Method for forming a mems device and a mems device

Abstract

The application relates to a MEMS device forming method and a MEMS device. The method comprises the following steps: forming a sacrificial layer on a substrate; forming a functional layer and a conductive connecting layer electrically connected with the functional layer on the sacrificial layer; forming a through slot penetrating through the conductive connecting layer; forming a protective layer covering at least the sidewall of the conductive connecting layer exposed via the through slot; forming a release slot exposing the sacrificial layer, the vertical projection of the release slot on the substrate plane falls into the vertical projection of the through slot on the substrate plane, so that the sidewall of the through slot remains a part of the thickness of the protective layer; and removing the sacrificial layer via the release slot. The MEMS device forming method and the MEMS device provided by the application make the structure of the air bridge more solid and the performance more stable.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for forming a MEMS device and a MEMS device. Background Technology

[0002] Infrared imaging technology is increasingly widely used in industrial sensing, image monitoring, the automotive industry, fire and search and rescue, and even in military applications such as navigation and night vision. An infrared focal plane detector (FFP) is an imaging sensor that simultaneously acquires and processes infrared information, and is the core component of infrared imaging technology. FFPs can be divided into cooled and uncooled types. Cooled FFPs have the advantage of high sensitivity, the ability to distinguish subtle temperature differences, and a longer detection range, and are mainly used in high-end military equipment. Uncooled FFPs do not require cooling and can operate at room temperature, offering advantages such as small size, light weight, low power consumption, long lifespan, low cost, and fast start-up. Although their sensitivity is not as high as cooled FFPs, the performance of uncooled FFPs already meets the technical needs of some military equipment and most civilian applications. In recent years, with the continuous advancement of uncooled FFP technology and the gradual decrease in manufacturing costs, their cost-effectiveness has rapidly improved, creating favorable conditions for the large-scale market application of uncooled FFPs.

[0003] Uncooled infrared focal plane detectors are primarily based on thermal sensors fabricated using Micro-Electro-Mechanical Systems (MEMS). They can be broadly categorized into thermopile / thermocouple, pyroelectric, optomechanical, and microbolometer types. An uncooled infrared focal plane detector typically includes a photosensitive element chip and a readout circuit. The photosensitive element chip comprises a focal plane array, which is composed of multiple air bridges. Each air bridge generally consists of two piers and a bridge surface, forming an air-containing cavity. The manufacturing process of an air bridge typically includes: forming a sacrificial layer on a substrate; depositing corresponding dielectric and conductive layers on the sacrificial layer to form the bridge surface; creating trenches connecting to the substrate; placing dielectric and conductive layers within the trenches to form piers; and then creating release grooves on the bridge surface connecting to the sacrificial layer. The sacrificial layer is removed through these release grooves, thus isolating the conductive lines from the substrate via air and reducing parasitic capacitance. However, during the process of removing the sacrificial layer, the sidewalls of the bridge surface exposed by the release slot are easily damaged, which leads to a decrease in the robustness of the air bridge structure, affecting the performance of the chip, and consequently affecting the performance of the uncooled infrared focal plane detector. Summary of the Invention

[0004] In view of this, embodiments of this application provide a method for forming a MEMS device and a MEMS device to solve at least one problem existing in the background art.

[0005] To achieve the above objectives, the technical solution of this application is implemented as follows:

[0006] In a first aspect, embodiments of this application provide a method for forming a MEMS device, the method comprising:

[0007] A sacrificial layer is formed on the substrate;

[0008] A functional layer and a conductive connection layer electrically connected to the functional layer are formed on the sacrificial layer;

[0009] A through-groove is formed that penetrates the conductive connection layer;

[0010] A protective layer is formed, which at least covers the sidewall of the conductive connection layer exposed via the through groove;

[0011] A release groove is formed to expose the sacrificial layer, and the vertical projection of the release groove on the substrate plane falls within the vertical projection of the conductive groove on the substrate plane, so that the sidewall of the conductive groove retains a portion of the thickness of the protective layer.

[0012] The sacrificial layer is removed via the release groove.

[0013] Optionally, forming a functional layer and a conductive connection layer electrically connected to the functional layer on the sacrificial layer includes:

[0014] A functional layer is formed on a predetermined area of ​​the sacrificial layer, and the functional layer is a light sensing layer;

[0015] A first trench is formed at a first location on the sacrificial layer, penetrating the sacrificial layer and exposing a first portion of the wiring layer, and a second trench is formed at a second location on the sacrificial layer, penetrating the sacrificial layer and exposing a second portion of the wiring layer; wherein the wiring layer is located between the substrate and the sacrificial layer;

[0016] A conductive connection layer is formed to be electrically connected to the functional layer. The conductive connection layer includes a first conductive connection structure and a second conductive connection structure that are separately disposed. The first conductive connection structure conductively connects one side of the light sensing layer to the wiring layer through the first trench. The second conductive connection structure conductively connects the other side of the light sensing layer to the wiring layer through the second trench.

