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

Abstract

A micro-electro-mechanical infrared light sensing device and a manufacturing method thereof are disclosed. The micro-electro-mechanical infrared light sensing device includes a substrate and an infrared light sensing element. The infrared light sensing element is disposed above the substrate. The infrared light sensing element includes a sensing plate and at least one support element. The sensing plate includes at least one infrared light absorbing layer, an infrared light sensing layer, a sensing electrode, and a plurality of metal elements. The sensing plate has a plurality of openings. The metal elements surround the openings. The sensing electrode is connected to the infrared light sensing layer. The metal elements are spaced apart from each other. The support element connects the sensing plate to the substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to a micro-electro-mechanical infrared light sensing device and a method for manufacturing the same. BACKGROUND

[0002] In recent years, micro-electro-mechanical infrared light sensing devices have been applied in various fields. In the future, the demand for micro-electro-mechanical infrared light sensing devices in the fields of industrial production, environmental monitoring, home care and temperature measurement will increase significantly. Generally, a micro-electro-mechanical infrared light sensing device mainly includes an infrared light absorbing layer and an infrared light sensing layer. The infrared light absorbing layer absorbs infrared light radiation energy and converts the radiation energy into heat energy. The heat energy converted by the absorbed infrared light causes the infrared light sensing layer or the electrode in contact with the infrared light sensing layer to heat up. The temperature change causes the resistance value of the infrared light sensing layer or the electrode to change, and the change in voltage value or current size can be observed due to the change in resistance value, thereby calculating the temperature of the measured object.

[0003] The material that can be used as the infrared light sensing layer needs to have a high temperature coefficient of resistance (TCR), so the selection of the material is limited. Currently, the industry generally uses materials that absorb infrared light with a wavelength of 10-14 microns (μm) as the infrared light sensing layer, which cannot effectively utilize the energy of infrared light with a wavelength less than 10 microns. For example, silicon nitride, which is widely used as an infrared light sensing layer in the industry, has an absorption rate of up to 85% for infrared light with a wavelength of 10-14 microns, but only 55% for infrared light with a wavelength less than 10 microns. SUMMARY

[0004] In view of the above problems, the present application provides a micro-electro-mechanical infrared light sensing device with high absorption rate for a wide infrared light band, and a method for manufacturing the same.

[0005] The micro-electro-mechanical infrared light sensing device disclosed in an embodiment of the present application includes a substrate and an infrared light sensing element disposed above the substrate. The infrared light sensing element includes a sensing plate and at least one support element. The sensing plate includes at least one infrared light absorbing layer, an infrared light sensing layer, a sensing electrode, and a plurality of metal elements. The sensing plate has a plurality of openings, and the metal elements each surround the openings. The sensing electrode is connected to the infrared light sensing layer, and the metal elements are spaced apart from each other. The support element connects the sensing plate and the substrate.

[0006] The manufacturing method of the micro-electro-mechanical infrared light sensing device includes: forming a sacrificial layer on a substrate; forming at least one support element in the sacrificial layer; forming a sensing plate on the sacrificial layer; forming a plurality of openings in the sensing plate, respectively penetrating the metal elements; and removing the sacrificial layer. The sensing plate includes at least one infrared light absorbing layer, an infrared light sensing layer, a sensing electrode, and a plurality of metal elements. The sensing electrode is connected with the infrared light sensing layer and the support element, and the metal elements are arranged at intervals.

[0007] According to the micro-electro-mechanical infrared light sensing device and the manufacturing method thereof, the sensing plate of the infrared light sensing element additionally includes a plurality of metal elements at intervals and a plurality of openings surrounded by the metal elements in addition to the infrared light absorbing layer. The metal elements help to improve the absorption rate of the sensing plate for the infrared light waveband with a wavelength of 8-10 microns, especially for the infrared light waveband with a wavelength of 8-9 microns. In combination with the high absorption rate of the infrared light absorbing layer itself for the infrared light waveband with a wavelength of 10-12 microns, the requirement of the infrared light sensing element for high absorption rate for a wide infrared light waveband is met.

