Sensor packaging structure and its fabrication method

Abstract

This invention provides a sensor packaging structure and a method for fabricating the sensor packaging structure, relating to the field of chip packaging technology. The structure includes a substrate, a base chip, a first stacked chip, a first adhesive layer, a second stacked chip, and a second adhesive layer. The second stacked chip is offset onto the base chip. A base step groove is formed on the base chip, and a first tuning fork wire is formed within the base step groove. A first cavity is formed by the first adhesive layer, and this first cavity communicates with the base step groove. The first tuning fork wire is disposed within this first cavity. Compared to existing technologies, this invention, by setting the base step groove, increases the volume of the first cavity, thereby increasing the volume of the sound cavity and improving the chip's sound quality and sensitivity. Simultaneously, the first tuning fork wire within the first cavity enables vibration within the cavity, increasing the sound pressure energy or amplifying the sound waves, thereby improving the chip's filtering function or further enhancing sound quality and sensitivity.

Description

Technical Field

[0001] This invention relates to the field of chip packaging technology, and more specifically, to a sensor packaging structure and a method for preparing the sensor packaging structure. Background Technology

[0002] The core of MEMS (Micro-Electro-Mechanical Systems) is the mutual conversion between "physical changes in mechanical structures" and "electrical signals from electronic circuits." Different types of MEMS (such as accelerometers, gyroscopes, pressure sensors, filters, and silicon microphones) have different specific mechanisms. For example, the core function of a silicon microphone is to accurately convert external sound signals (mechanical vibrations) into electrical signals; its principle is essentially a three-stage conversion: "sound pressure → mechanical deformation → electrical signal."

[0003] Traditional silicon microphone chips have relatively small acoustic cavities, resulting in lower energy for low-frequency sounds (such as 20-200Hz, like drum sounds and bass vocals). If the cavity volume is too small, the low-frequency sound pressure will attenuate rapidly within the cavity, leading to insufficient low-frequency signal capture by the silicon microphone, manifesting as "muddy bass and lack of layering during recording." Furthermore, if the cavity volume is too small (such as the miniature acoustic cavity in TWS earphones), the "rigidity" of the air inside the cavity will increase. This causes the air inside the cavity to exert a "reaction force" on the silicon microphone diaphragm when external sound pressure is introduced, resulting in a reduced diaphragm vibration amplitude and a weakened output signal (decreased sensitivity). Summary of the Invention

[0004] The purpose of this invention is to provide a sensor packaging structure and a method for preparing the sensor packaging structure, which can significantly increase the volume of the sound cavity and enhance the sound pressure energy or amplify the sound waves through a tuning fork, thereby improving the sound quality and sensitivity.

[0005] In a first aspect, the present invention provides a sensor packaging structure, comprising: substrate; A substrate chip is mounted on the substrate and electrically connected to the substrate. A substrate step groove is provided on the edge of the side surface of the substrate chip away from the substrate. A first tuning fork wire is provided in the substrate step groove and the first tuning fork wire is connected to the substrate. The first stacked chip has a front side covering the stepped groove of the substrate and a first transducer region is provided. One side of the first transducer region is attached to the surface of the substrate chip away from the substrate. The other side of the first transducer region is provided with a first conductive post, which is connected to the substrate. A first adhesive layer is disposed on the substrate and located outside the first conductive post, so that a first cavity is formed inside the first conductive post. The first cavity is connected to the substrate stepped groove, and the first tuning fork wire is disposed in the first cavity. The second stacked chip has a second transducer area on its front side. One side of the second transducer area is attached to the back side of the first stacked chip. The other side of the second transducer area has a second conductive post, which is connected to the side of the substrate chip away from the substrate. A second adhesive layer is disposed at least on the substrate chip and extends along the edge of the second stacked chip, and the second adhesive layer is located outside the second conductive post so that a second cavity is formed inside the second conductive post.

[0006] In an optional embodiment, the bottom wall of the substrate stepped groove is provided with a substrate metal layer, the surface of the substrate is provided with a substrate pad, one end of the first tuning fork wire is connected to the substrate metal layer, and the other end is connected to the substrate pad.

[0007] In an optional embodiment, the sensor packaging structure further includes a molding layer disposed on the substrate and covering the base chip, the first stacked chip, and the second stacked chip.

[0008] In an optional embodiment, a first stepped groove is provided on the back side of the first stacked chip, a second tuning fork wire is provided in the first stepped groove, the second tuning fork wire is disposed in the second cavity and connected to the side surface of the substrate chip away from the substrate, and the front side of the second stacked chip covers the first stepped groove.

[0009] In an optional embodiment, a first metal layer is provided on the bottom wall of the first stepped groove, and a stacked pad is provided on the surface of the substrate chip away from the substrate. One end of the second tuning fork wire is connected to the first metal layer, and the other end is connected to the stacked pad.

