MEMS microphone

Abstract

A MEMS microphone according to one embodiment of the present invention comprises: a second substrate having an auxiliary pad; a MEMS structure disposed on the second substrate and having a body pad; and a signal processing element spaced apart from the MEMS structure, disposed on the second substrate, and having a signal pad, wherein the auxiliary pad may be in contact with and electrically connected to at least one of the body pad or the signal pad.

Description

MEMS Microphone

[0001] The present invention relates to a MEMS microphone, and more specifically, to a MEMS microphone characterized by a flip chip bonding structure of the element.

[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 technical problem to be solved by the present invention is to provide a MEMS microphone that utilizes a flip-chip structure of the device for miniaturization and noise removal.

[0006] In order to solve the above technical problem, a MEMS microphone according to an embodiment of the present invention includes: a second substrate having an auxiliary pad formed thereon; a MEMS structure disposed on the second substrate and having a body pad formed thereon; and a signal processing element disposed on the second substrate and spaced apart from the MEMS structure and having a signal pad formed thereon; wherein the auxiliary pad can be electrically connected to at least one of the body pad and the signal pad by making contact with it.

[0007] In addition, the present invention may further include a combination that indirectly contacts at least one of the auxiliary pad, the body pad, and the signal pad.

[0008] In addition, the combination may include a first stud that contacts at least one of the body pad and the signal pad and has a diameter that becomes narrower as it goes down, a second stud that contacts the auxiliary pad and has a diameter that becomes narrower as it goes up, and a connecting bumper that connects the first stud and the second stud.

[0009] Additionally, the first stud, the second stud, and the connecting bumper may include Au.

[0010] Additionally, the combination may further include a seal formed to surround the first stud and the second stud.

[0011] Additionally, the sealant may include one or more of silicone and epoxy.

[0012] Additionally, the composite may include one or more conductive films.

[0013] Additionally, the conductive film may include an anistropic conductive film (ACF) in which conduction is performed only in a set direction.

[0014] Additionally, the conductive film may include an adhesive material and a plurality of conductive particles disposed within the adhesive material.

[0015] Additionally, the conductive particles may be made of a polymer and a metal material coating the outside of the polymer.

[0016] In addition, the MEMS structure may include a body disposed on the upper portion of the second substrate, in which an acoustic hole is formed, and in which the body pad is disposed on the lower surface, a vibration plate and a back plate disposed to be spaced apart from the acoustic hole of the body in the vertical direction.

[0017] Additionally, the vibration plate and the back plate may be positioned lower than the center of the body and electrically connected to the body pad.

[0018] In addition, the MEMS structure may include a body disposed on the upper portion of the second substrate, in which an acoustic hole is formed, the body pad is disposed on the upper surface, and a body hole extending from the body pad to the lower portion is formed and filled with a conductive material inside, and a vibration plate and a back plate disposed to be spaced apart from the acoustic hole of the body in the vertical direction.

[0019] Additionally, the vibration plate and the back plate may be positioned above the center of the body and electrically connected to the body pad.

[0020] Additionally, it may further include a capacitor connected to the signal processing element and the second substrate.

[0021] The MEMS microphone according to an embodiment of the present invention has the following effects.

[0022] Since the MEMS structure and signal processing elements are mounted on the substrate in the form of flip chips, not only can the package structure be miniaturized compared to the existing wire bonding, but the overall structure can be miniaturized while maintaining the size of the accommodation space inside the housing, i.e. the size of the back volume, thereby achieving the same noise effect.

[0023] Additionally, there is an effect that allows the back volume to be reduced or increased depending on the structure of the acoustic device in which the MEMS microphone is mounted. In particular, the size of the back volume can be adjusted depending on the arrangement of the diaphragm and back plate of the MEMS structure. Therefore, depending on the specifications of the installed product, the back volume size can be increased to improve the SNR, or conversely, the front volume can be increased to allow more efficient inflow of external sound.