[0017] The method of forming a through-channel through the conductive connection layer includes: forming the through-channel in the region of the first conductive connection structure between the first trench and the light sensing layer, and / or forming the through-channel in the region of the second conductive connection structure between the second trench and the light sensing layer.

[0018] Optionally, forming the release groove that exposes the sacrificial layer includes:

[0019] Multiple release grooves are formed to expose the sacrificial layer;

[0020] The MEMS device includes a first sidewall and a second sidewall that are opposite to each other in a second direction. A portion of the multiple release slots extends from the first sidewall toward the second sidewall but does not extend to the second sidewall, while another portion of the release slots extends from the second sidewall toward the first sidewall but does not extend to the first sidewall. The portion of the release slots and the other portion of the release slots are located at different positions in a first direction. The first direction, the second direction, and the thickness direction of the substrate are perpendicular to each other.

[0021] Optionally, the light-sensing layer includes a thermally sensitive material layer.

[0022] Optionally, the thermosensitive material layer includes a thermosensitive thin film, a dielectric film, and an infrared absorption film arranged sequentially from top to bottom.

[0023] Optionally, the material of the sacrificial layer includes silicon dioxide.

[0024] Secondly, embodiments of this application provide a MEMS device, including:

[0025] Substrate;

[0026] A functional layer is formed above the substrate, and a cavity exists between the functional layer and the substrate;

[0027] A conductive connection layer is electrically connected to the functional layer, and a conductive groove is formed in the conductive connection layer;

[0028] A protective layer is formed on the conductive connection layer and in the conductive groove;

[0029] The release groove penetrates the protective layer in the guide groove and communicates with the cavity, and the sidewall of the guide groove retains a portion of the thickness of the protective layer.

[0030] Optionally, the functional layer is a light sensing layer;

[0031] The conductive connection layer includes a first conductive connection structure and a second conductive connection structure, which are located on both sides of the light sensing layer, respectively.

[0032] A wiring layer is located on the substrate, and the first conductive connection structure and the second conductive connection structure respectively conductively connect the two sides of the light sensing layer to the wiring layer.

[0033] Optionally, the number of the release slots may be multiple;

[0034] The MEMS device includes a first sidewall and a second sidewall that are opposite to each other in a second direction. A portion of the multiple release slots extends from the first sidewall toward the second sidewall but does not extend to the second sidewall, while another portion of the release slots extends from the second sidewall toward the first sidewall but does not extend to the first sidewall. The portion of the release slots and the other portion of the release slots are located at different positions in a first direction. The first direction, the second direction, and the thickness direction of the substrate are perpendicular to each other.

[0035] Optionally, the light-sensing layer includes a thermally sensitive material layer.

[0036] This application provides a method for forming a MEMS device and a MEMS device, comprising: forming a sacrificial layer on a substrate; forming a functional layer and a conductive connection layer electrically connected to the functional layer on the sacrificial layer; forming a through-hole penetrating the conductive connection layer; forming a protective layer, the protective layer at least covering the sidewalls of the conductive connection layer exposed through the through-hole; forming a release groove exposing the sacrificial layer, the vertical projection of the release groove on the substrate plane falling within the vertical projection of the through-hole on the substrate plane, so that the sidewalls of the through-hole retain a portion of the thickness of the protective layer; and removing the sacrificial layer through the release groove. The protective layer at least covers the sidewalls of the conductive connection layer exposed through the through-hole, which can prevent damage to the conductive connection layer when removing the sacrificial layer through the release groove, thereby avoiding any impact on the performance of the MEMS device. Thus, the method for forming a MEMS device and the MEMS device provided in this application can avoid damage to the sidewalls of the conductive connection layer, making the MEMS device structure more robust and its performance more stable.

[0037] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0038] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0039] Figure 1 A schematic flowchart illustrating the method for forming a MEMS device provided in an embodiment of this application;

[0040] Figures 2 to 6 , Figures 8 to 10 This is a cross-sectional schematic diagram of each process in the method for forming a MEMS device provided in the embodiments of this application;

[0041] Figure 7 for Figure 6 Top view of the structure;

[0042] Figure 11 for Figure 10 Top view of the structure;

[0043] Figure 12 This is a schematic diagram of the structure of the MEMS device provided in the embodiments of this application.

[0044] Explanation of reference numerals in the attached figures:

[0045] 20. Substrate; 21. Wiring layer; 22. Sacrificial layer; 23. Cavity; 24. First dielectric layer; 25. Insulating layer; 30. Conductive connection layer; 31. Conductive trench; 32. Metal support layer; 40. Protective layer; 50. Release trench; 61. First trench; 62. Second trench; 63. Third dielectric layer; 70. Light sensing layer; 71. Second dielectric layer; 81. First sidewall; 82. Second sidewall. Detailed Implementation

[0046] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the disclosure of the present application to those skilled in the art.

