the small working area of ​​the forked electrode structure 441, the size of the infrared light sensing layer 430 that needs to overlap with the forked electrode structure 441 can also be reduced. This means that the working area of ​​the infrared light absorption layer used to absorb infrared light energy increases, further increasing the fill factor of the microelectromechanical infrared light sensing device 1.

[0063] Furthermore, in the manufacturing method disclosed in this embodiment, since the lower infrared light absorption structure 410 of the infrared light sensing element 40 is formed on the sacrificial layer 50, and the upper surface of the sacrificial layer 50 is treated with a chemical mechanical planarization process, after removing the sacrificial layer 50, the lower infrared light absorption structure 410 has a flat surface on the side facing the infrared light reflecting layer 20. The lower infrared light absorption structure 410 with a flat lower surface can ensure that the gap size between the infrared light sensing element 40 and the infrared light reflecting layer 20 remains consistent, enabling the microelectromechanical infrared light sensing device 1 to achieve optimal sensing performance. Moreover, the symmetrically configured infrared light absorption structure design can further improve the manufacturing yield of the microelectromechanical infrared light sensing device 1.

[0064] Figure 13 This is a cross-sectional schematic diagram of a microelectromechanical infrared (MEMS) light sensing device according to another embodiment of the present invention. In this embodiment, the MEMS infrared light sensing device 2 includes a substrate 10, an infrared light reflecting layer 20, a support element 30, and an infrared light sensing element 40", wherein the infrared light sensing element 40" includes a lower infrared light absorbing structure 410", an upper infrared light absorbing structure 420", an infrared light sensing layer 430, and a sensing electrode 440. Both the lower infrared light absorbing structure 410" and the upper infrared light absorbing structure 420" are single infrared light absorbing layers, and the materials of the lower infrared light absorbing structure 410" and the upper infrared light absorbing structure 420" are different. For example, the upper infrared light absorbing structure 420" is a single silicon oxide layer, and the lower infrared light absorbing structure 410" is a single silicon nitride layer.

[0065] Figure 14This is a cross-sectional schematic diagram of a microelectromechanical infrared (MEMS) light sensing device according to another embodiment of the present invention. In this embodiment, the MEMS infrared light sensing device 3 includes a substrate 10, an infrared light reflecting layer 20, a support element 30, and an infrared light sensing element 40A. The infrared light sensing element 40A includes a lower infrared light absorbing structure 410A, an upper infrared light absorbing structure 420A, an infrared light sensing layer 430, and a sensing electrode 440. The lower infrared light absorbing structure 410A and the upper infrared light absorbing structure 420A together form an infrared light absorbing stack formed by the alternating stacking of multiple infrared light absorbing layers.

[0066] In detail, Figure 14 The lower infrared light absorption structure 410A shown includes an infrared light absorption layer 413 and an infrared light absorption layer 414 located below the sensing electrode 440. The infrared light absorption layers 413 and 414 can be made of different materials; for example, the infrared light absorption layer 413 is made of silicon oxide, and the infrared light absorption layer 414 is made of silicon nitride. The upper infrared light absorption structure 420A includes two infrared light absorption layers 423 and one infrared light absorption layer 424 located above the sensing electrode 440. The infrared light absorption layers 423 and 424 can be made of different materials; for example, the infrared light absorption layer 423 is made of silicon oxide, and the infrared light absorption layer 424 is made of silicon nitride.

[0067] Figure 15 This is a cross-sectional schematic diagram of a microelectromechanical infrared (MEMS) light sensing device according to another embodiment of the present invention. In this embodiment, the MEMS infrared light sensing device 4 includes a substrate 10, an infrared light reflecting layer 20, a support element 30, and an infrared light sensing element 40B. The infrared light sensing element 40B includes a lower infrared light absorbing structure 410B, an upper infrared light absorbing structure 420B, an infrared light sensing layer 430, and a sensing electrode 440. The lower infrared light absorbing structure 410B and the upper infrared light absorbing structure 420B together form an infrared light absorbing stack formed by the alternating stacking of multiple infrared light absorbing layers.

[0068] In detail, Figure 15 The lower infrared light absorption structure 410B shown includes two infrared light absorption layers 413 and one infrared light absorption layer 414 located below the sensing electrode 440. The infrared light absorption layers 413 and 414 can be made of different materials; for example, the infrared light absorption layer 413 is made of silicon oxide, and the infrared light absorption layer 414 is made of silicon nitride. The upper infrared light absorption structure 420B includes one infrared light absorption layer 423 and one infrared light absorption layer 424 located above the sensing electrode 440. The infrared light absorption layers 423 and 424 can be made of different materials; for example, the infrared light absorption layer 423 is made of silicon oxide, and the infrared light absorption layer 424 is made of silicon nitride.

