CN113023664B

CN113023664B - Photoelectric detection chip and preparation method thereof

Info

Publication number: CN113023664B
Application number: CN202110227413.3A
Authority: CN
Inventors: 李刚; 胡维; 李萍萍
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2021-03-01
Filing date: 2021-03-01
Publication date: 2023-08-29
Anticipated expiration: 2041-03-01
Also published as: CN113023664A

Abstract

The invention discloses a micro-electromechanical detection chip and a preparation method thereof. The micro-electromechanical detection chip comprises: a substrate; the air cavity is positioned on the first surface of the substrate, wherein the air cavity comprises a reticular structure film and a cavity, the reticular structure film covers the cavity, the reticular structure film is provided with at least one release hole, and the cavity is used for communicating different release holes; the suspension structure is located on the first surface of the substrate and covers the air cavity, wherein the suspension structure sequentially comprises a supporting layer and a photoelectric conversion device in a direction away from the air cavity. The technical scheme provided by the embodiment of the invention reduces the process difficulty of the micro-electromechanical detection chip.

Description

Photoelectric detection chip and preparation method thereof

Technical Field

The embodiment of the invention relates to the technical field of semiconductors, in particular to a photoelectric detection chip and a preparation method thereof.

Background

The Micro-Electro-Mechanical System (MEMS) photoelectric detection chip is used for absorbing optical signals with preset wavelength and converting the optical signals with the preset wavelength into corresponding electric signals, and has wide application in the photoelectric detection field.

The MEMS thermopile infrared sensor mostly adopts a silicon wafer back side corrosion technology to form a closed film structure, the scheme is that a bottom surface pattern is designed by utilizing a double-sided exposure technology, and then a thermopile infrared chip with the closed film structure is further obtained by etching a silicon substrate from the back side. Therefore, a front side release technology compatible with CMOS processes is preferred, employing a front side open release support film structure. However, it should be noted that before the front-side release technique, the thermopile pattern is completed, and additional protection measures are required to protect the complete structure of the device during the process of etching the cavity from the front side of the substrate through the opening, but the thermopile pattern is still damaged, which not only increases the manufacturing difficulty, but also increases the cost. In addition, due to the non-uniformity of the compressive stress of the suspended film, the problem of incomplete corrosion usually exists in the front release, the performance of a device can be influenced, and the risk of film breakage is easily caused, so that the difficulty of the front release process is greatly improved.

Therefore, the process difficulty is great for obtaining the micro-electromechanical detection chip with the quality meeting the standard.

Disclosure of Invention

In view of the above, the embodiment of the invention provides a photoelectric detection chip and a manufacturing method thereof, so as to solve the problems of membrane breakage and structure damage caused in the cavity releasing process in the prior art, and reduce the process difficulty of the micro-electromechanical photoelectric detection chip.

The embodiment of the invention provides a micro-electromechanical detection chip, which comprises:

a substrate;

the air cavity is positioned on the first surface of the substrate, wherein the air cavity comprises a mesh-shaped structure film and a cavity, the mesh-shaped structure film covers the cavity, and the mesh-shaped structure film is provided with at least one release hole, and the cavity is used for communicating different release holes; the suspension structure is located on the first surface of the substrate and covers the air cavity, wherein the suspension structure sequentially comprises a supporting layer and a photoelectric conversion device in a direction away from the air cavity.

The embodiment of the invention also provides a preparation method of the micro-electromechanical detection chip, which comprises the following steps:

providing a substrate;

forming an air cavity on the first surface of the substrate, wherein the air cavity comprises a mesh-shaped structure film and a cavity, the mesh-shaped structure film covers the cavity, the mesh-shaped structure film is provided with at least one release hole, and the cavity is used for communicating different release holes;

And forming a suspension structure on the first surface of the substrate, wherein the suspension structure covers the air cavity, and the suspension structure sequentially comprises a supporting layer and a photoelectric conversion device in a direction away from the air cavity.

According to the technical scheme, the air cavity comprises a reticular structure film and a cavity, the reticular structure film covers the cavity, the reticular structure film is provided with at least one release hole, the cavity is used for communicating different release holes, based on the structural arrangement, etching reactants can enter the substrate from the release holes formed in the reticular structure film in the air cavity, and therefore the cavity inside the substrate is formed. Therefore, the technical scheme can finish the preparation of the air cavity first and then finish the preparation of the suspension structure, compared with the prior art, the technical problem that the photoelectric conversion device in the suspension structure is easily damaged by the etching reactant in the process of forming the air cavity because the etching reactant enters the substrate from the release hole in the suspension structure after the suspension structure is formed is avoided, and the yield of the photoelectric conversion device in the suspension structure is improved and the process difficulty is reduced. In addition, according to the first aspect, based on the structural arrangement, the technical scheme does not need to form the release hole in the suspension structure, so that damage to the suspension structure when the release hole is formed is avoided. According to the second aspect, based on the structural arrangement, etching reactants directly enter the substrate from the release holes arranged on the reticular structure film in the air cavity, so that the substrate can be sufficiently etched, the technical problems that in the prior art, the etching reactants enter the substrate from the release holes in the suspension structure, the etching path is complex, and underetching or overetching exists are avoided. According to the third aspect, based on the structural arrangement, the suspension structure can be prepared after the air cavity is formed, so that the problem that etching reactants enter the substrate from the release holes in the suspension structure in the prior art, the supporting layer is damaged, the mechanical strength is reduced, and the photoelectric conversion device is not sufficiently supported is avoided.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:

FIG. 1 is a schematic structural diagram of a MEMS detection chip according to an embodiment of the present application;

FIG. 2 is a top view of the web film of FIG. 1;

FIG. 3 is a schematic structural diagram of another MEMS detection chip according to an embodiment of the present application;

FIG. 4 is a schematic structural diagram of another MEMS detection chip according to an embodiment of the present application;

FIG. 5 is a schematic structural diagram of another MEMS detection chip according to an embodiment of the present application;

FIG. 6 is a schematic structural diagram of another MEMS detection chip according to an embodiment of the present application;

FIG. 7 is a schematic flow chart of a method for manufacturing a MEMS detection chip according to an embodiment of the present application;

FIG. 8 is a flow chart corresponding to step 120 in FIG. 7;

FIG. 9 is a flowchart corresponding to step 130 in FIG. 7;

FIG. 10 is a schematic flow chart of another method for manufacturing a MEMS detection chip according to an embodiment of the present application;

FIG. 11 is a flowchart corresponding to step 140 in FIG. 10;

Fig. 12 to 15 are cross-sectional views corresponding to steps of a method for manufacturing a microelectromechanical probe chip according to an embodiment of the invention.

Detailed Description

The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.

