TWI838706B - Far ir sensing device and manufacturing method thereof - Google Patents

Abstract

A far infrared (IR) sensing device includes a substrate, a light absorption layer, a sensing layer, a conductive layer, a plurality of pillars, an upper electrode, and a joint structure. The light absorption layer is disposed on the substrate, and the sensing layer is disposed in the light absorption layer. The conductive layer is disposed in the light absorption layer, wherein the conductive layer includes a lower electrode, a first support arm, a second support arm, and a connect portion for the upper electrode. The lower electrode is disposed below the sensing layer and is formed a continuous structure with the first support arm. The connect portion for the upper electrode is disposed below the sensing layer and is separated from the lower electrode, and the connect portion for the upper electrode is formed a continuous structure with the second support arm. The pillars are electrically connected to one end of the first support arm and the substrate and to one end of the second support arm and the substrate respectively, and form a heat insulation space between the light absorption layer and the substrate. The upper electrode is disposed on the sensing layer in the light absorption layer. The joint structure is electrically connected to the upper electrode and the connect portion for the upper electrode of the conductive layer.

Description

Far infrared sensing element and manufacturing method thereof

The present invention relates to a far infrared sensing technology, and in particular to a far infrared sensing element and a manufacturing method thereof.

An IR Micro-Bolometer is a temperature sensor that senses far infrared rays emitted by the human body and converts them into electrical signals for output.

At present, the far-infrared sensing electrodes used in far-infrared microthermal radiometers are generally planar interdigitated. The high resistance characteristics of the electrodes require that the number of holes be increased to reduce the impact of resistance on temperature sensing. However, increasing the number of electrode holes will also increase the surface area of the electrode, making it impossible to reduce the area of the overall far-infrared sensing element.

The present invention provides a far infrared sensor element having a small area and low resistance.

The present invention also provides a method for manufacturing a far infrared sensor element, which can manufacture a far infrared sensor element with a smaller area and low resistance.

The far infrared sensing element of the present invention comprises a substrate, a light absorbing layer, a sensing layer, a conductor layer, a plurality of pillars, an upper electrode and a bonding structure. The light absorbing layer is disposed on the substrate, and the sensing layer is disposed in the light absorbing layer. The conductor layer is disposed in the light absorbing layer, wherein the conductor layer has a lower electrode, a first branch arm, a second branch arm and an upper electrode connecting portion, wherein the lower electrode is located below the sensing layer and is a continuous structure with the first branch arm, the upper electrode connecting portion is located below the sensing layer and is separated from the lower electrode, and the upper electrode connecting portion is a continuous structure with the second branch arm. A plurality of pillars electrically connect one end of the first arm to the substrate and one end of the second arm to the substrate, respectively, and form a heat-insulating space between the light-absorbing layer and the substrate. An upper electrode is disposed in the light-absorbing layer on the sensing layer, and a bonding structure electrically connects the upper electrode to the upper electrode connection portion of the conductive layer.

In one embodiment of the present invention, the etching selectivity of the upper electrode is greater than the etching selectivity of the conductive layer and the light absorbing layer.

In one embodiment of the present invention, the far infrared sensor element further includes a reflective layer disposed on the surface of the substrate below the light absorbing layer.

In one embodiment of the present invention, the material of the sensing layer includes amorphous silicon or vanadium oxide (VO _x ).

In one embodiment of the present invention, the material of the conductive layer includes titanium nitride (TiN).

In one embodiment of the present invention, the material of the upper electrode includes indium tin oxide (ITO) or a combination of titanium nitride and tungsten.

In one embodiment of the present invention, the material of the light absorbing layer includes silicon nitride, silicon oxide or a combination thereof.

In one embodiment of the present invention, the bonding structure includes a first conductive plug, a second conductive plug and a wire. The first conductive plug is formed in the light absorbing layer and connected to the upper electrode connecting portion. The second conductive plug is formed in the light absorbing layer and connected to the upper electrode. The wire is formed on the light absorbing layer and connects the first conductive plug and the second conductive plug.