[0010] In an optional embodiment, the back side of the substrate chip is attached to the substrate, the substrate stepped groove is disposed on the front edge of the substrate chip, and the front side of the substrate chip is provided with a connection pad, the connection pad is provided with an electrical connection line, and the electrical connection line is connected to the substrate to make the substrate chip electrically connected to the substrate.

[0011] In an optional embodiment, a substrate transducer region is provided on the front side of the substrate chip, and substrate conductive bumps are provided around the substrate transducer region. The substrate conductive bumps are connected to the substrate so that the substrate chip is electrically connected to the substrate. A substrate cavity is also formed between the substrate transducer region and the surface of the substrate, and the substrate cavity is connected to the first cavity.

[0012] In an optional embodiment, the second adhesive layer extends to the surface of the substrate and along the edge of the substrate chip.

[0013] In an optional embodiment, the substrate chip is further provided with a substrate conductive pillar, and a wiring layer is provided on the back side of the substrate chip. One end of the substrate conductive pillar is connected to the wiring layer, and the other end is connected to at least one of the substrate conductive bumps. The second conductive pillar is connected to the wiring layer.

[0014] In an optional implementation, the first adhesive layer covers the edge of the first stacked chip.

[0015] In an optional embodiment, the sensor packaging structure further includes a third stacked chip, the front side of which is provided with a third transducer region, one side of which is attached to the back side of the second stacked chip, and the other side of which is provided with a third conductive post, which is connected to the substrate.

[0016] In an optional embodiment, the back edge of the second stacked chip is further provided with a second stepped groove, and the front side of the third stacked chip covers the second stepped groove.

[0017] In an optional embodiment, the first adhesive layer extends along the edge of the third stacked chip and is located outside the third conductive pillar. A third cavity is formed between the front surface of the third stacked chip and the front surface of the first stacked chip, and the third cavity communicates with the first cavity.

[0018] In an optional embodiment, the sensor packaging structure further includes a third adhesive layer, the first adhesive layer extending along the edge of the second stacked chip, the third adhesive layer being disposed on the substrate and extending along the edge of the third stacked chip, a third cavity being formed between the front side of the third stacked chip and the front side of the first stacked chip, and the first adhesive layer being used to separate the third cavity and the first cavity.

[0019] Secondly, the present invention provides a method for preparing a sensor packaging structure, used to prepare the sensor packaging structure as described in the foregoing embodiments, the method comprising: Provide a substrate; A substrate chip is mounted on the substrate, wherein a substrate step groove is provided on the edge of the side surface of the substrate chip away from the substrate. A first tuning fork wire is formed in the stepped groove of the substrate, wherein the first tuning fork wire is connected to the substrate. A first stacked chip is mounted on the side surface of the substrate chip away from the substrate and on the substrate. The front side of the first stacked chip covers the stepped groove of the substrate and is provided with a first transducer region. One side of the first transducer region is mounted on the side surface of the substrate chip away from the substrate, and a first conductive post is provided on the other side of the first transducer region. The first conductive post is connected to the substrate. A first adhesive layer is formed on the substrate, wherein the first adhesive layer is located outside the first conductive post, so that a first cavity is formed inside the first conductive post, the first cavity is connected to the substrate stepped groove, and the first tuning fork wire is disposed in the first cavity. A second stacked chip is mounted on the back side of the first stacked chip and on the substrate chip. The second stacked chip has a second transducer region on its front side. One side of the second transducer region is mounted on the back side of the first stacked chip. A second conductive post is provided on the other side of the second transducer region. The second conductive post is connected to the side of the substrate chip away from the substrate. A second adhesive layer is formed on at least the substrate chip, wherein the second adhesive layer extends along the edge of the second stacked chip and is located outside the second conductive post, so that a second cavity is formed inside the second conductive post, and the second cavity communicates with the first cavity; A molding layer is formed on the substrate, wherein the molding layer encapsulates the base chip, the first stacked chip, and the second stacked chip; The molding layer and the substrate are cut along the cutting path.

[0020] The beneficial effects of the embodiments of the present invention include: The sensor packaging structure and its fabrication method provided in this invention first involve mounting a substrate chip onto a substrate. A substrate step groove is formed on the edge of the surface of the substrate chip away from the substrate, and a first tuning fork wire is disposed in the substrate step groove. The front side of a first stacked chip covers the substrate step groove, and a first adhesive layer is disposed on the substrate to seal the periphery of the first stacked chip, thereby forming a first cavity below the first stacked chip. The first cavity communicates with the substrate step groove, thereby increasing the volume of the sound cavity. Simultaneously, the first tuning fork wire is disposed in the first cavity. A second stacked chip is mounted on the front side of the first stacked chip, and a second adhesive layer is disposed on the substrate chip to seal the periphery of the second stacked chip, thereby forming a second cavity below the second stacked chip.

