Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to a micro-electro-mechanical system (MEMS) package technology. More particularly, the present invention relates to a MEMS package, such as the MEMS microphone capable of being chip-size scale. 
         [0003]    2. Description of Related Art 
         [0004]    MEMS microphone has been popular gradually due to the excellent features comparing to the conventional ECM microphone. The features of MEMS microphone includes: 1. thin and small size. 2. SMD(surface mountable device) indicating easy assembly with sold flow. 3. high stability and environmental resistance. However, in comparison with the IC package, the requirements of microphone package include receiving the sound pressure from acoustic signal, inducing mechanical motion and transferring to electrical signal. Therefore it needs an acoustic path to receive the sound pressure, a transducer to response the sound pressure, a sufficient back volume for transducer to reduce the damping coefficient and a good shielding to protect it from EMI. Currently, the most popular package is that the transducer is mounted on PCB and electrically couple to such PCB, and the conductive housing with an aperture is attached to the PCB enclosing the transducer. ( FIG. 1 ) However, in such a way, the back volume of a transducer is only decided by the volume of the cavity of a transducer, indicating a small back volume and high damping coefficient to degrade the microphone performance. 
         [0005]    Currently, most transducers have two chips in the package. One is the pure MEMS devices; the other is sensing IC. The drawbacks are: 1. large package size, 2. parasitic effect for the electrical connection between IC and MEMS devices. 3. high cost for extra sensing IC. It is inevitably intended for the miniature package size and low cost. Moreover, CSP(chip scale package) and wafer level package becomes more popular due to high electrical performance, small package size (as small as the chip size) and low cost. Such two chips in one package is not suitable to such CSP or WLP process. By the way, the size of a package mentioned above is also always larger than that of the transducer because the transducer has to be enclosed in the package. 
       (* Move to the Invention *) 
       [0006]      FIG. 1  is a cross-sectional view, schematically illustrating a structure of conventional MEMS microphone. In  FIG. 1 , the conventional MEMS microphone includes a substrate  100 . A MEMS microphone device  104 , serving as a transducer, is formed on the substrate  100 . MEMS microphone device  104  has a cavity  102  and a diaphragm over the cavity, allowing the diaphragm to vibrate with the acoustic sound. An integrate circuit (IC)  106  is also formed on the substrate  100 . The bonding wire is used for the electric connection, so that the MEMS microphone device  104  is connected with the IC  106  for operation. Usually, the MEMS microphone package also needs a cover  108  to protect the MEMS microphone device  104  and the IC  106 . In order to sense the acoustic sound from the environment, an aperture  110  is made to receive the acoustic sound. However, since the volume of the cavity  102  of the MEMS microphone device  104  is small. The sensitivity is insufficient. 
         [0007]    How to design a MEMS microphone with more sensitivity or even in chip-size scale is still under development. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a MEMS package with improved sensitivity and reduced size, such as about the same size as the MEMS chip. 
         [0009]    The present invention provides a micro-electro-mechanical systems (MEMS) microphone package. The MEMS microphone device has a first substrate and an acoustic sensing element, wherein the MEMS sensing element includes at least a portion of first substrate, wherein the sensing element includes a moveable diaphragm, a perforated rigid back plate and a gap between the diaphragm and back plate, wherein a first chamber in the MEMS microphone device is connected to the sensing element via the perforated back plate, wherein the first chamber has an open opposite to the sensing element, wherein if there is no covering layer, the open is served as an aperture and coupled to an environment, A second substrate is disposed over the MEMS microphone device to provide a second chamber in the second substrate over the sensing element opposite to the first chamber. 
         [0010]    In a further aspect of the MEMS package, for example, the MEMS device does not include a first chamber and the sensing element is coupled to an environment directly. 
         [0011]    In a further aspect of the MEMS package, for example, the MEMS microphone device further comprises a integrated circuit and the second substrate has an interconnect structure for coupling an I/O terminal of the integrated circuit out, wherein the electrical coupling includes a metal bump or conductive paste, e.g. stud bump, B-stage conductive epoxy or solder paste. 
         [0012]    In a further aspect of the MEMS package, for example, the MEMS microphone device further comprises a structural dielectric layer on first substrate of the MEMS microphone device. 
