Patent Publication Number: US-2011075875-A1

Title: Mems microphone package

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to the art of microphones and, more particularly, to a micro-electro-mechanical-systems (MEMS) microphone package. 
     2. Description of Related Art 
     Silicon based condenser microphones, known as acoustic transducers, have been researched and developed for more than 20 years. Because of potential advantages in miniaturization, performance, reliability, environmental endurance, low cost, and mass production capability, silicon based microphones are widely recognized to be the next generation product to replace electret condenser microphones (ECM) that has been widely used in communication devices, multimedia players, and hearing aids. 
     For extreme miniaturization of a microphone, an electrical capacity structure is realized on a silicon wafer in a die shape using semiconductor-manufacturing technology and micromachining technology. A silicon condenser microphone chip or a MEMS microphone chip is such a capacitive structure. MEMS microphone chips must be packaged for being protected against exterior interferences. 
     As disclosed in U.S. Pat. No. 7,166,910 B2, U.S. Pat. No. 7,242,089 B2, and U.S. Pat. No. 7,023,066 B2, such a capacitive microphone generally includes a MEMS die having a silicon substrate, a backplate arranged on the substrate, and a moveable diaphragm separated from the backplate for forming a capacitor. While external sound waves reach the diaphragm, the diaphragm will be activated to vibrate relative to the backplate, which changes the distance between the diaphragm and the backplate and changes the capacitance value. As a result, the sound waves are converted into electrical signals. In fact, the electrical signals converted from sound waves include noise signals and the currents of the electrical signals are tiny. Therefore, there&#39;s a need to provide an ASIC (Application Specific Integrated Circuit) chip to cancel the noise signals and to amplify the tiny currents. Generally, the ASIC chip is connected to the MEMS die by lead wires. 
     However, it is more difficult to miniaturize the volume of the microphone, because the lead wires occupies space thereof. So an improved MEMS microphone package is desired to overcome the disadvantage mentioned above. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a MEMS (Micro-Electro-Mechanical-System) microphone package comprises a housing, a MEMS die and an ASIC chip. The housing includes a base, a sidewall extending from the base, and a cover supported by the sidewall for forming a receiving space. The housing defines an acoustic hole for receiving external sound waves. The MEMS die is accommodated in the housing and the MEMS die defines a plurality of first conductive pads. The ASIC chip is accommodated in the housing and the ASIC chip defines a plurality of second conductive pads. The housing defines a plurality of first conductive areas for electrically connecting to the first conductive pads, a plurality of second conductive areas for connecting to the second conductive pads, and a circuit embedded therein for electrically connecting the first conductive areas to the second conductive areas. 
     Other features of the present invention will become more apparent to those skilled in the art upon examination of the following drawings and detailed description of exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of a MEMS microphone package in accordance with a first embodiment of the present invention; 
         FIG. 2  is a schematic cross-sectional view of a MEMS microphone in accordance with a second embodiment of the present invention; 
         FIG. 3  a schematic cross-sectional view of a MEMS microphone in accordance with a third embodiment of the present invention; and 
         FIG. 4  is a schematic cross-sectional view of a MEMS microphone in accordance with a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made to describe the exemplary embodiments of the present invention in detail. 
     Referring to  FIG. 1 , a MEMS microphone package of a first embodiment of the present invention is disclosed. The MEMS microphone package includes a base  11 , a sidewall  12  extending from the base  11 , and a cover  13  supported by the sidewall  12 . The combination of the base  11 , the sidewall  12  and the cover  13  forms a housing for providing a receiving space  10 . The housing defines an acoustic hole  5  for receiving external sound waves into the receiving space  10 . The MEMS microphone package further includes a MEMS die  2  and a chip  3 , such as an ASIC (Application Specific Integrated Circuit) chip  3  accommodated in the receiving space  10 . As shown in  FIG. 1 , the MEMS die  2  and the ASIC chip  3  are both mounted on the base  11 . The MEMS die  2  defines a plurality of first conductive pads  211 , and the ASIC chip  3  defines a plurality of second conductive pads  311 . Corresponding to the first conductive pads  211  and the second conductive pads  311  respectively, the base  11  defines a plurality of first conductive areas  111  and a plurality of second conductive areas  112 . The MEMS die  2  is electrically connected to the base  11  by the electrical connection between the first conductive pads  211  and the first conductive areas  111 . The ASIC chip  3  is electrically connected to the base  11  by the electrical connection between the second conductive pads  311  and the second conductive areas  112 . The base  11  has circuits  113  embedded therein for electrically connecting the first conductive areas  111  to the second conductive areas  311 . Thus, the MEMS die  2  is electrically connected to the ASIC chip  3  without lead wires. 