[0047] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, to avoid confusion with this application, some technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0048] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0049] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0050] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0051] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0052] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solution of this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0053] To address the technical problems in the prior art, embodiments of this application provide a method for forming a MEMS device, combined with... Figures 1 to 12 The method includes:

[0054] Step 101: Form a sacrificial layer 22 on the substrate 20;

[0055] Step 102: Form a functional layer and a conductive connection layer 30 electrically connected to the functional layer on the sacrificial layer 22;

[0056] Step 103: Form a through groove 31 that penetrates the conductive connection layer 30;

[0057] Step 104: Form a protective layer 40, which at least covers the sidewall of the conductive connection layer 30 exposed via the through groove 31;

[0058] Step 105: Form a release groove 50 that exposes the sacrificial layer 22, wherein the vertical projection of the release groove 50 on the plane of the substrate 20 falls within the vertical projection of the through groove 31 on the plane of the substrate 20, so that the sidewall of the through groove 31 retains a portion of the thickness of the protective layer.

[0059] Step 106: Remove the sacrificial layer 22 via the release groove 50.

[0060] The MEMS device fabrication method provided in this application can be used to fabricate photosensitive element chips in infrared focal plane detectors. Specifically, the fabrication method in this application is mainly used to fabricate a portion of the air bridge structure in the focal plane array of the photosensitive element chip. The following description primarily uses the photosensitive element chip as an example. It is understood that the MEMS device fabrication method in this application can also be used to fabricate other MEMS devices. For simplicity, the accompanying drawings of this embodiment only show one air bridge. It is understood that the MEMS device fabrication method provided in this application can be used to fabricate all air bridges in the focal plane array of the photosensitive element chip. Fabricating all air bridges can include fabricating all air bridges simultaneously or fabricating all air bridges separately.

[0061] In step 101 above, see Figure 1-5The substrate 20 can be the base of a MEMS device, serving as a carrier for adding subsequent material layers. The substrate may include a top surface for forming the MEMS device and a bottom surface opposite the top surface. Ignoring the flatness of the top and bottom surfaces, the direction perpendicular to the top and bottom surfaces of the substrate is defined as the thickness direction of the substrate. The thickness direction of the substrate is also the stacking direction for subsequent material layers deposited on the substrate, or the height direction of the device. Exemplarily, the sacrificial layer 22 can be a process layer in the fabrication process, which needs to be removed after achieving its intended purpose; that is, the sacrificial layer 22 is not present in the final MEMS device. In some embodiments, the sacrificial layer 22 can be formed by a deposition process. Exemplarily, the formed sacrificial layer 22 can completely cover the substrate 20 or partially cover it. In this embodiment, the sacrificial layer 22 can be removed after the bridge piers and bridge surface of the air bridge are fabricated to form an air-accommodating cavity 23, allowing the conductive lines on the bridge to be separated from the substrate 20 by air as a medium. In some embodiments, the material of the sacrificial layer 22 may include silicon dioxide (SiO2).

[0062] In step 102 above, see Figure 5 The functional layer can be the light-sensing layer 70 in the photosensitive element chip, also known as the sensitive element region, used to receive infrared light from the outside world to detect humans or other organisms that emit infrared light. The conductive connection layer 30 can be a conductive layer that serves as a connection. In this embodiment, the conductive connection layer 30 can transmit the signal received by the sensitive element region in the photosensitive element chip. In some embodiments, the material of the conductive connection layer 30 can include titanium (Ti). In some embodiments, the conductive connection layer 30 can be formed by performing a sputtering deposition process.

[0063] In step 103 above, see Figure 6 and Figure 7 The conductive groove 31 extends downward from the top surface of the conductive connection layer 30, penetrates the conductive connection layer 30, and exposes part of the sidewall of the conductive connection layer 30 to facilitate the setting of the protective layer 40 in step 104.

[0064] In some embodiments, the conductive groove 31 can be formed by photolithography. Specifically, a mask material is first deposited on the conductive connection layer 30, and then a predetermined formation position of the conductive groove 31 is defined in the mask material through photolithography and etching processes, thereby forming a patterned mask layer. The predetermined formation position of the conductive groove 31 is related to the position of the release groove 50 in step 105. The photolithography process requires forming photoresist on the mask material, patterning the photoresist using a mask and a light source, and then etching the patterned mask layer using the patterned photoresist. This process is well known to those skilled in the art and will not be described in detail here. Next, using the patterned mask layer as a mask, the conductive connection layer 30 is etched until the conductive groove 31 is formed.

[0065] In step 104 above, see Figure 9 The protective layer 40 is used to cover the sidewall of the conductive connection layer 30 exposed via the conductive groove 31, and when the release groove 50 is formed in step 105, the protective layer 40 is also at least partially retained so that the portion of the conductive connection layer 30 covered by the protective layer 40 is not exposed.

[0066] In some embodiments, the protective layer 40 can be formed by performing a deposition process. In some embodiments, the material of the protective layer 40 can be an insulating dielectric material. In some embodiments, the material of the protective layer 40 can be silicon nitride (SiN).