As described in the background art above, the technological difficulty is great in obtaining a micro-electro-mechanical detection chip with quality meeting the standard by the front-side release technology based on the existing manufacturing method and the structural arrangement of the existing micro-electro-mechanical detection chip. For this reason, in the existing microelectromechanical optical detection chip, a release hole is usually formed in a suspension structure, so that after the suspension structure is formed, etching reactants enter the substrate from the release hole in the suspension structure, thereby forming an air cavity, and the photoelectric conversion device in the suspension structure is easily damaged by the etching reactants in the process of forming the air cavity.

Aiming at the technical problems, the embodiment of the invention provides the following technical scheme:

Fig. 1 is a schematic structural diagram of a microelectromechanical probe chip according to an embodiment of the present invention. Referring to fig. 1, the micro electro-mechanical detection chip includes: a substrate 10; an air cavity 11, the air cavity 11 being located on the first surface 10A of the substrate 10, wherein the air cavity 11 comprises a mesh film 110 and a cavity 111, the mesh film 110 covers the cavity 111, and the mesh film 110 is provided with at least one release hole 110A, the cavity 111 is used for communicating with different release holes 110A; a suspension structure 20, the suspension structure 20 being located on the first surface 10A of the substrate 10, the suspension structure 20 covering the air cavity 11, wherein the suspension structure 20 comprises, in order, a support layer 21 and a photoelectric conversion device 22 in a direction away from the air cavity 11.

Alternatively, referring to fig. 1, the cross-sectional dimension H of the release hole 110A perpendicular to the plane of the substrate 10 is greater than or equal to 10 micrometers and less than or equal to 30 micrometers, so that etching reactants can be ensured to enter the substrate 10 from the release hole 110A to form the cavity 111, and gas reactants can be prevented from entering the air cavity 11 during epitaxial growth, so that the material contained in the support layer 21 cannot be formed in the air cavity 11.

In this embodiment, the substrate 10 may be a silicon base. The support layer 21 may be any one of silicon oxide, silicon nitride, and a stack of silicon oxide and silicon nitride.

Compared with the prior art, which is limited to the structure arrangement of arranging the release holes in the suspension structure, the air cavity 11 comprises the mesh structure film 110 and the cavity 111, the mesh structure film 110 covers the cavity 111, the mesh structure film 110 is provided with at least one release hole 110A, the cavity 111 is used for communicating different release holes 110A, and based on the structure arrangement, etching reactants can enter the substrate 10 from the release holes 110A arranged on the mesh structure film 110 in the air cavity 11, so that the cavity 111 inside the substrate 10 is formed. Therefore, the above technical scheme can complete the preparation of the air cavity 11 first and then complete the preparation of the suspension structure 20, so that the problem that the photoelectric conversion device 22 in the suspension structure 20 is easily damaged by etching reactants in the process of forming the air cavity 11 due to the fact that etching reactants enter the substrate 10 from the release holes in the suspension structure 20 after the suspension structure 20 is formed is avoided, the yield of the photoelectric conversion device 22 in the suspension structure 20 is improved, and the process difficulty is reduced. Furthermore, in the first aspect, based on the above-described structural arrangement, the present solution does not require forming the release hole 110A in the suspension structure 20, and avoids damage to the suspension structure 20 when forming the release hole 110A. In the second aspect, based on the above structure arrangement, the etching reactant directly enters the substrate 10 from the release hole 110A formed in the mesh-shaped film 110 in the air cavity 11, so that the substrate 10 can be sufficiently etched, and the technical problems that the etching reactant enters the substrate 10 from the release hole in the suspension structure 20 in the prior art, the etching path is complex, and underetching or overetching exists are avoided. In the third aspect, based on the above structure arrangement, the suspension structure 20 can be prepared after the air cavity 11 is formed, so as to avoid the problem that the etching reactant enters the substrate 10 from the release hole in the suspension structure 20 in the prior art, the supporting layer 21 is damaged, the mechanical strength is reduced, and the photoelectric conversion device 22 is not sufficiently supported.

Alternatively, referring to fig. 1, the surface of the mesh film 110 adjacent to the cavity 111 is provided with an inverted triangle structure 100B, and the surface of the substrate 10 adjacent to the cavity 111 is provided with a regular triangle structure 100C.

Specifically, the substrate 10 is anisotropically etched using an etching process, and different crystal planes within the substrate 10 are etched at different speeds to form a mesh film 110 including an inverted triangle structure 100B, the substrate 10 including a regular triangle structure 100C, and a cavity 111 between the mesh film 110 including the inverted triangle structure 100B and the substrate 10 including the regular triangle structure 100C. Wherein the two inclined surfaces of the inverted triangle structure 100B are different crystal planes. The two inclined surfaces of the regular triangle structure 100C are different crystal planes. The mesh film 110 including the inverted triangle structure 100B has higher mechanical strength than the planar structure, and can improve stability, reliability, and durability of the mesh film 110 for supporting the suspension structure 20. For example, the reactant of the anisotropic wet etching process may be an alkaline solution such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH), which has different etching rates for the two inclined surfaces of the inverted triangle structure 100B, and simultaneously, the two inclined surfaces of the right triangle structure 100C.

Optionally, based on the above technical solution, the depth of the release hole 110A is greater than or equal to 1/2 of the thickness of the substrate 10 and less than or equal to 2/3 of the thickness of the substrate 10.

Specifically, the depth of the release holes 110A is too small to be less than 1/2 of the thickness of the substrate 10, resulting in etching reactants entering the substrate 10 from the release holes 110A provided on the mesh film 110, and the depth of the formed cavities 111 is too small, so that the thermal insulation effect on the hot end of the thermopile 220 is poor when the suspension structure 20 includes the thermopile 220. Increasing the depth of the relief holes 110A may reduce heat loss and achieve better thermal isolation of the thermopile structure. When the depth of the release hole 110A is too large to be greater than 2/3 of the thickness of the substrate 10, the mechanical properties of the substrate 10 are poor and insufficient to support the suspension structure 20.

Fig. 2 is a top view of the web film of fig. 1. Wherein fig. 2 shows a top view of 6 mesh films 110.

Alternatively, based on the above technical solution, referring to fig. 2, the cross-sectional shape of the release hole 110A in the plane of the mesh film 110 is a circle or a polygon.

Specifically, the etching reactant may enter the inside of the substrate 10 from the release holes 110A provided on the mesh-like structure film 110 to form the cavity 111. The cross-section of the release hole 110A on the plane of the mesh film 110 is circular or polygonal, and the shape is regular, so that the release hole is formed by an etching process.

Alternatively, based on the above technical solution, referring to fig. 2c and fig. 2d, the cross-sectional shape of the release hole 110A on the plane where the mesh film 110 is located is circular, and the release hole 110A encloses a plurality of concentric circles on the mesh film, so that the etching reactant can enter the substrate 10 from the release hole 110A disposed on the mesh film 110, and a columnar cavity 111 is formed. Specifically, the speed of the columnar cavity 111 may be formed by controlling the flow rate of the etching reactant, the interval between concentric rings, and the area of the release hole 110A.

