MEMS microphone

Abstract

An MEMS microphone according to an embodiment of the present invention comprises: a first substrate provided with a pad which becomes conductive via electricity from an external element; an embedded capacitor laminated on the first substrate; a second substrate laminated on the embedded capacitor; a MEMS structure disposed on the second substrate; and a signal processing element disposed on the second substrate, distanced from the MEMS structure, wherein the embedded capacitor can eliminate RF noise.

Description

MEMS Microphone

[0001] The present invention relates to a MEMS microphone, and more specifically, to a MEMS microphone having a feature of arranging an embedded capacitor.

[0002] Typically, audio devices use electrodes to vibrate a diaphragm to generate sound. Recent technological advancements have led to significant advancements in the audio device field. These devices are increasingly used in diverse applications, including portable terminals and hearing aids. As the devices they are used in become slimmer, the size of the audio devices themselves is also shrinking.

[0003] Additionally, microphones utilizing MEMS (Micro Electro Mechanical Systems), a semiconductor technology, have recently been developed and used. MEMS is a technology that enables the manufacturing of tiny mechanical components on the surface of silicon wafers. These MEMS microphones can be categorized into electrostatic and piezoelectric types, including the common condenser type.

[0004] Recently, electronic devices such as mobile communication terminals, tablet PCs, and MP3 players are becoming increasingly miniaturized. Consequently, the components of these devices are also becoming smaller. Therefore, Micro Electro Mechanical System (MEMS) technology is needed to overcome the physical limitations of these components.

[0005] The biggest challenges with these MEMS microphones are their size and noise. MEMS microphones are primarily used in audio devices like earphones, and with the trend toward miniaturization of earphones used in smartphones and other devices, miniaturization is also becoming a key trend for MEMS microphones.

[0006] In addition, as the size of MEMS microphones becomes smaller, noise is generated by the connected power or the electrical signals generated, and continuous efforts are needed to reduce this noise.

[0007] The technical problem to be solved by the present invention is to provide a MEMS microphone that utilizes an embedded capacitor inserted into a device in the form of a substrate for miniaturization and noise removal.

[0008] In order to solve the above technical problem, a MEMS microphone according to an embodiment of the present invention may include a first substrate including at least one first insulating layer, a first metal layer disposed on an upper surface of the first insulating layer, and a second metal layer disposed on a lower surface of the first insulating layer; an embedded capacitor stacked on the first substrate; a second substrate stacked on the embedded capacitor and including a metal plate; a MEMS structure disposed on the second substrate; and a signal processing element disposed on the second substrate and spaced apart from the MEMS structure.

[0009] In addition, the embedded capacitor may include a first electrode layer disposed on an upper surface of the first substrate, a second electrode layer disposed on a lower surface of the second substrate, and a second insulating layer disposed between the first electrode layer and the second electrode layer.

[0010] Additionally, it may include a first bonding sheet disposed between the first substrate and the first electrode layer; and a second bonding sheet disposed between the second substrate and the second electrode layer.

[0011] In addition, the first bonding sheet and the second bonding sheet include a conductive material, and the first bonding sheet can conduct electricity between at least a portion of the first metal layer of the first substrate and the first electrode layer of the embedded capacitor, and the second bonding sheet can conduct electricity between the second electrode layer of the embedded capacitor and the second substrate.

[0012] Additionally, the second substrate may include a first cavity vertically overlapping at least a portion of the first metal layer of the first substrate, and the embedded capacitor may include a second cavity vertically overlapping at least a portion of the first cavity.

[0013] Additionally, a portion of the second electrode layer may vertically overlap the first cavity and be electrically connected to the signal processing element.

[0014] Additionally, the second bonding sheet may include a non-conductive material.

[0015] Additionally, the second insulating layer may include BaTiO3.

[0016] In addition, the second substrate may be divided and arranged symmetrically with respect to a central axis, and the embedded capacitor may include a first electrode layer arranged on an upper surface of the first substrate, a second electrode layer divided and arranged symmetrically with respect to a shape corresponding to the second substrate on a lower surface of the second substrate, and a second insulating layer arranged between the first electrode layer and the second electrode layer.

[0017] In addition, the second substrate may include a first split substrate arranged on one side and a second split substrate arranged on the other side so as to have a shape symmetrical to the first split substrate, and the second electrode layer may include a first split electrode layer arranged on a lower side of the first split substrate so as to be electrically conductive to the first split substrate, and a second split electrode layer arranged on a lower side of the second split substrate so as to be electrically conductive to the second split substrate.

[0018] Additionally, the pad may include a first power pad to which an analog circuit power supply is connected; and a second power pad to which a digital circuit power supply is connected.

[0019] Additionally, the first split substrate and the first split electrode layer may be electrically connected to the first power pad, and the second split substrate and the second split electrode layer may be electrically connected to the second power pad.

[0020] Additionally, the above embedded capacitors can be stacked in multiples.

[0021] Additionally, the embedded capacitor may include a first embedded capacitor disposed on the first substrate and a second embedded capacitor disposed on the first embedded capacitor and below the second substrate.

[0022] In addition, the third bonding sheet may be further included between the first embedded capacitor and the second embedded capacitor, and the third bonding sheet may include a non-conductive material.

[0023] Additionally, the first substrate may include one of a 2Metal COF substrate, an FPCB, and a PI-based COF substrate.

[0024] Additionally, the second substrate may include a substrate made of a metal material.

[0025] The MEMS microphone according to an embodiment of the present invention has the following effects.

[0026] By placing the capacitors placed between the substrates as embedded capacitors to improve the performance of the MEMS microphone, the space required for placing separate capacitors is reduced, enabling the miniaturization of the product.

