TWM504415U - Back chamber expanded type stereo array mems mic chip scale package - Google Patents

Description

Back cavity enlarged stereo array type micro electromechanical microphone package structure

This creation is about the field of MEMS chip packaging, especially related to a back cavity enlarged stereo array type MEMS microphone package structure.

The traditional Electret Condenser Microphone (ECM) uses an electret material that retains a permanent charge, eliminating the need to power the capacitor. The internal structure of the conventional electret condenser microphone includes a plurality of electret materials at the bottom and the back electrode; the back electrode is connected to the ground wire; and the plurality of electret materials are connected by conductive rings; the upper conductive ring and a pressure sense The membranes are joined to form an air gap that communicates with the lower closed chamber; and the entire internal structure is covered with metal; an opening above the outer metal allows sound to enter the pressure sensitive membrane. The conventional electret microphone module has the problems of large external dimensions, high power consumption, low shock resistance, low sensitivity, and suppression of ambient interference such as temperature changes, vibration, electromagnetic interference, power fluctuations, and the like. Poor, more can not withstand the high temperature reflow furnace operation ... and other shortcomings.

National Patent No. I365525 "Ultra-thin package structure of electroacoustic sensing MEMS" reveals a micro-electromechanical ultra-thin package structure with electroacoustic sensing The wafer is a microphone base structure, and the electroacoustic sensor wafer is electrically connected to the substrate by a conductive bump. The size of the substrate is much larger than that of the electroacoustic sensor wafer, and the conductive ball and the electroacoustic sensor wafer are disposed on the same lower surface of the substrate. A vent hole passes through the substrate, and a cavity is located between the surface of the substrate and the surface of the wafer and is in communication with the vent. Moreover, after the rear cavity backplane is located on the back side of the wafer, the cavity between the substrate and the wafer cannot be used as a back cavity. The back cavity, which must be a confined space, is located inside the electroacoustic sensor chip, so the space of the back cavity is subject to the hollowed out volume of the wafer. Although the micro-electromechanical ultra-thin package structure has an ultra-thin shape, the enlargement of the substrate size makes the surface of the conventional micro-electromechanical ultra-thin package more than the wafer size. Increase. In addition, wafer level packaging process requirements for MEMS microphone chips are not available.

National Patent No. I350703 "Microphone Module and Method of Manufacturing Same" discloses a microphone module. The module includes a carrier plate having a perforation. A microphone is disposed on the first side of the carrier and corresponds to the perforation. A processing chip is disposed on the first side of the carrier and coupled to the microphone. A sealant material is disposed on the first side of the carrier to encapsulate the microphone and process the wafer. The microphone module also uses a perforation of the carrier as a vent. The microphone should also be a structure in which the well-sealed back cavity is completely inside the MEMS wafer. This conventional microphone module not only has a large surface joint area but also a space for improving the clarity of the sound.

In order to solve the above problems, the main purpose of the present invention is to provide a back cavity enlarged stereo array type micro electromechanical microphone package structure, which is The combined array MEMS microphone chip can be used with wafer level packaging technology instead of the general electret microphone module architecture, which can effectively reduce the volume of the finished product and meet the application range of micro technology, which can effectively reduce the cost of saving gold wire materials and can be applied. It adheres to the high-temperature surface adhesion process and has the effect of significantly improving high-receiving clarity, high shock resistance, low power consumption, and resistance to environmental electromagnetic waves.

The purpose of this creation and solving its technical problems are achieved by the following technical solutions. The present invention discloses a back cavity enlarged stereo array type micro electromechanical microphone package structure, comprising a microelectromechanical wafer, a circuit substrate, an annular plastic frame and a back cavity expansion cover. The MEMS wafer has an active surface and a back surface, the back surface is formed with a back cavity facing the back surface, and the bottom of the back cavity is provided with a plurality of arrays of vent holes, and the active surface is provided with a pressure Sensory film. The circuit substrate has a bonding surface, an outer bonding surface, and a sound hole extending through the circuit substrate. The bonding surface is attached to the active surface of the MEMS wafer in a gap manner. The annular plastic frame is bonded to the periphery of the active surface of the MEMS wafer and the bonding surface of the circuit substrate. The back cavity expansion cover is coupled to the back surface of the MEMS wafer to hermetically seal the back cavity, and the back cavity expansion cover has a concave cover space to make the back cavity and the cover space It is an enlarged airtight back cavity space. Thereby, the radio clarity is improved and electromagnetic interference (EMI) is avoided.