The manufacturing method of the far infrared sensing element of the present invention includes forming a sacrificial layer on a substrate, forming a plurality of pillars in the sacrificial layer, and forming a first light absorbing layer on the sacrificial layer and the plurality of pillars. Then, a conductive layer is formed on the first light absorbing layer, and a portion of the conductive layer is defined to form a lower electrode and an upper electrode connecting portion separated from each other. A sensing layer and an upper electrode are sequentially formed on the lower electrode, and then a second light absorbing layer is formed to cover the upper electrode, the sensing layer, and the conductive layer. An etching process is performed to define a first contact window, a second contact window, a first arm, and a second arm, wherein the first contact window exposes the upper electrode connection portion, the second contact window exposes the top surface of the upper electrode, the first arm and the lower electrode are continuous structures, the upper electrode connection portion and the second arm are continuous structures, and the portion other than the first arm and the second arm is used as a release hole to expose the sacrificial layer. A bonding structure is formed on the first contact window, the second contact window, and the second light absorption layer to electrically connect the upper electrode to the upper electrode connection portion of the conductive layer. The sacrificial layer is removed through the release hole.

In another embodiment of the present invention, the etching selectivity of the upper electrode is greater than the etching selectivity of the conductive layer, the first light absorption layer and the second light absorption layer.

In another embodiment of the present invention, the method for forming the sensing layer and the upper electrode comprises forming the sensing layer on the conductive layer and the first light absorbing layer, and then forming the upper electrode on the sensing layer. Forming a patterned mask layer at a predetermined position of the upper electrode. Performing an etching process to remove the sensing layer and the upper electrode outside the predetermined position. Then removing the mask layer.

In another embodiment of the present invention, the step of forming the bonding structure includes forming a first conductive plug and a second conductive plug in the first contact window and the second contact window, respectively, wherein the first conductive plug is connected to the upper electrode connection portion and the second conductive plug is connected to the upper electrode. Then, a conductive line is formed on the light absorbing layer to connect the first conductive plug and the second conductive plug.

In another embodiment of the present invention, the etching process further includes defining a plurality of third contact windows, which are formed at one end of the first arm and the second arm and penetrate through the first light absorbing layer to expose the top surfaces of the plurality of pillars.

In another embodiment of the present invention, while forming the first conductive plug and the second conductive plug, a plurality of third conductive plugs are further formed in the third contact windows to electrically connect one end of the first arm to the substrate and one end of the second arm to the substrate respectively.

Based on the above, the far infrared sensing element of the present invention improves the configuration of the electrode and the sensing layer, so that the sensing electrode of the far infrared sensing element is vertically distributed, so as to greatly reduce the area of the element and have the characteristics of low resistance. In addition, the manufacturing method of the present invention can simultaneously define the upper electrode connection part and the lower electrode and the support arm, and can simultaneously define the conductive plug connected to the upper electrode and the conductive plug connected to the support, thereby simplifying the manufacturing process steps.

In order to make the above features and advantages of the present invention more clearly understood, embodiments are specifically cited below and described in detail with reference to the accompanying drawings.

The following content provides many different implementations or examples for implementing different features of the present invention. Moreover, these examples are only illustrative and are not intended to limit the scope and application of the present invention. Furthermore, for the sake of clarity, the relative sizes (such as length, thickness, spacing, etc.) and relative positions of various regions or structural elements may be reduced or enlarged. In addition, similar or identical element symbols are used in various drawings to represent similar or identical elements or features.

1A and 1B are respectively a cross-sectional schematic diagram and a top view schematic diagram of a far infrared sensor element according to the first embodiment of the present invention, wherein FIG1A is drawn according to the section line A-A' of FIG1B .