[0069] In summary, according to the microelectromechanical infrared (MEMS) light sensing device and its manufacturing method disclosed in this invention, the infrared light absorption structure helps to improve the absorption rate, thereby increasing the fill factor value of the MEMS infrared light sensing device. Furthermore, it avoids warping of the infrared light sensing element or excessive thermal stress, thus improving the manufacturing yield of the MEMS infrared light sensing device. The finger electrode structure can reduce the working area while meeting thermal sensitivity requirements, and the size of the infrared light sensing layer can also be reduced, increasing the working area of ​​the infrared light absorption layer and further increasing the fill factor of the MEMS infrared light sensing device. The symmetrical infrared light absorption structure ensures overall stress balance, making the infrared light absorption structure flat and avoiding warping. Therefore, it ensures that the gap size between the infrared light sensing element and the infrared light reflecting layer remains consistent, allowing the MEMS infrared light sensing device to maintain optimal stability and accuracy. Through one or more of the above features, a MEMS infrared light sensing device with both low noise equivalent temperature difference and a large fill factor can be achieved.

Claims

1. A microelectromechanical infrared light sensing device, comprising: Substrate; and An infrared light sensing element is disposed above the substrate. The infrared light sensing element has non-overlapping sensing areas and light absorption areas, and the infrared light sensing element includes: Two infrared light absorption structures, each containing at least one infrared light absorption layer, and the two infrared light absorption structures are distributed throughout the sensing area and the light absorption area. An infrared light sensing layer, situated between the two infrared light absorbing structures, is located within the sensing region but does not extend into the light absorption region; and A fork electrode structure is located in the sensing area, and the fork electrode structure is in electrical contact with the infrared light sensing layer; in, The two infrared light absorption structures are a lower infrared light absorption structure close to the substrate and an upper infrared light absorption structure far from the substrate, and the upper infrared light absorption structure covers and directly contacts the upper surface and side of the infrared light sensing layer.

2. The microelectromechanical infrared light sensing device as claimed in claim 1, wherein the lower infrared light absorption structure and the upper infrared light absorption structure each comprise a plurality of infrared light absorption layers superimposed on each other.

3. The microelectromechanical infrared light sensing device as described in claim 1, wherein the lower infrared light absorption structure and the upper infrared light absorption structure have the same thickness, and the lower infrared light absorption structure and the upper infrared light absorption structure each contain a plurality of infrared light absorption layers with the same composition.

4. The microelectromechanical infrared light sensing device as claimed in claim 1, wherein the lower infrared light absorption structure includes a lower first infrared light absorption layer and a lower second infrared light absorption layer between the infrared light sensing layer and the lower first infrared light absorption layer, the upper infrared light absorption structure includes an upper first infrared light absorption layer and an upper second infrared light absorption layer between the infrared light sensing layer and the upper first infrared light absorption layer, the lower first infrared light absorption layer and the upper first infrared light absorption layer have the same first material, the lower second infrared light absorption layer and the upper second infrared light absorption layer have the same second material, and the first material and the second material are different.

5. The microelectromechanical infrared light sensing device as claimed in claim 4, wherein the lower infrared light absorbing structure and the upper infrared light absorbing structure have the same thickness.

6. The microelectromechanical infrared light sensing device as claimed in claim 4, wherein the lower first infrared light absorption layer and the upper first infrared light absorption layer have the same thickness, and the lower second infrared light absorption layer and the upper second infrared light absorption layer have the same thickness.

7. The microelectromechanical infrared light sensing device as claimed in claim 1, wherein the lower infrared light absorbing structure and the upper infrared light absorbing structure form an infrared light absorbing stack, and the infrared light absorbing stack comprises a plurality of infrared light absorbing layers having a first material and a plurality of infrared light absorbing layers having a second material alternately stacked, and the first material and the second material are different.

8. The microelectromechanical infrared light sensing device as claimed in claim 1 further includes an infrared light reflecting layer, and the infrared light reflecting layer is disposed between the substrate and the infrared light sensing element.

9. The microelectromechanical infrared light sensing device as claimed in claim 1, wherein the finger electrode structure is located between the infrared light sensing layer and any one of the two infrared light absorbing structures.

10. The microelectromechanical infrared light sensing device as claimed in claim 1, further comprising a plurality of support elements disposed on the substrate, the support elements being connected to the infrared light sensing element so that the infrared light sensing element is suspended above the substrate.