The purpose of this creation and solving its technical problems can be further realized by the following technical measures.

In the foregoing package structure, a plurality of external guiding ends may be further disposed on the outer bonding surface of the circuit substrate.

In the foregoing package structure, the active surface layer is preferably formed with a protective layer for fixing the pressure sensitive film, and a first air gap is left between the pressure sensitive film and the vent holes. The vent is connected to the enlarged airtight back cavity space. Therefore, the pressure sensitive film can be prevented from contacting the vent holes and causing failure.

In the foregoing package structure, a second air gap is preferably left between the bonding surface and the pressure sensitive film, and the external sound hole is connected to the second air gap. Therefore, the pressure sensitive film can be prevented from contacting the bonding surface of the circuit substrate to cause failure.

In the foregoing package structure, a first surface coverage dimension of the circuit substrate is preferably close to a second surface coverage of the MEMS wafer, and between 0.8 and 1.5 times the second surface coverage dimension . Thereby, it can conform to the wafer level wafer size packaging process of the MEMS microphone package.

In the foregoing package structure, a plurality of internal conductive elements may be further disposed between the MEMS wafer and the circuit substrate to electrically connect the MEMS wafer and the circuit substrate.

In the foregoing package structure, the inner conductive elements specifically comprise a plurality of ball bumps and the annular plastic frame is sealed.

In the above package structure, the inner conductive elements and the annular plastic frame are specifically conductive thermosetting colloids of the same material.

In the foregoing package structure, the periphery of the bonding surface of the circuit substrate is specifically provided with a protruding pad which is covered by the annular plastic frame.

In the aforementioned package structure, the hood space is specifically larger than the back cavity.

With the above technical means, this creation can achieve the following effects:

1. Micro-electromechanical microphone package structure can be applied to wafer-level packaging technology, replacing the general electret microphone module architecture, which can effectively reduce the volume of finished products, meet the application range of micro-technology, and can be applied to wearable body-sensing or smart 3C devices. .

Second, the use of bumps combined on the substrate or wafer can effectively reduce the cost of gold wire materials and can be applied to high temperature surface adhesion processes to achieve high mass production capability of MEMS microphone chip packages.

Third, through the stereo array type MEMS microphone structure, the tiny array of vent holes in the wafer, making the sound more detailed, and wafer-level packaging technology can significantly improve high-definition clarity, high shock resistance, low power consumption , resistant to environmental electromagnetic interference.

