MEMS microphone device and manufacturing method thereof
By etching the back surface of the substrate of the MEMS microphone device to form shallow grooves that communicate with the outside, the deformation or rupture of the diaphragm caused by negative pressure in the back cavity during the test is solved, and the stability of the device is achieved.
Patent Information
- Application Number
- CN202510394898.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-07-08
AI Technical Summary
The diaphragm is prone to deform or rupture during performance testing, because negative pressure is generated in the back cavity.
A shallow groove communicating with the outside is formed on the back surface of the substrate, so that the back cavity is connected to the outside world, and avoid negative pressure in the back cavity.
Effectively prevent the diaphragm from deforming or rupturing during performance testing, ensuring device stability.
Smart Images
Figure CN120282080A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and particularly relates to a MEMS microphone device and a manufacturing method thereof. Background Art
[0002] A MEMS microphone is an electroacoustic transducer fabricated by micromachining technology, which has the characteristics of small size, good frequency response characteristics, and low noise.
[0003] Currently, most MEMS microphones are composed of a substrate, a diaphragm and a backplate located on the substrate. The backplate is usually exposed to the air, and sound holes are formed thereon to receive external sounds. The diaphragm is opposite to the backplate and there is a cavity between the two, thus forming a parallel-plate capacitor. The diaphragm and the backplate serve as the two electrodes of the parallel-plate capacitor respectively. In addition, a back cavity is formed in the substrate, and the back cavity is located below the suspended part of the diaphragm. The diaphragm vibrates under the action of sound waves to change the distance between it and the backplate, thereby changing the capacitance of the parallel-plate capacitor to convert the sound wave signal into an electrical signal.
[0004] In the formation process of the MEMS microphone, it is necessary to support the backplate and space the diaphragm and the backplate by first forming a sacrificial layer, and then release the sacrificial layer so that a cavity can be formed between the diaphragm and the backplate, and the part of the diaphragm located above the back cavity is suspended, so that the diaphragm is a movable structure.
[0005] After the MEMS microphone is formed, the back surface of the MEMS microphone substrate needs to be attached to a test film supported by a support ring for subsequent performance testing. However, it is found that there is a phenomenon that the diaphragm is prone to deformation or even membrane rupture when performing performance testing on a MEMS microphone device without air leakage holes in the diaphragm. Summary of the Invention
[0006] The purpose of the present invention is to provide a MEMS microphone device with a semiconductor structure and a manufacturing method thereof to solve the problem that the diaphragm of the existing MEMS microphone device is prone to deformation and rupture during performance testing after film attachment.
[0007] To solve the above problems, the present invention provides a MEMS microphone device, comprising:
[0008] a substrate, the substrate having a plurality of back cavities, each of the back cavities penetrating along the thickness direction of the substrate, and the plurality of back cavities being arranged in sequence along a set direction. The back surface of the substrate has a shallow groove extending along the set direction, at least one end of the shallow groove communicating with the outside, and the shallow groove communicating with the back cavity;
[0009] A sacrificial layer, a diaphragm, and a back plate formed on the front surface of the substrate, the sacrificial layer being formed between the diaphragm and the substrate and between the diaphragm and the back plate, and the sacrificial layer located above the back cavity being removed, so that the diaphragm is a movable structure.
[0010] Optionally, in the MEMS microphone device, the set direction includes a first direction and a second direction that intersect each other, and the shallow grooves include: a plurality of first shallow grooves extending in the first direction and arranged at intervals from each other, and a plurality of second shallow grooves extending in the second direction and arranged at intervals from each other.
[0011] Optionally, in the MEMS microphone device, the first direction and the second direction are orthogonal to each other.
[0012] Optionally, in the MEMS microphone device, the back cavity is formed at the intersection of the first shallow groove and the second shallow groove.
[0013] Optionally, in the MEMS microphone device, both ends of the shallow groove are in communication with the outside.