[0027] In addition, it has the effect of preventing the performance degradation of SNR and PSRR due to RF noise without placing a separate capacitor in the MEMS microphone, and in addition, when placing a separate capacitor, it has the effect of increasing noise removal performance by using the capacitor to remove power noise and the embedded capacitor to remove RF noise.

[0028] In particular, since the capacitor performance of an embedded capacitor is determined by the area of ​​the first metal layer and the second metal layer and the material of the insulating layer, there is an effect of being able to derive the desired capacitor performance by changing the type of insulating material of the insulating layer to a material having the desired permittivity.

[0029] In addition, by dividing the second substrate and the second metal layer of the embedded capacitor and electrically connecting them to the analog circuit power supply and the digital circuit power supply, respectively, there is an effect of reducing the RF noise of two power supplies using one embedded capacitor, thereby exhibiting the performance of two capacitors.

[0030] In addition, by implementing a parallel structure of capacitors through the stacked structure of embedded capacitors, it is possible to significantly improve noise reduction performance by reducing RF noise having different frequencies.

[0031] FIG. 1 is a cross-sectional side view of a MEMS microphone according to one embodiment of the present invention.

[0032] FIG. 2 is a perspective view of a MEMS microphone according to one embodiment of the present invention.

[0033] Figure 3 is an exploded perspective view of the substrate unit of a MEMS microphone according to one embodiment of the present invention.

[0034] FIG. 4 is an exploded perspective view illustrating an embedded capacitor structure of a MEMS microphone according to one embodiment of the present invention.

[0035] FIG. 5 is a top view of a structure in which a second substrate of a MEMS microphone according to one embodiment of the present invention serves as a ground.

[0036] FIG. 6 is a top view of a structure in which a second substrate of a MEMS microphone according to one embodiment of the present invention functions as a power source.

[0037] FIG. 7 is a drawing showing the configuration surface of a substrate unit of a MEMS microphone according to one embodiment of the present invention.

[0038] Figure 8 is a top view of a MEMS microphone according to another embodiment of the present invention.

[0039] FIG. 9 is a drawing showing the configuration surface of a substrate unit of a MEMS microphone according to another embodiment of the present invention.

[0040] Fig. 10 is an exploded perspective view of a substrate unit of a MEMS microphone according to another embodiment of the present invention.

[0041] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0042] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0043] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0044] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0045] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0046] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

[0047] And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

[0048] Additionally, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," the meaning may include not only the upward direction but also the downward direction based on one component.

[0049] Variations according to the present embodiment may include some components of each embodiment and some components of other embodiments. That is, a variation may include one embodiment among various embodiments, but may omit some components and include some components of the corresponding other embodiment. Or, the opposite may be true. The features, structures, effects, etc. described in the embodiments are included in at least one embodiment and are not necessarily limited to just one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment may be combined or modified in other embodiments by a person having ordinary skill in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be construed as being included within the scope of the embodiments.

[0050] FIG. 1 is a side cross-sectional structural diagram of a MEMS microphone according to an embodiment of the present invention, FIG. 2 is a perspective view of a MEMS microphone according to an embodiment of the present invention, FIG. 3 is an exploded perspective view of a substrate unit of a MEMS microphone according to an embodiment of the present invention, FIG. 4 is an exploded perspective view showing an embedded capacitor structure of a MEMS microphone according to an embodiment of the present invention, FIG. 5 is a top view of a structure in which a second substrate of a MEMS microphone according to an embodiment of the present invention serves as a ground, FIG. 6 is a top view of a structure in which a second substrate of a MEMS microphone according to an embodiment of the present invention serves as a power source, and FIG. 7 is a diagram showing a configuration surface of a substrate unit of a MEMS microphone according to an embodiment of the present invention.

[0051] Referring to FIGS. 1 to 7, a MEMS microphone according to an embodiment of the present invention may include a first substrate (100), a second substrate (200), a MEMS structure (300), a housing (400), a signal processing element (500), at least one capacitor (600), an embedded capacitor (700), and a bonding sheet (800). Here, a single substrate configuration in which the first substrate (100), the second substrate (200), the embedded capacitor (700), and the bonding sheet (800) are laminated is defined as a substrate unit for convenience of explanation. In addition, the capacitor (600) may not be arranged as necessary.

[0052] The first substrate (100) is placed at the bottom of the MEMS microphone and is a substrate on which a circuit can be formed in a plate shape. The first substrate (100) is a flexible substrate and may be a COF (Chip on Film) substrate or a flexible printed circuit board (FPCB). A COF (Chip on Film) substrate is a substrate formed by forming a circuit or mounting elements such as chips on a base film, and since it has a film shape, it is a substrate that is considerably thinner than other substrates. By using a COF substrate as the substrate of the MEMS microphone, the thickness can be reduced compared to when using a conventional rigid substrate.

[0053] The first substrate (100) is a COF substrate and may include a 2-metal COF substrate. The 2-metal COF may be formed in a structure in which metal layers are laminated on the upper and lower surfaces of the base film so that circuits can be formed on both sides of the base film or devices can be mounted.

[0054] The first substrate (100) may include a via hole. In this case, the first substrate (100) may connect circuits or elements formed on both sides through a metal layer (e.g., a via) formed in the via hole. Here, the via hole may be a micro via hole and may be configured with a size of 25 um or less. Compared to a single-sided COF, the degree of integration can be increased, the degree of freedom during packaging is improved, and a fine pitch is possible by arranging circuits or elements on both sides. When only a rigid substrate is used, the basic thickness is thick during design, making it difficult to apply a fine pitch, but when a COF substrate is used, it is significantly thinner than the substrate, making it possible to apply a fine pitch, so the size of the MEMS microphone package can be reduced by more than 50%.

[0055] A flexible printed circuit board (FPCB) is a flexible circuit board. It is also flexible and thinner than standard PCBs, allowing for a reduction in the thickness of the MEMS microphone substrate. Other types of flexible substrates may also be included.