Optionally, based on the above technical solution, referring to fig. 2c, the areas of the release holes 110A are the same, specifically, the areas of the release holes 110A are the same, so that the difficulty of etching different release holes 110A is reduced.

Alternatively, based on the above technical solution, referring to fig. 2d, the area of the release holes 110A far from the center of the mesh film 110 is smaller than the area of the release holes 110A near the center of the mesh film 110. Specifically, the area of the release hole 110A far from the center of the mesh film 110 is smaller than the area of the release hole 110A near to the center of the mesh film 110, that is, the etching rate of the etching reactant corresponding to the release hole 110A far from the center of the mesh film 110 is smaller than the etching rate of the etching reactant corresponding to the release hole 110A near to the center of the mesh film 110, so that the etching reactant can enter the substrate 10 from the release hole 110A provided on the mesh film 110 to form the cavity 111 with controllable edge shape.

Alternatively, based on the above technical solution, referring to fig. 2b, the cross-sectional shape of the release hole 110A on the plane where the mesh film 110 is located is square, and the release hole 110A encloses a block-shaped area in the mesh film 110. The square release holes 110A are relatively regular in shape, so that etching reactants can enter the substrate 10 from the release holes 110A formed in the mesh-like structure film 110 to form square cavities 111. In particular, the rate of formation of square cavity 111 may be controlled by controlling the flow rate of the etching reactants and the spacing between release holes 110A. The shapes of the release holes 110A are the same, reducing the difficulty of the process of etching different release holes 110A.

Alternatively, based on the above technical solution, referring to fig. 2a, 2e and 2f, the cross-sectional shape of the release holes 110A on the plane of the mesh film 110 is rectangular, and adjacent release holes 110A are arranged in parallel or vertically at a preset interval. Specifically, in the top view of the mesh film 110 shown in fig. 2a and 2f, adjacent release holes 110A are arranged in parallel. The rectangular release holes 110A are relatively regular in shape, so that etching reactants can enter the substrate 10 from the release holes 110A formed in the mesh-like structure film 110 to form square cavities 111. In particular, the rate of formation of square cavity 111 may be controlled by controlling the flow rate of the etching reactants and the spacing between release holes 110A. In the top view of the mesh film 110 shown in fig. 2e, the adjacent release holes 110A are vertically arranged at a preset interval, so as to achieve the effect of reducing the number of the release holes 110A, thereby improving the efficiency of etching the release holes 110A.

The orientation of the above release holes 110A on the plane of the mesh film 110 corresponds to the crystallographic orientation of the bottom silicon substrate, and by means of different arrangements and combinations of adjacent release holes 110A on the mesh film 110, etching reactants can enter the substrate 10 from the release holes 110A disposed on the mesh film 110, and the etching reactants effectively cross-etch adjacent cavities to form the cavity 111, so that the largest etching cavity effect is achieved by the surface opening with the smallest area, and good release and mechanical integrity of the mesh film 110 can be ensured after the etching process and the etching process are finished.

The specific structure of the suspension structure 20 in the microelectromechanical photo-detection chip is further refined below. Fig. 3 is a schematic structural diagram of another microelectromechanical probe chip according to an embodiment of the invention. Referring to fig. 3, the levitation structure 20 includes: a support layer 21, the support layer 21 being located on the first surface 10A side of the substrate 10, and the support layer 21 covering the air cavity 11; a thermopile 220, the thermopile 220 being located on a surface of the support layer 21 on a side remote from the air cavity 11; a passivation layer 221, the passivation layer 221 being located on a surface of the thermopile 220 on a side remote from the substrate 10; the infrared absorption layer 222, the infrared absorption layer 222 is located on the surface of the passivation layer 221 far away from the side of the thermopile 220, wherein the projection of the thermopile 220 on the substrate 10 surrounds the projection of the infrared absorption layer 222 on the substrate 10, one end of the thermopile 220 close to the infrared absorption layer 222 serves as a hot end, one end of the thermopile 220 far away from the infrared absorption layer 222 serves as a cold end, the cold end of the thermopile 220 serves as an electrode to guide an electric signal corresponding to an infrared light signal to the second surface 10B of the substrate 10 opposite to the first surface 10A through a conductive through hole, and the infrared absorption layer 222, the passivation layer 221 and the thermopile 220 form the photoelectric conversion device 22.

In this embodiment, the passivation layer 221 is used to protect the thermopile 220 and may provide a flat plane for when the infrared absorbing layer 222 is formed. Specifically, the infrared absorption layer 222 of the mems probe chip in this embodiment absorbs the infrared light signal, and the thermopile 220 converts the infrared light signal into a corresponding electrical signal. The principle in which the thermopile 220 converts infrared light signals into corresponding electrical signals is as follows:

based on the seebeck effect, the infrared absorption layer 222 absorbs the infrared light signal, a temperature difference occurs between the hot end and the cold end of the thermopile 220, the hot end of the thermopile 220 is close to the infrared absorption layer 222, the temperature of the hot end is higher than that of the cold end of the thermopile 220, and the hot end and the cold end of the thermopile 220 generate thermoelectric voltage so as to realize the function of converting the infrared light signal into a corresponding electric signal by the thermopile 220. The infrared absorbing layer 222 may be a metal film, a porous black metal, or a film stacked of silicon oxide, silicon nitride, or the like.

Alternatively, referring to fig. 3, the thermopile 220 includes a first conductive layer 220A and a second conductive layer 220B made of different conductive materials, and an insulating layer 223 disposed between the first conductive layer 220A and the second conductive layer 220B, the first conductive layer 220A being located on a surface of the support layer 21 on a side away from the substrate 10, and the second conductive layer 220B being located on a surface of the insulating layer 223 on a side away from the first conductive layer 220A. One end of the first conductive layer 220A near the infrared absorbing layer 222 and one end of the second conductive layer 220B near the infrared absorbing layer 222 are electrically connected as a hot end of the thermopile 220. The end of the first conductive layer 220A remote from the infrared absorbing layer 222 serves as the cold end of the thermopile 220 while multiplexing as the first electrode 220C of the thermopile 220, and the end of the second conductive layer 220B remote from the infrared absorbing layer 222 serves as the cold end of the thermopile 220 while multiplexing as the second electrode 220D of the thermopile 220. The first electrode 220C leads an electrical signal of the first electrode 220C to the second surface 10B of the substrate 10 through the first conductive via 10C. The second electrode 220D leads an electrical signal of the second electrode 220D to the second surface 10B of the substrate 10 through the second conductive via 10D. Optionally, the microelectromechanical probe chip further includes a first solder 12 and a second solder 13, where the first solder 12 is electrically connected to the first conductive via 10C, and the second solder 13 is electrically connected to the second conductive via 10D. The first conductive via 10C and the second conductive via 10D are filled with a conductive material 14, and an insulating layer 223 is provided between the conductive material 14 and the substrate 10. Alternatively, a solder resist layer 15 is provided on the second surface 10B of the substrate 10, and the solder resist layer 15 is provided with an opening structure exposing the first conductive via 10C and the second conductive via 10D. The arrangement of the first soldering portion 12 and the second soldering portion 13 can lead the thermoelectromotive force of the thermopile 220 to the second surface 10B of the substrate 10, and is convenient for the mems photoelectric detection chip to be electrically connected with an external device through an automated surface mounting process. The material of the first conductive layer 220A and the material of the second conductive layer 220B are two different electrical conductors or semiconductors, such as polysilicon, aluminum metal, and the like.