Please refer to FIG. 1A and FIG. 1B simultaneously. The far infrared sensing element 10 of the first embodiment includes a substrate 100, a light absorbing layer 200, a sensing layer 310, a conductive layer 300, a plurality of pillars 104, an upper electrode 320, and a bonding structure 510. Although the substrate 100 is shown as a block, it should be known that in order to output the sensing signal (such as the resistance value) and analyze it, a transistor (not shown) and an internal connection (not shown) and other structures are generally arranged in the substrate 100. The light absorbing layer 200 is arranged on the substrate 100 to enhance the absorption of light. In this embodiment, the material of the light absorbing layer 200 includes silicon nitride, silicon oxide or a combination thereof, but the present invention is not limited thereto. The sensing layer 310 is disposed in the light absorbing layer 200 . In this embodiment, the material of the sensing layer 310 includes amorphous silicon (a-Si) or vanadium oxide (VO _x ).

Continuing to refer to FIG. 1A and FIG. 1B , the conductive layer 300 is disposed in the light absorbing layer 200, wherein the conductive layer 300 has a lower electrode 302, a first arm 306, a second arm 308, and an upper electrode connecting portion 304. The relative positions of the lower electrode 302, the first arm 306, the second arm 308, and the upper electrode connecting portion 304 are shown in FIG. 1B , and the light absorbing layer 200, the sensing layer 310, and the upper electrode 320 are omitted in the top view of FIG. 1B , so as to more clearly show the detailed structure of the conductive layer 300. The lower electrode 302 is located below the sensing layer 310 and is continuous with the first arm 306. The upper electrode connection portion 304 is located below the sensing layer 310 and is separated from the lower electrode 302. The upper electrode connection portion 304 is continuous with the second arm 308. In this embodiment, the material of the conductive layer 300 includes titanium nitride (TiN), however, the present invention is not limited thereto.

In FIG1A , one support 104 electrically connects the first arm 306 to the substrate 100, and another support 104 electrically connects the second arm 308 to the substrate 100, and forms an insulating space between the light absorbing layer 200 and the substrate 100. In this embodiment, the insulating space can be filled with nitrogen (N ₂ ) or has air, however, the present invention is not limited thereto, and the insulating space can also be in a vacuum state. In this embodiment, the first arm 306 and the second arm 308 are designed as a meandering structure, as shown in FIG1B , to further prevent heat output by increasing the path transmitted through a plurality of supports 104.

1A, the upper electrode 320 is disposed on the sensing layer 310. In the present embodiment, the material of the upper electrode 320 includes indium tin oxide (ITO) or a combination of titanium nitride and tungsten. The bonding structure 510 is used to electrically connect the upper electrode 320 to the upper electrode connection portion 304 of the conductive layer 300. In the present embodiment, the bonding structure 510 includes a first conductive plug 502, a second conductive plug 504, and a wire 508. The first conductive plug 502 is formed in the light absorbing layer 200 and connected to the upper electrode connection portion 304. The second conductive plug 504 is also formed in the light absorbing layer 200 and connected to the upper electrode 320. The wire 508 is formed on the light absorbing layer 200 and connects the first conductive plug 502 and the second conductive plug 504. In this embodiment, the material of the bonding structure 510 includes AlCu, however, the present invention is not limited thereto. Since the upper electrode 320 and the lower electrode 302 for sensing are vertically arranged, the area of the far infrared sensing element 10 can be greatly reduced and at the same time have the characteristics of low resistance.