[0056] The first substrate (100) may include an acoustic hole (10). The cross-sectional area of ​​the acoustic hole (10) may be circular, but is not limited thereto. The hole formed in the first substrate (100) may be arranged to communicate with a hole formed in the second substrate (200) described later, and a MEMS structure (300) may be arranged above the hole communicated by the first substrate (100) and the second substrate (200).

[0057] The first substrate (100) may be electrically connected to a signal processing element (500) and a capacitor (600). A metal layer may be formed on the first substrate (100) to be electrically connected to the signal processing element (500) and the capacitor (600). Here, the metal layer may include a plurality of pads, a plurality of connection circuits, and a plurality of vias. The pads may vertically overlap with the vias and contact them, or may contact an external substrate or element. The connection circuits may connect between pads arranged on the same layer. The vias may be formed in via holes penetrating a base film or an insulating layer. Hereinafter, to help understanding the description, the pads formed on the first substrate (100) are referred to as pads (110), and the circuits connecting the pads (110) are referred to as connection circuits (120).

[0058] Pads (110) and connection circuits (120) of the same or different shapes may be formed on the upper surface (100a) and the lower surface (100b) of the first substrate (100). A plurality of first pads (110a) and a first connection circuit (120a) may be formed on the upper surface (100a) of the first substrate (100), and a plurality of second pads (110b) and a second connection circuit (120b) may be formed on the lower surface (100b) of the first substrate (100). In this case, a plurality of pads (110a) formed on the upper surface (100a) of the first substrate (100) may be electrically connected to a plurality of pads (110b) formed on the lower surface (100b) of the first substrate (100). A plurality of pads (110a) formed on the upper surface (100a) of the first substrate (100) can be electrically connected to a plurality of pads (110b) formed on the lower surface (100b) of the first substrate (100) through vias and connection circuits (120a, 120b). In addition, the plurality of pads (110a) formed on the upper surface (100a) of the first substrate (100) can be arranged at the same position as the plurality of pads (110b) formed on the lower surface (100b) of the first substrate (100) or can be arranged at different positions. That is, there is no limitation on the arrangement as long as the pads (110a) arranged on the upper surface (100a) of the first substrate (100) are electrically connected to the pads (110b) formed on the lower surface (100b) of the first substrate (100). The signal processing element (500) and capacitor (600) can be electrically connected to the first substrate (100) through a pad (110) formed on the upper surface of the first substrate (100).

[0059] The pad (110) may include a first power pad (112) to which an analog circuit power supply (AVDD) is connected, a second power pad (111) to which a digital circuit power supply (DVDD) is connected, a ground pad (113) that performs a grounding function, and one or more data pads (114) that transmit and receive data. In particular, the power pads (111, 112) may be formed separately as a first power pad (112) that is an analog circuit power supply and a second power pad (111) that is a digital circuit power supply, respectively, in order to distinguish the driving voltage and noise. However, this is just one example, and only one of the first power pad (112) or the second power pad (111) may be arranged as the power pad.

[0060] The first substrate (100) can be connected to an embedded capacitor (700) and serve as a ground. In detail, the first substrate (100) is placed on the lower side of the substrate unit and connected to an external source such as a power source, and can serve as a ground for grounding when the embedded capacitor (700) is placed between the first substrate (100) and the second substrate (200).

[0061] The second substrate (200) is laminated to be placed on top of the first substrate (100) and has a plate shape. The second substrate (200) may be placed on top of the first substrate (100). An embedded capacitor (700) may be placed between the first substrate (100) and the second substrate (200).

[0062] The second substrate (200) is laminated to be placed on top of the first substrate (100) and has a plate shape. The second substrate (200) may be a rigid substrate to supplement the rigidity of the first substrate (100), and may include, for example, one or more of a metal plate, a SUS, and a reinforcing plate. SUS is a type of steel in which chromium is mixed with iron to enhance corrosion resistance, and refers to a high-strength substrate. In addition to the above-described configuration, various reinforcing plates made of metal materials may be used for the second substrate (200). Since the second substrate (200) supplements the rigidity of the first substrate (100), the flexible first substrate (100) can maintain its shape.

[0063] The second substrate (200) may include one or more cavities (200a). The second substrate (200) may be disposed on the first substrate (100), and the first substrate (100) may be exposed to the upper portion of the second substrate (200) through the cavities (200a) of the second substrate (200). At least a portion of the pad (110) and the connection circuit (120) of the first substrate (100) may be disposed in the space where the cavities (200a) of the second substrate (200) are formed, and may be exposed to the upper portion of the second substrate (200). Specifically, at least a portion of the first pad (110a) and the connection circuit (120a) may be disposed in an area where the cavities (200a) of the second substrate (200) and the upper surface of the first substrate (100) vertically overlap. In this case, since the upper surface (100a) of the first substrate (100) is placed under the second substrate (200), the first pad (110a) and the first connection circuit (120a) formed on the upper surface (100a) of the first substrate (100) can be exposed to the upper portion of the second substrate (200) through the cavity (200a) of the second substrate (200). The first pad (110a) formed on the upper surface (100a) of the first substrate (100) can be electrically connected to the signal processing element (500) and the capacitor (600) through the cavity (200a) formed on the second substrate (200).

[0064] The second substrate (200) may include an acoustic hole. The cross-sectional area of ​​the acoustic hole may be circular, but is not limited thereto, and may have a size corresponding to the acoustic hole formed in the first substrate (100). The acoustic hole formed in the second substrate (200) may be in communication with the acoustic hole formed in the first substrate (100) to form one acoustic hole (10), and a MEMS structure (300) may be arranged on the acoustic hole (10).