[0008] The above description of the present application and the following description of the embodiments are used to demonstrate and explain the principles of the present application, and provide further explanation of the claims of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 A perspective view of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application;

[0010] Figure 2 A top view of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application; Figure 1

[0011] A cross-sectional view of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application; Figure 3 Figure 1 An exploded view of an infrared light sensing element of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application;

[0012] Figure 4 Figure 1 A cross-sectional view of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application;

[0013] Figure 5 A partial enlarged view of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application; Figure 4

[0014] Figures 6 to 13 A manufacturing flowchart of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application; Figure 1

[0015] A manufacturing flowchart of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application; Figure 14 Figure 1 ​​​​Absorption rate diagram of the micro-electro-mechanical infrared light sensing device of the present application for different infrared light wave bands;

[0016] Figure 15 A perspective view of a micro-electro-mechanical infrared light sensing device according to another embodiment of the present application.

[0017] Legend

[0018] 1, 2 Micro-electro-mechanical infrared light sensing device

[0019] 10 Substrate

[0020] 20 Infrared light reflecting layer

[0021] 30, 30" Infrared light sensing element

[0022] 310 Support element

[0023] 320, 320" Sensing plate

[0024] 321 Lower infrared light absorbing layer

[0025] 321a First lower infrared light absorbing sub-layer

[0026] 321b Second lower infrared light absorbing sub-layer

[0027] 321" Infrared light absorbing layer

[0028] 322 Upper infrared light absorbing layer

[0029] 322a First upper infrared light absorbing sub-layer

[0030] 322b Second upper infrared light absorbing sub-layer

[0031] 323, 323" Infrared light sensing layer

[0032] 324, 324" Sensing electrode

[0033] 324a Interdigital electrode structure

[0034] 324b Connecting arm structure

[0035] 325, 325" Metal element

[0036] 326, 326" Aperture

[0037] 327 Elastic support arm

[0038] 3251 Central hole

[0039] 3252 Inner annular surface

[0040] 50 Sacrificial layer

[0041] 510 through hole

[0042] A1 sensing region

[0043] A2 light absorption region

[0044] A3 working region

[0045] d outermost diameter of the metal ring

[0046] W width of the metal ring

[0047] t thickness of the metal ring

[0048] Dint center-to-center distance between two adjacent metal rings DETAILED DESCRIPTION

[0049] The detailed characteristics and advantages of the present application are described in the following embodiments in detail, which are sufficient for any person skilled in the related art to understand the technical content of the present application and to implement it, and according to the content disclosed in the specification, claims and drawings, any person skilled in the related art can easily understand the related purposes and advantages of the present application. The following examples further illustrate the ideas of the present application, but do not limit the scope of the present application in any way.

[0050] Please refer to Figure 1 and Figure 2 , wherein Figure 1 is a perspective view of a micro-electro-mechanical infrared light sensing device according to an embodiment of the present application, Figure 2 is Figure 1 a top view of the micro-electro-mechanical infrared light sensing device of In this embodiment, the micro-electro-mechanical infrared light sensing device 1 includes a substrate 10, an infrared light reflecting layer 20, and an infrared light sensing element 30.

[0051] The substrate 10 is, for example but not limited to, a silicon substrate with a readout circuit. The infrared light reflecting layer 20 is, for example but not limited to, a metal film, which is disposed on the substrate 10.

[0052] The infrared light sensing element 30 is disposed above the substrate 10, and the infrared light reflecting layer 20 is between the substrate 10 and the infrared light sensing element 30. The infrared light sensing element 30 includes at least one support element 310 and a sensing plate 320. The support element 310 is, for example but not limited to, a metal column, which is disposed on the substrate 10, and the support element 310 is electrically connected to the readout circuit of the substrate 10. The sensing plate 320 is suspended above the substrate 10 and the infrared light reflecting layer 20 by the support element 310. Figure 1 A plurality of support elements 310 are shown to be disposed on the substrate 10, but the number of support elements 310 is not intended to limit the present application.