         [0013]    In a further aspect of the MEMS package, for example, the structural dielectric layer in MEMS microphone device includes a patterned conductive layer for the coupling between the sensing element and the integrated circuit, wherein the second substrate disposed on the first substrate includes an adhesive layer to adhere the second substrate to the structural dielectric layer, wherein the adhesive layer includes an conductive material. 
         [0014]    In a further aspect of the MEMS package, for example, the second substrate has an aperture for coupling the second chamber to an environment. 
         [0015]    In a further aspect of the MEMS package, for example, the MEMS device further comprises a covering layer on the first substrate of the MEMS microphone device to cover the first chamber, wherein the covering layer has an aperture for coupling the first chamber to an environment. 
         [0016]    In a further aspect of the MEMS package, for example, it further includes a third substrate over the second substrate layer, wherein the third substrate has a third chamber over the second chamber of the second substrate in which the second substrate has an aperture for coupling the second chamber and the third chamber. 
         [0017]    In a further aspect of the MEMS package, for example, it further includes a covering layer on the first substrate of the MEMS microphone device to cover the first chamber, wherein the covering layer has a side gap for coupling the first chamber to an environment. 
         [0018]    In a further aspect of the MEMS package, for example, it further include a third substrate disposed on the MEMS microphone device over the second chamber of the substrate, wherein the third substrate has an indent space for adapting the second substrate and the third substrate has an interconnect structure for coupling I/O terminals of the integrated circuit of the MEMS microphone device out, wherein a filling material is filled in the gap formed by MEMS microphone device, second substrate and third substrate to provide a reliable package. 
         [0019]    In a further aspect of the MEMS device, for example, it further includes a covering layer on the first substrate to cover the first chamber of the MEMS microphone device, wherein the covering layer has an aperture for coupling the first chamber to an environment. 
         [0020]    In a further aspect of the MEMS package, for example, the first substrate also comprises an interconnect structure for coupling an I/O terminal of the integrated circuit from one side of first substrate to another side of first substrate, wherein the interconnect structure includes interconnections through the first substrate. 
         [0021]    In a further aspect of the MEMS package, for example, it further includes a printed circuit board for coupling the interconnect structure of the first substrate and cover the first chamber, wherein the printed circuit board has an aperture for coupling the first chamber to an environment. 
         [0022]    In a further aspect of the MEMS package, for example, it further includes a printed circuit board for coupling an interconnect structure in the second substrate and then coupling to the integrated circuit. 
         [0023]    In a further aspect of the MEMS package other than the acoustical sensing MEMS package, for example, it further includes a covering layer to cover first chamber, wherein the first chamber and the second chamber of the second substrate are not connected to environment, wherein the sensing element includes inertial sensing element, actuator or other MEMS sensor needed hermetic package. 
         [0024]    In a further aspect of the MEMS package, for example, wherein the second substrate is a cap structure without interconnect structure. 
         [0025]    In a further aspect of the MEMS package, for example, wherein the first substrate also comprises an interconnect structure for coupling an I/O terminal of the integrated circuit from one side to another side of first substrate, wherein the interconnect structure includes interconnections through the first substrate. 
         [0026]    In a further aspect of the MEMS package, for example, the cap structure has an aperture for coupling the second chamber to an environment, wherein the two apertures is used for the application of directional microphone. 
         [0027]    In a further aspect of the MEMS package, for example, it further includes a covering layer to cover the first chamber of the MEMS microphone device, wherein the covering layer also has an interconnect structure for coupling to the integrated circuit and an aperture for coupling the first chamber to an environment. 
         [0028]    In a further aspect of the MEMS package, for example, it further includes a covering layer to cover the first chamber of the MEMS microphone device, wherein the covering layer also has an interconnect structure for coupling to the integrated circuit and the covering layer has a side aperture for coupling the first chamber to an environment. 
         [0029]    In a further aspect of the MEMS package, for example, the covering layer has an indent region to expand the first chamber. 
         [0030]    In a further aspect of the MEMS package, for example, it further includes a covering layer to cover the first chamber of the MEMS microphone device, wherein the covering layer also has an interconnect structure for coupling to the integrated circuit and the second substrate has an aperture for coupling the second chamber to an environment. 