[0014] The present invention also provides a manufacturing method of an MEMS microphone device, which is characterized by including:
[0015] Providing a substrate, and forming a sacrificial layer, a diaphragm, and a back plate on the front surface of the substrate, the sacrificial layer being formed between the diaphragm and the substrate and between the diaphragm and the back plate;
[0016] Etching the back surface of the substrate to form shallow grooves, the shallow grooves extending in a set direction, and at least one end of the shallow grooves being in communication with the outside;
[0017] Etching the substrate to form a plurality of back cavities, each of the back cavities penetrating in the thickness direction, and the plurality of back cavities being arranged in sequence along the set direction; and,
[0018] Etching and removing the sacrificial layer located above the back cavity, so that the diaphragm is a movable structure.
[0019] Optionally, in the manufacturing method of the MEMS microphone device, the set direction includes a first direction and a second direction that intersect each other, and the shallow grooves include: a plurality of first shallow grooves extending in the first direction and arranged at intervals from each other, and a plurality of second shallow grooves extending in the second direction and arranged at intervals from each other.
[0020] Optionally, in the manufacturing method of the MEMS microphone device, the first direction and the second direction are orthogonal to each other.
[0021] Optionally, in the manufacturing method of the MEMS microphone device, the back cavity is formed at the intersection of the first shallow groove and the second shallow groove.
[0022] Optionally, in the manufacturing method of the MEMS microphone device, both ends of the shallow groove are in communication with the outside.
[0023] In summary, the MEMS microphone device provided by the present invention includes: a substrate, and a sacrificial layer, a diaphragm, and a back plate located on the front surface of the substrate. The back surface of the substrate has a shallow groove formed by etching. The shallow groove is in communication with the back cavity of the substrate and the outside. Thus, when the back surface of the substrate of the MEMS microphone device without air vents in the diaphragm is attached to the test film for performance testing, it will not cause a negative pressure in the back cavity and cause the diaphragm to deform or even rupture. Description of the Drawings
[0024] Figure 1 It is a schematic structural diagram after a sacrificial layer, a diaphragm, and a back plate are arranged on the front surface of the substrate in an embodiment of the present invention;
[0025] Figure 2 It is a schematic structural diagram of arranging a shallow groove on the back surface of the substrate in an embodiment of the present invention;
[0026] Figure 3 For Figure 2 It is a schematic cross-sectional structural diagram of A-A' in
[0027] Figure 4 It is a schematic structural diagram of forming a back cavity in the substrate in an embodiment of the present invention;
[0028] Figure 5 For Figure 4 It is a schematic cross-sectional structural diagram of B-B' in
[0029] Figure 6 It is another schematic structural diagram of forming a shallow groove and a back cavity in the substrate in an embodiment of the present invention;
[0030] Figure 7 It is a schematic structural diagram of the MEMS microphone device provided by the embodiment of the present invention before releasing the sacrificial layer;
[0031] Figure 8 It is a schematic structural diagram of the MEMS microphone device provided by the embodiment of the present invention;
[0032] Among them, the descriptions of the reference numerals are as follows:
[0033] 100 - Substrate; 111 - First shallow trench; 112 - Second shallow trench; 120 - Back cavity; 200 - Sacrificial layer; 210 - First sacrificial layer; 220 - Second sacrificial layer; 300 - Diaphragm; 400 - Backplate; 410 - Conductive layer; 420 - Insulating layer; 510 - First electrode; 520 - Second electrode. Detailed implementation manners
[0034] The inventors' research found that in the existing MEMS microphone without air vent holes in the diaphragm, the reason why the diaphragm is prone to deformation or membrane breakage during the test is that during the back - film pasting process, the negative pressure in the process makes the pressure in the sealed back cavity lower than the external pressure after film pasting, resulting in diaphragm deformation or membrane breakage.
[0035] In view of this, the present invention provides a MEMS microphone device and its manufacturing method, by conducting the back cavity to the outside to avoid the problem of diaphragm deformation or rupture when performing performance tests on the MEMS microphone device after film pasting.
