Inertial sensor and method for manufacturing same, electronic device

Abstract

The application discloses an inertial sensor and a preparation method thereof and an electronic device. The preparation method comprises the following steps: providing a support substrate; forming a cavity on the support substrate; forming an insulating layer on the surface of the support substrate with the cavity; performing a graphic treatment on the insulating layer in the cavity; arranging a device layer above the cavity and bonding the device layer with the support substrate; and etching a gap on the device layer above the cavity to form a suspended structure. In the embodiment of the application, the graphic treatment is performed on the insulating layer in the cavity, and the insulating material in the cavity can be basically removed. In the subsequent over-etching process for forming the suspended structure, a part of the support substrate is etched away in the over-etching process, so that the rebound effect of etching ions caused by charge accumulation can be eliminated, and the bottom defect problem of the suspended structure can be eliminated.

Description

Technical Field

[0001] This application relates to the field of semiconductor device technology, and more specifically, to an inertial sensor and its fabrication method, and an electronic device. Background Technology

[0002] Inertial MEMS sensors typically require suspended device layers (actuating or sensing structures). Current inertial MEMS sensor fabrication processes usually employ bonding transfer techniques to bond the device layer to the substrate. In existing technologies, to ensure high insulation between the device layer and the substrate, an insulating oxide layer is typically added between them. The bonding between the insulating oxide layer and the device layer achieves the bonding between the device layer and the substrate.

[0003] During the etching of suspended structures, after the device layer is etched through, a period of over-etching is required to ensure that all device layers on the entire wafer are fully etched. During this over-etching process, the etching plasma accumulates charges in the bottom oxide layer, causing a repulsive rebound effect on subsequent plasma. Ultimately, this results in the bottom of the suspended structure, especially the bottom corners, being etched by the rebounded plasma, forming... Figure 1 The bottom defect phenomenon is shown. Defects can have a serious negative impact on device performance. Summary of the Invention

[0004] In view of this, this application provides an inertial sensor and its fabrication method, as well as an electronic device, to solve the problem in the prior art where over-etching during the etching of suspended structures leads to defects at the bottom of the suspended structure.

[0005] To address the above problems, embodiments of the present invention provide the following technical solutions:

[0006] The first aspect of this invention discloses a method for fabricating an inertial sensor, comprising:

[0007] Provide a supporting substrate;

[0008] A cavity is formed on the supporting substrate;

[0009] An insulating layer is formed on the surface of the supporting substrate that forms the cavity;

[0010] The insulating layer inside the cavity is graphically processed;

[0011] The device layer is disposed above the cavity and bonded to the supporting substrate;

[0012] A void is etched into the device layer above the cavity to form a suspended structure.

[0013] Optionally, the patterning process forms an insulating layer within the cavity, comprising:

[0014] The insulating layer located in the cavity is removed by photolithography etching.

[0015] Optionally, the process of forming the insulating layer within the cavity through the patterning process further includes:

[0016] An adhesive layer is formed inside the cavity using a spraying process.

[0017] Optionally, after the device layer is disposed above the cavity and bonded to the supporting substrate, the method further includes:

[0018] The device layer is thinned to a preset thickness.

[0019] A second aspect of this invention discloses a method for fabricating an inertial sensor, comprising:

[0020] Provide a supporting substrate;

[0021] A cavity is formed on the supporting substrate;

[0022] An insulating layer is formed on the surface of the supporting substrate that forms the cavity;

[0023] A conductive layer is formed on a portion of the insulating layer;

[0024] The device layer is disposed above the cavity and bonded to the supporting substrate;

[0025] A void is etched into the device layer above the cavity to form a suspended structure.

[0026] Optionally, after depositing a conductive layer in the cavity, the method further includes:

[0027] A coating layer is formed on the conductive layer using a spraying process.

[0028] Optionally, the step of disposing the device layer above the cavity and bonding it to the supporting substrate includes:

[0029] The device layer is placed above the cavity, and the device layer is bonded to the supporting substrate by a low-temperature bonding method, wherein the low temperature is no higher than 600 degrees Celsius.

[0030] Optionally, the conductive material of the conductive layer includes Al, Cu, or low-resistivity silicon.

[0031] Optionally, after the device layer is disposed above the cavity and bonded to the supporting substrate, the method further includes:

[0032] The device layer is thinned to a preset thickness.

[0033] A third aspect of this invention discloses an inertial sensor, the inertial sensor comprising:

[0034] Support substrate;

[0035] The supporting substrate has a cavity, and the cavity has a discontinuous insulating layer inside;

[0036] The device layer disposed in the direction of the cavity opening has an insulating layer in the area where the supporting substrate and the device layer partially overlap;

[0037] The gap on the device layer above the cavity.