In order to further improve the light absorption efficiency of the near infrared absorption layer 222 for absorbing infrared light, the embodiment of the invention further provides the following technical scheme:

based on the above technical solution, referring to fig. 3, the microelectromechanical detecting chip further includes: the preset wavelength optical signal filter 30, the preset wavelength optical signal filter 30 is located on the surface of the suspension structure 20 far away from the air cavity 11, and is used for transmitting the preset wavelength optical signal and protecting the suspension structure 20 and the substrate 10.

Specifically, the preset wavelength optical signal filter 30 has light transmittance, and can transmit the preset wavelength optical signal, and block the transmission of the non-preset wavelength optical signal, so as to increase the transmittance of the preset wavelength optical signal, and further improve the photoelectric conversion efficiency of the micro electro-mechanical detection chip. In addition, the preset wavelength optical signal filter 30 may also be used to protect the suspension structure 20 and the substrate 10 from external forces.

Optionally, the preset wavelength optical signal filter 30 and the passivation layer 221 may be bonded together by the adhesive layer 40, where the suspension structure 20 and the preset wavelength optical signal filter 30 form a vacuum chamber, so that the influence of the fluctuation of the surrounding environment on the photoelectric detection performance of the photoelectric conversion device 22 in the suspension structure 20 may be reduced, and the distance between the preset wavelength optical signal filter 30 and the suspension structure 20 may be adjusted by adjusting the height of the adhesive layer 40.

The specific structure of the preset wavelength optical signal filter 30 is specifically refined below. On the basis of the above technical solution, referring to fig. 3, the preset wavelength optical signal filter 30 includes an optical antireflection film layer 31, a filter protection layer 32 and a metal reflection layer 33 that are sequentially stacked, where the optical antireflection film layer 31 is used for transmitting the preset wavelength optical signal and blocking the transmission of the non-preset wavelength optical signal; the optical filtering protection layer 32 is configured to transmit an optical signal with a preset wavelength, the optical filtering protection layer 32 includes a light-transmitting region 32A and a non-light-transmitting region 32B surrounding the light-transmitting region, the metal reflecting layer 33 is located on a surface of the optical filtering protection layer 32, which is far from the optical anti-reflection film layer 31, and the metal reflecting layer 33 is located on the non-light-transmitting region 32B; the optical anti-reflection film 31 is immediately adjacent to the suspension structure 20.

Specifically, the optical anti-reflection film layer 31 is configured to transmit an optical signal with a preset wavelength and block transmission of an optical signal with a non-preset wavelength, thereby increasing transmittance of the optical signal with the preset wavelength and further improving photoelectric conversion efficiency of the micro-electromechanical detection chip. The filter protection layer 32 is used to transmit a preset wavelength optical signal and protect the inner suspension structure 20 and the substrate 10. The metal reflective layer 33 is located in the non-transparent region 32B and can define the viewing angle of the mems probe chip, specifically, the metal reflective layer 33 can reflect the infrared radiation incident on the non-transparent region 32B from the outside back to the surrounding environment, and limit the incident light path within the range of the transparent region 32A, and then convert the incident light path into a corresponding electrical signal, so as to improve the photoelectric conversion efficiency of the mems probe chip. Illustratively, the material of the metal reflective layer 33 may be selected from metal aluminum having good reflective properties.

On the basis of the above technical solution, referring to fig. 3, a surface of a side of the filter protection layer 32 adjacent to the optical anti-reflection film layer 31 is provided with a groove 30A.

Specifically, the recess 30A forms a concave cavity structure on the surface of the side of the optical filter protection layer 32 adjacent to the optical anti-reflection film layer 31, so that the thickness of the light transmission area 32A of the optical filter protection layer 32 is reduced, the transmission distance of the optical signal in the optical filter protection layer 32 is reduced, the loss of the optical signal is further reduced, and the transmittance of the infrared light signal is increased.

Alternatively, referring to fig. 3, the longitudinal cross-sectional shape of the groove 30A is an inverted trapezoid. Specifically, the longitudinal section of the groove 30A is in an inverted trapezoid shape, and a certain included angle is formed between the side surface and the bottom surface of the groove 30A, so that the optical signal reflected to the side surface of the groove 30A can be reflected back into the range of the light transmission area 32A, and the photoelectric conversion efficiency of the micro-electromechanical detection chip is improved.

Fig. 4 is a schematic structural diagram of another microelectromechanical probe chip according to an embodiment of the invention. Wherein fig. 4b is a schematic structural view of the preset wavelength optical signal filter 30 shown in fig. 4 a. Fig. 5 is a schematic structural diagram of another microelectromechanical probe chip according to an embodiment of the invention. Wherein fig. 5b is a schematic structural view of the preset wavelength optical signal filter 30 shown in fig. 5 a. Fig. 6 is a schematic structural diagram of another microelectromechanical probe chip according to an embodiment of the invention. Wherein fig. 6b is a schematic structural view of the preset wavelength optical signal filter 30 shown in fig. 6 a.

On the basis of the above technical solution, referring to fig. 4, 5 and 6, a fresnel diffraction structure 32C is disposed on a surface of the filter protection layer 32 on a side far away from the optical anti-reflection film layer 31, and the fresnel diffraction structure 32C is used for focusing the optical signal with the preset wavelength onto the infrared absorption layer 222.

Illustratively, referring to FIGS. 4, 5 and 6, the projection of the Fresnel diffraction structure 32C onto the substrate 10 overlies the infrared absorbing layer 222. The fresnel diffraction structure 32C is configured to focus an optical signal with a preset wavelength onto the infrared absorption layer 222, so that the intensity of the infrared absorption layer 222 for absorbing the infrared signal is increased, and the photoelectric conversion efficiency of the micro-electromechanical detection chip is improved.

Alternatively, referring to fig. 4, 5 and 6, the fresnel diffraction structure 32C includes a central region, and at least one annular slit surrounding the central region.

It should be noted that, referring to fig. 4b, the fresnel diffraction structure 32C includes a central region a, and at least one annular slit surrounding the central region, and the annular slits are respectively an annular slit b, an annular slit d, and an annular slit f. Referring to fig. 5b, the fresnel diffraction structure 32C includes a central region a, and at least one annular slit surrounding the central region, the annular slits being an annular slit b, an annular slit d, an annular slit f, and an annular slit h, respectively. Referring to fig. 6b, the fresnel diffraction structure 32C includes a central region a, and at least one annular slit surrounding the central region, the annular slits being an annular slit b, an annular slit d, an annular slit f, and an annular slit h, respectively. Wherein the radial distance of the annular slit from the central area a is related to the wavelength of the preset wavelength optical signal, the distance (focal length) of the bottom surface of the central area a from the infrared absorbing layer 222.