11‧‧‧Steps for wafer placement

12‧‧‧Steps for wafer singulation

21‧‧‧Steps for substrate placement

22‧‧‧Steps of printing an annular frame on a substrate

23‧‧‧Steps of bonding the wafer to the substrate

24‧‧‧Steps of combining the cavity expansion cover on the wafer

25‧‧‧Steps for curing the ring frame

26‧‧‧Steps for single-sided cutting

27‧‧‧Steps for wafer sorting

28‧‧‧Packaging steps

31‧‧‧Steps for wafer placement

32‧‧‧Steps for wafer singulation

41‧‧‧Steps for substrate placement

42‧‧‧Steps for placing bumps on the substrate

43‧‧‧Steps of printing the annular frame on the substrate

44‧‧‧Steps of bonding the wafer to the substrate

45‧‧‧Steps of combining the cavity expansion cover on the wafer

46‧‧‧Steps for curing the ring frame

47‧‧‧Steps of single-sided cutting

48‧‧‧Steps for wafer sorting

100‧‧‧Back cavity enlarged stereo array MEMS microphone package structure

110‧‧‧Microelectromechanical Wafer

111‧‧‧Active surface

112‧‧‧Back

113‧‧‧Back cavity

114‧‧‧vents

115‧‧‧Pressure film

116‧‧‧Protective layer

117‧‧‧First air gap

118‧‧‧Second air gap

120‧‧‧Line substrate

121‧‧‧Fitting surface

122‧‧‧ external joint

123‧‧‧Outer sound hole

124‧‧‧ protruding pads

130‧‧‧Ring plastic frame

140‧‧‧Back cavity expansion cover

141‧‧ ‧ hood space

142‧‧‧Linking layer

150‧‧‧External terminal

160‧‧‧Expanded airtight back cavity space

170‧‧‧Internal conductive elements

200‧‧‧Back cavity enlarged stereo array MEMS microphone package structure

270‧‧‧Internal conductive elements

FIG. 1 is a cross-sectional view showing a back cavity enlarged stereo array type micro electromechanical microphone package structure according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a process block of the back cavity enlarged stereo array type micro electromechanical microphone package structure according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing another back cavity enlarged stereo array type micro electromechanical microphone package structure according to the second embodiment of the present invention.

FIG. 4 is a schematic diagram of a process block of the back cavity enlarged stereo array type micro electromechanical microphone package structure according to the second embodiment of the present invention.

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, It should be noted that the illustrations are simplified schematic diagrams, and only the schematic diagrams are used to illustrate the basic architecture or implementation method of the present invention. Therefore, only the components and combinations related to the present invention are shown, and the components shown in the figures are not The actual number, shape, and size of the actual implementation are drawn in equal proportions, and some ratios of dimensions and other related dimensions are either exaggerated or simplified to provide a clearer description. The actual number, shape and size ratio of the implementation is an optional design, and the detailed component layout may be more complicated.

According to the first embodiment of the present invention, a back cavity enlarged stereo array type micro electromechanical microphone package structure 100 is illustrated in a cross-sectional view of FIG. 1 and a process block diagram of FIG. A back cavity enlarged stereo array type micro electromechanical microphone package structure 100 includes a microelectromechanical wafer 110, a circuit substrate 120, an annular plastic frame 130, and a back cavity expansion cover 140.

In this embodiment, the MEMS 110 has an active surface 111 and a back surface 112. The back surface 112 defines a back cavity 113 having an opening facing the back surface 112. The bottom of the back cavity 113 is provided with a plurality of bottoms. The vents 114 of the array are provided with a pressure sensitive film 115. In the embodiment, the active surface 111 is preferably formed with a protective layer 116 for fixing the pressure sensitive film 115, and a first air gap 117 is left between the pressure sensitive film 115 and the vent holes 114. It is communicated to the enlarged airtight back cavity space 160 via the vent holes 114. Therefore, the pressure sensitive film 115 can be prevented from contacting the vent holes 114 to cause failure.

In this embodiment, the circuit substrate 120 has a bonding surface 121, an outer bonding surface 122, and a sound hole 123 extending through the circuit board 120. The bonding surface 121 is attached to the wiring surface 121. The active surface of the MEMS wafer 110 111. In this embodiment, the first surface coverage of the circuit substrate 120 is preferably close to a second surface coverage of the MEMS wafer 110, and between 0.8 and 1.5 times the second surface coverage. between. Thereby, it can conform to the wafer level wafer size packaging process of the MEMS microphone package. In the present embodiment, a second air gap 118 is preferably left between the bonding surface 121 and the pressure sensitive film 115, and the external sound hole 123 is connected to the second air gap 118. Therefore, the pressure sensitive film 115 can be prevented from contacting the bonding surface 121 of the circuit substrate 120 and causing failure.

The annular bead frame 130 is specifically bonded to the periphery of the active surface 111 of the MEMS wafer 110 and the periphery of the bonding surface 121 of the circuit substrate 120. The material of the annular frame 130 may be a thermosetting epoxy compound. Preferably, the periphery of the bonding surface 121 of the circuit substrate 120 is provided with an annular protruding pad 124 which is covered by the annular plastic frame 130. The annular bead frame 130 is formed on the annular protruding pad 124 to prevent the annular bezel 130 from overflowing to other regions of the bonding surface 121 of the circuit substrate 120 before curing. Moreover, the thickness of the protruding pad 124 can be used to ensure a minimum lower limit gap of the second air gap 118 between the bonding surface 121 and the pressure sensitive film 115.