[0065] The second substrate (200) can be connected to an embedded capacitor (700) to serve as a ground or power source. In detail, the second substrate (200) is arranged to form the upper surface of the substrate unit and can be combined with the MEMS structure (300) and the signal processing element (500), and the embedded capacitor (700) is arranged between the first substrate (100) and the second substrate (200) so that the second substrate (200) can serve as a ground or power source.

[0066] Referring to FIG. 5, the second substrate (200) can serve as a ground. In this case, the second substrate (200) can be electrically connected to a ground pad (113) that serves as a grounding area among the pads (110) of the first substrate (100). For example, as shown in FIG. 5, a portion of the upper surface of the second substrate (200) can be wire-bonded with the ground pad (113) among the pads (110) of the first substrate (100).

[0067] In addition, a part of the embedded capacitor (700) may be exposed to the outside through the cavity (200a) of the second substrate (200). In detail, a part of the second electrode layer (720), which is the upper surface of the embedded capacitor (700), may be exposed to the outside through the cavity (200a) of the second substrate (200). The second substrate (200) may be electrically connected to the signal processing element (500) and the power pads (111, 112) in the form of wire bonding through the second electrode layer (720) of the embedded capacitor (700) exposed to the cavity (200a). When the second electrode layer (720) of the embedded capacitor (700) is exposed through the cavity (200a) of the second substrate (200), the signal processing element (500) and the exposed second electrode layer (720) are connected by wire bonding, and the exposed second electrode layer (720) and the power pads (111, 112) of the pad (110) are connected by wire bonding, so that the second substrate (200) can be electrically connected to a power source. In this case, the bonding sheet (820) disposed between the second substrate (200) and the embedded capacitor (700) is made of a non-conductive material, so that a short circuit between the second substrate (200) and the second electrode layer (720) of the embedded capacitor (700) can be prevented.

[0068] Referring to FIG. 6, the second substrate (200) can serve as a power source. In this case, the second substrate (200) can be electrically connected to the first power pad (111) or the second power pad (112) among the pads (110) of the first substrate (100). The second substrate (200) can serve as a power source by being wire-bonded to the first power pad (111) of the first substrate (100) or wire-bonded to the second power pad (112). For example, as shown in FIG. 6, the second substrate (200) can be electrically connected to the second power pad (112) through wire bonding.

[0069] In addition, the bonding sheet (820) disposed between the second substrate (200) and the embedded capacitor (700) is made of a conductive material, so that the second metal layer (720) of the second substrate (200) and the embedded capacitor (700) are electrically connected, thereby allowing the second electrode layer (720) of the second substrate (200) and the embedded capacitor (700) to be electrically connected.

[0070] An embedded capacitor (700) may be placed between a first substrate (100) and a second substrate (200). The embedded capacitor (700) may be placed so as to be bonded to the upper surface of the first substrate (100) and to the lower surface of the second substrate (200). The embedded capacitor (700) may be bonded to the first substrate (100) and the second substrate (200) by a bonding sheet (800). Since the first substrate (100) functions as a ground and the second substrate (200) functions as a ground or power source, the embedded capacitor (700) may be placed therebetween and may function as a capacitor between the power source and the ground.

[0071] The embedded capacitor (700) may include an acoustic hole. The cross-sectional area of ​​the acoustic hole may be circular, but is not limited thereto, and may have a size corresponding to the acoustic holes formed in the first substrate (100) and the second substrate (200). The acoustic hole formed in the embedded capacitor (700) may be in communication with the acoustic holes formed in the first substrate (100) and the second substrate (200) to form one acoustic hole (10), and a MEMS structure (300) may be arranged on the acoustic hole (10).

[0072] The embedded capacitor (700) may include an insulating layer (730) and electrode layers (710, 720). In detail, the embedded capacitor (700) has electrode layers (710, 720) arranged on the upper and lower surfaces, respectively, and an insulating layer (730) formed between the electrode layers (710, 720), thereby performing the function of a capacitor by a high-dielectric material between the planar areas of the electrode layers (710, 720).

[0073] The electrode layers (710, 720) may include a first electrode layer (710) whose lower surface is disposed on the upper surface of the first substrate (100) and whose upper surface covers the insulating layer (730), and a second electrode layer (720) whose upper surface is disposed on the lower surface of the second substrate (200) and whose lower surface covers the insulating layer (730). That is, in a state where the first electrode layer (710) and the second electrode layer (720) are laminated with each other, the insulating layer (730) may be disposed in the space between the first electrode layer (710) and the second electrode layer (720). Through this, the first electrode layer (710) and the second electrode layer (720) may be electrically insulated from each other. The electrode layers may include a conductive metal material such as Cu or Au.

[0074] The insulating layer (730) is a means for generating a capacitor function by being disposed between the first electrode layer (710) and the second electrode layer (720). The insulating layer (730) may be formed of an insulating material having a high dielectric constant. The insulating material may be a material in which a ceramic-based material is compressed, and may include, for example, BaTiO3, but is not limited thereto, and various insulating materials having a high dielectric constant may be used without limitation. Since the first electrode layer (710) is electrically connected to the ground and the second electrode layer (720) is electrically connected to the power source by the insulating layer (730), the first electrode layer (710) and the second electrode layer (720) can perform the functions of the ground and the power source, respectively, and the embedded capacitor (700) can perform the function of a capacitor by the insulating layer (730).

[0075] The first electrode layer (710) can be electrically connected to the first substrate (100). The first electrode layer (710) can be electrically connected to the first substrate (100) and can serve as a ground integrally with the first substrate (100). In this case, the bonding sheet (810) that adheres the first electrode layer (710) and the first substrate (100) can be made of a conductive material, and the first electrode layer (710) and the first substrate (100) can be electrically connected by the bonding sheet (810).