[0067] In step 105 above, see Figure 10 The release groove 50 is used to introduce an etchant when removing the sacrificial layer 22; the etchant can generally be a gas. The fact that the vertical projection of the release groove 50 onto the plane of the substrate 20 falls within the vertical projection of the conductive groove 31 onto the plane of the substrate 20 means that the projected area of ​​the release groove 50 is smaller than the projected area of ​​the conductive groove 31, and it is completely surrounded by the conductive groove 31 in a direction parallel to the bottom surface of the substrate 20. For example, if both the release groove 50 and the conductive groove 31 are circular holes, they can be concentric circles, and the diameter of the release groove 50 is smaller than the diameter of the conductive groove 31. Thus, after forming the release groove 50, at least a portion of the protective layer 40 is retained so that the portion of the conductive connection layer 30 covered by the protective layer 40 is not exposed. For example, the position of the release groove 50 can be set according to the process requirements for removing the sacrificial layer 22. For example, the position of the release groove 50 can be set to facilitate the introduction of etchant and to facilitate the uniform diffusion of etchant above the sacrificial layer 22.

[0068] In some embodiments, see Figure 5The formation of a functional layer and a conductive connection layer 30 electrically connected to the functional layer on the sacrificial layer 22 includes:

[0069] A functional layer, namely a light sensing layer 70, is formed on a predetermined area of ​​the sacrificial layer 22.

[0070] A first trench 61 is formed at a first location on the sacrificial layer 22, penetrating the sacrificial layer 22 and exposing a first portion of the wiring layer 21; and a second trench 62 is formed at a second location on the sacrificial layer 22, penetrating the sacrificial layer 22 and exposing a second portion of the wiring layer 21; wherein the wiring layer 21 is located between the substrate and the sacrificial layer 22.

[0071] Exemplarily, the first trench 61 and the second trench 62 are primarily used to expose the wiring layer 21 so as to establish a conductive connection with the light sensing layer 70 through the conductive connection layer 30. In this embodiment, the wiring layer 21 establishes a conductive connection with the light sensing layer 70 on the bridge surface through the piers and bridge surface in the air bridge, and the lines that realize the conductive connection are isolated from the substrate 20 by the air medium, reducing parasitic capacitance. Exemplarily, the MEMS device also has an insulating layer 25 for isolating the wiring layer 21 from the substrate or the sacrificial layer 22. The insulating layer 25 surrounds the wiring layer 21, and the first trench 61 and the second trench 62 expose the wiring layer 21 by passing through the insulating layer 25.

[0072] A conductive connection layer 30 is formed that is electrically connected to the light sensing layer 70. The conductive connection layer 30 includes a first conductive connection structure and a second conductive connection structure that are separately disposed. The first conductive connection structure conductively connects one side of the light sensing layer 70 to the wiring layer 21 via the first trench 61. The second conductive connection structure conductively connects the other side of the light sensing layer 70 to the wiring layer 21 via the second trench 62.

[0073] For example, the first conductive connection structure and the second conductive connection structure may be axially symmetrical, and the axis may be the center line of the air bridge in the length direction. The first conductive connection structure serves to establish a conductive connection between the light sensing layer 70 and the wiring layer 21 exposed by the first trench 61, and the second conductive connection structure serves to establish a conductive connection between the light sensing layer 70 and the wiring layer 21 exposed by the second trench 62.

[0074] The formation of the through groove 31 penetrating the conductive connection layer 30 includes:

[0075] The conductive groove 31 is formed in the region of the first conductive connection structure between the first trench 61 and the light sensing layer 70, and / or the conductive groove 31 is formed in the region of the second conductive connection structure between the second trench 62 and the light sensing layer 70.

[0076] That is, conductive grooves 31 are provided on both the first conductive connection structure and the second conductive connection structure of the phase separation of the conductive connection layer 30, so that release grooves 50 are provided on both the first conductive connection structure and the second conductive connection structure of the phase separation of the conductive connection layer 30, and the efficiency of releasing the sacrificial layer 22 in step 106 is higher.

[0077] In some embodiments, see Figure 5 The formation of the light-sensing layer 70 on the sacrificial layer 22 includes:

[0078] A first dielectric layer 24 is formed on the sacrificial layer 22;

[0079] The light sensing layer is formed on the first dielectric layer 24.

[0080] Since the sacrificial layer 22 is removed in the final product, the bottom of the light-sensing layer formed on the sacrificial layer 22 will come into contact with the etchant used to remove the sacrificial layer 22 during the removal process, which may cause damage to the light-sensing layer. Furthermore, after the sacrificial layer 22 is removed, the bottom of the light-sensing layer is exposed and may come into contact with air or other substances, causing damage such as oxidation. Therefore, it is necessary to provide a first dielectric layer 24 between the sacrificial layer 22 and the light-sensing layer, which can both isolate the etchant during the removal of the sacrificial layer 22 and isolate it from air and other substances after the removal of the sacrificial layer 22, thus preventing damage to the light-sensing layer.