[0038] A fourth aspect of this invention discloses an inertial sensor, the inertial sensor comprising:

[0039] Support substrate;

[0040] The supporting substrate has a cavity;

[0041] The device layer disposed in the direction of the cavity opening has an insulating layer in the area where the supporting substrate and the device layer partially overlap;

[0042] An insulating layer disposed inside the cavity;

[0043] A conductive layer disposed on a portion of the insulating layer inside the cavity;

[0044] The gap on the device layer above the cavity.

[0045] Optionally, the conductive material of the conductive layer includes Al, Cu, or low-resistivity silicon.

[0046] A fifth aspect of the present invention discloses an electronic device, wherein the electronic device is provided with an inertial sensor prepared using the inertial sensor preparation method disclosed in the first or second aspect of the present invention; or, the electronic device is provided with an inertial sensor disclosed in the third or fourth aspect of the present invention.

[0047] Based on the above embodiments of the present invention, an inertial sensor and its fabrication method, and an electronic device, the fabrication method includes providing a supporting substrate; forming a cavity on the supporting substrate; forming an insulating layer on the surface of the supporting substrate forming the cavity; patterning the insulating layer within the cavity; placing a device layer above the cavity and bonding it to the supporting substrate; and etching gaps on the device layer above the cavity to form a suspended structure. In the embodiments of the present invention, patterning the insulating layer within the cavity can essentially remove the insulating material within the cavity. During the subsequent over-etching process to form the suspended structure, because a portion of the supporting substrate will be etched away during the over-etching process, the rebound effect of etched ions due to charge accumulation can be eliminated, thereby eliminating the bottom defect problem of the suspended structure. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0049] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0050] Figure 1 A simplified cross-sectional view of a MEMS inertial sensor structure in the prior art;

[0051] Figure 2 A schematic flowchart illustrating a method for fabricating an inertial sensor according to an embodiment of the present invention;

[0052] Figures 3 to 7 This is a partial process flow diagram of a method for fabricating an inertial sensor according to an embodiment of the present invention;

[0053] Figure 8 A schematic flowchart illustrating another method for fabricating an inertial sensor according to an embodiment of the present invention;

[0054] Figures 9 to 11 A process flow diagram of another method for fabricating an inertial sensor provided in an embodiment of the present invention;

[0055] Figure 12This is a schematic diagram of the structure of an inertial sensor provided in an embodiment of the present invention.

[0056] Among them, there are a supporting substrate 1, an upper surface 11 of the supporting substrate 1, a lower surface 12 of the supporting substrate 1, a cavity 2, an insulating layer 3, a device layer 4, a gap 5, and a conductive layer 6. Detailed Implementation

[0057] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0058] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] like Figure 2 The diagram shown is a flowchart illustrating a method for fabricating an inertial sensor according to an embodiment of the present invention. Figures 3 to 7 This is a partial process flow diagram of an inertial sensor disclosed in an embodiment of the present invention. The fabrication method of the inertial sensor mainly includes the following steps:

[0060] S201: Provide a support substrate 1.

[0061] In S201, the supporting substrate 1 is a supporting wafer. The supporting substrate 1 includes, but is not limited to, a semiconductor substrate. The supporting substrate has an upper surface 11 and a lower surface 12.

[0062] S202: A cavity 2 is formed on the support substrate 1.

[0063] Execution of S202 forms a complete support on 1. Figure 3 Cavity 2 is shown.

[0064] In one embodiment of the present invention, a cavity 2 is formed on the upper surface 11 of the support substrate 1.

[0065] S203: An insulating layer 3 is formed on the surface of the supporting substrate that forms the cavity 2.

[0066] In one embodiment of the present invention, the insulating layer 3 formed on the upper surface 11 of the support substrate 1 forming the cavity 2 can be a chemical vapor deposition oxide (CVD oxide) that only covers the upper surface 11 of the support substrate 1. The specific structure after formation is as follows: Figure 4 As shown.

[0067] In one embodiment of the present invention, the insulating layer 3 formed on the upper surface 11 of the support substrate 1 forming the cavity 2 may be a thermal oxide film covering the upper surface 11 and lower surface 12 of the support substrate 1.

[0068] S204: Graphical processing of the insulating layer 3 within the cavity 2.

[0069] In the specific execution of S204, the insulating layer 3 located in the cavity 2 is removed by photolithography etching.