[0036] The following further details the MEMS microphone device and its manufacturing method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are all in very simplified forms and use non - precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structures. Specifically, the focus of each drawing needs to be different, and sometimes different scales are used. It should be recognized that relative terms such as "above", "below", "top", "bottom" shown in the drawings can be used to describe the relationships between various elements with respect to each other. These relative terms are intended to cover different orientations of the elements other than the orientations depicted in the drawings. For example, if the device is inverted relative to the view in the drawing, an element described as "above" another element will now be below that element. It should also be understood that unless specifically stated or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish each component, element, step, etc. in the specification, rather than to represent the logical relationship or sequential relationship between each component, element, step, etc.
[0037] Please refer to Figure 8 , an embodiment of the present invention provides a MEMS microphone device, and the MEMS microphone device includes:
[0038] Substrate 100, the substrate 100 has a plurality of back cavities 120, each of the back cavities 120 penetrates along the thickness direction of the substrate 100, and the plurality of back cavities 120 are arranged in sequence along a set direction. The back surface of the substrate 100 has a shallow groove 110 extending along the set direction. The shallow groove 110 has opposite ends along the extending direction, at least one end of the shallow groove 110 is communicated with the outside, and the shallow groove 110 is communicated with the back cavity 120; and,
[0039] A sacrificial layer 200, a diaphragm 300 and a back plate 400 located on the front surface of the substrate 100. The sacrificial layer 200 is formed between the diaphragm 300 and the substrate 100, and between the diaphragm 300 and the back plate 400. The sacrificial layer 200 located above the back cavity 120 is etched away, so that the diaphragm 300 is a movable structure.
[0040] In the MEMS microphone device provided by the embodiment of the present invention, the back surface of the substrate 100 has a shallow groove 110, and the back cavity 120 can be communicated with the outside through the shallow groove 110. Thus, although the diaphragm 300 of the MEMS microphone device provided by the embodiment of the present invention has no air vent holes, when the back surface of the substrate 100 is attached to the test film for performance testing, it will not cause a negative pressure in the back cavity 120 to cause the diaphragm 300 to deform or even rupture.
[0041] The following combines Figures 1-7 Describe the manufacturing method of the MEMS microphone device provided by the embodiment of the present invention. According to the following description, the further structural features of the MEMS microphone device will be clearer.
[0042] First, as Figure 1 shown, perform step S1, provide a substrate 100, and form a sacrificial layer 200, a diaphragm 300 and a back plate 400 on the front surface of the substrate 100. The sacrificial layer 200 is formed between the diaphragm 300 and the substrate 100, and between the diaphragm 300 and the back plate 400.
[0043] The sacrificial layer 200 between the diaphragm 300 and the substrate 100 is called the first sacrificial layer 210, and the sacrificial layer 200 between the diaphragm 300 and the back plate 400 is called the second sacrificial layer 220.
[0044] Specifically, the specific process of step S1 can be as follows:
[0045] Clean the substrate 100, and the substrate 100 can specifically be a silicon wafer;
[0046] Deposit a first sacrificial layer 210 on the substrate 100. The specific deposition process can adopt low-pressure chemical vapor deposition (LPCVD). The first sacrificial layer 210 can be made of materials such as phosphosilicate glass (PSG) or photoresist silica;
[0047] Deposit the material for forming the diaphragm 300 on the first sacrificial layer 210. The specific material can be silicon nitride or polysilicon, etc. The specific deposition process can adopt plasma-enhanced chemical vapor deposition (PECVD), etc.;
[0048] Deposit a second sacrificial layer 220. The second sacrificial layer 220 wraps the first sacrificial layer 210 and the diaphragm 300. The second sacrificial layer 220 can be formed by the same deposition process as the first sacrificial layer 210, or can adopt the same material as the first sacrificial layer 210;
[0049] Form a backplate 400. The backplate 400 forms a parallel plate capacitor with the diaphragm 300, and the backplate 400 has acoustic holes. The subsequent etchant enters through these acoustic holes to etch the sacrificial layer 200 located between the backplate 400 and the diaphragm 300.
[0050] The backplate 400 specifically includes a conductive layer 410 and an insulating layer 420 that are stacked in sequence. The insulating layer 420 is used to prevent the conductive layer 410 from being exposed, and at the same time is beneficial to improving the mechanical strength of the backplate 400, avoiding the problem of collapse of the suspended backplate 400 during the subsequent release of the sacrificial layer 200.