Alternatively, referring to fig. 4, 5 and 6, the center of the annular slit coincides with the center of the central region a.

Alternatively, the annular slit comprises a circular annular slit or a polygonal annular slit. I.e. the slit with a circular cross-sectional shape of the annular slit is a circular annular slit. The cross section of the annular slit is polygonal, and the polygonal annular slit is formed.

Optionally, the fresnel diffraction structure further comprises a slit spacing region, the slit spacing region being located between two adjacent annular slits.

Referring to FIG. 4, the Fresnel diffraction structure 32C also includes slit spacing regions that are located between adjacent two annular slits. Wherein the slit spacing region c is located between the adjacent two annular slits b and d and the slit spacing region e is located between the adjacent two annular slits d and f. The slit interval region g serves to isolate the annular slit f.

Referring to fig. 5, the fresnel diffraction structure 32C further includes a slit spacing region located between two adjacent annular slits. Wherein the slit spacing region c is located between the adjacent two annular slits b and d, the slit spacing region e is located between the adjacent two annular slits d and f, and the slit spacing region g is located between the adjacent two annular slits f and h.

Note that, the fresnel diffraction structure 32C shown in fig. 4 and 6 is a circular slit formed by etching the filter protection layer 32. The fresnel diffraction structure 32C shown in fig. 5 is a fresnel diffraction structure 32C obtained by patterning and etching a metal film layer formed on a surface of the filter protection layer 32 on a side away from the optical antireflection film layer 31.

The embodiment of the invention also provides a preparation method of the micro-electromechanical detection chip. Fig. 7 is a schematic flow chart of a method for manufacturing a microelectromechanical probe chip according to an embodiment of the invention. Fig. 12 to 15 are cross-sectional views corresponding to steps of a method for manufacturing a microelectromechanical probe chip according to an embodiment of the invention. Referring to fig. 7, the method for manufacturing the micro-electro-mechanical detection chip includes the following steps:

step 110, providing a substrate.

Referring to fig. 12a, a substrate 10 is provided. In this embodiment, the substrate 10 may be illustratively a monocrystalline silicon material.

Step 120, forming an air cavity on the first surface of the substrate, wherein the air cavity comprises a mesh-shaped film and a cavity, the mesh-shaped film covers the cavity, and the mesh-shaped film is provided with at least one release hole, and the cavity is used for communicating different release holes.

Referring to fig. 12b, an air cavity 11 is formed at the first surface 10A of the substrate 10, wherein the air cavity 11 includes a mesh film 110 and a cavity 111, the mesh film 110 covers the cavity 111, and the mesh film 110 is provided with at least one release hole 110A, the cavity 111 is used to communicate with different release holes 110A.

And 130, forming a suspension structure on the first surface of the substrate, wherein the suspension structure covers the air cavity, and the suspension structure sequentially comprises a supporting layer and a photoelectric conversion device in a direction away from the air cavity.

Referring to fig. 12c, a suspension structure 20 is formed on the first surface 10A of the substrate 10, the suspension structure 20 covering the air cavity 11, wherein the suspension structure 20 sequentially includes a support layer 21 and a photoelectric conversion device 22 in a direction away from the air cavity 11.

Compared with the prior art, the method for forming the micro-electromechanical detection chip comprises the steps of providing a substrate, forming a suspension structure on the first surface of the substrate, arranging a release hole in the suspension structure, and finally enabling etching reactants to enter the substrate from the release hole in the suspension structure, so that an air cavity is formed, and the photoelectric conversion device in the suspension structure is easily damaged by the etching reactants in the process of forming the air cavity.

In the technical solution of this embodiment, the forming order of the air cavity 11 and the suspension structure 20 is changed, and before the suspension structure 20 is formed, the air cavity 11 is formed on the first surface 10A of the substrate 10, where the air cavity 11 includes a mesh-like structure film 110 and a cavity 111, the mesh-like structure film 110 covers the cavity 111, and the mesh-like structure film 110 is provided with at least one release hole 110A, and the cavity 111 is used for communicating with different release holes 110A. Therefore, the above technical scheme can complete the preparation of the air cavity 11 first and then complete the preparation of the suspension structure 20, thereby avoiding the technical problem that the photoelectric conversion device 22 in the suspension structure 20 is easily damaged by etching reactants in the process of forming the air cavity 11 because etching reactants enter the substrate 10 from the release holes in the suspension structure 20 to form the air cavity after the suspension structure 20 is formed in the prior art, further improving the yield of the photoelectric conversion device 22 in the suspension structure 20 and reducing the process difficulty. Furthermore, in the first aspect, based on the above-mentioned preparation method, the present solution does not need to form the release hole 110A in the suspension structure 20, so as to avoid damage to the suspension structure 20 when forming the release hole 110A. In the second aspect, based on the above preparation method, the etching reactant directly enters the substrate 10 from the release hole 110A provided on the mesh-shaped film 110 in the air cavity 11, so that the substrate 10 can be sufficiently etched, and the technical problems that the etching reactant enters the substrate 10 from the release hole in the suspension structure 20 in the prior art, the etching path is complex, and underetching or overetching exists are avoided. In the third aspect, based on the above preparation method, the suspension structure 20 may be prepared after the air cavity 11 is formed, so as to avoid the problem that the etching reactant enters the substrate 10 from the release hole in the suspension structure 20 in the prior art, the supporting layer 21 is damaged, the mechanical strength is reduced, and the supporting of the photoelectric conversion device 22 is insufficient.

Fig. 8 is a flow chart corresponding to step 120 in fig. 7. Based on the above technical solution, referring to fig. 8, step 120 of forming an air cavity on the first surface of the substrate includes:

step 1201, forming a dielectric layer on a first surface of a substrate.

Referring to fig. 13a, the substrate 10 may be monocrystalline silicon, and the dielectric layer 16 may be formed on the first surface 10A of the substrate 10 by a deposition process, and the dielectric layer may be a silicon oxide or silicon nitride layer. The deposition process includes Low Pressure Chemical Vapor Deposition (LPCVD), plasma chemical vapor deposition (PECVD), or a thermal oxidation process.

Step 1202, performing patterning etching on the dielectric layer to form at least one groove.

Referring to fig. 13b, the dielectric layer 16 may be patterned etched by photolithography, dry etching, or wet etching processes to form a mask pattern of the mesh-structured film 110 including at least one recess 16A.

Step 1203, forming at least one release hole on the first surface of the substrate, wherein the release hole is communicated with the groove.