         [0031]    The present invention also provides a micro-electro-mechanical systems (MEMS) package. The MEMS microphone device, having a first substrate and at least a MEMS sensing element, wherein a first chamber in the MEMS microphone device is connected to the MEMS sensing element; a cap structure without any interconnection structure, disposed over the MEMS microphone device to provide a second chamber in  10  the cap structure over the MEMS sensing element opposite to the first chamber; and a bonding structure at an outside region of the cap structure on the MEMS microphone device, wherein a bonding structure includes a metal bump or a conductive paste, wherein the metal bump includes a stud bump, wherein the conductive paste includes a B-stage conductive epoxy or solder paste. 
         [0032]    In a further aspect of the MEMS package, for example, wherein the MEMS sensing element includes at least a portion of the first substrate. 
         [0033]    In a further aspect of the MEMS package, for example wherein the MEMS device further comprises an integrated circuit on first substrate, wherein the bonding structure is electrically coupled to an I/O terminal of the integrated circuit. 
         [0034]    In a further aspect of the MEMS package, for example, wherein the MEMS device comprises a structural dielectric layer on the first substrate, wherein the structural dielectric layer includes patterned conductive layers for the coupling between an integrated circuit on the first substrate and the MEMS sensing element. 
         [0035]    In a further aspect of the MEMS package, for example, the cap structure has an aperture for coupling the second chamber to environment or fully seals over the sensing element. 
         [0036]    In a further aspect of the MEMS package, for example, it further includes a covering layer on the first substrate to cover the first chamber, wherein the covering layer has an aperture for coupling the first chamber to an environment. 
         [0037]    In a further aspect of the MEMS package, for example, it further includes a cap covering layer on the first substrate to fully cover the first chamber and expands a volume of the first chamber. 
         [0038]    In a further aspect of the MEMS package, for example, it further includes: a third substrate with an interconnect structure disposed on the first substrate to cover the first chamber, wherein the third substrate has an aperture for coupling the first chamber to an environment; a bonding wire coupling the interconnect structure to the integrated circuit of the MEMS microphone device; and a protection structure over the bonding wire for protection. 
         [0039]    In a further aspect of the MEMS package, for example, the third substrate comprises semiconductor substrate or printed circuit board. 
         [0040]    In a further aspect of the MEMS package, for example, the protection structure is a molding compound or a cap, if the cap includes a conductive layer, the cap can protect the bonding wire from EMI. 
         [0041]    In a further aspect of the MEMS package, for example, it further includes a third substrate with an interconnect structure disposed on the first substrate to fully cover the first chamber, wherein the third substrate has an indent region to expand a volume of the first chamber; a bonding wire coupling the interconnect structure of the third substrate to the bonding structure of the first substrate; and a protection structure over the bonding wire for protection. 
         [0042]    In a further aspect of the MEMS package, for example, the third substrate comprises semiconductor substrate or printed circuit board. 
         [0043]    In a further aspect of the MEMS package other than acoustical sensing MEMS package, for example, the first chamber in the MEMS device and the second chamber in the cap structure are sealed and not connected to an environment, wherein the sensing element are packaged hermetically, wherein the sensing element includes inertial sensing element, actuator or other MEMS sensor needed hermetic package. 
         [0044]    The present invention also provides a micro-electro-mechanical systems (MEMS) package, comprising a MEMS microphone device. The MEMS microphone device has a first substrate and an acoustic MEMS sensing element, wherein the MEMS sensing element includes at least a portion of first substrate, wherein such an acoustic MEMS sensing element includes a moveable diaphragm, a rigid perforated back plate and a gap between the diaphragm and back plate, A first chamber in the MEMS element device is connected to the gap via the perforated back plate. A second substrate, serving as a cap, is disposed on the MEMS microphone device to cover the first chamber. A third substrate has an interconnect structure in coupling with the MEMS microphone device at opposite side to the second substrate. An adhesive layer is disposed between the MEMS microphone device and the third substrate. Wherein, a second chamber is formed under the sensing element between the MEMS microphone device and the third substrate. 
         [0045]    In a further aspect of the MEMS package, for example, the third substrate has a ditch under the sensing element to expand the second chamber and is for coupling the second chamber to an environment. 