[0081] In some embodiments, see Figure 3 The step of forming the light-sensing layer on the first dielectric layer 24 includes:

[0082] A light sensing layer 70 is formed on a preset area of ​​the first dielectric layer 24. Exemplarily, the preset area can be set according to the function of the light sensing layer 70 in the MEMS device. For example, for a photosensitive element chip, the light sensing layer 70 can be a functional area for collecting light signals. Therefore, the preset area can be set according to the needs of collecting light signals, such as setting the size of the preset area according to the type of light signal.

[0083] In some embodiments, see Figure 2 and Figure 3 A light-sensing layer 70 is formed on a predetermined area of ​​the first dielectric layer 24, comprising:

[0084] 1) The light sensing layer 70 is formed on the first dielectric layer 24;

[0085] 2) A second dielectric layer 71 is formed on the light sensing layer 70;

[0086] 3) Define the preset area of ​​the light sensing layer 70.

[0087] Exemplarily, the second dielectric layer 71 is used to cover the light sensing layer 70 from above. Thus, the second dielectric layer 71 and the first dielectric layer 24 form a combination, together covering the exposed surface of the light sensing layer 70 to protect the light sensing layer 70 during the fabrication of the MEMS device. In this embodiment, the light sensing layer 70 can be a sensitive element region, and the preset region defining the light sensing layer 70 can define the pixel size of the photosensitive element chip. Exemplarily, the larger the preset region, the larger the pixels of the photosensitive element chip.

[0088] In some embodiments, forming the release groove 50 that exposes the sacrificial layer 22 includes:

[0089] Multiple release grooves 50 are formed to expose the sacrificial layer 22;

[0090] The MEMS device includes a first sidewall 81 and a second sidewall 82 that are opposite to each other in a second direction. A portion of the plurality of release slots 50 extends from the first sidewall 81 toward the second sidewall 82 but does not extend to the second sidewall 82. Another portion of the release slots 50 extends from the second sidewall 82 toward the first sidewall 81 but does not extend to the first sidewall 81. The portion of the release slots and the other portion of the release slots are located at different positions in a first direction. In this embodiment, the portion of the release slots and the other portion of the release slots are staggered in pairs in the first direction, that is, in the first direction, each portion of the release slot is adjacent to another portion of the release slot. The first direction, the second direction, and the thickness direction of the substrate are perpendicular to each other.

[0091] For example, such as Figure 11 As shown, multiple release slots 50 can be provided in both the first and second conductive connection structures of the conductive connection layer 30, and as described above, they are provided corresponding to the conductive slots 31. Therefore, the number of release slots 50 provided in step 105 corresponds to the number of conductive slots 31 opened in step 103. Figure 8As shown. As described above, a portion of the release groove 50 extends from the first sidewall 81 towards the second sidewall 82 but does not extend to the second sidewall 82, while another portion of the release groove 50 extends from the second sidewall 82 towards the first sidewall 81 but does not extend to the first sidewall 81. It can be understood that the release groove 50 is open at one end and closed at the other in the second direction. In this way, most of the conductive connection layer is cut off and separated by the release groove 50, leaving only a portion near the first sidewall 81 or the second sidewall 82. Furthermore, the portion of the release groove and the other portion of the release groove are staggered in the first direction, causing the conductive path of the conductive connection layer to form an "S" shape. Therefore, during the transmission of signals received by the sensitive element area in the photosensitive chip, the conductive connection layer can only transmit along the "S"-shaped path, with no other paths. Compared to the release grooves that are closed at both ends, the "S"-shaped path has paths on both sides near the first sidewall 81 and the second sidewall 82, concentrating the signal in only one path, resulting in less energy loss.

[0092] In some embodiments, the number of release slots 50 is four, with two slots each provided in the first conductive connection structure and the second conductive connection structure. The two release slots 50 in the first conductive connection structure or the second conductive connection structure are open at one end and closed at the other end in the second direction, and are staggered from each other in the first direction.

[0093] In some embodiments, the light-sensing layer 70 includes a thermosensitive material layer. Exemplarily, the thermosensitive material layer can sense the heat emitted by infrared radiation and then transmit the signal through the conductive connection layer 30. Specifically, the thermosensitive material layer includes a thermosensitive thin film, a dielectric film, and an infrared absorbing film arranged sequentially from top to bottom. This allows for better absorption of the heat emitted by infrared radiation.

[0094] In some embodiments, removing the sacrificial layer 22 via the release groove 50 includes:

[0095] Hydrogen fluoride gas is introduced through the release tank 50 to remove the sacrificial layer 22.

[0096] For example, using hydrogen fluoride as the etching gas to perform chemical etching has the advantages of high etching efficiency and low cost.