[0024] In addition, by forming a redistribution layer as a second substrate, which is a combination body and a second substrate, a fine pitch is possible due to the pattern redistribution effect of the second substrate, so that not only the integration of the substrate of the device is increased, but also the pattern circuit formation of the substrate itself is possible, so the design freedom of the device is increased, and not only the wire bonding but also the device can be directly mounted in the form of a flip chip, so that not only the size can be reduced, but also the material cost of gold, which is the main wire material, can be reduced. In particular, as the flip chip structure is implemented, the wire bonding of the capacitor can be omitted, and this enables the arrangement of one or more capacitors, thereby reducing power noise and RF noise and increasing the back volume, which has the effect of improving the SNR, PSR, and PSRR performance.

[0025] In addition, the combination is designed to utilize the structure used in existing wire bonding, so that the flip chip form is maintained and the process equipment used in the existing process is utilized, thereby utilizing the existing line and reducing additional equipment costs.

[0026] In addition, by utilizing a conductive film that allows electricity to be conducted in a specific direction in the bonding material, not only can the bonding stability be improved and the electrical connection efficiency be increased, thereby reducing noise generation, but also the bonding process can be simplified using ACF, and low-temperature curing is possible, thereby reducing the thermal stress applied to the MEMS structure, thereby reducing the defect rate.

[0027] By simplifying the process, time can be shortened. Furthermore, the metal plate hole etching area can be reduced, reducing process management points. Design freedom for hole shape and size reduction can be increased. Capacitor capacity can be increased. The increased bonding area of ​​the conductive adhesive layer prevents delamination, thereby enhancing reliability.

[0028] Figures 1 to 4 are drawings illustrating the structure of a MEMS microphone according to one embodiment of the present invention.

[0029] FIG. 5 is a drawing for explaining a second substrate lamination process of a MEMS microphone according to one embodiment of the present invention.

[0030] FIG. 6 and FIG. 7 are drawings showing the structure of a MEMS microphone according to another embodiment of the present invention.

[0031] FIGS. 8 to 12 are drawings illustrating the structure of a MEMS microphone according to another embodiment of the present invention.

[0032] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] FIGS. 1 to 4 are drawings illustrating the structure of a MEMS microphone according to one embodiment of the present invention.

[0042] Referring to FIGS. 1 to 4, 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), and at least one capacitor (610, 620). The first substrate (100) is disposed 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 has a film shape, so 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 the case where a conventional rigid substrate is used.

[0043] 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.

[0044] 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%.

[0045] 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.

[0046] 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).

[0047] The first substrate (100) may be electrically connected to the signal processing element (500) and the capacitors (610, 620). The first substrate (100) may have a metal layer formed thereon for electrically connecting the signal processing element (500) and the capacitors (610, 620). 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 the base film or the insulating layer. Hereinafter, to help understanding the description, the pads formed on the first substrate (100) are referred to as main pads (110).

[0048] Main pads (110) and connection circuits having the same or different shapes may be formed on the upper and lower surfaces of the first substrate (100). A plurality of main pads (110) and connection circuits may be formed on the upper and lower surfaces of the first substrate (100). In this case, a plurality of main pads (110) formed on the upper surface of the first substrate (100) may be electrically connected to a plurality of main pads (110) formed on the lower surface of the first substrate (100). A plurality of main pads (110) formed on the upper surface of the first substrate (100) may be electrically connected to a plurality of main pads (110) formed on the lower surface of the first substrate (100) through vias. In addition, a plurality of main pads (110) formed on the upper surface of the first substrate (100) may be arranged at the same position as a plurality of main pads (110) formed on the lower surface of the first substrate (100) or may be arranged at different positions. That is, there is no limitation on the arrangement as long as the main pads (110) arranged on the upper surface of the first substrate (100) are electrically connected to the main pads (110) formed on the lower surface of the first substrate (100). The signal processing element (500) and capacitors (610, 620) may be electrically connected to the first substrate (100) through the main pads (110) formed on the upper surface of the first substrate (100).

[0049] The main pad (110) may include an AVDD pad to which an analog circuit power supply (AVDD) is connected and a DVDD pad to which a digital circuit power supply (DVDD) is connected. The main pad (110) may be formed by separating the AVDD pad and the DVDD pad to distinguish the driving voltage and noise.

[0050] A bonding sheet may be placed on the first substrate (100). The bonding sheet may bond the first substrate (100) and the second substrate (200). The bonding sheet may bond the first substrate (100) and an embedded capacitor (700) to be described later.