[0051] After forming the backplate 400, it may also include the step of forming electrodes. Please refer to Figure 1 ., The electrodes specifically can include a first electrode 510 and a second electrode 520. The first electrode 510 and the second electrode 520 can be formed by sputtering metal (such as aluminum, etc.) on the backplate 400. The first electrode 510 and the second electrode 520 are electrically connected to the diaphragm 300 and the backplate 400 respectively. The part of the backplate 400 where the first electrode 510 is formed and the part where the second electrode 520 is formed are spaced apart from each other. The part of the backplate 400 where the first electrode 510 is formed serves as the electrical connection part between the first electrode 510 and the diaphragm 300.
[0052] Secondly, execute step S2. Please refer to Figure 2 and Figure 3 , Etch the back surface of the substrate 100 to form a shallow groove 110. The shallow groove 110 extends along a set direction, and at least one end of the shallow groove 110 communicates with the outside. This set direction determines the arrangement direction of the back cavity 120, or in other words, this set direction is defined by the target arrangement direction of the back cavity 120.
[0053] Optionally, the number of the shallow grooves 110 may be one or more, and the shape of the shallow grooves 110 may be linear, curved, or the like.
[0054] In this embodiment, the set direction may include a first direction and a second direction intersecting each other. The shallow grooves 110 include: a plurality of first shallow grooves 111 extending along the first direction and arranged at intervals from each other, and a plurality of second shallow grooves 112 extending along the second direction and arranged at intervals from each other.
[0055] Preferably, both ends of the first shallow groove 111 and / or the second shallow groove 112 are in communication with the outside. Further preferably, both ends of the first shallow groove 111 and the second shallow groove 112 are in communication with the outside. In this way, a negative pressure in the back cavity 120 can be more effectively avoided.
[0056] For the convenience of arrangement, preferably, the first direction and the second direction are two orthogonal directions. As an example, as Figure 2 shown, on two diametrical directions perpendicular to each other of the substrate 100, one first shallow groove 111 and one second shallow groove 112 are respectively provided. The other first shallow grooves 111 are arranged on both sides of the first shallow groove 111 provided in the diametrical direction, and the other second shallow grooves 112 are arranged on both sides of the second shallow groove 112 provided in the diametrical direction. All the first shallow grooves 111 and all the second shallow grooves 112 are arranged at uniform intervals.
[0057] In some other embodiments, it may also be as Figure 6 shown. Two or more of the first shallow grooves 111 are in a group, and multiple groups are arranged at uniform intervals. Similarly, two or more of the second shallow grooves 112 are in a group, and multiple groups are arranged at uniform intervals. Figure 6 As shown in, it is schematically shown with two first shallow grooves 111 in a group and two second shallow grooves 112 in a group.
[0058] Next, step S3 is executed. As Figure 4 and Figure 5 shown, the substrate 100 is etched to form a plurality of back cavities 120. Specifically, a deep reactive ion etching (DRIE) process may be adopted for etching. Each of the back cavities 120 penetrates along the thickness direction, and a plurality of the back cavities 120 are arranged in sequence along the set direction.
[0059] Specifically, corresponding to each of the first shallow grooves 111 and each of the second shallow grooves 112, a plurality of the back cavities 120 can be provided along their extending directions.
[0060] In a preferred embodiment, the back cavity 120 is formed at the intersection of the first shallow groove 111 and the second shallow groove 112. Specifically, as Figure 4 shown, a back cavity 120 can be formed at the intersection of each first shallow groove 111 and each second shallow groove 112. Or, as Figure 6 shown, the back cavity 120 is formed at the intersection of each group of the first shallow grooves 111 and each group of the second shallow grooves 112, such that the back cavity 120 communicates with the outside in both the first direction and the second direction. In this way, a negative pressure generated in the back cavity 120 during performance testing can be more effectively avoided.
[0061] Figure 3 And Figure 5 shown, the specific device structure of the MEMS microphone device located on the front side of the substrate 100 is not shown. For the specific device structure after etching the substrate to form the shallow grooves 110 and the back cavity 120, please refer to Figure 7 .