[0097] For example, taking a photosensitive chip as an example of a MEMS device, this embodiment fabricates an air bridge portion in the photosensitive chip. The first trench 61, the first dielectric layer 24, the protective layer 40, and the first conductive connection structure of the conductive connection layer 30 can constitute part of the pier at one end of the air bridge, and the second trench 62, the first dielectric layer 24, the protective layer 40, and the second conductive connection structure of the conductive connection layer 30 can constitute part of the pier at the other end of the air bridge. The light sensing layer 70, the first dielectric layer 24, and the second dielectric layer 71 can constitute part of the bridge surface of the air bridge.

[0098] In some embodiments, see Figure 8 The method further includes:

[0099] A metal support layer 32 is formed on the portion of the conductive connection layer 30 located in the first trench 61 or the second trench 62.

[0100] The metal support layer 32 supports the conductive connection layer 30, thereby stabilizing the structure of the bridge pier. In some embodiments, the material of the metal support layer 32 may include aluminum (Al). In some embodiments, the metal support layer 32 may be formed by performing a sputtering deposition process.

[0101] In some embodiments, see Figure 4 Before forming the conductive connection layer 30, the method further includes:

[0102] A third dielectric layer 63 is formed in the first trench 61 and the second trench 62, the third dielectric layer 63 covering the sidewalls of the first trench 61 and the second trench 62 and a portion of the first dielectric layer 24.

[0103] In this way, the conductive connection layer 30 can be separated from the sidewalls of the first trench 61, the sidewalls of the second trench 62, and the top surface of the first dielectric layer, so as to better function as a conductive connection layer. For example, after the third dielectric layer 63 is formed, the first dielectric layer 24 and the third dielectric layer 63 can overlap in some positions to form a more complete insulating dielectric material layer.

[0104] This application also provides a MEMS device, such as... Figure 12 As shown, the MEMS device includes:

[0105] Substrate 20;

[0106] A functional layer is formed above the substrate 20, and a cavity is formed between the functional layer and the substrate 20;

[0107] A conductive connection layer 30 is electrically connected to the functional layer, and a conductive groove 31 is formed in the conductive connection layer;

[0108] A protective layer 40 is formed on the conductive connection layer 30 and in the conductive groove 31;

[0109] The release groove 50 penetrates the protective layer 40 in the guide groove 31 and communicates with the cavity 23, and the sidewall of the guide groove 31 retains a portion of the thickness of the protective layer.

[0110] Exemplarily, the substrate 20 can be the base of a MEMS device, serving as a carrier for adding subsequent material layers. The substrate may include a top surface for forming the MEMS device and a bottom surface opposite the top surface. Ignoring the flatness of the top and bottom surfaces, the direction perpendicular to the top and bottom surfaces of the substrate is defined as the thickness direction of the substrate. The thickness direction of the substrate is also the stacking direction for subsequent deposition of various material layers on the substrate, or the height direction of the device. The functional layer can be the light-sensing layer 70 in a photosensitive element chip, also known as the sensitive element region, used to receive infrared light from the outside world to detect humans or other organisms that emit infrared light. In some embodiments, the light-sensing layer 70 can be formed by a deposition process. The conductive connection layer 30 can be a conductive connection layer that serves as a connection. In this embodiment, the conductive connection layer 30 can transmit the signal received by the sensitive element region in the photosensitive element chip. In some embodiments, the material of the conductive connection layer 30 may include titanium (Ti). In some embodiments, the conductive connection layer 30 can be formed by performing a sputtering deposition process.

[0111] In some embodiments, the protective layer 40 can be formed by performing a deposition process. In some embodiments, the material of the protective layer 40 can be an insulating dielectric material. In some embodiments, the material of the protective layer 40 can be silicon nitride (SiN).

[0112] For example, the release groove 50 is used to introduce an etchant when removing the sacrificial layer 22, and the etchant can generally be a gas. The position of the release groove 50 can be set according to the process requirements for removing the sacrificial layer 22, such as facilitating the introduction of the etchant and facilitating uniform diffusion above the sacrificial layer 22. The sacrificial layer 22 can be understood by referring to the description of the method embodiments above.

[0113] In some embodiments, the MEMS device further includes:

[0114] A first dielectric layer 24 is located between the conductive connection layer 30 and the cavity 23, and the first dielectric layer 24 covers the bottom of the conductive connection layer 30 above the cavity 23.

[0115] For example, during the removal of the sacrificial layer 22, the bottom of the light-sensing layer formed on the sacrificial layer 22 may come into contact with the etchant used to remove the sacrificial layer 22, thereby causing damage to the light-sensing layer. Furthermore, after the sacrificial layer 22 is removed, the bottom of the light-sensing layer 70 is exposed and may come into contact with air or other substances, causing damage such as oxidation. Therefore, the first dielectric layer 24 is provided to isolate the light-sensing layer from the etchant during the removal of the sacrificial layer 22 and from air and other substances after the removal of the sacrificial layer 22, thus preventing damage to the light-sensing layer.

[0116] In some embodiments, the conductive connection layer 30 includes a first conductive connection structure and a second conductive connection structure, which are located on both sides of the light sensing layer 70, respectively.