     Referring to  FIG. 2 , a MEMS microphone package of a second embodiment of the present invention is disclosed. The MEMS microphone package includes a base  11   a , a sidewall  12   a  extending from the base  11   a , and a cover  13   a  supported by the sidewall  12   a . The combination of the base  11   a , the sidewall  12   a  and the cover  13   a  forms a housing for providing a receiving space  10   a . The cover  13   a  defines an acoustic hole  5   a  for receiving external sound waves. The MEMS microphone package further includes a MEMS die  2   a  and an ASIC chip  3   a  accommodated in the receiving space  10   a . As shown in  FIG. 2 , the MEMS die  2   a  and the ASIC chip  3   a  are both mounted on the base  11   a . The MEMS die  2   a  defines a plurality of first conductive pads  211   a , and the ASIC chip  3   a  defines a plurality of second conductive pads  311   a . Corresponding to the first conductive pads  211   a  and the second conductive pads  311   a  respectively, the base  11   a  defines a plurality of first conductive areas  111   a  and a plurality of second conductive areas  112   a . The MEMS die  2   a  is electrically connected to the base  11   a  by the electrical connection between the first conductive pads  211   a  and the first conductive areas  111   a . The ASIC chip  3   a  is electrically connected to the base  11   a  by the electrical connection between the second conductive pads  311   a  and the second conductive areas  112   a . The base  11   a  has circuits  113   a  embedded therein for electrically connecting the first conductive areas  111   a  to the second conductive areas  311   a . Thus, the MEMS die  2   a  is electrically connected to the ASIC chip  3   a  without lead wires. In addition, the MEMS die  2   a  defines a back volume  212   a  overlapping a part of the acoustic hole  5   a . Moreover, a sealing belt  213   a  is provided between the cover  13   a  and the MEMS die  2   a  for isolating the back volume  212   a  from the receiving space  10   a , which enables the sound waves directly reaches the back volume  212   a  without leak. 
     Referring to  FIG. 3 , a MEMS microphone package of a third embodiment of the present invention is disclosed. The MEMS microphone package includes a base  11   b , a sidewall  12   b  extending from the base  11   b , and a cover  13   b  supported by the sidewall  12   b . The combination of the base  11   b , the sidewall  12   b  and the cover  13   b  forms a housing for providing a receiving space  10   b . The cover  13   b  defines an acoustic hole  5   b  for receiving external sound waves into the receiving space  10   b . The MEMS microphone package further includes a MEMS die  2   b  and an ASIC chip  3   b  accommodated in the receiving space  10   b . As shown in  FIG. 3 , the MEMS die  2   b  is mounted on the cover and the ASIC chip  3   b  is mounted on the base  11   b . The MEMS die  2   b  defines a plurality of first conductive pads  211   b , and the ASIC chip  3   b  defines a plurality of second conductive pads  311   b . Corresponding to the first conductive pads  211   b , the cover  13   b  defines a plurality of first conductive areas  111   b . Corresponding to the second conductive pads  311   b , the base  11   b  defines a plurality of second conductive areas  112   b . Thus, the MEMS die  2   b  is electrically connected to the cover  13   b  by the electrical connection between the first conductive pads  211   b  and the first conductive areas  111   b . The ASIC chip  3   b  is electrically connected to the base  11   b  by the electrical connection between the second conductive pads  311   b  and the conductive areas  112   b . The housing has circuits  113   b  embedded therein for electrically connecting the first conductive areas  111   b  to the second conductive areas  311   b , which enables the MEMS die  2   b  to be electrically connected to the ASIC chip  3   b  without lead wires. 
     Referring to  FIG. 4 , a MEMS microphone package in accordance with a fourth embodiment is disclosed. The MEMS microphone package includes a base  11   c , a sidewall  12   c  extending from the base  11   c , and a cover  13   c  supported by the sidewall  12   c . The combination of the base  11   c , the sidewall  12   c  and the cover  13   c  forms a housing for providing a receiving space  10   c . The cover  13   c  defines an acoustic hole  5   c  for receiving external sound waves. The MEMS microphone package further includes a MEMS die  2   c  and an ASIC chip  3   c  accommodated in the housing. MEMS die  2   c  is mounted on the cover  13   c  with the back volume  212   c  overlapping the acoustic hole  5   c . A sealing belt  213   c  is provided for isolating the back volume  212   c  from the receiving space  10   c . The sealing belt  213   c  defines a plurality of first conductive pads  211   c  for electrically connecting to the first conductive areas  111   c  on the cover  13   c . The ASIC chip  3   c  is mounted on the base  11   c  by second conductive pads  311   c  and the second conductive areas  112   c . The MEMS die  2   c  is electrically connected to the ASIC chip  3   c  by circuits  113   c  embedded in the housing. 
     MEMS microphone packages of the present invention have volumes smaller than the conventional packages. 