The far infrared sensing element 10 of the first embodiment may further include a plurality of third conductive plugs 506 formed in the light absorbing layer 200, and respectively connecting the first arm 306 to the pillar 104 and connecting the second arm 308 to another pillar 104. Moreover, the third conductive plug 506 may be formed by the same process as the first conductive plug 502 and the second conductive plug 504, so that the complexity of the process is not increased. Furthermore, since there are other components and internal connections (not shown) on the substrate 100, the first conductive plug 502, the second conductive plug 504 and the third conductive plug 506 may be manufactured together with the pad above the internal connection structure, without the need for redundant masking processes. Therefore, in this embodiment, the semiconductor process can be integrated so that the sensing layer 310 is electrically connected to the first arm 306 through the lower electrode 302, and the first arm 306 outputs the sensing signal (such as the resistance value) through the third conductive plug 506 and the pillar 104; similarly, the sensing layer 310 is electrically connected to the second arm 308 through the upper electrode 320, the bonding structure 510, and the upper electrode connecting portion 304, and the second arm 308 outputs the sensing signal (such as the resistance value) through another third conductive plug 506 and another pillar 104. However, the present invention is not limited thereto, and the third conductive plug 506 may not be disposed between the first arm 306 and the pillar 104, but an opening exposing the pillar 104 may be formed in the light absorbing layer 200, and then the opening may be filled in the process of forming the conductive layer 300, so that the first arm 306 is directly electrically connected to the pillar 104. Similarly, the third conductive plug 506 may not be disposed between the second arm 308 and another pillar 104, and they may be directly electrically connected.

In this embodiment, the far infrared sensor element 10 further includes a reflective layer 106 disposed on the surface of the substrate 100 below the light absorbing layer 200. The reflective layer 106 is, for example, a metal layer, and can also serve as an internal connection of the far infrared sensor element 10, and is patterned to be connected to different pillars 104 but electrically isolated from each other. In addition, a silicon oxide (SiO _x ) film (not shown) can be covered on the reflective layer 106. FIG. 1A also shows a release hole 410, through which a sacrificial layer (not shown) below the light absorbing layer 200 can be etched during the manufacturing process to form an insulating space between the light absorbing layer 200 and the substrate 100. Moreover, in the present embodiment, if the etching selectivity of the upper electrode 320 and the sensing layer 310 are both greater than the etching selectivity of the lower electrode 302 and the etching selectivity of the light absorbing layer 200, the release hole 410 and the openings for forming the first conductive plug 502, the second conductive plug 504 and the third conductive plug 506 can be formed simultaneously during the manufacturing process of the far-infrared sensing element 10, thereby eliminating an additional mask process, thereby significantly reducing the manufacturing cost.

2 to 13 are schematic diagrams of a manufacturing process of a far infrared sensor element according to the second embodiment of the present invention, wherein FIGS. 2 to 5, 6A, 7 to 8, 9A, 10, 11A, 12A and 13 are schematic cross-sectional views; and FIGS. 6B, 9B, 11B and 12B are schematic top views of FIGS. 6A, 9A, 11A and 12A, respectively.

Referring to FIG. 2 , a substrate 100 is provided, and then a sacrificial layer 102 is formed on the surface of the substrate 100, wherein the material of the sacrificial layer 102 includes amorphous silicon. However, the present invention is not limited thereto, and polyimide can also be used as the sacrificial layer 102. In addition, a reflective layer (not shown) is formed on the substrate 100, wherein the position and material of the reflective layer can refer to the first embodiment, and will not be described in detail.

Then, referring to FIG. 3 , a plurality of pillars 104 are formed in the sacrificial layer 102, wherein the plurality of pillars 104 penetrate the sacrificial layer 102 and are connected to the substrate 100. The plurality of pillars 104 are formed by, for example, first forming a plurality of openings in the sacrificial layer 102, then forming titanium nitride on the surface of the openings as a barrier layer, then filling tungsten (W) in the openings, and removing the tungsten outside the openings by W CMP. However, the present invention is not limited thereto, and the material of the pillars 104 can also be changed as required.

4 , a first light absorbing layer 202 is formed on the sacrificial layer 102 and the plurality of pillars 104 , wherein the material of the first light absorbing layer 202 includes silicon nitride, silicon oxide or a combination thereof. The first light absorbing layer 202 is formed by, for example, chemical vapor deposition.

5, a conductive layer 300 is formed on the first light absorbing layer 202. In this embodiment, the conductive layer 300 is formed by, for example, chemical vapor deposition or sputtering. The material of the conductive layer 300 includes titanium nitride (TiN), however, the present invention is not limited thereto.