[0076] The second electrode layer (720) can be electrically connected to the second substrate (200). When the second substrate (200) functions as a power source, the second electrode layer (720) can be electrically connected to the second substrate (200) to function as a power source integrally with the second substrate (200), or when the second substrate (200) functions as a ground, the second electrode layer (720) can be electrically connected to a signal processing element (500) laminated on the second substrate (200) and a power pad (112) among the pads (110) of the first substrate (100) to function as a power source.

[0077] There are two methods that can be utilized for the electrical connection between the second electrode layer (720) and the second substrate (200). The first is when the second substrate (200) functions as a power source. In this case, the bonding sheet (820) that bonds the second electrode layer (720) and the second substrate (200) is formed of a conductive material, and thus the second electrode layer (720) and the second substrate (200) can be electrically connected by the bonding sheet (820).

[0078] The second case is when the second substrate (200) serves as a ground. In this case, the bonding sheet (820) that bonds the second electrode layer (720) and the second substrate (200) is formed of a non-conductive material, and accordingly, the second electrode layer (720) exposed to the outside through the cavity (200a) of the second substrate (200) is wire-bonded with the power pad (112) among the pads (110) of the first substrate (100) and the signal processing element (500), so that the second electrode layer (720) serves as a power supply, and the second substrate (200) can serve as a ground.

[0079] In addition, the embedded capacitor (700) can perform the role of a capacitor. In detail, the insulating layer (730) of the embedded capacitor (700) performs the role of an insulator, and at the same time, the first electrode layer (710) and the second electrode layer (720) perform the role of a ground and a power source, respectively, based on the insulating layer (730), so that the embedded capacitor (700) can perform the role of a capacitor. The embedded capacitor (700) can be used to filter RF noise generated in a MEMS microphone. Accordingly, even without arranging a separate capacitor, there is an effect of improving SNR and PSRR performance.

[0080] The embedded capacitor (700) may include a cavity (700a) that vertically overlaps with the cavity (200a) formed on the second substrate (200). In this case, the size of the cavity (700a) of the embedded capacitor (700) may be the same as or smaller than the size of the cavity (200a) formed on the second substrate (200). In addition, the cavity (200a) and the cavity (700a) may vertically overlap each other at least partially.

[0081] For example, when the second substrate (200) serves as a ground, the set position width of the cavity (200a) of the second substrate (200) may have a width greater than the set position width of the cavity (700a) of the embedded capacitor (700). As a result, a portion of the second electrode layer (720) of the embedded capacitor (700) may be exposed to the outside through the cavity (200a) of the second substrate (200a).

[0082] The bonding sheet (800) is a means for attaching the embedded capacitor (700) to the first substrate (100) and the second substrate (200). In detail, the bonding sheet (800) may include a first bonding sheet (810) arranged between the lower surface of the embedded capacitor (700) and the upper surface of the first substrate (100), and a second bonding sheet (820) arranged between the upper surface of the embedded capacitor (700) and the lower surface of the second substrate (200).

[0083] The first bonding sheet (810) is positioned between the first metal layer (710) and the first substrate (100) and may be made of a conductive material. The first electrode layer (710) of the embedded capacitor (700) may be electrically connected to the first substrate (100) through the first bonding sheet (810) and thus may be grounded.

[0084] The second bonding sheet (820) is placed between the second electrode layer (720) and the second substrate (200) and may be made of a conductive material or a non-conductive material.

[0085] When the second bonding sheet (820) is made of a conductive material, the second electrode layer (720) of the embedded capacitor (700) is electrically connected to the second substrate (200) through the second bonding sheet (820), so that the second electrode layer (720) and the second substrate (200) can integrally function as a power source.

[0086] When the second bonding sheet (820) is made of a non-conductive material, a portion of the second electrode layer (720) of the embedded capacitor (700) can be exposed to the outside through the cavity (200a) of the second substrate (200), and the signal processing element (500) and the power pad (112) can be connected to the second electrode (720) exposed through the cavity (200a) so that the second electrode layer (720) can serve as a power source. In this case, the second substrate (200) can serve as a ground.

[0087] A housing (400), a MEMS structure (300), a signal processing element (500), and a capacitor (600) may be placed on the second substrate (200). The capacitor (600) may be selectively placed on the second substrate (200) as needed.

[0088] The housing (400) is a means for being placed on the upper side of the second substrate (200) and forming an accommodation space therein. The housing (400) may be formed in a cover shape with an open lower surface, and the lower side of the housing (400) may be bonded to the upper side of the second substrate (200) to form the accommodation space. In detail, the housing (400) may be bonded to the lower side of the second substrate (200) by solder being placed on the upper side of the second substrate (200). Depending on the size (Back Volume) of the accommodation space formed inside the housing (400), noise conditions such as SNR, PSR, and PSRR may be determined.

[0089] The housing (400) may be composed of nickel silver or SUS. Nickel silver is a material containing 15-30% zinc and 10-20% nickel in copper, and solder joints can be made without plating in the raw material state. When plating is applied to the seating area of ​​the housing (400), solder joint adhesion can be improved. Ni+Au plating can be applied. Both electroless and electrolytic plating processes can be applied. Although SUS contains nickel, solder joint adhesion may be reduced if plating is not performed. Therefore, plating can be applied. Unlike nickel silver, when electroless plating is applied, plating adhesion on the SUS surface may be reduced, so plating can be performed using an electrolytic plating process.

[0090] The MEMS structure (300) may be placed within a receiving space formed by the housing (400). The MEMS structure (300) may include a body (310), a back plate (330), and a vibration plate (320). The MEMS structure (300) may be placed on the upper portion of the second substrate (200), and the lower portion of the MEMS structure (300) may be placed at a position adjacent to the sound hole (10) of the second substrate (200).

[0091] The body (310) is a means that can form a partition wall by surrounding the sound hole (10) formed in the second substrate (200). The body (310) can be coupled to the second substrate (200) so as to be electrically connected to the first substrate (100) through the second substrate (200). In addition, an sound hole (360) that communicates with the sound hole (10) can be formed in the body (310). The body (310) can be directly connected to the second substrate (200), but if necessary, the body (310) can be directly connected to the first substrate (100) through a cavity of the second substrate (200), and there is no limitation thereto.