[0021] Compared to existing technologies, this invention, by setting a stepped groove in the substrate, increases the volume of the first cavity, thereby increasing the volume of the sound cavity and thus improving the chip's sound quality and sensitivity. Simultaneously, a first tuning fork wire is provided within the first cavity, which enables vibration within the sound cavity, increasing the sound pressure energy within the cavity or amplifying the sound waves, thereby improving the chip's filtering function or further enhancing sound quality and sensitivity. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the first sensor packaging structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a second sensor packaging structure provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a third sensor packaging structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the fourth sensor packaging structure provided in the embodiments of the present invention; Figures 5 to 13 This is a schematic diagram of the process steps corresponding to the fabrication method of the sensor packaging structure provided in the embodiment of the present invention.

[0024] Icons: 100 - Sensor package structure; 110 - Substrate; 111 - Substrate pad; 120 - Substrate chip; 121 - Substrate stepped groove; 122 - First tuning fork wire; 123 - Substrate metal layer; 124 - Stacked pad; 125 - Connecting pad; 126 - Electrical connection wire; 127 - Substrate transducer region; 128 - Substrate conductive bump; 129 - Substrate cavity; 130 - First stacked chip; 131 - First transducer region; 132 - First conductive pillar; 133 - First cavity; 134 - First stepped groove ; 135 - Second tuning fork wire; 136 - First metal layer; 140 - First adhesive layer; 150 - Second stacked chip; 151 - Second transducer region; 152 - Second conductive pillar; 153 - Second cavity; 154 - Second stepped groove; 155 - Second metal layer; 160 - Second adhesive layer; 170 - Molding layer; 180 - Substrate conductive pillar; 181 - Wiring layer; 190 - Third stacked chip; 191 - Third transducer region; 192 - Third conductive pillar; 193 - Third adhesive layer; 194 - Third cavity. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0028] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0029] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0030] As disclosed in the background section, traditional silicon microphone chips have relatively small acoustic cavities. Low-frequency sounds (such as those in the 20-200Hz range, like drum sounds and bass vocals) have low energy. If the acoustic cavity is too small, the low-frequency sound pressure will attenuate rapidly within the cavity, resulting in insufficient low-frequency signal capture by the silicon microphone, manifesting as "muddy bass and lack of depth during recording." Furthermore, if the acoustic cavity is too small (such as the miniature acoustic cavity in TWS earphones), the "stiffness" of the air inside the cavity will increase. This causes the air inside the cavity to exert a "reaction force" on the silicon microphone diaphragm when external sound pressure is introduced, resulting in a reduced diaphragm vibration amplitude and a weakened output signal (decreased sensitivity). Therefore, the acoustic cavity volume is crucial to the chip's sound quality and sensitivity.

[0031] Furthermore, in existing technologies using dual silicon microphone designs, separate acoustic cavity structures need to be fabricated, and the acoustic cavities are separated from each other. When sound comes from a specific direction, it will first reach the "silicon microphone unit closer to the sound source" and then reach the "silicon microphone unit farther from the sound source," thus creating a slight time difference. This undoubtedly affects the chip's sensitivity and sound quality.

[0032] To address the aforementioned problems, embodiments of the present invention provide a novel sensor packaging structure and a method for fabricating the sensor packaging structure. It should be noted that, unless otherwise specified, features in the embodiments of the present invention can be combined with each other.

[0033] See Figure 1 This invention provides a sensor packaging structure 100 that can significantly increase the volume of the sound cavity and enhance sound pressure energy or amplify sound waves through a tuning fork, thereby improving sound quality and sensitivity.

[0034] The sensor packaging structure 100 provided in this embodiment of the invention includes a substrate 110, a base chip 120, a first stacked chip 130, a first adhesive layer 140, a second stacked chip 150, and a second adhesive layer 160. The base chip 120 is mounted on the substrate 110 and electrically connected to the substrate 110. A base stepped groove 121 is provided on the edge of the surface of the base chip 120 away from the substrate 110. A first tuning fork wire 122 is provided in the base stepped groove 121 and is connected to the substrate 110. The front side of the first stacked chip 130 covers the base stepped groove 121 and is provided with a first transducer region 131. One side of the first transducer region 131 is mounted on the surface of the base chip away from the substrate 110, and a first conductive post 132 is provided on the other side of the first transducer region 131 and is connected to the substrate 110. A first adhesive layer 140 is disposed on the substrate 110 and located outside the first conductive post 132, so that a first cavity 133 is formed inside the first conductive post 132. The first cavity 133 communicates with the substrate stepped groove 121, and a first tuning fork wire 122 is disposed in the first cavity 133. A second transducer region 151 is disposed on the front side of the second stacked chip 150. One side of the second transducer region 151 is attached to the back side of the first stacked chip 130, and a second conductive post 152 is disposed on the other side of the second transducer region 151. The second conductive post 152 is connected to the side of the substrate chip 120 away from the substrate 110. A second adhesive layer 160 is disposed at least on the substrate chip 120 and extends along the edge of the second stacked chip 150. The second adhesive layer 160 is located outside the second conductive post 152, so that a second cavity 153 is formed inside the second conductive post 152. The second cavity 153 communicates with the first cavity 133.