[0051] The second substrate (200) is laminated to be placed on the first substrate (100) and has a plate shape. The second substrate (200) can be bonded to the first substrate (100) by a bonding sheet. The second substrate (200) can be formed of at least one insulating layer and a plurality of metal layers. Here, the metal layers can include a plurality of pads, a plurality of connection circuits, and a plurality of vias. The pads can be placed on the upper or lower surface of the insulating layer to vertically overlap and contact the vias, or can contact an external substrate or element. The connection circuits can connect between pads placed on the same layer. The vias can be formed in via holes penetrating the insulating layers. Hereinafter, to help understanding the explanation, the pads formed on the second substrate (200) are referred to as auxiliary pads (210), and the connection circuits formed on the second substrate (200) are referred to as pattern circuits (220). In one embodiment, the second substrate (200) may be formed of a plurality of vertically stacked insulating layers.

[0052] The second substrate (200) can perform the function of electrically connecting at least one of the MEMS structure (300), the signal processing element (500), and the capacitor (610, 620) to the first substrate (100) having a fine pitch, and this can be referred to as a redistribution layer (RDL).

[0053] The insulating layer may include polyimide (PI). The insulating layer may include photosenetic polyimide (PSPI). However, the present disclosure is not limited thereto, and the insulating layer may include a resin. For example, the insulating layer may include a resin, a curing agent, a photoinitiator, a pigment, a solvent, a filler, an additive, an acrylic monomer, and the like, and may further include glass fiber or GCP (Glass Core Primer) according to an embodiment. In other words, the insulating layer is not limited in material as long as an insulating material capable of performing insulation is used.

[0054] The second substrate (200) can electrically connect the main pad (110) and the components of the first substrate (100). For example, when the components are arranged on the second substrate (200) in a flip-chip form and connected to the auxiliary pad (210), the second substrate (200) can electrically connect the components to the first substrate (100) through the auxiliary pad (210), the pattern circuit (220), and the via. In this case, implementation in the flip-chip form is possible without the need for separate wire bonding, but if necessary, the flip-chip and wire bonding can be combined, or only wire bonding can be used.

[0055] Additionally, the second substrate (200) can electrically connect elements. For example, when a MEMS structure (300), a signal processing element (500), or a capacitor (610, 620) is connected to an auxiliary pad (210) on the upper surface of the second substrate (200), the second substrate (200) can connect the elements through at least one of a pattern circuit (220) and a via.

[0056] The second substrate (200) may be formed to have a strength greater than the set strength. The second substrate (200) may be arranged to supplement the rigidity of the first substrate (100), and for this purpose, an insulating layer may be laminated in multiple layers. The insulating layer may be laminated in 2 to 4 layers. If the insulating layer is laminated in 5 or more layers, the rigidity increases, but the thickness may increase and the process and material costs may increase. The second substrate (200) may include an acoustic hole (10). The cross-sectional area of ​​the acoustic hole (10) may be circular, but is not limited thereto. The acoustic hole (10) formed in the second substrate (200) may be in communication with the acoustic hole (10) formed in the first substrate (100) to form one acoustic hole (10).

[0057] Below, a process for laminating a second substrate (200) on a first substrate (100) is described. Fig. 5 is a drawing for explaining a process for laminating a second substrate (200) of a MEMS microphone according to one embodiment of the present invention.

[0058] Referring to FIG. 5, a first substrate (100) having a main pad (110) disposed on the upper surface is prepared. In this case, the main pad (110) may be disposed on the bottom layer of the hole (a). Thereafter, a first insulating layer is laminated on the first substrate (100), and a first metal layer is formed on the first insulating layer (b). The first metal layer and the first insulating layer are etched to form a first through hole (c). A metal is plated on the first through hole to form a first via, and a portion of the remaining area of ​​the first metal layer is etched to form at least one first pad and a connection circuit (d). A second insulating layer is laminated on the first insulating layer, and a second metal layer is formed on the second insulating layer (e). The second metal layer and the second insulating layer are etched to form a second through hole. In this case, the second through hole may be arranged in a direction perpendicular to the first through hole, and the second through hole may be arranged at a position laterally spaced apart from the first through hole in a direction perpendicular to the first through hole (f). Metal is plated in the second through hole to form a second via, and a portion of the remaining area of ​​the second metal layer is etched to form at least one second pad and a second connection circuit (g). Steps (e) to (g) in the above process may be repeated corresponding to the number of insulating layers constituting the second substrate (200).