[0092] The body (310) may be formed with an acoustic hole (10). When the body (310) is coupled to the second substrate (200), the acoustic hole (10) formed in the first substrate (100) and the second substrate (200) and the acoustic hole (10) of the body (310) may be arranged to be in communication with each other, and thus, sound from the outside may be designed to be introduced through the acoustic hole (10).

[0093] The back plate (330) and the vibration plate (320) may be placed in the sound hole (10) formed in the body (310). The vibration plate (320) may vibrate due to the sound pressure when sound is introduced from the outside through the sound hole (10), and the back plate (330) may sense the sound signal by measuring the capacitance according to the vibration of the vibration plate (320). In the drawing, the back plate (330) is depicted as being positioned above the vibration plate (320), but the vibration plate (320) may also be positioned above the back plate (330).

[0094] One or more body pads for electrical connection may be formed on the upper surface of the body (310). The body pads may be electrically connected to the back plate (330) and the vibration plate (320), and may be electrically connected to a signal processing element (500) to be described later via wires or the like. The body pads serve as a means for electrical connection, and their shapes and materials are known in the art, so a description thereof will be omitted.

[0095] The signal processing element (500) is electrically connected to the MEMS structure (300) and can process an electric signal sensed by the MEMS structure (300). The MEMS structure (300) and the signal processing element (500) can be electrically connected via a body pad. For example, the MEMS structure (300) and the signal processing element (500) can be connected via a wire through wire bonding. In another example, the MEMS structure (300) and the signal processing element (500) can be electrically connected while being mounted on a second substrate (200) in a flip-chip form. When the MEMS structure (300) and the signal processing element (500) are wire bonded, a signal pad can be arranged on the signal processing element (500) to be connected to the body pad of the MEMS structure (300) through wire bonding.

[0096] The signal processing element (500) can amplify a signal sensed by the MEMS structure (300). Here, the signal processing element (500) may include an application-specific integrated circuit (ASIC), but is not limited thereto. The signal processing element (500) may be formed as a single module and may be formed in a chip form. The signal processing element (500) may include an ASIC and an En-cap that coats the ASIC.

[0097] The signal processing element (500) may be placed on the second substrate (200). The signal processing element (500) may be electrically connected to the first substrate (100) through the second substrate (200) or the embedded capacitor (700). The signal processing element (500) may be placed on the second substrate (200) so as to be spaced apart from the MEMS structure (300). The signal processing element (500) may be placed so as to be spaced apart from the MEMS structure (300) in an accommodation space formed inside the housing (400) and may receive a signal from the MEMS structure (300). Since signal transmission between the MEMS structure (300) and the signal processing element (500) occurs in the accommodation space formed by the housing (400), external interference is reduced, thereby reducing noise.

[0098] The signal processing element (500) can be electrically connected to the first substrate (100) or the embedded capacitor (700). The signal processing element (500) can be electrically connected to the first substrate (100). When the second substrate (200) serves as a power source, the signal processing element (500) can be electrically connected to the first substrate (100). The signal processing element (500) can be electrically connected to the pad (110) of the first substrate (100) through wire bonding, or can be electrically connected by being mounted in a flip-chip form. The signal processing element (500) can be directly electrically connected to the first substrate (100) through wire bonding, or can be electrically connected to the first substrate (100) by being mounted in a cavity of the second substrate (200) in a flip-chip form. The signal processed in the signal processing element (500) is transmitted to the pad (110) and connection circuit formed on the first substrate (100), and can be transmitted to the outside that requires the signal through the pad (110) and connection circuit formed on the first substrate (100).

[0099] The signal processing element (500) can be electrically connected to the embedded capacitor (700). When the second substrate (200) serves as a ground, the signal processing element (500) can be electrically connected to the second electrode layer (720) of the embedded capacitor (700). The second electrode layer (720) can be exposed to the outside through the cavity (200a) of the second substrate (200), and the signal processing element (500) can be electrically connected to the exposed second electrode layer (720) through wire bonding. The pad (110) formed on the first substrate (100) is electrically connected to the second electrode layer (720) exposed to the outside through the cavity (200a) of the second substrate (200), so that the signal processed in the signal processing element (500) can be transmitted to the outside that requires the signal through the second electrode (720) of the embedded capacitor (700) and the pad (110) formed on the first substrate (100) and the connection circuit (120).

[0100] A capacitor (600) may be selectively placed on the second substrate (200) as needed. When the capacitor (600) is placed, the PSRR performance, which is RF-related noise, may be improved, and the PSR performance, which is power-related noise, may be improved. That is, noise-related performances such as SNR, PSRR, and PSR may be improved through the capacitor (600). The capacitor (600) may be electrically connected to the signal processing element (500). As a result, the capacitor (600) may remove noise during the signal processing process in the signal processing element (500).

[0101] The capacitor (600) may be placed on the second substrate (200) and electrically connected to the signal processing element (500) and the first substrate (100). The capacitor (600) may be electrically connected to the signal processing element (500) and the first substrate (100) via a wire. When the capacitor (600) is connected to the first substrate (100) via a wire, it may be connected to a pad (110) or a connection circuit formed on the first substrate (100) exposed through the cavity (200a) of the second substrate (200) and the cavity (700a) of the embedded capacitor (700) via a wire.

[0102] However, the capacitor (600) may be electrically connected to the first substrate (100) by being mounted on the second substrate (200) or the signal processing element (500) in a flip-chip form as well as by bonding through wires. For example, the capacitor (600) may be mounted on the second substrate (200) and electrically connected to the first substrate (100) or may be mounted on the signal processing element (500) and electrically connected to the first substrate (100). The capacitor may be arranged in multiple numbers as needed to have the effect of removing desired noise.