Then, please refer to FIG. 6A and FIG. 6B simultaneously. FIG. 6A is a schematic cross-sectional view of FIG. 6B along the section line B-B'. In this step, a portion of the conductive layer 300 is defined to form a lower electrode 302 and an upper electrode connecting portion 304 separated from each other. The method of forming the lower electrode 302 and the upper electrode connecting portion 304 is, for example, to first form a patterned photoresist (not shown) on the conductive layer 300, and use the photoresist as a mask to etch the conductive layer 300 to transfer the pattern to the conductive layer 300.

7 , a sensing layer 310 and an upper electrode 320 are sequentially formed on the first light absorbing layer 202 and the conductive layer 300. In this embodiment, the sensing layer 310 is made of amorphous silicon or vanadium oxide (VO _x ), and the upper electrode 320 is made of indium tin oxide (ITO) or a combination of titanium nitride and tungsten.

Next, referring to FIG. 8 , in order to define the upper electrode 320 , a mask layer 330 is formed at a predetermined position thereon, wherein the mask layer 330 may be silicon nitride or photoresist.

Then, please refer to FIG. 9A and FIG. 9B at the same time. FIG. 9A is a schematic cross-sectional view of FIG. 9B along the section line C-C'. The mask layer 330 in the previous figure is used as an etching mask to remove the sensing layer 310 and the upper electrode 320 outside the predetermined position. After removing the mask layer 330, the sensing layer 310 and the upper electrode 320 formed at the predetermined position will only cover the lower electrode 302 of the conductive layer 300 (as shown in the dotted line portion in FIG. 9B), exposing the rest of the conductive layer 300 and the upper electrode connecting portion 304.

Then, referring to FIG. 10 , a second light absorbing layer 204 is formed to cover the upper electrode 320, the sensing layer 310, and the conductive layer 300. In this embodiment, the second light absorbing layer 204 is made of the same material as the first light absorbing layer 202, so the first light absorbing layer 202 plus the second light absorbing layer 204 constitute the light absorbing layer 200, however, the present invention is not limited thereto, and the material of the first light absorbing layer 202 and the material of the second light absorbing layer 204 may also be different.

Then, please refer to FIG. 11A and FIG. 11B at the same time. FIG. 11A is a schematic cross-sectional view of FIG. 11B along the section line D-D'. In this step, an etching process is performed to define the first contact window 402, the second contact window 404, the first arm 306 and the light absorption layer 200 covering the upper and lower sides thereof, and the second arm 308 and the light absorption layer 200 covering the upper and lower sides thereof. In FIG. 11B, the light absorption layer 200 in the sensing area is retained, while the light absorption layer 200 covering the upper and lower sides of the first arm 306 and the second arm 308 is omitted, so as to more clearly show the detailed structure of the first arm 306 and the second arm 308. The first contact window 402 in the sensing area penetrates the light absorbing layer 200 and the upper electrode connecting portion 304, and the second contact window 404 exposes the top surface of the upper electrode 320. The first arm 306 and the lower electrode 302 are continuous structures, the upper electrode connecting portion 304 and the second arm 308 are continuous structures, and the portion outside the first arm 306 and the second arm 308 is used as a release hole 410 to expose the sacrificial layer 102. In this embodiment, because the etching selectivity of the upper electrode 320 is greater than the etching selectivity of the conductive layer 300 and the light absorption layer 200, the first contact window 402, the second contact window 404 and the release hole 410 can be formed simultaneously through the same etching process, eliminating additional processes and masks, thereby significantly reducing the manufacturing cost. In other words, the process of forming the second contact window 404 will only penetrate the light absorption layer 200 on the top surface of the upper electrode 320, and the upper electrode 320 will hardly be etched during the entire etching process.

In the steps of FIG. 11A and FIG. 11B , the etching process may also include simultaneously defining a plurality of third contact windows 406, which are formed at the ends of the first arm 306 and the second arm 308 far from the lower electrode 302, and penetrate the light absorption layer 200 to expose the top surfaces of the plurality of pillars 104. Furthermore, since there are other components and internal connections (not shown) on the substrate 100, the first contact window 402, the second contact window 404, the release hole 410 and the opening of the pad above the internal connection structure can be manufactured together without unnecessary mask processes.