[0059] A housing (400), a MEMS structure (300), a signal processing element (500), and capacitors (610, 620) may be placed on the second substrate (200). The capacitors (610, 620) may be selectively placed on the second substrate (200) as needed.

[0060] 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), a noise state such as SNR, PSR, PSRR, etc. may be determined. A detailed description thereof will be provided later.

[0061] 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.

[0062] 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).

[0063] 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.

[0064] 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).

[0065] 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 is depicted as being positioned above the vibration plate (320), but the vibration plate (320) may also be positioned above the back plate.

[0066] One or more body pads (340) for electrical connection may be formed on the upper surface of the body (310). The body pads (340) 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 (340) are a means for electrical connection, and their shape and material are known technologies, so a description thereof will be omitted.

[0067] The signal processing element (500) is electrically connected to the MEMS structure (300) and can process an electrical 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 (340). For example, the MEMS structure (300) and the signal processing element (500) can be connected via wires via wire bonding. As 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 (510) may be placed on the signal processing element (500) to be connected to the body pad (340) of the MEMS structure (300) through wire bonding.

[0068] 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.

[0069] 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). 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.

[0070] The signal processing element (500) can be electrically connected to the MEMS structure (300) and the first substrate (100). The signal processing element (500) can be electrically connected to the MEMS structure (300). The signal processing element (500) can be electrically connected to the body pad (340) formed on the body (310) of the MEMS structure (300) by having a signal pad (510) disposed thereon. The signal pad (510) of the signal processing element (500) and the body pad (340) of the MEMS structure (300) can be electrically connected through wire bonding, or the body pad (340) and the auxiliary pad (210) formed on the second substrate (200) are wire bonded, and the pattern circuit (220) electrically connects the auxiliary pad (210) and the signal pad (520), thereby electrically connecting the signal processing element (500) and the MEMS structure (300).

[0071] 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 first substrate (100) through wire bonding, or can be electrically connected by being mounted in a flip-chip form. Since the auxiliary pad (210) is formed on the surface of the second substrate (200), the signal processing element (500) can be directly electrically connected to the first substrate (100) through wire bonding, and can also 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 main pad (110) and connection circuit formed in the first substrate (100), and can be transmitted to the outside that requires the signal through the main pad (110) and connection circuit formed in the first substrate (100).

[0072] A capacitor (610, 620) may be selectively placed on the upper portion of the second substrate (200) as needed. When the capacitor (610, 620) 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 (610, 620). The capacitor (610, 620) may be electrically connected to the signal processing element (500). As a result, the capacitor (610, 620) may remove noise during the process of processing a signal in the signal processing element (500).

[0073] The capacitors (610, 620) may be placed on the second substrate (200) and electrically connected to the signal processing element (500) and the first substrate (100). The capacitors (610, 620) may be electrically connected to the signal processing element (500) and the first substrate (100) via wires. When the capacitors (610, 620) are connected to the first substrate (100) via wires, they may be connected to pads or connection circuits formed on the first substrate (100) exposed through the cavity of the second substrate (200) via wires.

[0074] However, the capacitors (610, 620) 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 first capacitor (610) may be mounted on the second substrate (200) and electrically connected to the first substrate (100), and the second capacitor (620) may be mounted on the signal processing element (500) and electrically connected to the first substrate (100). Since multiple first capacitors (610) and second capacitors (620) are arranged, there is an effect of removing desired noise for each capacitor (610, 620). In the case of a MEMS microphone, since miniaturization is essential, there are many cases where the capacitors (610, 620) are not arranged in the circuit design due to insufficient space for arranging the capacitors (610, 620). 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 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 they have different frequency bands. When multiple capacitors are arranged, the filtering noise frequency of each capacitor can be determined differently, and accordingly, there is an effect that all performance improvements of SNR, PSR, and PSRR are possible.

[0075] FIG. 6 and FIG. 7 are drawings showing the structure of a MEMS microphone according to another embodiment of the present invention.

[0076] Referring to FIGS. 6 and 7, a MEMS microphone according to another embodiment of the present invention may include a first substrate (100), an embedded capacitor (700), a second substrate (200), a MEMS structure (300), a housing (400), a signal processing element (500), and capacitors (610, 620). Duplicate descriptions of common components with respect to the MEMS microphone of the aforementioned embodiment are omitted, and only different components are described below.