[0103] In the case of a MEMS microphone, since miniaturization is essential, there are cases where only one capacitor (600) is placed or none is placed due to insufficient layout space in the circuit design. In this case, a problem occurs in which the performance of SNR, PSR, and PSRR is degraded due to power noise or RF noise. In particular, in the case of power noise filtering for improving SNR and PSR performance, the frequency of the noise is at the level of 0.1uF to 10uF, whereas in the case of RF noise filtering for improving SNR and PSRR performance, the frequency of the noise is at the level of 10pF to 500pF, so there is a problem in that different capacitors are required because they have different frequency bands. The MEMS microphone according to an embodiment of the present invention has the effect of placing multiple capacitors by having the capacitor (600) filtering power noise and the embedded capacitor (700) filtering RF noise, and has the effect of improving all noise performances of SNR, PSR, and PSRR.

[0104] FIG. 8 is a top view of a MEMS microphone according to another embodiment of the present invention, and FIG. 9 is a drawing showing the configuration surface of a substrate unit of a MEMS microphone according to another embodiment of the present invention.

[0105] Referring to FIGS. 8 and 9, a MEMS microphone according to another embodiment of the present invention may include a first substrate (100), a second substrate (200), a MEMS structure (300), a housing (400), a signal processing element (500), a capacitor (600), an embedded capacitor (700), and a bonding sheet (800). Duplicate descriptions of common components with respect to the MEMS microphone of the aforementioned embodiment will be omitted, and only different components will be described. In addition, a MEMS microphone according to another embodiment of the present invention will be described based on a case where the second substrate (200) serves as a power source.

[0106] In a MEMS microphone according to another embodiment of the present invention, the second substrate (200), the second electrode layer (720) of the embedded capacitor (700), the second bonding sheet (820) attaching the second substrate (200) and the embedded capacitor (700) may be spaced apart and divided to have shapes that are laterally symmetrical to each other. However, the second substrate (200), the second electrode layer (720), and the second bonding sheet (820) may be arranged to have shapes that are asymmetrical to each other depending on the capacitor capacity, and there is no limitation thereto. Below, the laminated structure of the second substrate (200), the second bonding sheet (800), and the second electrode (720) is defined as a power substrate.

[0107] The power boards can be divided and spaced apart so as to have shapes that are symmetrical laterally, and in this case, the power board can include a first power board arranged on one side and a second power board arranged on the other side. That is, the power board can be formed by being divided into a first power board and a second power board. The first power board and the second power board can be arranged to be spaced apart from each other by a set interval based on the center. In this case, both the first power board and the second power board can function as a power source.

[0108] When the first power board and the second power board are spaced apart from each other, an acoustic hole and cavity (700a) can be formed. In this case, the cavity (700a) can be arranged so that a square opening is formed in each of the first power board and the second power board so as to be symmetrical to each other in the left-right direction and communicate with each other. That is, the cavity (700a) can have a shape that is symmetrical with respect to the central axis.

[0109] The first power board can be electrically connected to the first power pad (112) among the pads (110) of the first substrate (100). The first power board can be electrically connected to the first power pad (112) through wire bonding. Here, since the first power pad (112) is a pad to which an analog circuit power is connected, the first power board can also perform the role of an analog circuit power.

[0110] The first power board may be configured in a form in which a first split board (210) divided from a second board (200) and placed on one side, a first split sheet (821) divided from a second bonding sheet (820) and placed on one side, and a first split electrode layer (721) divided from a second electrode layer (720) of an embedded capacitor (700) and placed on one side are sequentially stacked.

[0111] The first split sheet (821) is formed of a conductive material so that the first split substrate (210) and the first split electrode layer (721) can be electrically connected, and the first split substrate (210), the first split sheet (821), and the first split electrode (721) can all function as a power source, so that the first power source substrate can function as an analog circuit power source.

[0112] The second power board can be electrically connected to the second power pad (111) among the pads (110) of the first substrate (100). The second power board can be electrically connected to the second power pad (111) through wire bonding. Here, since the second power pad (111) is a pad to which a digital circuit power is connected, the second power board can also function as a digital circuit power supply.

[0113] The second power board may be configured in a form in which a second split board (220) is divided from the second substrate (200) and placed on the other side and has a shape symmetrical to the first split board (210), a second split sheet (822) is divided from the second bonding sheet (820) and placed on the other side and has a shape symmetrical to the first split sheet (821), and a second split electrode layer (722) is divided from the second electrode layer (720) of the embedded capacitor (700) and placed on the other side and has a shape symmetrical to the first split electrode layer (721) in that order are laminated. That is, the second power board may be placed spaced apart from one side of the first power board and have a shape symmetrical to the first power board.

[0114] In addition, when the first split substrate (210) of the first power substrate and the second split substrate (220) of the second power substrate perform the power function, the first split substrate (210) and the second split substrate (220) may be electrically connected to the first power pad (111) and the second power pad (112) among the pads (110) of the first substrate (100), respectively. The first split substrate (210) may be electrically connected to the first power pad (111) through wire bonding, and the second split substrate (220) may be electrically connected to the second power pad (112) through wire bonding. However, the present invention is not limited thereto, and the first split substrate (210) may be electrically connected to the second power pad (112) and the second split substrate (220) may be electrically connected to the first power pad (111).

[0115] The second split sheet (822) is formed of a conductive material so that the second split substrate (220) and the second split electrode layer (722) can be electrically connected, and the second split substrate (220), the second split sheet (822), and the second split electrode layer (722) can all function as a power source, so that the second power substrate can function as a digital circuit power source.