[0035] It should be noted that the substrate chip 120 and the first stacked chip 130 are stacked in a staggered manner, as are the first stacked chip 130 and the second stacked chip 150. The second stacked chip 150 can be stacked above the substrate chip 120. This staggered arrangement forms a first cavity 133 and a second cavity 153 at the edges, increasing the volume of the sound cavity. Furthermore, by providing a substrate stepped groove 121, the volume of the first cavity 133 is increased, thereby increasing the sound cavity volume and improving the chip's sound quality and sensitivity. Additionally, a first tuning fork wire 122 is provided within the first cavity 133, which enables vibration within the sound cavity, increasing the sound pressure energy within the cavity or amplifying the sound waves, thereby improving the chip's filtering function or further enhancing sound quality and sensitivity. Here, the base chip 120, the first stacked chip 130, and the second stacked chip 150 are all MEMS chips, such as silicon microphone chips or filter chips (SAW and BAW filters). When filter chips are stacked, the inherent vibration frequency can be designed using tuning fork wires, thereby amplifying the filtered wave generated by the diaphragm (the frequency of the filtered sound wave is consistent with the inherent vibration frequency, and it resonates to amplify the sound wave), thereby improving the filtering function of the chip.

[0036] It should also be noted that, in this embodiment of the invention, the first cavity 133 and the second cavity 153 can be interconnected, further increasing the volume of the acoustic cavity. Of course, the first cavity 133 and the second cavity 153 can also be separated and independent, thereby achieving different frequency designs.

[0037] In some embodiments, a base metal layer 123 is provided on the bottom wall of the substrate stepped groove 121, and a base pad 111 is provided on the surface of the substrate 110. One end of the first tuning fork wire 122 is connected to the base metal layer 123, and the other end is connected to the base pad 111. Specifically, the base metal layer 123 in the substrate stepped groove 121 can serve as a wire bonding pad, facilitating the fabrication of the first tuning fork wire 122, wherein the first tuning fork wire 122 can be a metal wire and formed by a wire bonding process. Furthermore, the base metal layer 123 can also improve the surface roughness of the substrate chip 120, thereby improving the heat dissipation performance of the chip.

[0038] In some embodiments, the sensor packaging structure 100 further includes a molding compound 170, which is disposed on the substrate 110 and covers the base chip 120, the first stacked chip 130, and the second stacked chip 150. Specifically, the first adhesive layer 140 covers the edge of the first stacked chip 130, and the molding compound 170 can cover both the first adhesive layer 140 and the second adhesive layer 160, thereby covering the entire stacked structure and providing good protection. It also provides structural support.

[0039] In some embodiments, a first stepped groove 134 is provided on the back side of the first stacked chip 130, and a second tuning fork wire is provided in the first stepped groove 134. The second tuning fork wire is disposed in the second cavity 153 and connected to the side surface of the substrate chip 120 away from the substrate 110. The front side of the second stacked chip 150 covers the first stepped groove 134. Specifically, the material and manufacturing process of the second tuning fork wire 135 are the same as those of the first tuning fork wire 122. The first cavity 133 can serve as the sound cavity of the first stacked chip 130, and the second cavity 153 can serve as the sound cavity of the second stacked chip 150. The first tuning fork wire 122 and the second tuning fork wire can achieve vibration within the sound cavity. The metal wire has a natural frequency (the natural vibration frequency determined by its own length, thickness, and material, which can be designed according to the sound wave frequency). When the sound wave frequency is close to the natural frequency of the metal wire, vibration can be generated, thereby generating sound waves, increasing the sound pressure energy within the sound cavity, and thus improving the chip's sound quality and sensitivity.

[0040] Furthermore, a first metal layer 136 is provided on the bottom wall of the first stepped groove 134, and a stacking pad 124 is provided on the surface of the substrate chip 120 away from the substrate 110. One end of the second tuning fork wire is connected to the first metal layer 136, and the other end is connected to the stacking pad 124. Specifically, the material and manufacturing process of the first metal layer 136 can be the same as those of the substrate metal layer 123. The first metal layer 136 in the first stepped groove 134 can serve as a wire bonding pad to facilitate the fabrication of the second tuning fork wire, which can be a metal wire formed by a wire bonding process. Additionally, the second metal layer 155 can also improve the surface roughness of the first stacked chip 130, thereby improving the chip's heat dissipation performance.