[0077] The embedded capacitor (700) may be placed between the first substrate (100) and the second substrate (200). At this time, the second substrate (200) may be formed on top of the embedded capacitor (700) through a process, and the first substrate (100) and the embedded capacitor (700) may be formed through a stacking process. That is, the MEMS microphone according to another embodiment of the present invention may further include a stacking process compared to the MEMS microphone according to one embodiment.

[0078] The embedded capacitor (700) may be laminated on the upper portion of the first substrate (100) with an insulating material disposed between the metal layers. The embedded capacitor (700) may be bonded to the upper portion of the first substrate (100) with a bonding sheet disposed on the lower surface.

[0079] The embedded capacitor (700) may include an insulating material and a metal layer. The metal layer may have a lower surface disposed on the first substrate (100) and an upper surface disposed on the lower side of the second substrate (200). The metal layer may include a first metal layer forming a lower surface and disposed on the upper side of the first substrate (100), and a second metal layer forming an upper surface and disposed on the lower side of the second substrate (200). An insulating material may be disposed between the first metal layer and the second metal layer. The first metal layer and the second metal layer may be laminated with each other, and the insulating material may be disposed between the first metal layer and the second metal layer, thereby forming the embedded capacitor (700). The metal layer may be formed of a metal material such as Cu or Au, and the insulating material may include an insulating material having a high dielectric constant. BaTiO3 may be used as the insulating material, but is not limited thereto, and various insulating materials having a high dielectric constant may be used without limitation.

[0080] The embedded capacitor (700) can function as a capacitor. In detail, the embedded capacitor (700) can be used for RF noise filtering because the internal insulating material functions as an insulator and the metal layer is connected to the first substrate and the second substrate, and thus, even without placing a separate capacitor, the SNR and PSRR performances are improved.

[0081] The embedded capacitor (700) can be electrically connected to the main pad (110) to remove RF noise. The embedded capacitor (700) can be connected to the AVDD pad and the DVDD pad of the main pad (110), respectively. In this case, the embedded capacitor (700) can include a first embedded capacitor and a second embedded capacitor that are arranged laterally symmetrically to each other. The first embedded capacitor is connected to the AVDD pad to remove RF noise generated by an analog voltage, and the second embedded capacitor is connected to the DVDD pad to remove RF noise generated by a digital voltage.

[0082] In addition, since the MEMS microphone according to another embodiment of the present invention has a total substrate thickness of 0.125 to 0.145 mm despite the embedded capacitor (700) being laminated, the substrate thickness is reduced by 20 to 50% compared to the case where an existing rigid substrate is used or a metal plate is laminated on a COF substrate, thereby improving the overall performance of the MEMS microphone and miniaturizing it.

[0083] FIGS. 8 to 12 are drawings illustrating the structure of a MEMS microphone according to another embodiment of the present invention.

[0084] Referring to FIGS. 8 to 12, 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 signal processing element (500), and a combination (800, 900). Duplicate descriptions of common components with respect to the MEMS microphone of the aforementioned embodiment are omitted, and only different components are described below.

[0085] The first substrate (100) may include a plurality of main pads (110). The first substrate (100) and the main pads (110) have been described above, and a duplicate description thereof will be omitted.

[0086] The second substrate (200) may include an auxiliary pad (210) and a pattern circuit (220). The auxiliary pad (210) and the pattern circuit (220) are described above, and the configuration of the auxiliary pad (210) is described. The auxiliary pad (210) may include a first auxiliary pad (211, 212), a second auxiliary pad (213), a third auxiliary pad (214), and a fourth auxiliary pad (215). The pattern circuit (220) is a circuit for electrical connection between pads, and is described as a general term for all pattern circuits without being distinguished separately.

[0087] The first auxiliary pad (211, 212) is a pad for electrically connecting the body (310) of the MEMS structure (300) and can be placed at a location where the MEMS structure (300) is laminated. The first auxiliary pad (211, 212) has a shape corresponding to the contact surface of the body (310) and can be electrically connected to the body pad (340) to electrically connect the body (310) to a signal processing element.