         [0046]    In a further aspect of the MEMS package, for example, the second chamber is coupled to an environment by a gap between the MEMS microphone device and the third substrate. 
         [0047]    In a further aspect of the MEMS package, for example, the third substrate has an aperture for coupling the second chamber to an environment. 
         [0048]    In a further aspect of the MEMS package, for example, the third substrate has an indent region to expand the second chamber. 
         [0049]    In a further aspect of the MEMS package, for example, the second substrate has an aperture for coupling the first chamber to an environment. 
         [0050]    The present invention also provides a micro-electro-mechanical systems (MEMS) package. The MEMS package includes a MEMS microphone device, having a first substrate and an acoustic MEMS sensing element, wherein the MEMS sensing element includes at least a portion of first substrate, wherein such an acoustic sensing element includes a moveable diaphragm, a rigid perforated back plate and a gap between the diaphragm and back plate, wherein a first chamber in the MEMS microphone device is connected to the gap via perforated back plate. A second substrate is disposed over the MEMS microphone device, wherein the second substrate has a second chamber over the sensing element opposite to the first chamber. A circuit board is for supporting and electric coupling the MEMS microphone device, wherein the circuit board has an indent region adapted to the second substrate without significantly adding thickness. 
         [0051]    In a further aspect of the MEMS package, for example, it further includes a cap structure over the first chamber of the MEMS microphone device for expanding a containing space. 
         [0052]    In a further aspect of the MEMS package, for example, the second substrate has a first aperture and the circuit board has a second aperture, so as to couple the second chamber to an environment through the first and second apertures. 
         [0053]    In a further aspect of the MEMS package, for example, the circuit board has a sub indent region coupled between the first and the second aperture. 
         [0054]    In a further aspect of the MEMS package, for example, the filling material is filled in the gap between the MEMS microphone device and the circuit board. 
         [0055]    The present invention also provides a method for forming a plurality of MEMS units on a substrate, wherein each of the MEMS units comprises at least a MEMS sensing element and a first chamber over a sensing element, wherein the MEMS units includes electric connection pads; forming a plurality of covering units correspondingly over the MEMS devices, wherein each of covering units provides a second chamber over the sensing element opposite to the first chamber; adhering the covering units to the MEMS units via the adhesive material; and dicing the MEMS units into singulated units. 
         [0056]    In a further aspect of the method for fabricating the MEMS package, for example, the covering units includes an adhesive material on the surface of covering units facing the MEMS devices. 
         [0057]    In a further aspect of the method for fabricating the MEMS package, for example, each covering unit includes an interconnection structure, wherein the interconnection structure includes a conductive paste. 
         [0058]    In a further aspect of the method for fabricating the MEMS package, for example, wherein the MEMS units includes a metal bump on the connection pad. 
         [0059]    In a further aspect of the method for fabricating the MEMS package, for example, the adhesive layer forms a ring to surround the sensing element and the bonding structure is outside the ring. 
         [0060]    In a further aspect of the method for fabricating the MEMS package, for example, the adhesive layer forms a ring to surround the sensing element and the bonding structure is included in the ring. 
         [0061]    In a further aspect of the method for fabricating the MEMS package, for example, the adhesive layer and conductive paste form a ring to surround the sensing element. 
         [0062]    In a further aspect of the method for fabricating the MEMS package, for example, the supporting layer is attached under the substrate of MEMS units for dicing. 
         [0063]    In a further aspect of the method for fabricating the MEMS package, for example, the step of dicing the MEMS microphone units is directly dicing a base substrate of the MEMS microphone units. 
         [0064]    In a further aspect of the method for fabricating the MEMS package, for example, before dicing the MEMS units, further comprising forming a supporting layer under the substrate of MEMS units covering the first chamber to protect sensing element from water jet during dicing. 
         [0065]    In a further aspect of the method for fabricating the MEMS package, for example, the covering units are formed on a substrate in joining together by a substrate portion. 
         [0066]    In a further aspect of the method for fabricating the MEMS package, for example, the covering units are formed on a continuous substrate with a joining portion, and the step of dicing the MEMS units comprising: removing the joining portion by etching; and dicing the continuous substrate of the MEMS units. 