[0053] The sensing plate 320 has a sensing region Al and a light absorption region A2 which are not overlapped with each other, and the light absorption region A2 surrounds the sensing region Al. The sensing plate 320 includes a plurality of infrared light absorption layers, an infrared light sensing layer 323, a sensing electrode 324, and a plurality of metal elements 325. Please refer to Figure 3 and Figure 4 wherein Figure 3 is a schematic diagram of the decomposition of an infrared light sensing element in a micro-electro-mechanical infrared light sensing device of Figure 1 Figure 4 is a schematic diagram of the cross section of a micro-electro-mechanical infrared light sensing device of Figure 1 In this embodiment, the sensing plate 320 includes a lower infrared light absorption layer 321 close to the infrared light reflection layer 20 and an upper infrared light absorption layer 322 away from the infrared light reflection layer 20.

[0054] The lower infrared light absorption layer 321 is distributed in the sensing region Al and the light absorption region A2, and the lower infrared light absorption layer 321 includes a plurality of infrared light absorption sub-layers. More specifically, the lower infrared light absorption layer 321 includes a first lower infrared light absorption sub-layer 321a and a second lower infrared light absorption sub-layer 321b between the infrared light sensing layer 323 and the first lower infrared light absorption sub-layer 321a, and the first lower infrared light absorption sub-layer 321a and the second lower infrared light absorption sub-layer 321b can have different materials to correspond to different absorption infrared light wave bands respectively. For example, the first lower infrared light absorption sub-layer 321a is made of silicon oxide, the second lower infrared light absorption sub-layer 321b is made of silicon nitride, and the absorption wavelength ranges of the two infrared light absorption sub-layers have different peaks.

[0055] The upper infrared light absorption layer 322 is distributed in the sensing region Al and the light absorption region A2, and the upper infrared light absorption layer 322 includes a plurality of infrared light absorption layers. More specifically, the upper infrared light absorption layer 322 includes a first upper infrared light absorption sub-layer 322a and a second upper infrared light absorption sub-layer 322b between the infrared light sensing layer 323 and the first upper infrared light absorption sub-layer 322a, and the first upper infrared light absorption sub-layer 322a and the second upper infrared light absorption sub-layer 322b can have different materials to correspond to different absorption infrared light wave bands respectively. For example, the first upper infrared light absorption sub-layer 322a is made of silicon oxide, the second upper infrared light absorption sub-layer 322b is made of silicon nitride, and the absorption wavelength ranges of the two infrared light absorption sub-layers have different peaks.

[0056] ​That is, the lower infrared light absorbing layer 321 and the upper infrared light absorbing layer 322 can have a stacked structure symmetrically arranged with respect to the infrared light sensing layer 323, and the multiple infrared light absorbing layers in each infrared light absorbing stacked structure correspond to different absorption bands of infrared light. In the present embodiment, the first lower infrared light absorbing sub-layer 321a of the lower infrared light absorbing layer 321 and the first upper infrared light absorbing sub-layer 322a of the upper infrared light absorbing layer 322 have the same material (silicon oxide), and the second lower infrared light absorbing sub-layer 321b and the second upper infrared light absorbing sub-layer 322b have the same material (silicon nitride). The present embodiment takes silicon oxide or silicon nitride as the material of the infrared light absorbing layer as an example, which is not intended to limit the present application. In other embodiments, the infrared light absorbing layer can be other materials (such as nitrogen-containing silicon oxide) or composite materials, and each infrared light absorbing stacked structure can include more than two layers of infrared light absorbing layers.

[0057] In the present embodiment, the lower infrared light absorbing layer 321 and the upper infrared light absorbing layer 322 also have the same thickness, and further, the first lower infrared light absorbing sub-layer 321a and the first upper infrared light absorbing sub-layer 322a have the same thickness, and the second lower infrared light absorbing sub-layer 321b and the second upper infrared light absorbing sub-layer 322b have the same thickness.

[0058] The lower infrared light absorbing layer 321 and the upper infrared light absorbing layer 322 of the present embodiment each have a stacked structure composed of multiple sub-layers, but the present application is not limited thereto. In other embodiments, both infrared light absorbing layers can be single material layers, or only one of the infrared light absorbing layers has a stacked structure. In addition, the sensing plate 320 of the present embodiment includes multiple infrared light absorbing layers, but the present application is not limited thereto. In other embodiments, the infrared light absorbing layer can be formed only above the infrared light sensing layer or below the sensing electrode.