11. The microelectromechanical infrared light sensing device of claim 10, wherein the supporting elements are made of metal, and the finger electrode structure is in electrical contact with the supporting elements.

12. The microelectromechanical infrared light sensing device as claimed in claim 1, wherein the lower infrared light absorption structure and the upper infrared light absorption structure each comprise a non-metallic infrared light absorption layer.

13. The microelectromechanical infrared light sensing device of claim 1, wherein the infrared light sensing element further includes a sensing electrode located in the sensing region and the light absorption region, and the sensing electrode includes the fork electrode structure located in the sensing region and electrically contacting the infrared light sensing layer.

14. A method for manufacturing a microelectromechanical infrared light sensing device, comprising: A sacrificial layer is formed on the substrate; A lower infrared light absorption structure is formed on this sacrificial layer; A fork electrode structure and an infrared light sensing layer are formed on the lower infrared light absorption structure. The infrared light sensing layer is located within the sensing area of ​​the infrared light sensing device and does not extend into the light absorption area of ​​the infrared light sensing device. The fork electrode structure is located within the sensing area and is in electrical contact with the infrared light sensing layer. The sensing area and the light absorption area do not overlap. An upper infrared light absorption structure is formed on the infrared light sensing layer; as well as Remove the sacrifice layer; The lower infrared light absorption structure and the upper infrared light absorption structure are distributed throughout the sensing area and the light absorption area, and the upper infrared light absorption structure covers and directly contacts the upper surface and side of the infrared light sensing layer.

15. The method for manufacturing the microelectromechanical infrared light sensing device as described in claim 14, further comprising: Multiple through holes are formed in the sacrificial layer; Conductive material is deposited in these through-holes; and Remove a portion of the conductive material to form multiple support elements.

16. The method of manufacturing the microelectromechanical infrared light sensing device as claimed in claim 15, wherein a portion of the conductive material is removed by a chemical mechanical planarization process.

17. The method of manufacturing a microelectromechanical infrared light sensing device as claimed in claim 15, wherein forming the finger electrode structure on the lower infrared light absorption structure comprises: Remove part of the lower infrared light absorption structure to expose the supporting elements; A conductive layer is deposited on the upper surface of the lower infrared light absorbing structure and on the supporting elements; and The conductive layer is patterned to form the finger electrode structure.

18. The method for manufacturing a microelectromechanical infrared light sensing device as claimed in claim 14, wherein the step of forming the lower infrared light absorption structure on the sacrificial layer includes forming a plurality of infrared light absorption layers of the lower infrared light absorption structure on the sacrificial layer, and the step of forming the upper infrared light absorption structure on the infrared light sensing layer includes forming a plurality of infrared light absorption layers of the upper infrared light absorption structure on the infrared light sensing layer.

19. The method for manufacturing a microelectromechanical infrared light sensing device as described in claim 14, wherein the lower infrared light absorption structure and the upper infrared light absorption structure have the same thickness, and each of the lower infrared light absorption structure and the upper infrared light absorption structure comprises a plurality of infrared light absorption layers with the same composition.

20. The method for manufacturing a microelectromechanical infrared light sensing device as claimed in claim 19, wherein the step of forming the lower infrared light absorption structure on the sacrificial layer includes forming a lower first infrared light absorption layer and a lower second infrared light absorption layer on the sacrificial layer, and the step of forming the upper infrared light absorption structure on the infrared light sensing layer includes forming an upper first infrared light absorption layer and an upper second infrared light absorption layer on the infrared light sensing layer, wherein the lower first infrared light absorption layer and the upper first infrared light absorption layer have the same thickness and material, and the lower second infrared light absorption layer and the upper second infrared light absorption layer have the same thickness and material.

21. The method for manufacturing a microelectromechanical infrared light sensing device as claimed in claim 20, wherein the step of forming the lower infrared light absorption structure on the sacrificial layer further includes forming the lower first infrared light absorption layer on the sacrificial layer and forming the lower second infrared light absorption layer on the lower first infrared light absorption layer, and the step of forming the upper infrared light absorption structure on the infrared light sensing layer further includes forming the upper second infrared light absorption layer on the infrared light sensing layer and forming the upper first infrared light absorption layer on the upper second infrared light absorption layer.

22. The method for manufacturing the microelectromechanical infrared light sensing device as described in claim 14, further comprising: Before forming the lower infrared light absorption structure, an infrared light reflective layer is formed on the substrate.

23. The method for manufacturing the microelectromechanical infrared light sensing device as described in claim 14, further comprising: Before removing the sacrificial layer, a portion of the lower infrared light absorbing structure and a portion of the upper infrared light absorbing structure are removed to form an elastic support in the light absorption region.

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