12A and 12B, FIG12A is a schematic cross-sectional view of FIG12B along the section line E-E'. A bonding structure 510 is formed on the first contact window 402, the second contact window 404 and the light absorbing layer 200 to electrically connect the upper electrode 320 to the upper electrode connecting portion 304 of the conductive layer 300. In this embodiment, the step of forming the bonding structure 510 includes forming a first conductive plug 502 and a second conductive plug 504 in the first contact window 402 and the second contact window 404, respectively, wherein the first conductive plug 502 is connected to the upper electrode connecting portion 304, and the second conductive plug 504 is connected to the upper electrode 320, and then forming a conductive line 508 on the light absorbing layer 200 to connect the first conductive plug 502 and the second conductive plug 504.

In this embodiment, while forming the first conductive plug 502 and the second conductive plug 504, a third conductive plug 506 may be formed in the third contact windows 406 to electrically connect one end of the first arm 306 to the substrate 100 and one end of the second arm 308 to the substrate 100 respectively.

Next, referring to FIG13 , the sacrificial layer 102 (in FIG12A ) is completely removed through the release hole 410 to form an insulating space. In this embodiment, the insulating space may be filled with nitrogen (N ₂ ) or air, however, the present invention is not limited thereto, and the insulating space may also be in a vacuum state.

In summary, the far infrared sensing element of the present invention improves the configuration of the electrode and the sensing layer, so that the sensing electrode of the far infrared sensing element is vertically distributed, has a smaller area and has the characteristics of low resistance. In addition, the manufacturing method of the present invention can simultaneously define the upper electrode connection part, the lower electrode and the two arms, so that complex processes and redundant masks are not required, thereby achieving the effect of simplifying the process steps.

Although the present invention has been disclosed as above by the embodiments, they are not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the scope of the attached patent application.

10: Far infrared sensor element 100: Substrate 102: Sacrificial layer 104: Pillar 106: Reflection layer 200: Light absorption layer 202: First light absorption layer 204: Second light absorption layer 300: Conductor layer 302: Lower electrode 304: Upper electrode connection part 306: First arm 308: Second arm 310: Sensing layer 320: Upper electrode 402: First contact window 404: Second contact window 406: Third contact window 410: Release hole 502: First conductive plug 504: Second conductive plug 506: Third conductive plug 508: Conductor 510:Joint structure

FIG. 1A is a schematic cross-sectional view of a far infrared sensing element according to the first embodiment of the present invention. FIG. 1B is a schematic top view of the far infrared sensing element of FIG. 1A . FIG. 2 to FIG. 13 are schematic diagrams of the manufacturing process of a far infrared sensing element according to the second embodiment of the present invention.

10: Far infrared sensor element

100: Substrate

104: Pillar

106: Reflective layer

200: Light absorption layer

300: Conductor layer

302: Lower electrode

304: Upper electrode connection part

306: First arm

308: Second arm

310: Sensing layer

320: Upper electrode

502: First conductive plug

504: Second conductive plug

506: Third conductive plug

508: Conductor

510:Joint structure

Claims (14)