[0059] The infrared light sensing layer 323 is, for example but not limited to, amorphous silicon (a-Si) or a composite material with a high temperature coefficient of resistance, which is between the lower infrared light absorbing layer 321 and the upper infrared light absorbing layer 322. Further, the infrared light sensing layer 323 is located in the sensing region A1 and does not extend to the light absorbing region A2.

[0060] The sensing electrode 324 is in thermal contact with the infrared light sensing layer 323. In detail, the sensing electrode 324 is between the lower infrared light absorbing layer 321 and the upper infrared light absorbing layer 322, and the sensing electrode 324 includes a finger electrode structure 324a located in the sensing region A1 and a connecting arm structure 324b located in the light absorbing region A2. The finger electrode structure 324a is in thermal contact with the infrared light sensing layer 323, and the finger electrode structure 324a is in electrical contact with the support element 310 through the connecting arm structure 324b.

[0061] Multiple metal elements 325 are disposed between the lower infrared light absorbing layer 321 and the upper infrared light absorbing layer 322, and these metal elements 325 are spaced apart from each other. Please refer to the above. Figure 5 ,for Figure 4 This is a partially enlarged schematic diagram of a microelectromechanical infrared light sensing device. These metal elements 325 are all located in the light absorption region A2, and at least some of the metal elements 325 are arranged periodically. The sensing electrode 324 is located on the same layer as these metal elements 325, and the metal elements 325 are electrically insulated from the sensing electrode 324. The sensing plate 320 also has multiple openings 326 formed at positions corresponding to the central holes 3251 of these metal elements 325, such that the metal elements 325 surround the corresponding openings 326. The openings 326 extend through the lower infrared light absorption layer 321, the central holes 3251, and the upper infrared light absorption layer 322, penetrating the sensing plate 320. The metal elements 325 are, for example, but not limited to, metal rings, and a portion of the inner wall surface of the opening 326 is the exposed inner ring surface 3252 of the metal ring; that is, the inner ring surface 3252 of the metal ring forms part of the hole wall surface of the opening 326. In this embodiment, each metal element 325 is a single square metal ring, while in other embodiments, the metal element may be a circular metal ring or other polygonal ring.

[0062] The phrase "metal element surrounding an opening" mentioned here includes situations where the central hole of the metal element is formed as part of the opening, and situations where the edge of the central hole of the metal element is spaced apart from the opening. Examples of the former include... Figure 4 , Figure 5 The central hole 3251 serves as part of the hole wall of the opening 326, an example of which is an infrared light absorbing layer filling the gap between the edge of the central hole and the opening, as in other embodiments.

[0063] The following describes the manufacturing method of the microelectromechanical infrared light sensing device 1. Please refer to the following instructions. Figures 6 to 13 ,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.

[0064] like Figure 6 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 about 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 dielectric layer (e.g., amorphous silicon with a thickness of 1000–1500 nanometers) is deposited on the substrate 10 and the infrared light reflective layer 20 as the sacrificial layer 50. Optionally, a protective layer (e.g., SiO2) can be formed on the infrared light reflective layer 20 before forming the dielectric layer. x (Material).

[0065] As shown in Figure 7 and Figure 8 , the support elements 310 are formed in the sacrificial layer 50. Specifically, portions of the sacrificial layer 50 are removed by etching to form through holes 510, and then the support elements 310 are formed in the through holes 510. A conductive material (e.g., tungsten) can be filled in the upper surface of the sacrificial layer 50 and the through holes 510, and portions of the conductive material on the upper surface of the sacrificial layer 50 are removed to form the support elements 310. More specifically, a chemical-mechanical planarization (CMP) process can be used to remove portions of the conductive material and portions of the sacrificial layer 50 to form the support elements 310, thereby ensuring that the upper surface of the sacrificial layer 50 is sufficiently planar.