[0088] The second auxiliary pad (213) is a pad for electrically connecting by contacting one side of the signal processing element (500). The second auxiliary pad (213) is a means for electrically connecting the signal processing element (500) and the body (310) by contacting the signal pads (510, 520) arranged on the lower side of one side of the signal processing element (500). In this case, the first auxiliary pads (211, 212) and the second auxiliary pad (213) are electrically connected by the pattern circuit (220) formed on the second substrate (200), so that the MEMS structure (300) and the signal processing element (500) are electrically connected, and an electrical signal collected from the MEMS structure (300) can be processed through the signal processing element (500).

[0089] The third auxiliary pad (214) is a pad for electrically connecting by contacting the other side of the signal processing element (500). The third auxiliary pad (214) is a means for electrically connecting the signal processing element (500) and the first substrate (100) by contacting the signal pad (520) arranged on the lower side of the other side of the signal processing element (500). In this case, the third auxiliary pad (214) can be electrically connected to the main pad (110) formed on the first substrate (100), and a pattern circuit (220) for electrically connecting the third auxiliary pad (214) and the main pad (110) can be formed on the second substrate (200). A signal processed in the signal processing element (500) by the third auxiliary pad (214) can be transmitted to the outside through the first substrate (100).

[0090] The fourth auxiliary pad (215) is a pad for electrical connection by contacting the housing (400). The fourth auxiliary pad (215) is arranged in a shape corresponding to the lower circumference of the housing (400) and is a means for electrically connecting the housing (400) and the first substrate (100) by contacting the contact surface of the housing (400). In this case, the fourth auxiliary pad (215) can be electrically connected to the main pad (110) formed on the first substrate (100), and a pattern circuit (220) for electrically connecting the fourth auxiliary pad (215) and the main pad (110) can be formed on the second substrate (200).

[0091] The assembly (800, 900) is a means for combining the MEMS structure (300) and the second substrate (200). In detail, the assembly (800, 900) is a means for electrically connecting the body pad (340) formed on the body (310) of the MEMS structure (300) and the auxiliary pad (210) of the second substrate (200).

[0092] According to another embodiment of the present invention, a MEMS microphone can be divided into first to eighth embodiments depending on the arrangement shape of the body (310) and the material and shape of the assembly (800, 900). The structure of the MEMS microphone according to each embodiment is described below.

[0093] Referring to FIG. 8, the MEMS structure (300) body (310), signal processing element (500), and assembly (800) of the MEMS microphone according to the first embodiment will be described. The body (310) of the MEMS structure (300) may form a partition wall that forms a hole so as to surround the sound hole (10) formed in the first substrate (100) and the second substrate (200). A body pad (340) may be arranged along the extension direction at the bottom of the body (310). In addition, the signal processing element (500) may also have a signal pad (510) arranged at the bottom. At this time, the MEMS structure (300) and the signal processing element (500) may be used by turning over a module that has been used previously. That is, the body pad (340) of the body (310) of the existing MEMS structure (300) formed on the upper side and the signal pad (510) of the signal processing element (500) can be placed on the lower side.

[0094] In addition, the back plate (330) and the vibration plate (320) may be placed in the sound hole (10) of the body (310) and may be placed closer to the lower portion than the upper portion of the body (310). That is, the back plate (330) and the vibration plate (320) may be placed lower relative to the center of the body (310). As the back plate (330) and the vibration plate (320) are placed lower than the body (310), the back volume inside the housing (400) may increase.

[0095] The back plate (330) and the vibration plate (320) can be electrically connected to the pattern circuit (220) connected to the auxiliary pad (210). The body pad (340) arranged on one side of the body (310) can be connected to the back plate (330), and the body pad (340) arranged on the other side of the body (310) can be connected to the vibration plate (320). Through this, the vibration of the vibration plate (320) can be transmitted to the back plate (330), converted into an acoustic signal, and then transmitted to a signal processing means. The vertical arrangement direction of the back plate (330) and the vibration plate (320) can be changed as needed and there is no limitation thereto.

[0096] The assembly (800) is a means for joining the body pad (340) positioned at the lower portion of the body (310) and the first auxiliary pads (211, 212) of the second substrate (200), and for joining the signal pad (510) of the signal processing element (500) and the second auxiliary pad (213) and the third auxiliary pad (214), respectively. The assembly (800) may include a first stud (810), a second stud (820), a connection bumper (830), and a sealing member (840).