[0070] In one embodiment of the present invention, a portion of the insulating layer 3 within the cavity 2 is removed using a photolithography etching process. Based on Figure 4 The structure of the insulating layer 3 inside cavity 2 after image processing is as follows: Figure 5 As shown.

[0071] In one embodiment of the present invention, the insulating layer 3 at the position corresponding to the opening of the suspended structure in the cavity 2 is removed by using photolithography etching process and determining the position of the opening of the suspended structure to be fabricated in the subsequent process.

[0072] In one embodiment of the present invention, if the depth of the cavity 2 is greater than 10 μm, the process of patterning the insulating layer 3 deposited in the cavity 2 further includes:

[0073] An adhesive layer is formed inside the cavity 2 using a spraying process.

[0074] S205: The device layer 4 is disposed above the cavity 2 and bonded to the supporting substrate 1.

[0075] In S205, device layer 4 is the device wafer.

[0076] based on Figure 5 In step S205, device layer 4 and supporting substrate 1 are bonded together to obtain the following result: Figure 6 The structure is shown. Device layer 4 is located above cavity 2.

[0077] In one embodiment of the present invention, after bonding the device layer 4 and the supporting substrate 1, the device layer 4 is thinned to a preset thickness.

[0078] S206: Etch gaps 5 on the device layer 4 above the cavity 2 to form a suspended structure.

[0079] based on Figure 6 In step S206, the required cavity 5 is etched onto the device layer 4 above cavity 2. To ensure that the device layer 4 at all locations on the entire wafer can be fully etched, over-etching is required for a period of time, thereby forming the cavity 5. Figure 7 The suspended structure shown. Figure 7As shown, during this process, a portion of the supporting substrate 1 will be etched away.

[0080] In the inertial sensor fabrication method disclosed in this invention embodiment, the insulating layer inside the cavity is patterned, which can essentially remove the insulating material inside the cavity. In the subsequent over-etching process to form the suspended structure, because a portion of the supporting substrate will be etched away during the over-etching process, the rebound effect of etched ions due to charge accumulation can be eliminated, thereby eliminating the bottom defect problem of the suspended structure.

[0081] like Figure 8 The diagram shown is a flowchart illustrating a method for fabricating an inertial sensor according to an embodiment of the present invention. Figures 9 to 11 This is a partial process flow diagram of an inertial sensor disclosed in an embodiment of the present invention. The fabrication method of the inertial sensor mainly includes the following steps:

[0082] S801: Provides a support substrate 1.

[0083] S802: A cavity 2 is formed on the support substrate 1.

[0084] S803: An insulating layer 3 is formed on the surface of the support substrate that forms the cavity 2.

[0085] The specific implementation process of S801 to S803 and the corresponding structure diagram obtained after execution are the same as the specific implementation process of S201 to S203 and the corresponding structure diagram obtained after execution, and will not be repeated here.

[0086] S804: A conductive layer 6 is formed on the insulating layer 3.

[0087] S804 is performed to form, as shown in the figure, on the insulating layer 3. Figure 9 The conductive layer 6 is shown.

[0088] In one embodiment of the present invention, a conductive layer is formed on the upper surface of a portion of the insulating layer 3.

[0089] In one embodiment of the present invention, the conductive material of the conductive layer 6 includes Al, Cu or low-resistivity silicon.

[0090] In one embodiment of the present invention, after forming a conductive layer 6 in the cavity 2, the method further includes: forming an adhesive layer on the conductive layer 6 using a spraying process.

[0091] S805: The device layer 4 is disposed above the cavity 2 and bonded to the supporting substrate 1.

[0092] based on Figure 9 In step S805, device layer 4 and supporting substrate 1 are bonded together to obtain the following result: Figure 10The structure is shown. Device layer 4 is located above cavity 2.

[0093] In one embodiment of the present invention, since the conductive material of the conductive layer, such as metal, is not resistant to high temperature, the specific bonding method includes: placing the device layer 4 above the cavity 2, and bonding the device layer 4 to the supporting substrate 1 by a low-temperature bonding method.

[0094] Optionally, the low temperature refers to the temperature during bonding or the annealing temperature after bonding, which is no higher than 600 degrees Celsius, i.e., the annealing temperature is no higher than 600 degrees Celsius.

[0095] In one embodiment of the present invention, after the device layer 4 is disposed above the cavity 2 and bonded to the supporting substrate 1, the invention further includes:

[0096] The device layer 4 is thinned to a preset thickness.

[0097] S806: Etch gaps 5 on the device layer 4 above the cavity 2 to form a suspended structure.