[0066] Then, the inductive plate 320 is formed on the sacrificial layer 50. As shown in Figure 9 , the lower infrared light absorbing layer 321 of the inductive plate 320 is formed on the sacrificial layer 50. Specifically, a silicon oxide layer with a thickness of about 40-100 nanometers is first deposited to cover the support elements 310 and the sacrificial layer 50, in which the silicon oxide layer and a silicon nitride layer are respectively used as a first lower infrared light absorbing sub-layer 321a and a second lower infrared light absorbing sub-layer 321b of the lower infrared light absorbing layer 321.

[0067] As shown in Figure 10 , the sensing electrode 324 and the metal element 325 of the inductive plate 320 are formed on the lower infrared light absorbing layer 321. Specifically, after the aforementioned step of depositing the silicon oxide layer and the silicon nitride layer to form the lower infrared light absorbing layer 321, portions of the silicon oxide layer and the silicon nitride layer are removed by etching to expose the support elements 310; or, before the aforementioned step of depositing the silicon oxide layer and the silicon nitride layer, the support elements 310 are covered with a mask before the deposition process is performed, so that the support elements 310 can be exposed after the deposition process is completed. Then, a conductive layer (e.g., titanium nitride with a thickness of about 50-100 nanometers) is deposited on the upper surface of the lower infrared light absorbing layer 321 and the support elements 310, and then the conductive layer is patterned by etching to form the sensing electrode 324 and the metal element 325. The patterning can be performed by a photolithography process and / or an etching process.

[0068] Referring to Figure 5 and Figure 10 , the metal element 325 has the following specifications and configurations: the outermost diameter d (i.e., twice the radial length from the center of the metal ring to the edge of the metal ring) of each metal ring is 1.3-1.5 micrometers, the width W of the metal ring is 0.1-0.15 micrometers, the thickness t of the metal ring is 50-70 nanometers, and the center-to-center distance Dint between adjacent metal rings is three times the outermost diameter d of the metal ring.

[0069] like Figure 11 As shown, an infrared light sensing layer 323 of the sensing plate 320 is formed on the sensing electrode 324. 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 324, and then the material layer is etched to pattern it so as to form the infrared light sensing layer 323 above the finger electrode structure 324a of the sensing electrode 324. The area where the material layer is removed by etching can be defined as the light absorption area A2 of the sensing plate 320, and the location of the infrared light sensing layer 323 and the finger electrode structure 324a can be defined as the sensing area A1. Figure 10 and Figure 11 The illustration shows the formation of the sensing electrode 324 followed by the formation of the infrared light sensing layer 323, but the invention is not limited thereto. In other embodiments, the infrared light sensing layer may be formed first, followed by the sensing electrode. Furthermore, the patterning may be performed using photolithography and / or etching processes.

[0070] like Figure 12 As shown, an upper infrared light absorption layer 322 of the sensing plate 320 is formed on the infrared light sensing layer 323. Specifically, a silicon nitride layer with a thickness of about 100-170 nanometers is first deposited to cover the infrared light sensing layer 323 and the sensing electrode 324. Then, a silicon oxide layer with a thickness of about 40-100 nanometers is deposited on this silicon nitride layer. Next, the silicon oxide layer and the silicon nitride layer are patterned by etching to form a first upper infrared light absorption sublayer 322a and a second upper infrared light absorption sublayer 322b of the upper infrared light absorption layer 322. The patterning can be performed by photolithography and / or etching processes.

[0071] like Figure 13 As shown, portions of the lower infrared light absorbing layer 321, the upper infrared light absorbing layer 322, and each metal element 325 are removed to form the opening 326 and the elastic support 327 of the sensing plate 320. Next, the sacrificial layer 50 is removed by etching, thereby forming a gap between the lower infrared light absorbing layer 321 and the infrared light reflecting layer 20.

[0072] 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 sensing plate 320 is absorbed by the lower infrared light absorption layer 321 and the upper infrared light absorption layer 322, causing the temperature of the infrared light sensing layer 323 to rise. Consequently, the temperature of the sensing electrode 324, which is in thermal contact with the infrared light sensing layer 323, also rises. The increase in temperature of the sensing electrode 324 causes a change in its resistance value, thus allowing the readout circuit of the substrate 10 to obtain an electrical signal (such as a change in voltage or current).