Referring to fig. 13c, a deep reactive ion silicon etching process (DRIE) may be used to etch the first surface 10A of the substrate 10, wherein at least one release hole 110A is formed due to the etch selectivity of the etching process to the dielectric layer 16 and the substrate 10, wherein the release hole 110A is in communication with the recess 16A. The size and shape of the release hole 110A may be determined according to the process and design requirements.

And 1204, forming an air cavity on the first surface of the substrate by adopting an etching process, wherein the etching process comprises an anisotropic deep reactive ion etching process and/or an anisotropic wet etching process, reactants of the anisotropic deep reactive ion etching process and/or the anisotropic wet etching process enter the substrate along release holes to form the mesh-shaped structure film and the cavity, the mesh-shaped structure film covers the cavity, and the mesh-shaped structure film is provided with at least one release hole, and the cavity is used for communicating different release holes.

Referring to fig. 13d, an etching process is used to form an air cavity 11 on the first surface 10A of the substrate 10, wherein the etching process includes an anisotropic deep reactive ion etching process and/or an anisotropic wet etching process, reactants of the anisotropic deep reactive ion etching process and/or the anisotropic wet etching process enter the inside of the substrate 10 along the release holes 110A, a portion of the monocrystalline silicon substrate under the dielectric layer 16 is etched and/or corroded away to form a mesh-like structure film 110 and a cavity 111, the mesh-like structure film 110 covers the cavity 111, and the mesh-like structure film 110 is provided with at least one release hole 110A, and the cavity 111 is used to communicate with different release holes 110A. Illustratively, the reactants of the anisotropic wet etch process may be an alkaline solution such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH). In the anisotropic wet etching process alone, the mesh film 110 forms a shrinkage end facing the cavity 111 due to the anisotropy of the etching solution, and in this embodiment, the shrinkage end has an inverted triangle shape along a section parallel to the vertical plane, and the section may have other shapes such as a rectangle. When an anisotropic Deep Reactive Ion Etching (DRIE) process is used alone, reactive ions are injected into the silicon substrate 10 through the release holes 110A to etch, and the mesh-structure thin film 110 and the cavity 111 can be obtained through appropriate process parameters.

Step 1205, removing the dielectric layer.

Referring to fig. 13e, the dielectric layer 16 may be removed by a dry etching or wet etching process, such that the mesh film 110 is exposed. Wherein the etching liquid of the wet etching may be buffered hydrofluoric acid (BOE).

Optionally, on the basis of the above technical solution, forming the air cavity on the first surface of the substrate in step 1204 by using an etching process includes:

referring to fig. 13d, the first surface 10A of the substrate 10 is anisotropically etched using an etching process to form a mesh film 110 including an inverted triangle structure 100B, the substrate 10 including a regular triangle structure 100C, and a cavity 111 between the mesh film 110 including the inverted triangle structure 100B and the substrate 10 including the regular triangle structure 100C, wherein a surface of the mesh film 110 adjacent to the cavity 111 is provided with the inverted triangle structure 100B, and a surface of the substrate 10 adjacent to the cavity is provided with the regular triangle structure.

In particular, the mesh film 110 including the inverted triangle structure 100B has higher mechanical strength than the planar structure, and can improve stability, reliability and durability of the mesh film 110 for supporting the suspension structure 20. Illustratively, the reactants of the anisotropic wet etch process may be an alkaline solution such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH).

The method of fabricating the suspended structure 20 in the microelectromechanical photo-detection chip is further detailed below. Fig. 9 is a flow chart corresponding to step 130 in fig. 7. Based on the above technical solution, referring to fig. 9, step 130 of forming a suspension structure on the first surface of the substrate includes:

step 1301, forming a supporting layer on the first surface side of the substrate, wherein the supporting layer covers the air cavity;

referring to fig. 14a, a support layer 21 is formed on the first surface 10A side of the substrate 10, the support layer 21 covering the air cavity 11. When the substrate 10 is monocrystalline silicon, the network structure film 110 may be used as a seed crystal, and a monocrystalline silicon film layer may be formed by an epitaxial monocrystalline silicon process. Since the cross-sectional dimension of the release hole 110A in the plane perpendicular to the substrate 10 is greater than or equal to 10 μm and less than or equal to 30 μm, it is difficult for the gaseous reactant to enter the inside of the air cavity 11 during epitaxial growth, so that a single crystal silicon thin film layer is not formed inside the air cavity 11, and a complete single crystal silicon thin film layer is always obtained due to isotropy of the deposition process. Thereafter, the monocrystalline silicon thin film layer is oxidized by a thermal oxidation process to obtain the support layer 21. And the thickness of the supporting layer 21 can be controlled according to the technological parameters, so that the supporting layer 21 is ensured to be within the preset thickness range, and the supporting structure 20 can be supported.

Step 1302, forming a thermopile on a surface of a side of the support layer remote from the air cavity.

Referring to fig. 14B and 14c, a first conductive layer 220A in the thermopile 220 is formed on a surface of the support layer 21 on a side away from the air cavity 11, and then an insulating layer 223 covering the first conductive layer 220A and a second conductive layer 220B in the thermopile 220 are sequentially formed.

And 1303, forming a passivation layer on the surface of the thermopile at the side far away from the substrate.

Referring to fig. 14c, a passivation layer 221 is formed on the surface of the thermopile on the side remote from the substrate. In this embodiment, the passivation layer 221 is used to protect the thermopile 220 and may provide a flat plane for when the infrared absorbing layer 222 is formed.

And 1304, forming an infrared absorption layer on the surface of one side of the passivation layer, which is far away from the thermopile, wherein the projection of the thermopile on the substrate surrounds the projection of the infrared absorption layer on the substrate, one end of the thermopile, which is close to the infrared absorption layer, is used as a hot end, one end of the thermopile, which is far away from the infrared absorption layer, is used as a cold end, the cold end of the thermopile is used as an electrode, an electric signal corresponding to an infrared light signal is led to a second surface, opposite to the first surface, of the substrate through a conductive through hole, and the infrared absorption layer, the passivation layer and the thermopile form a photoelectric conversion device.

Referring to fig. 14d, an infrared absorption layer 222 is formed on a surface of the passivation layer 221 on a side remote from the thermopile 220. Wherein the projection of the thermopile 220 on the substrate 10 surrounds the projection of the infrared absorption layer 222 on the substrate 10, one end of the thermopile 220 close to the infrared absorption layer 222 is used as a hot end, one end of the thermopile 220 far away from the infrared absorption layer 222 is used as a cold end, the cold end of the thermopile 220 is used as an electrode to guide an electric signal corresponding to an infrared light signal to the second surface 10B of the substrate 10 opposite to the first surface 10A through a conductive through hole, and the infrared absorption layer 222, the passivation layer 221 and the thermopile 220 form the photoelectric conversion device 22.