[0097] The first stud (810) is a means that protrudes downwardly and comes into contact with the body pad (340) formed at the lower portion of the body (310) or the signal pad (510) of the signal processing element (500). The first stud (810) may be formed in a shape in which the area protruding downwardly is spherical or has a diameter that narrows as it goes downward. That is, the first stud (810) may be formed in a shape in which a metal pad for electrical connection and a solder ball are combined.

[0098] The second stud (820) is a means that protrudes upwardly and contacts the auxiliary pad (210) of the second substrate (200). The second stud (820) may be formed in a spherical shape or in a shape in which the diameter narrows as it goes upward. In other words, the second stud (820) may be formed in a shape in which a metal pad for electrical connection and a solder ball are combined.

[0099] The first stud (810) and the second stud (820) are manufactured based on a process for manufacturing existing wires, so that the wire maintains its shape just before being extended, and since the equipment used in the wire process is used as is, there is no need to add a separate process or introduce additional equipment.

[0100] The connecting bumper (830) is a means for joining the first stud (810) and the second stud (820). The connecting bumper (830) is a means for joining the first stud (810) and the second stud (820) so that they are stably combined and electrically connected, and may have the same material as the first stud (810) and the second stud (820). The connecting bumper (830) can join the first stud (810) and the second stud (820) through a thermal compression method.

[0101] The first stud (810), the second stud (820), and the connecting bumper (830) may be formed of a conductive material, and a material with low resistance may be utilized. For example, the first stud (810), the second stud (820), and the connecting bumper (830) may be formed of Au, but the present disclosure is not limited thereto, and it is sufficient if they are formed of a metal material with high conductivity and low resistance.

[0102] The sealing member (840) is arranged to surround the first stud (810) and the second stud (820) and serves as a means for protecting the studs. The sealing member (840) may be formed of an insulating material capable of buffering, and may be formed of a silicone or epoxy material, but the present disclosure is not limited thereto, and it is sufficient if it is formed of a material capable of buffering and insulating. The MEMS structure (300) and the signal processing element (500) can be stably coupled to the second substrate (200) by the sealing member (840).

[0103] Referring to FIG. 9, the MEMS microphone according to the second embodiment may have a shape in which the body (310) of the MEMS structure (300) is turned over in the configuration of the first embodiment, that is, a shape in which the body pad (340) is arranged on the upper part of the body (310) of the MEMS structure (300). In this case, unlike the configuration of the first embodiment, the back plate (330) and the diaphragm (320) may be arranged in the sound hole (10) of the body (310) and may be arranged at a position closer to the upper part than the lower part of the body (310). That is, the back plate (330) and the diaphragm (320) may be arranged on the upper side based on the center of the body (310).

[0104] In addition, a body pad (340) may be arranged on the upper portion of the body (310) of the MEMS structure (300). In this case, in order to electrically connect the lower portion of the body (310) of the MEMS structure (300) and the first auxiliary pads (211, 212) of the second substrate (200) by the combination body (800), a body hole (350) extending downward from the body pad (340) may be formed in the body (310) of the MEMS structure (300). The body hole (350) is arranged to extend downward from the body pad (340) of the body (310), and a conductive material, for example, a metal material, may be plated or filled inside the body hole (350) for electrical connection. For example, the conductive material may have a material that is the same as or different from that of the auxiliary pad. Through this, the vibration plate (320) and the back plate (330) can be electrically connected to the second substrate (200).

[0105] Referring to FIGS. 10 and 11, the MEMS microphones according to the third and fourth embodiments have the same structure and configuration as the MEMS microphones according to the first and second embodiments, respectively, but differ only in the structure of the assembly (900). The structure of the assembly (900) will be described below.