[0073] In this embodiment, the metal elements 325 and the corresponding holes 326 in the light absorption region A2 help to improve the absorption rate of the sensing plate 320 for the infrared light waveband with a wavelength of 8-10 microns, especially for the infrared light waveband with a wavelength of 8-9 microns. Figure 14 For Figure 1 The absorption rate graph of the micro-electro-mechanical infrared light sensing device for different infrared light wavebands. The micro-electro-mechanical infrared light sensing device without metal elements and holes in the sensing plate is taken as a comparative example, and its absorption rate for the infrared light waveband with a wavelength of 8 microns is only 55%. Compared with the comparative example without metal elements and holes in the sensing plate, the sensing plate provided with the plurality of titanium nitride metal rings and the holes can effectively improve the absorption rate for the infrared light waveband with a wavelength of 8-10 microns, especially for the infrared light waveband with a wavelength of 8 microns, and the absorption rate is increased by at least 25% (from 55% to 82.5%). Figure 14 In this embodiment, the absorption rate for the infrared light waveband with a wavelength of 8 microns is increased from 55% to 82.5%, which is increased by 27.5%. In other embodiments of the present application, the same specification sensing plate formed by using different metal materials also proves to be able to improve the absorption rate. For example, the absorption rate of the sensing plate provided with the plurality of metal rings made of gold and the holes for the infrared light waveband with a wavelength of 8 microns is increased from 55% to 89%, and the absorption rate of the sensing plate provided with the plurality of metal rings made of copper and the holes for the infrared light waveband with a wavelength of 8 microns is increased from 55% to 91%.

[0074] In this embodiment, each infrared light absorption layer structure (lower infrared light absorption layer 321 and upper infrared light absorption layer 322) includes a plurality of infrared light absorption layers for absorbing different wavebands of infrared light energy. The infrared light absorption layer structure helps to improve the absorption rate to increase the fill factor value of the micro-electro-mechanical infrared light sensing device 1. In addition, the lower infrared light absorption layer 321 and the upper infrared light absorption layer 322 arranged symmetrically can have the same or similar material properties (such as the coefficient of thermal expansion or the Young's modulus), structure and size, so that the sensing plate 320 can be prevented from warping or generating excessive thermal stress during the manufacturing process of the infrared light sensing device 1, and the manufacturing yield of the micro-electro-mechanical infrared light sensing device 1 can be improved.

[0075] In addition, in the present embodiment, the sensing electrode 324 comprises a finger electrode structure 324a, and the finger electrode structure 324a has the advantages of short electrode spacing and low resistance value compared to conventional electrode structures, so the finger electrode structure 324a provides a smaller working area than conventional electrode structures to have a small enough noise equivalent temperature difference (NETD) to meet the thermal sensitivity requirements of the micro-electromechanical infrared light sensing device 1, in line with the miniaturization development trend. At the same time, due to the small size of the working area of the finger electrode structure 324a, the size of the infrared light sensing layer 323 overlapping the finger electrode structure 324a can also be reduced, which means that the working area of the infrared light absorbing layer for absorbing infrared light energy is increased, and the fill factor of the micro-electromechanical infrared light sensing device 1 is further increased.

[0076] Furthermore, in the manufacturing method disclosed in the present embodiment, the lower infrared light absorbing layer 321 of the sensing plate 320 is formed on the sacrificial layer 50, and the upper surface of the sacrificial layer 50 is processed by a chemical mechanical planarization manufacturing process, so that after the sacrificial layer 50 is removed, the lower infrared light absorbing layer 321 has a flat surface on the side facing the infrared light reflecting layer 20. The lower infrared light absorbing layer 321 with a flat lower surface can ensure that the gap size between the sensing plate 320 and the infrared light reflecting layer 20 remains consistent, so that the micro-electromechanical infrared light sensing device 1 can achieve optimal sensing performance, and the symmetrically configured infrared light absorbing stack structure design can further improve the manufacturing yield of the micro-electromechanical infrared light sensing device 1.

[0077] In the embodiment shown in Figures 1 to 5 , the area of the infrared light sensing layer 323 in the sensing plate 320 is smaller than the area of the upper and lower infrared light absorbing layers 322, 321, and the opening 326 of the sensing plate 320 extends through the upper and lower infrared light absorbing layers 322, 321 and does not extend through the infrared light sensing layer 323, but the present application is not limited thereto.