     A method of manufacturing a MEMS microphone package in accordance with a first embodiment is disclosed. Referring to  FIG. 1 , the method is that providing a MEMS die  2  defining a plurality of first conductive pads  211 , an ASIC chip  3  defining a plurality of second conductive pads  311 , and a housing defining a plurality of first conductive areas  111  for electrically connecting to the first conductive pads  211  and a plurality of second conductive areas  112  for connecting to the second conductive pads  311 , embodying a circuit  113  in the housing, accommodating the MEMS die  2  and the ASIC die  3  in the housing, electrically connecting the first conductive pads  211  to the second conductive pads  112  by the circuit  113 . The housing also defines an acoustic hole  5  for receiving external sound waves. The housing comprises a base  11 , a sidewall  12  extending from the base  11 , and a cover  13  supported by the sidewall  12  for forming a receiving space  10 . As shown in  FIG. 1 , both the MEMS die  2  and the ASIC chip  3  are mounted on the base  11 , and the circuit  113  is defined in the base  11 . 
     A method of manufacturing a MEMS microphone package in accordance with a second embodiment is disclosed. Referring to  FIG. 2 , the method is that providing a MEMS die  2   a  defining a plurality of first conductive pads  211   a , an ASIC chip  3   a  defining a plurality of second conductive pads  311   a , and a housing defining a plurality of first conductive areas  111   a  for electrically connecting to the first conductive pads  211   a  and a plurality of second conductive areas  112   a  for connecting to the second conductive pads  311   a , embodying a circuit  113   a  in the housing, accommodating the MEMS die  2   a  and the ASIC die  3   a  in the housing, electrically connecting the first conductive pads  211   a  to the second conductive pads  112   a  by the circuit  113   a . The housing also defines an acoustic hole  5   a  for receiving external sound waves. The housing comprises a base  11   a , a sidewall  12   a  extending from the base  11   a , and a cover  13   a  supported by the sidewall  12   a  for forming a receiving space  10   a . As shown in  FIG. 1 , both the MEMS die  2   a  and the ASIC chip  3   a  are mounted on the base  11   a , and the circuit  113   a  is defined in the base  11   a . The acoustic hole  5   a  is defined in the cover  13   a  and a back volume  212   a  is defined in the MEMS die  2   a , the back volume  212   a  is overlapping a part of the acoustic hole  5   a . A sealing belt  213   a  is arranged between the cover  13   a  and the MEMS die  2   a , the back volume  212   a  is isolated to the receiving space  10   a  by the sealing belt  213   a.    
     A method of manufacturing a MEMS microphone package in accordance with a third embodiment is disclosed. Referring to  FIG. 3 , the method is that providing a MEMS die  2   b  defining a plurality of first conductive pads  211   b , an ASIC chip  3   b  defining a plurality of second conductive pads  311   b , and a housing defining a plurality of first conductive areas  111   b  for electrically connecting to the first conductive pads  211   b  and a plurality of second conductive areas  112   b  for connecting to the second conductive pads  311   b , embodying a circuit  113   b  in the housing, accommodating the MEMS die  2   b  and the ASIC die  3   b  in the housing, electrically connecting the first conductive pads  211   b  to the second conductive pads  112   b  by the circuit  113   b . The housing also defines an acoustic hole  5   b  for receiving external sound waves. The housing comprises a base  11   b , a sidewall  12   b  extending from the base  11   b , and a cover  13   b  supported by the sidewall  12   b  for forming a receiving space  10   b . As shown in  FIG. 1 , both the MEMS die  2   b  and the ASIC chip  3   b  are mounted on the base  11   b , and the circuit  113   b  is defined in the base  11   b . The MEMS die  2   b  is mounted on the cover  13   b  by electrical connection between the first conductive pads  111   b  and the first conductive areas  211   b , and the ASIC chip  3   b  is mounted on the base  11   b  by electrical connection between the second conductive pads  311   b  and the conductive areas  112   b.    
     A method of manufacturing a MEMS microphone package in accordance with a fourth embodiment is disclosed. Referring to  FIG. 4 , the method is that providing a MEMS die  2   c  defining a plurality of first conductive pads  211   c , an ASIC chip  3  defining a plurality of second conductive pads  311   c , and a housing defining a plurality of first conductive areas  111  for electrically connecting to the first conductive pads  211   c  and a plurality of second conductive areas  112   c  for connecting to the second conductive pads  311   c , embodying a circuit  113   c  in the housing, accommodating the MEMS die  2   c  and the ASIC die  3   c  in the housing, electrically connecting the first conductive pads  211  to the second conductive pads  112   c  by the circuit  113   c . The housing also defines an acoustic hole  5   c  for receiving external sound waves. The housing comprises a base  11   c , a sidewall  12   c  extending from the base  11   c , and a cover  13   c  supported by the sidewall  12   c  for forming a receiving space  10   c . As shown in  FIG. 1 , both the MEMS die  2   c  and the ASIC chip  3   c  are mounted on the base  11   c , and the circuit  113   c  is defined in the base  11   c . A back volume  212   c  is defined in the MEMS die  2   c  and the back volume  212   c  being overlapping the acoustic hole  5   c . A sealing belt  213   c  is located between the cover  13   c  and the MEMS die  2   c  and the first conductive pads  211   c  is defined in the sealing belt  213   c.    
     While the present invention has been described with reference to the specific embodiments, the description of the invention is illustrative and is not to be construed as limiting the invention. Various of modifications to the present invention can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.