The back cavity expansion cover 140 is coupled to the back surface 112 of the MEMS wafer 110 to hermetically seal the back cavity 113, and the back cavity expansion cover 140 has a concave cover space 141 for the back cavity The cavity 113 and the cover space 141 are formed as an enlarged airtight back cavity space 160. The bonding relationship between the back cavity expansion cover 140 and the MEMS wafer 110 can utilize a bonding layer 142, such as a thermosetting conductive paste, which can be made of the same material as the annular plastic frame 130. The back cavity expansion cover 140 can be a metal cover, specifically The circuit board 120 can be grounded via the MEMS wafer 110, for example, to the ground pad of the circuit substrate 120. The hood space 141 can be larger than the back cavity 113. When the MEMS wafer 110 is in a thinned form, the back cavity 113 can also be reduced, and the acoustic back cavity volume can be contributed by the hood space 141 by more than 50%.

In addition, the back cavity enlarged stereo array type micro electromechanical microphone package structure 100 can further include a plurality of outer guiding ends 150 disposed on the outer bonding surface 122 of the circuit substrate 120. The external guiding end 150 is used as an external terminal of the back cavity enlarged stereo array type micro electromechanical microphone package structure 100, and may be selected from one of a metal pad, a metal ball, a metal needle, a conductive paste, and a conductive adhesive. In this embodiment, the outer guiding ends 150 are metal flat pads.

In this embodiment, the back cavity enlarged stereo array MEMS microphone package structure 100 can further include a plurality of inner conductive elements 170 disposed between the MEMS wafer 110 and the circuit substrate 120 for electrical connection. The circuit board 120 is connected to the circuit board 120. In this embodiment, the inner conductive elements 170 and the annular plastic frame 130 are electrically conductive thermosetting colloids of the same material.

The fabrication of the back cavity enlarged stereo array type microelectromechanical microphone package structure 100 can be applied to the wafer process step as shown in FIG. 2, and cooperates with the structure of FIG. In step 11 of "wafer placement", a plurality of the above-described MEMS wafers 110 are integrally formed in a wafer. In step 12 of "wafer singulation", the MEMS wafer 110 is singulated into a grain pattern. Next, in the step 21 of "substrate placement", a plurality of the above-mentioned circuit boards 120 can be integrally formed in a substrate mother substrate. In step 22 of "ring-shaped frame printing on the substrate", the ring-shaped frame The pre-curing conductive adhesive system of 130 is printed on the bonding surface 121 of the circuit substrate 120. In this step, the pre-curing conductive colloid of the inner conductive member 170 of the same material as the annular plastic frame 130 can also be printed on the bonding surface. On the circuit substrate 120. In step 23 of "bonding the wafer to the substrate", the MEMS wafer 110 is bonded to the wiring substrate 120. In the step 24 of "the back cavity expansion cover is coupled to the wafer", the back cavity expansion cover 140 is coupled to the back surface 112 of the MEMS wafer 110, so that the back cavity 113 and the cover space 141 are formed in an enlarged manner. Airtight back cavity space 160. In step 25 of the "ring frame curing", the annular frame 130 is heated and cured, so that the second space gap 118 is fixed and non-changeable. When the back cavity enlarges the connecting layer 142 of the cover 140 and the ring rubber The frame 130 is made of the same material, and the bonding layer 142 can be simultaneously cured. Therefore, when the circuit substrate 120 is combined with the MEMS wafer 110, the MEMS wafer 110 and the back cavity expansion cover 140 are also bonded. In step 26 of "substrate secant dicing", the substrate mother substrate is diced to form the circuit substrate 120 in a single shape, that is, the above-described back cavity enlarged stereo array type micro electromechanical microphone package structure 100 is fabricated. Finally, in step 27 of the "Chip Classification", a good MEMS wafer 110 is tested and the grading is selected for the "packaging" step 28 for shipping.

According to a second embodiment of the present invention, another back cavity enlarged stereo array type micro electromechanical microphone package structure 200 is illustrated in a cross-sectional view of FIG. 3 and a process block diagram of FIG. The back cavity enlarged stereo array micro-electromechanical microphone package structure 200 includes a microelectromechanical wafer 110, a circuit substrate 120, an annular plastic frame 130, and a back cavity expansion cover 140.