[0098] based on Figure 10 The S806 process etches the required cavity 5 on the device layer 4 above cavity 2. To ensure that the device layer 4 at all locations on the entire wafer can be fully etched, a continuous over-etching process is required for a period of time, thereby forming a cavity 5 as described above. Figure 11 The suspended structure shown.

[0099] In the inertial sensor fabrication method disclosed in this embodiment of the invention, a conductive layer is formed in the cavity. During the subsequent over-etching process to form the suspended structure, ions will not accumulate due to the presence of the conductive layer. Therefore, the rebound effect of etched ions due to charge accumulation can be eliminated, thereby eliminating the bottom defect problem of the suspended structure.

[0100] Based on the inertial sensor fabrication method provided in the above embodiments of the present invention, the following can be specifically obtained: Figure 7 and Figure 11 Inertial sensors.

[0101] like Figure 12 As shown, this embodiment of the invention also discloses an inertial sensor, which includes:

[0102] Support substrate 1.

[0103] In one embodiment of the present invention, the supporting substrate 1 is a supporting wafer.

[0104] The supporting substrate 1 has a cavity 2.

[0105] The device layer 4 is disposed in the opening direction of the cavity 2, and the supporting substrate 1 has an insulating layer 3 in the area where it partially overlaps with the device layer 4.

[0106] The gap 5 is located on the device layer 4 above the cavity 2.

[0107] In one embodiment of the present invention, the cavity 2 has a discontinuous insulating layer 3 inside. That is, the portion of the cavity 2 that is not opposite to the gap 5 has an insulating layer.

[0108] In one embodiment of the present invention, if the depth of the cavity 2 is greater than 10 μm, the adhesive coating process for the patterning process of the insulating layer 3 can be selected as a spray coating process.

[0109] In one embodiment of the present invention, the device layer 4 is a thinned device layer.

[0110] In one embodiment of the present invention, the device layer 4 is a device wafer.

[0111] In the inertial sensor disclosed in the embodiments of the present invention, there is no insulating material in the cavity. During the over-etching process of forming the suspended structure, a portion of the supporting substrate will be etched away during the over-etching process, thereby eliminating the rebound effect of etched ions due to charge accumulation, and thus eliminating the bottom defect problem of the suspended structure.

[0112] This invention also discloses an inertial sensor, specifically as shown in Figure 11, comprising:

[0113] Support substrate 1.

[0114] In one embodiment of the present invention, the supporting substrate 1 is a supporting wafer. The supporting substrate 1 includes, but is not limited to, a semiconductor substrate.

[0115] The supporting substrate 1 has a cavity 2. A device layer 4 is disposed in the opening direction of the cavity 2, and an insulating layer 3 is present in the partially overlapping area of ​​the supporting substrate 1 and the device layer 4.

[0116] An insulating layer 3 is disposed inside the cavity 2.

[0117] The conductive layer 6 is disposed on the insulating layer 3 inside the cavity 2.

[0118] The gap 5 is located on the device layer 4 above the cavity 2.

[0119] In one embodiment of the present invention, the conductive layer 6 is a conductive layer 6 disposed on the upper surface of a portion of the insulating layer inside the cavity.

[0120] In one embodiment of the present invention, the insulating layer 3 disposed in the cavity 2 and the insulating layer 3 at the point where the supporting substrate 1 overlaps with the device layer 4 can be formed simultaneously.

[0121] In one embodiment of the present invention, the conductive material of the conductive layer 4 includes Al, Cu or low-resistivity silicon.

[0122] In one embodiment of the present invention, the patterning of the conductive layer 4 can be achieved using a spray coating process.

[0123] In one embodiment of the present invention, the device layer 4 is a thinned device layer.

[0124] In one embodiment of the present invention, the device layer 4 is a device wafer.

[0125] In the inertial sensor fabrication method disclosed in this invention embodiment, a conductive layer is formed in the cavity. During the subsequent over-etching process to form the suspended structure, ions will not accumulate due to the presence of the conductive layer, thus eliminating the rebound effect of etched ions due to charge accumulation, thereby eliminating the bottom defect problem of the suspended structure.

[0126] It should be noted that the inertial sensor prepared by the inertial sensor preparation method provided in the above embodiments of the present invention can be a MEMS inertial sensor.

[0127] This invention also discloses an electronic device, which is equipped with the above-described... Figures 2 to 7 ,or Figures 8 to 11 The provided method for fabricating an inertial sensor produces an inertial sensor.