[0078] Figure 15FIG. 6 is a perspective view of a micro-electro-mechanical infrared light sensing device according to another embodiment of the present application. In this embodiment, the micro-electro-mechanical infrared light sensing device 2 includes a substrate 10, an infrared light reflecting layer 20, and an infrared light sensing element 30". The infrared light sensing element 30" includes a support element 310 and a sensing plate 320", and the sensing plate 320" includes at least one infrared light absorbing layer 321", an infrared light sensing layer 323", sensing electrodes 324", and metal elements 325". The infrared light sensing layer 323" is disposed on the infrared light absorbing layer 321" and covers all areas of the infrared light absorbing layer 321". The sensing electrodes 324" include a plurality of finger electrodes. The apertures 326" of the sensing plate 320" extend through the infrared light sensing layer 323" and the infrared light absorbing layer 321". Each metal element 325" is a single metal ring surrounding a corresponding aperture 326", and the inner surface of the metal ring forms part of the aperture wall surface of the aperture 326".

[0079] In this embodiment, the metal elements 325" and the apertures 326" are spaced apart on all areas of the sensing plate 320". Further, for a working area A3 defined by some of the finger electrodes of the sensing electrodes 324", the infrared light absorbing layer 321" and the infrared light sensing layer 323" of the sensing plate 320" cover the entire working area A3. After forming the infrared light absorbing layer 321", the infrared light sensing layer 323", and the metal elements 325", some of the infrared light sensing layer 323", some of the infrared light absorbing layer 321", and some of the metal elements 325" can be removed to form the apertures 326". In any working area A3, the metal elements 325" and the apertures 326" are periodically arranged. As shown in FIG. 6, the spacing distance between two metal elements 325" of different working areas A3 can depend on the width of the finger electrodes of the sensing electrodes 324". Figure 15

[0080] In summary, according to the micro-electro-mechanical infrared light sensing device and the manufacturing method thereof disclosed in the present application, the sensing plate of the infrared light sensing element includes, in addition to the infrared light absorbing layer, a plurality of metal elements spaced apart and a plurality of apertures surrounded by the metal elements. The metal elements help to improve the absorption rate of the sensing plate for the infrared light wavelength band of 8-10 microns, especially for the infrared light wavelength band of 8-9 microns. In combination with the high absorption rate of the infrared light absorbing layer itself for the infrared light wavelength band of 10-12 microns, the requirement of the infrared light sensing element for high absorption rate for a wide infrared light wavelength band is satisfied.​

Claims

1. A micro-electro-mechanical infrared light sensing device, comprising a substrate and an infrared light sensing element disposed above the substrate, and the infrared light sensing element comprises: a sensing plate, comprising at least one infrared light absorbing layer, an infrared light sensing layer, a sensing electrode, and a plurality of metal elements, the sensing plate having a plurality of openings, the metal elements each surrounding the openings, the sensing electrode connected to the infrared light sensing layer, and the metal elements spaced apart from each other; and at least one supporting element connecting the sensing plate and the substrate.

2. The micro-electro-mechanical infrared light sensing device of claim 1, wherein the number of the at least one infrared light absorbing layer is two, and the infrared light sensing layer and the metal elements are located between the two infrared light absorbing layers.

3. The micro-electro-mechanical infrared light sensing device of claim 2, wherein the openings extend through the infrared light sensing layer and the two infrared light absorbing layers and are periodically arranged with equal spacing from each other, and the metal elements are periodically arranged with equal spacing from each other.

4. The micro-electro-mechanical infrared light sensing device of claim 1, wherein the metal elements are each a metal ring, and an inner surface of the metal ring forms part of a hole wall surface of the openings.

5. The micro-electro-mechanical infrared light sensing device of claim 1, wherein the sensing plate of the infrared light sensing element has a sensing region and a light absorbing region that do not overlap each other, the at least one infrared light absorbing layer is distributed throughout the sensing region and the light absorbing region, the infrared light sensing layer is located in the sensing region and does not extend to the light absorbing region, and the metal elements and the openings are both located in the light absorbing region.