The MEMS wafer 110 has an active surface 111 and a back surface 112. The back surface 112 defines a back cavity 113 having an opening facing the back surface 112. The bottom of the back cavity 113 is provided with a plurality of arrays of vent holes 114. The active surface 111 is provided with a pressure sensitive film 115. In the embodiment, the active surface 111 is preferably formed with a protective layer 116 for fixing the pressure sensitive film 115, and a first air gap 117 is left between the pressure sensitive film 115 and the vent holes 114. It is communicated to the enlarged airtight back cavity space 160 via the vent holes 114. Therefore, the pressure sensitive film 115 can be prevented from contacting the vent holes 114 to cause failure.

The circuit board 120 has a bonding surface 121 , an outer bonding surface 122 , and a sound hole 123 extending through the circuit board 120 . The bonding surface 121 is attached to the MEMS 110 in a gap manner. Active surface 111. In this embodiment, a first surface coverage dimension of the circuit substrate 120 is preferably close to and not greater than a second surface coverage of the MEMS wafer 110, and 0.8 of the second surface coverage dimension. Between 1.5 times. Thereby, it can conform to the wafer level wafer size packaging process of the MEMS microphone package. More specifically, a second air gap 118 is preferably left between the bonding surface 121 and the pressure sensitive film 115, and the external sound hole 123 is connected to the second air gap 118. Therefore, the pressure sensitive film 115 can be prevented from contacting the bonding surface 121 of the circuit substrate 120 to cause failure. In this embodiment, the annular bead frame 130 is specifically bonded to the periphery of the active surface 111 of the MEMS wafer 110 and the periphery of the bonding surface 121 of the circuit substrate 120. The back cavity expansion cover 140 is coupled to the back surface 112 of the MEMS wafer 110 to hermetically seal the back cavity 113, and the back cavity expansion cover 140 has a concave cover space 141 for the back cavity The cavity 113 and the cover space 141 are formed as an enlarged airtight back cavity space 160. The hood space 141 can be larger than the back cavity 113.

In addition, the back cavity enlarged stereo array micro-electromechanical microphone package structure 200 can further include a plurality of external guiding ends 150 disposed on the outer bonding surface 122 of the circuit substrate 120. The back cavity enlarged stereo array micro-electromechanical microphone package structure 200 can further include a plurality of inner conductive elements 270 disposed between the microelectromechanical wafer 110 and the circuit substrate 120 to electrically connect the microelectromechanical wafer 110 with The circuit substrate 120. In this embodiment, the inner conductive elements 270 specifically include a plurality of ball bumps and the annular plastic frame 130 is sealed and coated. For example, the inner conductive elements 270 may be gold stud bumps formed by wire bonding, which are bonded to the pads of the microelectromechanical wafer 110 to replace the conduction of the metal bonding wires. The inner conductive elements 270 can serve as a gap-off to provide a second air gap 118 between the abutment surface 121 and the pressure sensitive film 115.

The fabrication of the back cavity enlarged stereo array type microelectromechanical microphone package structure 200 can be applied to the wafer fabrication steps as shown in FIG. 4, and cooperates with the structure of FIG. In step 31 of "wafer placement", a plurality of the above-described MEMS wafers 110 are integrally formed in a wafer. In step 32 of "wafer singulation", the MEMS wafer 110 is singulated into a grain pattern. Next, in the step 41 of "substrate placement", a plurality of the above-mentioned circuit boards 120 can be integrally formed in a substrate mother substrate. In the step 42 of "the bumps are disposed on the substrate", the inner conductive member 270 specifically includes a plurality of ball bumps disposed on the circuit substrate 120. In the step 43 of "the annular frame is printed on the substrate", the pre-curing adhesive system of the annular bezel 130 is printed on the peripheral region of the bonding surface 121 of the circuit substrate 120. In step 44 of "bonding the wafer to the substrate", the inner conductive elements 270 and the ring are The plastic frame 130 is bonded to the circuit substrate 120. In the step 45 of "the back cavity expansion cover is bonded to the wafer", the back cavity expansion cover 140 is coupled to the back surface 112 of the MEMS wafer 110 to form an enlarged airtight back cavity space 160. In step 46 of the "ring frame curing", the annular frame 130 is heated and cured, so that the second space gap 118 is fixed, and the MEMS wafer 110 and the back cavity expansion cover 140 can be bonded together. That is, the above-described back cavity enlarged stereo array type micro electromechanical microphone package structure 200 is fabricated. Finally, in step 27 of the "wafer classification", a good MEMS wafer 110 is tested and the grading is selected.