[0128] This invention also discloses an electronic device, which is provided with such... Figure 7 , Figure 11 ,or Figure 12 The inertial sensor shown.

[0129] The various embodiments in this specification are described in a progressive, parallel, or combined manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

[0130] It should be noted that, in the description of this application, the drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments identify the same structures. Additionally, for ease of understanding and description, the thicknesses of some layers, films, panels, regions, etc., may be exaggerated in the drawings. It is also understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element may be directly on the other element or there may be intermediate elements. Furthermore, "on" means positioning an element on or below another element, but does not inherently mean positioning it above another element according to the direction of gravity.

[0131] The terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the middle.

[0132] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0133] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of manufacturing an inertial sensor, characterized by, include: Provide a supporting substrate; A cavity is formed on the supporting substrate; An insulating layer is formed on the surface of the supporting substrate that forms the cavity; The insulating layer inside the cavity is patterned at the location where the opening of the suspended structure is subsequently fabricated, and the insulating layer inside the cavity is basically removed to eliminate the bottom defects caused by charge accumulation and rebound during the over-etching process of forming the suspended structure. The device layer is disposed above the cavity and bonded to the supporting substrate; A void is etched into the device layer above the cavity to form a suspended structure.

2. The method of claim 1, wherein, The patterning process forms an insulating layer within the cavity, including: The insulating layer located in the cavity is removed by photolithography etching.

3. The method according to claim 1, characterized in that, The process of forming the insulating layer within the cavity through patterning also includes: An adhesive layer is formed inside the cavity using a spraying process.

4. The method according to any one of claims 1 to 3, characterized in that, After the device layer is disposed above the cavity and bonded to the supporting substrate, the method further includes: The device layer is thinned to a preset thickness.

5. A method for fabricating an inertial sensor, characterized in that, include: Provide a supporting substrate; A cavity is formed on the supporting substrate; An insulating layer is formed on the surface of the supporting substrate that forms the cavity; A conductive layer is formed on a portion of the insulating layer inside the cavity; Based on the conductive layer, bottom defects caused by charge accumulation and rebound during the over-etching process of forming the suspended structure are eliminated; The device layer is disposed above the cavity and bonded to the supporting substrate; A void is etched into the device layer above the cavity to form a suspended structure.

6. The method according to claim 5, characterized in that, After depositing a conductive layer within the cavity, the method further includes: A coating layer is formed on the conductive layer using a spraying process.

7. The method according to claim 5, characterized in that, The step of disposing the device layer above the cavity and bonding it to the supporting substrate includes: The device layer is placed above the cavity, and the device layer is bonded to the supporting substrate by a low-temperature bonding method, wherein the low temperature is no higher than 600 degrees Celsius.

8. The method according to claim 5, characterized in that, The conductive material of the conductive layer includes Al, Cu, or low-resistivity silicon.

9. The method according to any one of claims 5 to 8, characterized in that, After the device layer is disposed above the cavity and bonded to the supporting substrate, the method further includes: The device layer is thinned to a preset thickness.

10. An inertial sensor, characterized in that, The inertial sensor includes: Support substrate; The supporting substrate has a cavity, and the cavity has a discontinuous insulating layer inside; the discontinuous insulating layer is formed by removing the insulating layer at the position corresponding to the opening of the suspended structure in the cavity; by substantially removing the insulating layer in the cavity, the bottom defects caused by charge accumulation and rebound during the subsequent over-etching process of forming the suspended structure are eliminated. The device layer disposed in the direction of the cavity opening has an insulating layer in the area where the supporting substrate and the device layer partially overlap; A gap on the device layer above the cavity, the gap being used to form a suspended structure.

11. An inertial sensor, characterized in that, The inertial sensor includes: Support substrate; The supporting substrate has a cavity; The device layer disposed in the direction of the cavity opening has an insulating layer in the area where the supporting substrate and the device layer partially overlap; An insulating layer disposed inside the cavity; A conductive layer is disposed on a portion of the insulating layer inside the cavity; based on the conductive layer, bottom defects caused by charge accumulation and rebound during the over-etching process of forming the suspended structure are eliminated; A gap on the device layer above the cavity, the gap being used to form a suspended structure.

12. The inertial sensor according to claim 11, characterized in that, The conductive material of the conductive layer includes Al, Cu, or low-resistivity silicon.

13. An electronic device, characterized in that, The electronic device is provided with an inertial sensor prepared using the method for preparing an inertial sensor according to any one of claims 1 to 9; or, the electronic device is provided with an inertial sensor according to any one of claims 10 to 12.

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