[0106] The assembly (900) of the MEMS microphone according to the third and fourth embodiments may include one or more conductive films. Specifically, the conductive film may include an anistropic conductive film (ACF) formed to conduct electricity only in a set direction. The ACF may include an adhesive material and conductive particles. Specifically, the adhesive material may include a thermosetting material, and examples thereof include epoxy, polyurethane, and acrylic. The conductive particles may include conductive balls having a size of 3 to 6 μm that are conductively arranged within the adhesive material, and the conductive balls may be formed by coating polymer particles with a metal material. In this case, the metal material used for the coating may include one or more of Au, Ni, and Pb. ACF can be bonded through thermal compression while being placed between the lower part where the body hole (350) is formed in the body (310) of the MEMS structure (300) and the auxiliary pad (210) of the second substrate (200), and the ACF can have a thickness of 10 to 40 um. The ACF can implement electrical connection through conductive particles.

[0107] Referring to FIG. 12, the MEMS microphone according to the fifth to eighth embodiments can be formed so that a capacitor (610) is added to the configuration of the first to fourth embodiments. For convenience of explanation, only the drawing in which the capacitor (610) is added in the first embodiment is added, but the remaining configurations can also be understood as configurations in which the capacitor (610) is added. The MEMS microphone according to the fifth to eighth embodiments of the present invention can be mounted on the second substrate (200) in a flip-chip form without wire bonding. As a result, since a separate pad or hole for wire bonding does not need to be formed in the second substrate (200), a space for mounting the capacitor (610) can be formed, and the capacitor (610) can be placed. The configuration and operation of the capacitor (610) have been described above in the MEMS microphone according to an embodiment of the present invention, and thus a detailed description thereof will be omitted. Meanwhile, although one capacitor (610) is illustrated and described as being placed in FIG. 12, it is of course possible for multiple capacitors to be placed in the same manner.

[0108] In the above description, the MEMS microphone (100) is illustrated and described as including a first substrate (110) and a second substrate (120) which are flexible substrates, but the present disclosure is not limited thereto. For example, the first substrate (110) and the second substrate (120) may be formed as a PCB integrally, and may be a rigid substrate including a rigid printed circuit board (Rigid PCB), a ceramic substrate, or the like. As another example, the first substrate (110) and the second substrate (120) may be rigid substrates, but may have different types of insulating layers.

[0109] 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 second substrate having an auxiliary pad formed thereon; A MEMS structure disposed on the second substrate and having a body pad formed thereon; A signal processing element is disposed on the second substrate and spaced apart from the MEMS structure and has a signal pad formed thereon; A MEMS microphone in which the auxiliary pad is electrically connected by contact with at least one of the body pad and the signal pad.

2. In paragraph 1, A MEMS microphone further comprising a combination that indirectly contacts at least one of the auxiliary pad, the body pad, and the signal pad.

3. In paragraph 2, The above combination is, A first stud that contacts at least one of the body pad and the signal pad and has a diameter that becomes narrower as it goes downward, A second stud whose diameter becomes narrower as it goes upwards when in contact with the auxiliary pad; and A MEMS microphone including a connecting bumper connecting the first stud and the second stud.

4. In paragraph 3, The above combination is, A MEMS microphone further comprising a seal formed to surround the first stud and the second stud.

5. In paragraph 2, The above assembly is a MEMS microphone comprising one or more conductive films.

6. In paragraph 5, The above conductive film is a MEMS microphone including an anistropic conductive film (ACF) that conducts only in the set direction.

7. In paragraph 5, The conductive film includes an adhesive material and a plurality of conductive particles arranged inside the adhesive material, The above conductive particles are a MEMS microphone made of a polymer and a metal material coating the outside of the polymer.

8. In paragraph 1, The above MEMS structure is, A body disposed on the upper part of the second substrate, having a sound hole formed therein, and having the body pad disposed on the lower surface; It includes a vibration plate and a back plate arranged to be spaced apart in the vertical direction in the sound hole of the above body, A MEMS microphone in which the above-mentioned diaphragm and the above-mentioned back plate are positioned lower than the center of the body and are electrically connected to the above-mentioned body pad.

9. In paragraph 1, The above MEMS structure is, A body disposed on the upper part of the second substrate, having a sound hole formed therein, and having the body pad disposed on the upper surface; It includes a vibration plate and a back plate arranged to be spaced apart in the vertical direction in the sound hole of the above body, The above body is a MEMS microphone in which a body hole is formed penetrating from the body pad to the bottom and the inside is filled with a conductive material.

10. In paragraph 9, A MEMS microphone in which the above diaphragm and the back plate are positioned above the center of the body and are electrically connected to the body pad.

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