[0116] In the present disclosure, the first split substrate (210) and the second split substrate (220), the first split sheet (821) and the second split sheet (822), the first split electrode layer (721) and the second split electrode layer (722) are illustrated and described as having shapes that are symmetrical to each other, but the present disclosure is not limited thereto, and it goes without saying that the split pairs may be implemented in shapes that are not symmetrical to each other depending on the embodiment.

[0117] In another embodiment of the present invention, a MEMS microphone is arranged such that a power substrate, which is a laminated structure from a second electrode (720) of an embedded capacitor (700) to a second substrate (200), is divided into a first power substrate and a second power substrate, and the first power substrate and the second power substrate are electrically connected to a first power pad and a second power pad, respectively, so that they perform the roles of an analog circuit power source and a digital circuit power source, respectively. Therefore, when the embedded capacitor (700) performs the role of a capacitor by an insulating layer, there is an effect of being able to perform the roles of capacitors for the analog circuit power source and the digital circuit power source, respectively. That is, by changing the structure of one embedded capacitor (700), there is an effect of arranging two capacitors for the analog circuit power source and the digital circuit power source, respectively.

[0118] FIG. 10 is a drawing showing the structure of a substrate unit of a MEMS microphone according to another embodiment of the present invention.

[0119] Referring to FIG. 10, a MEMS microphone according to another embodiment of the present invention may include a first substrate (100), a second substrate (200), a MEMS structure (300), a housing (400), a signal processing element (500), a capacitor (600), two or more embedded capacitors (700), and a bonding sheet (800).

[0120] According to another embodiment of the present invention, a substrate unit of a MEMS microphone may be arranged so that two or more embedded capacitors (700) are stacked between a first substrate (100) and a second substrate (200). The embedded capacitors (700) may include a first embedded capacitor arranged on an upper side of the first substrate (100) and a second embedded capacitor arranged on an upper side of the first capacitor and a lower side of the second substrate. That is, the substrate unit may be stacked in the order of the first substrate (100), the first embedded capacitor, the second embedded capacitor, and the second substrate (200), and a bonding sheet (800) may be arranged between each component.

[0121] The bonding sheet (800) may include a first bonding sheet (810) between the first substrate (100) and the first embedded capacitor, a second bonding sheet (820) between the second embedded capacitor and the second substrate (200), and a third bonding sheet (830) between the first embedded capacitor and the second embedded capacitor. The first bonding sheet and the second bonding sheet have the same structure as described above, so a duplicate description thereof will be omitted. The third bonding sheet may be made of a non-conductive material, but is not limited thereto.

[0122] The first embedded capacitor and the second embedded capacitor have the same structure as the embedded capacitor (700) of the MEMS microphone according to one embodiment of the present invention, and thus a duplicate description thereof will be omitted. However, since the first embedded capacitor and the second embedded capacitor are stacked vertically, the first embedded capacitor and the second embedded capacitor can function as two capacitors connected in parallel with each other.

[0123] Those skilled in the art will appreciate that the present invention can be implemented in modified forms without departing from the essential characteristics of the above-described description. Therefore, the disclosed methods should be considered illustrative rather than restrictive. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. A first substrate including at least one first insulating layer, a first metal layer disposed on an upper surface of the first insulating layer, and a second metal layer disposed on a lower surface of the first insulating layer; An embedded capacitor laminated on the first substrate; A second substrate laminated on the above embedded capacitor and including a metal plate; A MEMS structure disposed on the second substrate; and A MEMS microphone including a signal processing element disposed on the second substrate and spaced apart from the MEMS structure.

2. In paragraph 1, The above embedded capacitor, A first electrode layer disposed on the upper surface of the first substrate, A second electrode layer disposed on the lower surface of the second substrate and A MEMS microphone comprising a second insulating layer disposed between the first electrode layer and the second electrode layer.

3. In paragraph 2, A first bonding sheet disposed between the first substrate and the first electrode layer; and A MEMS microphone comprising a second bonding sheet disposed between the second substrate and the second electrode layer.

4. In paragraph 3, The first bonding sheet and the second bonding sheet include a conductive material, The first bonding sheet electrically connects at least a portion of the first metal layer of the first substrate and the first electrode layer of the embedded capacitor, The above second bonding sheet is a MEMS microphone that conducts electricity between the second electrode layer of the embedded capacitor and the second substrate.

5. In paragraph 2, The second substrate includes a first cavity vertically overlapping at least a portion of the first metal layer of the first substrate, A MEMS microphone, wherein the embedded capacitor includes a second cavity vertically overlapping at least a portion of the first cavity.

6. In paragraph 5, A MEMS microphone in which a portion of the second electrode layer vertically overlaps the first cavity and is electrically connected to the signal processing element.

7. In paragraph 1, The above second substrates are divided and arranged symmetrically with respect to the central axis, The above embedded capacitor, A first electrode layer disposed on the upper surface of the first substrate, A second electrode layer divided and arranged symmetrically on the lower surface of the second substrate in a shape corresponding to the second substrate; and A MEMS microphone comprising a second insulating layer disposed between the first electrode layer and the second electrode layer.

8. In paragraph 7, The above second substrate, It includes a first split substrate arranged on one side and a second split substrate arranged on the other side so as to have a shape symmetrical to the first split substrate, The second electrode layer is, A MEMS microphone comprising a first split electrode layer arranged on the lower side of the first split substrate so as to be electrically conductive to the first split substrate, and a second split electrode layer arranged on the lower side of the second split substrate so as to be electrically conductive to the second split substrate.

9. In paragraph 1, The above embedded capacitor is, A first embedded capacitor disposed on the first substrate and A MEMS microphone including a second embedded capacitor arranged above the first embedded capacitor and below the second substrate.

10. In paragraph 9, Further comprising a third bonding sheet disposed between the first embedded capacitor and the second embedded capacitor, The above third bonding sheet is a MEMS microphone containing a non-conductive material.

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