Therefore, the present invention discloses a back cavity enlarged stereo array type micro electromechanical microphone package structure, so as to avoid the conventional appearance of the electret condenser microphone module, such as large size, high power consumption, low shock resistance, low sensitivity, and Disadvantages such as poor suppression of ambient interference and inability to withstand high temperature reflow furnace operations. Furthermore, the back cavity enlarged stereo array type micro electromechanical microphone chip is used, and the wafer level packaging technology is applied to meet the application range of the micro technology.

The above disclosure is only the preferred embodiment of the present invention, and it is of course not possible to limit the scope of the present invention. Therefore, equivalent changes made in accordance with the present invention are still within the scope of the present invention.

100‧‧‧Back cavity enlarged stereo array MEMS microphone package structure

110‧‧‧Microelectromechanical Wafer

111‧‧‧Active surface

112‧‧‧Back

113‧‧‧Back cavity

114‧‧‧vents

115‧‧‧Pressure film

116‧‧‧Protective layer

117‧‧‧First air gap

118‧‧‧Second air gap

120‧‧‧Line substrate

121‧‧‧Fitting surface

122‧‧‧ external joint

123‧‧‧Outer sound hole

124‧‧‧ protruding pads

130‧‧‧Ring plastic frame

140‧‧‧Back cavity expansion cover

141‧‧ ‧ hood space

142‧‧‧Linking layer

150‧‧‧External terminal

160‧‧‧Expanded airtight back cavity space

170‧‧‧Internal conductive elements

Claims (10)

A back cavity enlarged stereo array type micro electromechanical microphone package structure comprises: a microelectromechanical chip having an active surface and a back surface, wherein the back surface is formed with a back cavity facing the back surface, and the bottom portion of the back cavity is a plurality of arrays of vent holes, wherein the active surface is provided with a pressure sensitive film; a circuit substrate having a bonding surface, an outer bonding surface, and a sound hole extending through the circuit substrate, the bonding surface Attached to the active surface of the MEMS wafer in a gap manner; an annular plastic frame is bonded to the periphery of the active surface of the MEMS wafer and the bonding surface of the circuit substrate; and a back cavity is enlarged a cover is coupled to the back surface of the MEMS wafer to hermetically seal the back cavity, and the back cavity expansion cover has a concave cover space, so that the back cavity and the cover space are configured to be enlarged Airtight back cavity space. The back cavity enlarged stereo array type micro electromechanical microphone package structure according to claim 1, further comprising a plurality of external guiding ends disposed on the outer joint surface of the circuit substrate. The back cavity enlarged stereo array type micro electromechanical microphone package structure according to claim 1, wherein the active surface is formed with a protective layer for fixing the pressure sensitive film, and the pressure sensitive film and the vent holes. A first air gap is left between the two through the vent holes to the enlarged airtight back cavity space. The back cavity enlarged stereo array type MEMS microphone package structure according to claim 3, wherein a second air gap is left between the bonding surface and the pressure sensitive film, and the external sound hole is connected to the first Two air gaps. The back cavity enlarged stereo array type micro electro mechanical microphone package structure according to claim 1, wherein a first surface coverage dimension of the circuit substrate is close to a second surface coverage size of the MEMS chip, Between 0.8 and 1.5 times the size of the second surface. The back cavity enlarged stereo array type microelectromechanical microphone package structure according to claim 1, further comprising a plurality of inner conductive elements disposed between the MEMS wafer and the circuit substrate. The back cavity enlarged stereo array type micro electromechanical microphone package structure according to claim 6, wherein the inner conductive elements comprise a plurality of ball bumps and the annular plastic frame is sealed. The back cavity enlarged stereo array type micro electromechanical microphone package structure according to claim 6, wherein the inner conductive elements and the annular plastic frame are conductive thermosetting colloids of the same material. The back cavity enlarged stereo array type micro electromechanical microphone package structure according to claim 8 , wherein a periphery of the bonding surface of the circuit substrate is provided with a protruding pad, which is bound by the annular plastic frame cover. The back cavity enlarged stereo array type micro electromechanical microphone package structure according to any one of claims 1 to 9, wherein the cover space is larger than the back cavity.