[0041] It should be noted that the stacked pad 124 here is a passive pad, which is not electrically connected to the internal circuitry of the substrate chip 120. Similarly, the substrate pad 111 is also a passive pad, which is not electrically connected to the internal circuitry of the substrate 110. Of course, in some preferred embodiments, the stacked pad 124 and the substrate pad 111 can also be electrically connected to a grounding circuit, thereby grounding the first tuning fork wire 122 and the second tuning fork wire 135.

[0042] It is worth noting that a second stepped groove 154 is also provided on the back side of the second stacked chip 150. A second metal layer 155 is provided on the bottom wall of the second stepped groove 154. The molding compound 170 fills the second stepped groove 154 and is in direct contact with the second metal layer 155. The second metal layer 155 can improve the surface roughness of the second stacked chip 150, thereby improving the heat dissipation performance of the second stacked chip 150 and enhancing the bonding force between the molding compound 170 and the second stacked chip 150.

[0043] Please continue reading Figure 1In some embodiments, the back side of the substrate chip 120 is attached to the substrate 110, a substrate stepped groove 121 is disposed on the front edge of the substrate chip 120, and a connection pad 125 is disposed on the front side of the substrate chip 120. An electrical connection line 126 is disposed on the connection pad 125 and connects to the substrate 110, thereby electrically connecting the substrate chip 120 to the substrate 110. Specifically, the substrate chip 120 is mounted using a front-mount process, with its back side attached to the surface of the substrate 110 via an adhesive layer, and the substrate stepped groove 121 is disposed on one edge of the front side of the substrate chip 120. The electrical connection line 126 is a metal wire, and the electrical connection line 126 can be located on the other edge of the front side of the substrate chip 120. The second adhesive layer 160 can be confined to the front side of the substrate chip 120, and the second adhesive layer 160 can cover the connection pad 125. The electrical connection line 126 can extend out of the second adhesive layer 160 and connect to the pad on the surface of the substrate 110.

[0044] See Figure 2 In some embodiments, a substrate transducer region 127 is provided on the front side of the substrate chip, and substrate conductive bumps 128 are provided around the substrate transducer region 127. The substrate conductive bumps 128 are connected to the substrate 110 to electrically connect the substrate chip 120 to the substrate 110. A substrate cavity 129 is also formed between the substrate transducer region 127 and the surface of the substrate 110, and the substrate cavity 129 is connected to the first cavity 133. Specifically, a substrate cavity 129 is formed on the bottom side of the substrate chip 120, and the substrate cavity 129 is connected to the first cavity 133, which allows the sound cavity volume to be further expanded, thereby improving sound quality and sensitivity. In addition, the substrate conductive bumps 128 can be soldered and fixed to the pads on the surface of the substrate 110 to achieve flip-chip bonding of the substrate chip 120 and form the substrate cavity 129. Due to the use of flip-chip, the overall mounting area can be reduced, and the wire bonding process is eliminated.

[0045] It should be noted that the substrate cavity 129 is connected to the first cavity 133, and the first cavity 133 is connected to the second cavity 153, thereby achieving acoustic wave synchronization of the substrate chip 120, the first stacked chip 130, and the second stacked chip 150, and reducing the time difference.

[0046] Furthermore, the second adhesive layer 160 extends to the surface of the substrate 110 and extends along the edge of the base chip 120. Specifically, the second adhesive layer 160 can simultaneously cover the edge of the base chip 120 and the edge of the second stacked chip 150. The first adhesive layer 140 and the second adhesive layer 160 can be formed in a single dispensing process and are integrally formed, thereby achieving edge sealing.

[0047] Furthermore, the substrate chip 120 also includes substrate conductive pillars 180, and a wiring layer 181 is provided on the back side of the substrate chip 120. One end of the substrate conductive pillar 180 is connected to the wiring layer 181, and the other end is connected to at least one of the substrate conductive bumps 128. A second conductive pillar 152 is connected to the wiring layer 181. Specifically, the substrate conductive pillar 180 can be a TSV conductive pillar that penetrates the substrate chip 120. The wiring layer 181 can be a metal layer, such as a copper layer. Through the wiring layer 181, an electrical connection can be achieved between the substrate conductive pillar 180 and the second conductive pillar 152, thereby enabling the second stacked chip 150 to achieve an electrical connection with the substrate 110 through the second conductive pillar 152 and the substrate conductive pillar 180, thus realizing chip stacking. Of course, the second stacked chip 150 can also be omitted, or the electrical connection between the second stacked chip 150 and the substrate 110 can be achieved through wire bonding, thus eliminating the need for the TSV structure.

[0048] See Figure 3 In some embodiments, the sensor package structure 100 further includes a third stacked chip 190. The front side of the third stacked chip 190 has a third transducer region 191. One side of the third transducer region 191 is attached to the back side of the second stacked chip 150, and the other side of the third transducer region 191 has a third conductive post 192 connected to the substrate 110. Specifically, the back edge of the second stacked chip 150 also has a second stepped groove 154, and the front side of the third stacked chip 190 covers the second stepped groove 154. The third conductive post 192 is located outside the first stacked chip 130 and connected to a pad on the surface of the substrate 110, serving a supporting and conductive function.