6. The micro-electro-mechanical infrared light sensing device of claim 5, wherein the openings are periodically arranged with equal spacing from each other in the light absorbing region, and the metal elements are periodically arranged with equal spacing from each other in the light absorbing region.

7. The micro-electro-mechanical infrared light sensing device of claim 5, wherein the number of the at least one infrared light absorbing layer is two, and the infrared light sensing layer and the metal elements are located between the two infrared light absorbing layers, and the openings extend through the two infrared light absorbing layers and do not extend through the infrared light sensing layer.

8. The micro-electro-mechanical infrared light sensing device of claim 1, wherein the sensing electrode defines an operating region of the sensing plate, the at least one infrared light absorbing layer and the infrared light sensing layer are distributed throughout the entire operating region, and the metal elements and the openings are both spaced apart in the operating region.

9. The micro-electro-mechanical infrared light sensing device of claim 8, wherein the metal elements and the openings are periodically arranged in the operating region.

10. The micro-electro-mechanical infrared light sensing device of claim 1, wherein the sensing electrode and the metal elements are located in the same layer, the sensing electrode is in thermal contact with the infrared light sensing layer, and the sensing electrode is electrically insulated from the metal elements.

11. The micro-electro-mechanical infrared light sensing device of claim 2, wherein the two infrared light absorbing layers have the same thickness.

12. The micro-electro-mechanical infrared light sensing device of claim 2, wherein at least one of the two infrared light absorbing layers comprises a plurality of infrared light absorbing sub-layers, and the corresponding materials of the infrared light absorbing sub-layers are different from each other.

13. The micro-electro-mechanical infrared light sensing device of claim 2, wherein the sensing electrode is between the two infrared light absorbing layers, and the sensing electrode comprises an interdigitated electrode structure.

14. A method for fabricating a micro-electro-mechanical infrared light sensing device, comprising: forming a sacrificial layer on a substrate; forming at least one support element in the sacrificial layer; forming a sensing plate on the sacrificial layer, wherein the sensing plate comprises at least one infrared light absorbing layer, an infrared light sensing layer, a sensing electrode, and a plurality of metal elements, the sensing electrode is connected to the infrared light sensing layer and the at least one support element, and the metal elements are spaced apart from each other; forming a plurality of openings in the sensing plate, wherein the openings respectively pass through the metal elements; and removing the sacrificial layer.

15. The method for fabricating a micro-electro-mechanical infrared light sensing device of claim 14, wherein forming the openings in the sensing plate comprises: removing portions of the infrared light sensing layer, portions of the at least one infrared light absorbing layer, and portions of each of the metal elements to form the openings.

16. The method for fabricating a micro-electro-mechanical infrared light sensing device of claim 14, wherein forming the openings in the sensing plate comprises: removing portions of the at least one infrared light absorbing layer and portions of each of the metal elements to form the openings, and none of the openings extends through the infrared light sensing layer.

17. The method for fabricating a micro-electro-mechanical infrared light sensing device of claim 14, wherein forming the at least one support element in the sacrificial layer comprises: forming a plurality of through holes in the sacrificial layer; filling a conductive material in the through holes; and removing portions of the conductive material to form the at least one support element.

18. The method for fabricating a micro-electro-mechanical infrared light sensing device of claim 17, wherein the portions of the conductive material are removed by a chemical mechanical planarization process.

19. The method for fabricating a micro-electro-mechanical infrared light sensing device of claim 14, wherein forming the sensing plate on the sacrificial layer comprises: forming a lower infrared light absorbing layer of the at least one infrared light absorbing layer on the sacrificial layer; removing portions of the lower infrared light absorbing layer to expose the at least one support element; depositing a conductive layer on an upper surface of the lower infrared light absorbing layer and the at least one support element; and patterning the conductive layer to form the sensing electrode and the metal elements; and forming the infrared light sensing layer on the sensing electrode.

20. The method for fabricating a micro-electro-mechanical infrared light sensing device of claim 19, wherein forming the sensing plate on the sacrificial layer further comprises: forming an upper infrared light absorbing layer on the infrared light sensing layer and the lower infrared light absorbing layer. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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