[0117] Wiring layer 21 is located on substrate 20, and the first conductive connection structure and the second conductive connection structure respectively conductively connect the two sides of light sensing layer 70 to the wiring layer.

[0118] The MEMS device also includes:

[0119] The third dielectric layer 63 covers the outer side of one end of the wiring layer where the first conductive connection structure and the second conductive connection structure are connected.

[0120] For example, since two first conductive connection structures or two second conductive connection structures are connected on the same wiring layer, and the two first conductive connection structures or two second conductive connection structures belong to two air bridges respectively, there are also two third dielectric layers 63 on the same wiring layer, which roughly form a trench with a notch at the bottom, namely the first trench 61 and the second trench 62 mentioned above.

[0121] For example, the first trench 61 and the second trench 62 are respectively located on both sides of the light sensing layer 70 in a first direction; the first direction is perpendicular to the thickness direction of the substrate 20; the wiring layer 21 is exposed by the first trench 61 or the second trench 62 so as to form a conductive connection with the light sensing layer 70 through the conductive connection layer 30, that is, to be connected to the light sensing layer 70 through the first conductive connection structure and the second conductive connection structure.

[0122] For example, a portion of the first conductive connection structure is located above the first dielectric layer 24 for conductive connection to the light sensing layer 70, and a portion is located within the first trench 61 or the second trench 62 for conductive connection to the wiring layer 21.

[0123] For example, taking a photosensitive element chip as an example, the light sensing layer 70 can be a functional area for collecting light signals. In this embodiment, the light sensing layer 70 can be a sensitive element region. The preset area can be set according to the function of the light sensing layer 70 in the MEMS device. For example, the size of the preset area can be determined according to the pixel size of the photosensitive element chip.

[0124] For example, the wiring layer 21 is used to electrically connect the light sensing layer 70 to other functional layers. In this embodiment, the wiring layer 21 can be used to receive the light signal obtained by the sensitive element region.

[0125] In some embodiments, the MEMS device further includes an insulating layer 25 for isolating the wiring layer 21 from the substrate or cavity 23. The insulating layer 25 surrounds the wiring layer 21, and the first trench 61 and the second trench 62 expose the wiring layer 21 by passing through the insulating layer 25.

[0126] In some embodiments, there are multiple release slots 50; wherein, the MEMS device includes a first sidewall 81 and a second sidewall 82 that are opposite to each other in a second direction, a portion of the multiple release slots 50 extend from the first sidewall 81 in a direction toward the second sidewall 82 but do not extend to the second sidewall 82, and another portion of the release slots extend from the second sidewall 82 in a direction toward the first sidewall 81 but do not extend to the first sidewall 81; the portion of the release slots and the other portion of the release slots are located at different positions in a first direction. In this embodiment, the portion of the release slots and the other portion of the release slots are staggered in pairs in the first direction, that is, in the first direction, each portion of the release slot is adjacent to another portion of the release slot; the first direction, the second direction, and the thickness direction of the substrate are perpendicular to each other.

[0127] For example, multiple release slots 50 can be provided in both the first conductive connection structure and the second conductive connection structure of the conductive connection layer 30. As described above, a portion of the release slots 50 extends from the first sidewall 81 in a direction toward the second sidewall 82 but does not extend to the second sidewall 82, while another portion of the release slots 50 extends from the second sidewall 82 in a direction toward the first sidewall 81 but does not extend to the first sidewall 81. It can be understood that the release slots 50 are open at one end and closed at the other end in the second direction. In this way, most of the area of ​​the conductive connection layer 30 is cut off and separated by the release slots 50, leaving only a portion near the first sidewall 81 or the second sidewall 82, and the portion of the release slots and the other portion of the release slots are staggered in pairs in the first direction, so that the conductive path of the conductive connection layer 30 forms an "S" shape. Therefore, during the process of transmitting the signal received by the sensitive element area in the photosensitive element chip, the conductive connection layer can only transmit along the "S"-shaped path, without any other path. Compared with the release groove which is closed at both ends, there are paths on both sides near the first sidewall 81 and the second sidewall 82. The signal of the "S"-shaped path is concentrated in only one path, resulting in less energy loss.

[0128] In some embodiments, the number of release slots 50 may be four, with two slots each provided in the first conductive connection structure and the second conductive connection structure. In this case, the two release slots 50 in the first conductive connection structure or the second conductive connection structure are open at one end and closed at the other end in the second direction, and are staggered from each other in the first direction.

[0129] In some embodiments, the light-sensing layer 70 includes a thermosensitive material layer. Exemplarily, the thermosensitive material layer can sense the heat emitted by infrared radiation and then transmit the signal through a conductive connection layer. Specifically, the thermosensitive material layer includes a thermosensitive thin film, a dielectric film, and an infrared absorbing film arranged sequentially from top to bottom. This allows for better absorption of the heat emitted by infrared radiation.