[0049] It should be noted that in the embodiments of the present invention, the base chip 120, the first stacked chip 130, the second stacked chip 150 and the third stacked chip 190 are all MEMS chips, which are designed with chip transducer regions (IDT: Interdigital Transducer), such as silicon microphone chips or filter chips.

[0050] Furthermore, the first adhesive layer 140 extends along the edge of the third stacked chip 190 and is located outside the third conductive post 192. A third cavity 194 is formed between the front surface of the third stacked chip 190 and the front surface of the first stacked chip 130, and the third cavity 194 communicates with the first cavity 133. Specifically, the first adhesive layer 140 is located outside the third conductive post 192. During adhesive dispensing, it can fill the gap between the edge of the third stacked chip 190 and the substrate 110, thereby forming a third cavity 194 on the bottom side of the third stacked chip 190. Since there is a gap between the third conductive post 192 and the first stacked chip 130, the third cavity 194 can communicate with the first cavity 133. By utilizing the height of the stacked structure, the volume of the sound cavity is greatly increased, thereby improving the chip's reception quality and sensitivity.

[0051] See Figure 4 In some embodiments, the sensor packaging structure 100 further includes a third adhesive layer 193. A first adhesive layer 140 extends along the edge of the second stacked chip 150, and the third adhesive layer 193 is disposed on the substrate 110 and extends along the edge of the third stacked chip 190. A third cavity 194 is formed between the front surface of the third stacked chip 190 and the front surface of the first stacked chip 130. The first adhesive layer 140 is used to separate the third cavity 194 and the first cavity 133. Specifically, the first adhesive layer 140 can seal the gap between the edge of the first stacked chip 130 and the substrate 110, while the third adhesive layer 193 can seal the gap between the edge of the third stacked chip 190 and the substrate 110. The first adhesive layer 140 can separate the third cavity 194 and the first cavity 133, thereby realizing different cavities. Furthermore, the first stacked chip 130 and the third stacked chip 190 can realize multiple frequency sound pressure structures, enabling different frequency mobile phones. For example, the design can be selected between mid-frequency (500MHz-2GHz), low-frequency (1MHz-500MHz), and mid-to-high frequency (2GHz-4GHz).

[0052] It should be noted that the base chip 120 can be mounted to the surface of the substrate 110 via an adhesive layer or flip-chip soldered to the surface of the substrate 110. The first stacked chip 130 can be mounted to the side of the base chip 120 away from the substrate 110 via adhesive material. The second stacked chip 150 can be mounted to the back side of the first stacked chip 130 via adhesive material, and the third stacked chip 190 can be mounted to the back side of the second stacked chip 150 via adhesive material. In this embodiment of the invention, the "front side" of the chip refers to the side surface of the chip with the transducer region and conductive bumps, while the "back side" of the chip refers to the side surface of the chip that does not have electrical connectivity.

[0053] It should also be noted that in other preferred embodiments of the present invention, a fourth stacked chip and a fifth stacked chip may be stacked sequentially on the third stacked chip 190, and the stacking method may refer to the method of the first stacked chip 130 and the second stacked chip 150.

[0054] This invention also provides a method for fabricating a sensor packaging structure 100, which is used to fabricate the sensor packaging structure 100 as described above. The method includes the following steps: S1: Provide a substrate 110.

[0055] See also Figure 5 First, take a substrate 110. The substrate 110 can be designed with a solder resist layer (green paint) and exposed pads on the surface of the substrate 110. The substrate 110 is designed with circuits and can realize external electrical connection.

[0056] S2: Mount the substrate chip 120 on the substrate 110.

[0057] See also Figure 6 Specifically, the substrate chip 120 can be mounted using adhesive film or silver paste and fixed to the substrate 110 by baking. The edge of the surface of the substrate chip 120 away from the substrate 110 is provided with a substrate step groove 121, and the bottom wall of the substrate step groove 121 is electroplated with a substrate metal layer 123.

[0058] Preferably, the back side of the substrate chip 120 can be bonded and fixed to the substrate 110, while the front side of the substrate chip 120 is provided with a connecting pad 125. The connecting pad 125 and the substrate step groove 121 are respectively provided on the two sides of the front side of the substrate chip 120.

[0059] S3: A first tuning fork line 122 is formed in the base step groove 121.

[0060] See Figure 7 The first tuning fork wire 122 is connected to the substrate 110. Specifically, the first tuning fork wire 122 can be formed by wire bonding process, wherein the first tuning fork wire 122 can connect the base metal layer 123 to the pads on the substrate 110.

[0061] S4: Attach the first stacked chip 130 to the surface of the substrate chip 120 away from the substrate 110 and to the substrate 110.