Optionally, referring to fig. 14e, after step 1304, the preparation of the first solder 12, the second solder 13, the first conductive via 10C, the second conductive via 10D, the conductive material 14, and the solder mask 15 is further included. Wherein, an end of the first conductive layer 220A near the infrared absorbing layer 222 and an end of the second conductive layer 220B near the infrared absorbing layer 222 are electrically connected as a hot end of the thermopile 220. The end of the first conductive layer 220A remote from the infrared absorbing layer 222 serves as the cold end of the thermopile 220 while multiplexing as the first electrode 220C of the thermopile 220, and the end of the second conductive layer 220B remote from the infrared absorbing layer 222 serves as the cold end of the thermopile 220 while multiplexing as the second electrode 220D of the thermopile 220. The first electrode 220C leads an electrical signal of the first electrode 220C to the second surface 10B of the substrate 10 through the first conductive via 10C. The second electrode 220D leads an electrical signal of the second electrode 220D to the second surface 10B of the substrate 10 through the second conductive via 10D. Optionally, the microelectromechanical probe chip further includes a first solder 12 and a second solder 13, where the first solder 12 is electrically connected to the first conductive via 10C, and the second solder 13B is electrically connected to the second conductive via 10D. The first conductive via 10C and the second conductive via 10D are filled with a conductive material 14, and an insulating material is provided between the conductive material 14 and the substrate 10. Alternatively, a solder resist layer 15 is provided on the second surface 10B of the substrate 10, and the solder resist layer 15 is provided with an opening structure exposing the first conductive via 10C and the second conductive via 10D. The arrangement of the first soldering portion 12 and the second soldering portion 13 can lead the thermoelectromotive force of the thermopile 220 to the second surface 10B of the substrate 10, and is convenient for the mems photoelectric detection chip to be electrically connected with an external device through an automated surface mounting process.

Fig. 10 is a schematic flow chart of a preparation method of another microelectromechanical probe chip according to an embodiment of the invention. On the basis of the above technical solution, referring to fig. 10, step 130 further includes, after forming the suspension structure on the first surface of the substrate:

and 140, forming a preset wavelength optical signal filter window on the surface of the side, far away from the air cavity, of the suspension structure.

Taking fig. 1 and 3 as an example for illustration, a preset wavelength optical signal filter 30 is formed on a surface of the suspension structure 20 on a side away from the air cavity 11.

Fig. 11 is a flow chart corresponding to step 140 in fig. 10. Based on the above technical solution, referring to fig. 11, forming, in step 140, a preset wavelength optical signal filter window on a surface of a side of the suspension structure away from the air cavity includes:

step 1401, forming a preset wavelength optical signal filter window, wherein the preset wavelength optical signal filter window comprises an optical antireflection film layer, a filtering protection layer and a metal reflecting layer which are sequentially laminated, and the optical antireflection film layer is used for transmitting the preset wavelength optical signal and blocking the transmission of the non-preset wavelength optical signal; the optical filter protection layer is used for transmitting the light signal with the preset wavelength and comprises a light transmission area and a non-light transmission area surrounding the light transmission area, the metal reflection layer is positioned on the surface of one side, far away from the optical antireflection film layer, of the optical filter protection layer, and the metal reflection layer is positioned in the non-light transmission area.

Referring to fig. 15a, a preset wavelength optical signal filter window is formed, wherein the preset wavelength optical signal filter window 30 includes an optical anti-reflection film layer 31, a filter protection layer 32 and a metal reflection layer 33, which are sequentially stacked, and the optical anti-reflection film 31 layer is used for transmitting preset wavelength optical signals and blocking transmission of non-preset wavelength optical signals; the optical filter protection layer 32 is configured to transmit an optical signal with a preset wavelength, the optical filter protection layer 32 includes a light-transmitting region 32A and a non-light-transmitting region 32B surrounding the light-transmitting region, the metal reflective layer 33 is located on a surface of the optical filter protection layer 32, which is far from the optical anti-reflection film layer 31, and the metal reflective layer 33 is located on the non-light-transmitting region 32B.

Alternatively, the groove 30A may be formed on the surface of the side of the filter protection layer 32 adjacent to the optical antireflection film layer 31. Specifically, the recess 30A forms a concave cavity structure on the surface of the side of the optical filter protection layer 32 adjacent to the optical anti-reflection film layer 31, so that the thickness of the light transmission area 32A of the optical filter protection layer 32 is reduced, the transmission distance of the optical signal in the optical filter protection layer 32 is reduced, the loss of the optical signal is further reduced, and the transmittance of the infrared light signal is increased. Alternatively, the longitudinal cross-sectional shape of the groove 30A is an inverted trapezoid. Specifically, the longitudinal section of the groove 30A is in an inverted trapezoid shape, and a certain included angle is formed between the side surface and the bottom surface of the groove 30A, so that the optical signal reflected to the side surface of the groove 30A can be reflected back into the range of the light transmission area 32A, and the photoelectric conversion efficiency of the micro-electromechanical detection chip is improved.

Alternatively, taking fig. 4, fig. 5, and fig. 6 as an example, a fresnel diffraction structure 32C may be further formed on a surface of the side of the filter protection layer 32 away from the optical anti-reflection film layer 31, where the fresnel diffraction structure 32C is used to focus an optical signal with a preset wavelength onto the infrared absorption layer 222, so as to improve the photoelectric conversion efficiency of the microelectromechanical optical detection chip.

Step 1402, forming an optical signal filter window with a preset wavelength on a side, far away from the supporting layer, of the suspension structure through a wafer-level low-temperature vacuum bonding process, wherein the optical anti-reflection film layer is closely adjacent to the suspension structure.

Referring to fig. 15b, on a side of the suspension structure 20 away from the supporting layer 21, a preset wavelength optical signal filter 30 is formed by a wafer level low temperature vacuum bonding process, wherein an optical anti-reflection film layer 31 is adjacent to the suspension structure 20.

Optionally, the preset wavelength optical signal filter 30 and the passivation layer 221 may be bonded together by the adhesive layer 40, where the suspension structure 20 and the preset wavelength optical signal filter 30 form a vacuum chamber, so that the influence of the fluctuation of the surrounding environment on the photoelectric detection performance of the photoelectric conversion device 22 in the suspension structure 20 can be reduced, the stability of the photoelectric conversion device 22 is improved, and the space between the preset wavelength optical signal filter 30 and the suspension structure 20 can be adjusted by adjusting the height of the adhesive layer 40.

The technical scheme provided by the embodiment of the invention is that a cavity structure is formed by releasing from the front surface, so that the problems that the etching window range and the thickness of a supporting film are difficult to control when etching is performed from the back surface of a silicon wafer can be overcome; on the other hand, compared with the prior art that firstly, the thermopile structure is formed, then the release hole on the supporting film structure is used for corroding the silicon substrate to form the cavity by utilizing the anisotropic wet etching (KOH/TMAH and the like) process or the isotropic dry etching process, the method has the advantages that firstly, the cavity structure is formed by etching on the silicon substrate, then the supporting part and the thermopile structure are formed, the damage of the post etching process to the existing thermopile structure is effectively avoided, the defects of underetching and overetching are overcome, the etching time is greatly shortened, the process difficulty is reduced, and the method is simple and practical. In addition, in the existing cavity releasing process, the supporting film is easy to break due to the problems of mismatch of tensile stress and corrosive liquid. The support film prepared according to the method is not affected in the subsequent etching or corrosion process, and the consistency and the uniformity are easy to control, so that a complete and uniform support film structure and a device are easy to obtain, and the problem of film breakage possibly existing in the post-etching process is effectively avoided.

Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.

Claims

1. A microelectromechanical probe chip, comprising:

a substrate;

the air cavity is positioned on the first surface of the substrate, wherein the air cavity comprises a mesh-shaped structure film and a cavity, the mesh-shaped structure film covers the cavity, and the mesh-shaped structure film is provided with at least one release hole, and the cavity is used for communicating different release holes;

the suspension structure is positioned on the first surface of the substrate and covers the air cavity, wherein the suspension structure sequentially comprises a supporting layer and a photoelectric conversion device in a direction away from the air cavity;

The preset wavelength optical signal filter window is positioned on the surface of one side, far away from the air cavity, of the suspension structure and is used for transmitting preset wavelength optical signals and protecting the suspension structure and the substrate;

the optical antireflection film layer is used for transmitting the optical signals with the preset wavelength and blocking the transmission of the optical signals with the non-preset wavelength; the optical filtering protection layer is used for transmitting light signals with preset wavelength, the optical filtering protection layer comprises a light transmission area and a non-light transmission area surrounding the light transmission area, the metal reflecting layer is positioned on the surface of one side, far away from the optical anti-reflection film layer, of the optical filtering protection layer, and the metal reflecting layer is positioned in the non-light transmission area; the optical anti-reflection film layer is closely adjacent to the suspension structure.

2. The microelectromechanical probe chip of claim 1, wherein the mesh film has an inverted triangular structure disposed adjacent to a surface of the cavity, and the substrate has a regular triangular structure disposed adjacent to a surface of the cavity.

3. The microelectromechanical probe chip of claim 1, characterized in that the depth of the release hole is greater than or equal to 1/2 of the thickness of the substrate and less than or equal to 2/3 of the thickness of the substrate.

4. The microelectromechanical probe chip of claim 1, characterized in that the cross-sectional shape of the release hole in the plane of the mesh film is circular or polygonal.

5. The microelectromechanical probe chip of claim 4, wherein the cross-sectional shape of the release holes in the plane of the mesh film is circular, and the release holes define a plurality of concentric rings in the mesh film.

6. The microelectromechanical probe chip of claim 5, characterized in that the areas of the release holes are the same;

alternatively, the area of the release holes away from the center of the mesh film is smaller than the area of the release holes near the center of the mesh film.

7. The microelectromechanical probe chip of claim 4, characterized in that the cross-sectional shape of the release hole in the plane of the mesh film is square, and the release hole encloses a block-shaped area in the mesh film;

or, the cross section of the release holes on the plane of the mesh-shaped structural film is rectangular, and the adjacent release holes are arranged in parallel or vertically at preset intervals.

8. The microelectromechanical probe chip of claim 1, characterized in that the suspension structure comprises:

a support layer located on the first surface side of the substrate, the support layer covering the air cavity;

the thermopile is positioned on the surface of one side, far away from the air cavity, of the supporting layer;

the passivation layer is positioned on the surface of one side of the thermopile away from the substrate;

the infrared absorption layer is positioned on the surface of one side, far away from the thermopile, of the passivation layer, wherein the projection of the thermopile on the substrate surrounds the projection of the infrared absorption layer on the substrate, one end, close to the infrared absorption layer, of the thermopile serves as a hot end, one end, far away from the infrared absorption layer, of the thermopile serves as a cold end, the cold end of the thermopile serves as an electrode to guide an electric signal corresponding to an infrared light signal to a second surface, opposite to the first surface, of the substrate through a conductive through hole, and the infrared absorption layer, the passivation layer and the thermopile form the photoelectric conversion device.

9. The preparation method of the micro-electromechanical detection chip is characterized by comprising the following steps of:

Providing a substrate;

forming a suspension structure on the first surface of the substrate, wherein the suspension structure covers the air cavity, and the suspension structure sequentially comprises a supporting layer and a photoelectric conversion device in a direction away from the air cavity;

forming a preset wavelength optical signal filter window on the surface of one side, far away from the air cavity, of the suspension structure, wherein the preset wavelength optical signal filter window is used for transmitting a preset wavelength optical signal and protecting the suspension structure and the substrate;

10. The method of claim 9, wherein forming an air cavity on the first surface of the substrate comprises:

forming a dielectric layer on the first surface of the substrate;

patterning and etching the dielectric layer to form at least one groove;

forming at least one release hole on the first surface of the substrate, wherein the release hole is communicated with the groove;

forming the air cavity on the first surface of the substrate by adopting an etching process, wherein the etching process comprises an anisotropic deep reactive ion etching process and/or an anisotropic wet etching process, reactants of the anisotropic deep reactive ion etching process and/or the anisotropic wet etching process enter the substrate along the release holes to form the mesh-shaped structure film and the cavity, the mesh-shaped structure film covers the cavity, the mesh-shaped structure film is provided with at least one release hole, and the cavity is used for communicating different release holes;

and removing the dielectric layer.

11. The method of claim 10, wherein forming the air cavity on the first surface of the substrate using an etching process comprises:

And carrying out anisotropic etching on the first surface of the substrate by adopting an etching process to form a reticular structure film comprising an inverted triangle structure, a substrate comprising a regular triangle structure and a cavity positioned between the reticular structure film comprising the inverted triangle structure and the substrate comprising the regular triangle structure, wherein the surface of the reticular structure film adjacent to the cavity is provided with the inverted triangle structure, and the surface of the substrate adjacent to the cavity is provided with the regular triangle structure.

12. The method of manufacturing a microelectromechanical probe chip of claim 9, wherein forming the suspension structure comprises:

forming a supporting layer on the first surface side of the substrate, wherein the supporting layer covers the air cavity;

forming a thermopile on the surface of one side of the supporting layer far away from the air cavity;

forming a passivation layer on the surface of one side of the thermopile away from the substrate;

and forming an infrared absorption layer on the surface of one side of the passivation layer, which is far away from the thermopile, wherein the projection of the thermopile on the substrate surrounds the projection of the infrared absorption layer on the substrate, one end of the thermopile, which is close to the infrared absorption layer, is used as a hot end, one end of the thermopile, which is far away from the infrared absorption layer, is used as a cold end, the cold end of the thermopile is used as an electrode to guide an electric signal corresponding to an infrared light signal to a second surface, which is opposite to the first surface, of the substrate through a conductive through hole, and the infrared absorption layer, the passivation layer and the thermopile form the photoelectric conversion device.