A far infrared sensing element comprises: a substrate; a light absorbing layer disposed on the substrate; a sensing layer disposed in the light absorbing layer; a conductor layer disposed in the light absorbing layer, wherein the conductor layer has a lower electrode, a first branch arm, a second branch arm and an upper electrode connecting portion, wherein the lower electrode is located below the sensing layer and is continuous with the first branch arm, the upper electrode connecting portion is located below the sensing layer and is separated from the lower electrode, and the upper electrode is connected to the upper electrode. The upper electrode portion is coplanar with the lower electrode, and the upper electrode connecting portion and the second arm are continuous structures; a plurality of pillars electrically connect one end of the first arm to the substrate and one end of the second arm to the substrate, and form a heat-insulating space between the light-absorbing layer and the substrate; an upper electrode is disposed in the light-absorbing layer on the sensing layer; and a bonding structure electrically connects the upper electrode to the upper electrode connecting portion of the conductive layer. A far infrared sensing element as described in claim 1, wherein the etching selectivity of the upper electrode is greater than the etching selectivity of the conductive layer and the light absorbing layer. The far infrared sensing element as described in claim 1 further includes a reflective layer disposed on the surface of the substrate below the light absorbing layer. The far infrared sensing element as claimed in claim 1, wherein the material of the sensing layer comprises amorphous silicon or vanadium oxide (VO _x ). A far infrared sensing element as described in claim 1, wherein the material of the conductive layer includes titanium nitride (TiN). A far infrared sensing element as described in claim 1, wherein the material of the upper electrode includes indium tin oxide (ITO) or a combination of titanium nitride and tungsten. A far infrared sensing element as described in claim 1, wherein the material of the light absorbing layer includes silicon nitride, silicon oxide or a combination thereof. The far infrared sensing element as described in claim 1, wherein the bonding structure includes: a first conductive plug formed in the light absorbing layer and connected to the upper electrode connecting portion; a second conductive plug formed in the light absorbing layer and connected to the upper electrode; and a conductive line formed on the light absorbing layer, connecting the first conductive plug and the second conductive plug. A method for manufacturing a far infrared sensor element, comprising: forming a sacrificial layer on a substrate; forming a plurality of pillars in the sacrificial layer; forming a first light absorbing layer on the sacrificial layer and the plurality of pillars; forming a conductive layer on the first light absorbing layer; defining a portion of the conductive layer to form a lower electrode and an upper electrode connecting portion separated from each other; forming a sensing layer and an upper electrode in sequence on the lower electrode; forming a second light absorbing layer to cover the upper electrode, the sensing layer and the conductive layer; performing an etching process to define a first contact window, a second contact window, a first arm and a second contact window; Two arms, wherein the first contact window exposes the upper electrode connection part, the second contact window exposes the top surface of the upper electrode, the first arm and the lower electrode are a continuous structure, the upper electrode connection part and the second arm are a continuous structure, and the first arm and the second arm are other than the second arm as a release hole to expose the sacrificial layer; a bonding structure is formed on the first contact window, the second contact window and the second light absorption layer to electrically connect the upper electrode to the upper electrode connection part of the conductive layer; and the sacrificial layer is removed through the release hole. A method for manufacturing a far infrared sensing element as described in claim 9, wherein the etching selectivity of the upper electrode is greater than the etching selectivity of the conductive layer, the first light absorbing layer, and the second light absorbing layer. The manufacturing method of the far infrared sensor element as described in claim 9, wherein the method of forming the sensing layer and the upper electrode comprises: forming the sensing layer on the conductive layer and the first light absorbing layer; forming the upper electrode on the sensing layer; forming a patterned mask layer at a predetermined position of the upper electrode; performing an etching process to remove the sensing layer and the upper electrode outside the predetermined position; and removing the mask layer. The manufacturing method of the far infrared sensing element as described in claim 9, wherein the step of forming the bonding structure includes: forming a first conductive plug and a second conductive plug in the first contact window and the second contact window respectively, the first conductive plug is connected to the upper electrode connection portion, and the second conductive plug is connected to the upper electrode; and forming a wire on the second light absorbing layer to connect the first conductive plug and the second conductive plug. The manufacturing method of the far infrared sensor element as described in claim 12, wherein the etching process further includes defining a plurality of third contact windows, formed at one end of the first arm and the second arm, and penetrating the first light absorbing layer to expose the top surfaces of the plurality of pillars. The manufacturing method of the far infrared sensor element as described in claim 13, wherein while forming the first conductive plug and the second conductive plug, it further includes forming a plurality of third conductive plugs in the plurality of third contact windows to electrically connect one end of the first arm to the substrate, and to electrically connect one end of the second arm to the substrate.

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