[0062] See Figure 8The first stacked chip 130 has its front side covering the substrate stepped groove 121 and has a first transducer region 131. One side of the first transducer region 131 is attached to the surface of the substrate chip away from the substrate 110, and the other side of the first transducer region 131 has a first conductive post 132 connected to the substrate 110. Specifically, the first stacked chip 130 can be stacked on the substrate chip 120 using a flip-chip process. The first stacked chip 130 is a flip-chip, and the first conductive post 132 on the front side can be fixed to the pads of the substrate 110 by reflow soldering. Furthermore, a first stepped groove 134 is also provided on one edge of the back side of the first stacked chip 130.

[0063] It should be noted that after the first stacked chip 130 is mounted, the second tuning fork wire and electrical connection wire 126 can be fabricated. The electrical connection wire 126 can connect the connection pad 125 to the pad on the substrate 110 to achieve electrical connection.

[0064] S5: Form a first adhesive layer 140 on the substrate 110.

[0065] See Figure 9 The first adhesive layer 140 is located outside the first conductive post 132, forming a first cavity 133 inside the first conductive post 132. The first cavity 133 connects to the substrate stepped groove 121, and the first tuning fork wire 122 is disposed in the first cavity 133. Specifically, a sealing adhesive layer is formed at the edge of the first stacked chip 130 through an adhesive dispensing process, thereby sealing the edge of the first stacked chip 130 and forming the first cavity 133. Because of the substrate stepped groove 121 connecting the first cavity 133, the volume of the first cavity 133 is increased, thus increasing the volume of the sound cavity and improving the chip's sound quality and sensitivity. Simultaneously, the first tuning fork wire 122 is disposed within the first cavity 133, which enables vibration within the sound cavity, increasing the sound pressure energy within the sound cavity or amplifying the sound waves, improving the chip's filtering function, or further enhancing sound quality and sensitivity.

[0066] S6: Attach the second stacked chip 150 to the back of the first stacked chip 130 and the base chip 120.

[0067] See Figure 10 The second stacked chip 150 has a second transducer region 151 on its front side. One side of the second transducer region 151 is attached to the back side of the first stacked chip 130, and the other side of the second transducer region 151 has a second conductive post 152. The second conductive post 152 is connected to the side of the substrate chip 120 away from the substrate 110. Specifically, using the same flip-chip process, the second stacked chip 150 is stacked on the back side of the first stacked chip 130, and the second stacked chip 150 can be electrically connected to the substrate chip 120 through the second conductive post 152.

[0068] S7: A second adhesive layer 160 is formed on at least the substrate chip 120.

[0069] See Figure 11 The second adhesive layer 160 extends along the edge of the second stacked chip 150 and is located outside the second conductive post 152, so that a second cavity 153 is formed inside the second conductive post 152, and the second cavity 153 is connected to the first cavity 133. Specifically, the adhesive dispensing process can be performed along the edge of the second stacked chip 150 to cover the edge sidewall of the second stacked chip 150, thereby forming the second cavity 153.

[0070] S8: Form a molding layer 170 on the substrate 110.

[0071] See Figure 12 The molding compound 170 covers the substrate chip 120, the first stacked chip 130, and the second stacked chip 150. Specifically, an injection molding process can be used to form a molding compound around the mounted chips, which protects the chip interconnect structure.

[0072] S9: Cut the molding layer 170 and the substrate 110 along the cutting path.

[0073] See Figure 13 Specifically, solder balls can be formed on the back of substrate 110 using a ball-planting process, and then the product can be separated into individual products using a cutting process.

[0074] In summary, the sensor packaging structure 100 and its fabrication method provided in this embodiment of the invention firstly mount a substrate chip 120 onto a substrate 110, and a substrate step groove 121 is provided on the edge of the surface of the substrate chip 120 away from the substrate 110. A first tuning fork wire 122 is disposed in the substrate step groove 121. The front side of the first stacked chip 130 covers the substrate step groove 121, and a first adhesive layer 140 is disposed on the substrate 110 to seal the periphery of the first stacked chip 130, thereby forming a first cavity 133 below the first stacked chip 130. The first cavity 133 communicates with the substrate step groove 121, thereby increasing the volume of the sound cavity. At the same time, the first tuning fork wire 122 is disposed in the first cavity 133. The front side of the second stacked chip 150 is mounted on the first stacked chip 130, and a second adhesive layer 160 is disposed on the substrate chip 120 to seal the periphery of the second stacked chip 150, thereby forming a second cavity 153 below the second stacked chip 150. Compared to existing technologies, this embodiment of the invention increases the volume of the first cavity 133 by setting a base stepped groove 121, thereby increasing the volume of the sound cavity and improving the chip's sound quality and sensitivity. Simultaneously, a first tuning fork wire 122 is provided within the first cavity 133, which enables vibration within the sound cavity, increasing the sound pressure energy within the cavity or amplifying the sound waves, thereby improving the chip's filtering function or further enhancing sound quality and sensitivity.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A sensor package structure, characterized by, The sensor package structure comprises a substrate, a base chip attached to the substrate and electrically connected to the substrate, and a base step groove provided on the edge of the side surface of the base chip away from the substrate, wherein the base step groove is provided with a first tuning fork line connected to the substrate. The first stack chip is attached to the side of the first transducing area of the base chip away from the substrate, and the other side of the first transducing area is provided with a first conductive column connected to the substrate. The first stack chip is attached to the side of the first transducing area of the base chip away from the substrate, and the other side of the first transducing area is provided with a first conductive column connected to the substrate. The first stack chip is attached to the side of the first transducing area of the base chip away from the substrate, and the other side of the first transducing area is provided with a first conductive column connected to the substrate. The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip. The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip. The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip.