[0062] Finally, step S4 is executed. As Figure 8 shown, the sacrificial layer 200 located above the back cavity 120 is etched away to make the diaphragm 300 a movable structure. This step is the step of releasing the sacrificial layer 200 described above.
[0063] Specifically, through this step, the part of the second sacrificial layer 220 located above the back cavity 120 is removed while other parts are retained, such that there is a cavity between the diaphragm 300 and the back plate 400. The part of the first sacrificial layer 210 located in the back cavity 120 is removed while other parts are retained, so that the part of the diaphragm 300 located above the back cavity 120 is suspended, thereby making the diaphragm 300 a movable structure. It should be understood that the "sacrificial layer 200 located above the back cavity 120" here refers to the region where the sacrificial layer 200 and the back cavity 120 substantially overlap in the height direction.
[0064] In summary, the MEMS microphone device provided by the embodiment of the present invention includes: a substrate, and a sacrificial layer, a diaphragm, and a back plate located on the front side of the substrate. The back side of the substrate has shallow grooves formed by etching, and the shallow grooves communicate with the back cavity of the substrate and the outside. In this way, when the back side of the substrate of the MEMS microphone device without air vents in the diaphragm is attached to the test film for performance testing, a negative pressure will not be generated in the back cavity, causing the diaphragm to deform or even rupture.
[0065] It should be noted that although the present invention has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the technical content disclosed above, or it can be modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A MEMS microphone device, characterized in that, Comprising: A substrate having a plurality of back cavities, each of the back cavities penetrating through the substrate in the thickness direction thereof, and the plurality of back cavities being arranged in sequence along a set direction. The back surface of the substrate has a shallow groove extending along the set direction, at least one end of the shallow groove communicating with the outside, and the shallow groove communicating with the back cavity. A sacrificial layer, a diaphragm, and a back plate formed on the front surface of the substrate. The sacrificial layer is formed both between the diaphragm and the substrate and between the diaphragm and the back plate, and the sacrificial layer located above the back cavity is removed, such that the diaphragm is a movable structure.
2. The MEMS microphone device according to claim 1, characterized in that, The set direction includes a first direction and a second direction intersecting each other. The shallow groove includes: a plurality of first shallow grooves extending along the first direction and arranged at intervals from each other, and a plurality of second shallow grooves extending along the second direction and arranged at intervals from each other.
3. The MEMS microphone device according to claim 2, wherein, The first direction and the second direction are orthogonal to each other.
4. The MEMS microphone device according to claim 2 or 3, characterized in that, The back cavity is formed at the intersection of the first shallow groove and the second shallow groove.
5. The MEMS microphone device according to claim 1, wherein Both ends of the shallow groove communicate with the outside.
6. A manufacturing method of a MEMS microphone device, characterized in that, Comprising: Providing a substrate, and forming a sacrificial layer, a diaphragm, and a back plate on the front surface of the substrate. The sacrificial layer is formed both between the diaphragm and the substrate and between the diaphragm and the back plate. Etching the back surface of the substrate to form a shallow groove, the shallow groove extending along a set direction, and at least one end of the shallow groove communicating with the outside. Etching the substrate to form a plurality of back cavities, each of the back cavities penetrating through in the thickness direction, and the plurality of back cavities being arranged in sequence along the set direction; and Etching and removing the sacrificial layer located above the back cavity, such that the diaphragm is a movable structure.
7. The manufacturing method of the MEMS microphone device according to claim 6, wherein, The set direction includes a first direction and a second direction intersecting each other. The shallow groove includes: a plurality of first shallow grooves extending along the first direction and arranged at intervals from each other, and a plurality of second shallow grooves extending along the second direction and arranged at intervals from each other.
8. The manufacturing method of the MEMS microphone device according to claim 7, characterized in that, The first direction and the second direction are orthogonal to each other.
9. The manufacturing method of the MEMS microphone device according to claim 7 or 8, characterized in that, The back cavity is formed at the intersection of the first shallow groove and the second shallow groove.
10. The manufacturing method of the MEMS microphone device according to claim 6, characterized in that, Both ends of the shallow groove communicate with the outside.