[0130] It should be noted that the MEMS device embodiments and the MEMS device formation method embodiments provided in this application belong to the same concept; the technical features in the technical solutions described in each embodiment can be arbitrarily combined without conflict. However, it should be further noted that the combination of technical features of the MEMS device provided in the embodiments of this application can already solve the technical problem to be solved by this application; therefore, the MEMS device provided in the embodiments of this application is not limited to the formation method of the MEMS device provided in the embodiments of this application, and any MEMS device prepared by a fabrication method that can form the MEMS device structure provided in the embodiments of this application is within the scope of protection of this application.

[0131] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of the present invention and do not limit the scope of protection of this patent.

Claims

1. A method for forming a MEMS device, characterized in that, The method includes: A sacrificial layer is formed on the substrate; A functional layer and a conductive connection layer electrically connected to the functional layer are formed on the sacrificial layer; a wiring layer located between the substrate and the sacrificial layer is also included on the substrate, and the conductive connection layer electrically connects the functional layer to the wiring layer. A through-groove is formed that penetrates the conductive connection layer; A protective layer is formed, which at least covers the sidewall of the conductive connection layer exposed via the through groove; A release groove is formed to expose the sacrificial layer, and the vertical projection of the release groove on the substrate plane falls within the vertical projection of the conductive groove on the substrate plane, so that the sidewall of the conductive groove retains a portion of the thickness of the protective layer. The sacrificial layer is removed via the release groove; wherein, The formation of the release groove that exposes the sacrificial layer includes: Multiple release grooves are formed to expose the sacrificial layer; The MEMS device includes a first sidewall and a second sidewall that are opposite to each other in a second direction. A portion of the multiple release slots extends from the first sidewall toward the second sidewall but does not extend to the second sidewall, while another portion of the release slots extends from the second sidewall toward the first sidewall but does not extend to the first sidewall. The portion of the release slots and the other portion of the release slots are misaligned in pairs in a first direction. The first direction, the second direction, and the thickness direction of the substrate are perpendicular to each other.

2. The method for forming a MEMS device according to claim 1, characterized in that, The formation of a functional layer and a conductive connection layer electrically connected to the functional layer on the sacrificial layer includes: A functional layer is formed on a predetermined area of ​​the sacrificial layer, and the functional layer is a light sensing layer; A first trench is formed at a first location on the sacrificial layer, penetrating the sacrificial layer and exposing a first portion of the wiring layer; and a second trench is formed at a second location on the sacrificial layer, penetrating the sacrificial layer and exposing a second portion of the wiring layer. A conductive connection layer is formed to be electrically connected to the functional layer. The conductive connection layer includes a first conductive connection structure and a second conductive connection structure that are separately disposed. The first conductive connection structure conductively connects one side of the light sensing layer to the wiring layer through the first trench. The second conductive connection structure conductively connects the other side of the light sensing layer to the wiring layer through the second trench. The through-groove forming the conductive connection layer includes: The conductive groove is formed in the region of the first conductive connection structure between the first trench and the light sensing layer, and / or the conductive groove is formed in the region of the second conductive connection structure between the second trench and the light sensing layer.

3. The method for forming a MEMS device according to claim 2, characterized in that, The light sensing layer includes a thermosensitive material layer.

4. The method for forming a MEMS device according to claim 3, characterized in that, The thermosensitive material layer includes a thermosensitive thin film, a dielectric film, and an infrared absorption film arranged sequentially from top to bottom.

5. The method for forming a MEMS device according to any one of claims 1 to 4, characterized in that, The material of the sacrificial layer includes silicon dioxide.

6. A MEMS device, characterized in that, include: Substrate; A functional layer is formed above the substrate, and a cavity exists between the functional layer and the substrate; A conductive connection layer is electrically connected to the functional layer, and a conductive groove is formed in the conductive connection layer; a wiring layer is also included on the substrate, and the conductive connection layer electrically connects the functional layer to the wiring layer. A protective layer is formed on the conductive connection layer and in the conductive groove; A release groove extends through the protective layer in the conductive groove and communicates with the cavity, and the sidewall of the conductive groove retains a portion of the thickness of the protective layer; there are multiple release grooves; The MEMS device includes a first sidewall and a second sidewall that are opposite to each other in a second direction. A portion of the multiple release slots extends from the first sidewall toward the second sidewall but does not extend to the second sidewall, while another portion of the release slots extends from the second sidewall toward the first sidewall but does not extend to the first sidewall. The portion of the release slots and the other portion of the release slots are misaligned in pairs in a first direction. The first direction, the second direction, and the thickness direction of the substrate are perpendicular to each other.

7. The MEMS device according to claim 6, characterized in that, The functional layer is a light sensing layer; The conductive connection layer includes a first conductive connection structure and a second conductive connection structure, which are located on both sides of the light sensing layer, respectively. The first conductive connection structure and the second conductive connection structure respectively conductively connect the two sides of the light sensing layer to the wiring layer.

8. The MEMS device according to claim 7, characterized in that, The light sensing layer includes a thermosensitive material layer.

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