2. The sensor package structure of claim 1, wherein, The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip.

3. The sensor package structure of claim 1, wherein, The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip.

4. The sensor package structure according to any one of claims 1-3, wherein, The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip.

5. The sensor package structure of claim 4, wherein, The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip.

6. The sensor package structure of claim 1, wherein, The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip.

7. The sensor package structure of claim 1, wherein, The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip.

8. The sensor package structure of claim 7, wherein, The second stack chip is provided with a second transducing area on the front side, and the side of the second transducing area is attached to the back of the first stack chip. The second stack chip is provided with a second transducing area on the front The second stack chip is provided with a second transducing area on the front The second point glue layer extends to the surface of the substrate and along the edge of the base chip. The second point glue layer extends to the surface of the substrate and along the edge of the base 9. The sensor package structure of claim 7, wherein, The base chip is further provided with a base conductive column, the back surface of the base chip is provided with a wiring layer, one end of the base conductive column is connected to the wiring layer, and the other end is connected to at least one base conductive bump, and the second conductive column is connected to the wiring layer.

10. The sensor package structure according to claim 6 or 7, wherein The first dispensing layer covers the edge of the first stacked chip.

11. The sensor package structure according to any one of claims 1-3, wherein, The sensor packaging structure further comprises a third stacked chip, the front surface of the third stacked chip is provided with a third transduction region, one side of the third transduction region is attached to the back surface of the second stacked chip, and the other side of the third transduction region is provided with a third conductive column, and the third conductive column is connected to the substrate.

12. The sensor package structure of claim 11, wherein, The back surface edge of the second stacked chip is further provided with a second step groove, and the front surface of the third stacked chip covers the second step groove.

13. The sensor package structure of claim 11, wherein, The first dispensing layer extends along the edge of the third stacked chip, and the first dispensing layer is located outside the third conductive column, a third cavity is formed between the front surface of the third stacked chip and the front surface of the first stacked chip, and the third cavity is in communication with the first cavity.

14. The sensor package structure of claim 11, wherein, The sensor packaging structure further comprises a third dispensing layer, the first dispensing layer extends along the edge of the second stacked chip, the third dispensing layer is arranged on the substrate and extends along the edge of the third stacked chip, a third cavity is formed between the front surface of the third stacked chip and the front surface of the first stacked chip, and the first dispensing layer is used to separate the third cavity and the first cavity.

15. A method for producing a sensor package structure according to claim 1, characterized by, The method comprises: providing a substrate; attaching a base chip on the substrate, wherein the edge of the side surface of the base chip away from the substrate is provided with a base step groove; forming a first tuning fork line in the base step groove, wherein the first tuning fork line is connected to the substrate; attaching a first stacked chip on the side surface of the base chip away from the substrate and the substrate, wherein the front surface of the first stacked chip covers the base step groove and is provided with a first transduction region, one side of the first transduction region is attached to the side surface of the base chip away from the substrate, and the other side of the first transduction region is provided with a first conductive column, and the first conductive column is connected to the substrate; forming a first dispensing layer on the substrate, wherein the first dispensing layer is located outside the first conductive column, so that a first cavity is formed inside the first conductive column, the first cavity is in communication with the base step groove, and the first tuning fork line is arranged in the first cavity; attaching a second stacked chip on the back surface of the first stacked chip and the base chip, wherein the front surface of the second stacked chip is provided with a second transduction region, one side of the second transduction region is attached to the back surface of the first stacked chip, and the other side of the second transduction region is provided with a second conductive column, and the second conductive column is connected to the side of the base chip away from the substrate; forming a second dispensing layer on the substrate chip, wherein the second dispensing layer extends along edges of the second stacked chip, and the second dispensing layer is located outside the second conductive column, so that a second cavity is formed inside the second conductive column, and the second cavity is communicated to the first cavity; forming a plastic encapsulation layer on the substrate, wherein the plastic encapsulation layer covers the substrate chip, the first stacked chip and the second stacked chip; cutting the plastic encapsulation layer and the substrate along the cutting path.

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