         [0067]    In a further aspect of the method for fabricating the MEMS package, for example, before dicing the MEMS units, further comprising forming a protection layer over the covering units at opposite side to the supporting layer to protect sensing element from water jet during dicing. 
         [0068]    In a further aspect of the method for fabricating the MEMS package, for example, the covering units are formed on a continuous substrate with a joining portion, and the step of dicing the MEMS units comprising: performing a first dicing to remove the joining portion; and dicing the continuous substrate of the MEMS units. 
         [0069]    In a further aspect of the method for fabricating the MEMS package, for example, the supporting layer protects the MEMS units from water jet during dicing. 
         [0070]    It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0071]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
           [0072]      FIG. 1  is a cross-sectional view, schematically illustrating a structure of conventional MEMS microphone. 
           [0073]      FIGS. 2-19  are drawings in cross-sectional view and/or top view, schematically illustrating structures of MEMS devices, according to various embodiments of the present invention. 
           [0074]      FIGS. 20-37  are cross-sectional views, schematically illustrating various fabrication processes for the MEMS device, according to embodiments of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0075]    In the present invention, the MEMS microphone is provided. The MEMS microphone has an additional room, connected to the sensing element of the MEMS microphone device. As a result, the sensitivity can be improved. Several embodiments are provided for descriptions of the invention. However, the present invention is not just limited to the embodiments. Further, the embodiments can be properly combined to each other without limited to an individual embodiment. 
         [0076]    To solve conventional issue, the invention proposes a novel method to form MEMS microphone package. For example, the MEMS transducer and sensing IC are integrated into a single chip. A cover made of, for example, silicon or PCB substrate is mounted on the surface of a single chip enclosing the MEMS area. The size of such package is as small as the microphone chip size. Moreover, the vent holes in the back plate of the transducer on the backside of the microphone chip can be acted as a sensing port to allow the acoustical signal to input. 
         [0077]    The invention uses, for example, the stud bumping technology, B-stage conductive Epoxy or solder paste to replace the electrical connection of conventional solder bumping. For the technology of solder bumping, it is necessary to grow the UBM (under bump metallurgy) before implanting solder bump. However, the MEMS structure is usually formed before the formation of UBM layer. The formation of UBM layer will damage the MEMS structure if the solder bump is formed on the surface of MEMS chip. However, the stud bumping does not need UBM layer. The metal bump can be formed directly on conductive PAD using such a technology. Therefore, the MEMS area is not damaged. The bump can be used to electrical connection efficiently. For another technology of B-stage conductive Epoxy, it is also not necessary to use UBM layer. It can be formed directly on the substrate of silicon wafer or PCB for MEMS covering units with stencil printing indicating easy and productive process. The electrical connection is finished by anticipating the attachment of two substrates with curing. The technology is suitable not only to microphone but various MEMS packages. 
         [0078]      FIGS. 2-19  are drawings in cross-sectional views and/or top view, schematically illustrating structures of MEMS packages, according to various embodiments of the present invention. In  FIG. 2 , an embodiment is shown in  FIG. 2(   a ), the MEMS packages in a basic structure includes a MEMS microphone device. The MEMS microphone device has a first substrate  124  and both a structural dielectric layer  120  and sensing element  130  on the first substrate  124 . Such an acoustic sensing element includes a moveable sensing diaphragm  131 , a rigid perforated back plate  133  and a gap  135  between the diaphragm and back plate. An integrated circuit  122  is also formed in the first substrate  124  and the structural dielectric layer  120  for driving the MEMS microphone device. A first chamber  126  in the MEMS microphone device is connected to the sensing element  130  through the holes  128  in back plate. The first chamber has an open  137  opposite to the sensing element. A second substrate  132  is disposed on the structural dielectric layer  120  of the MEMS microphone device to provide a second chamber  136  in the second substrate  132  over the sensing element  130  opposite to the first chamber  126 . 
         [0079]    The second substrate  132  can be, for example, about the same size as the MEMS microphone device as a chip. The second substrate  132  can be adhered to the structural dielectric layer  120  by adhesive material  134 . As can be understood, the second substrate  132  has an interconnect structure including, for example, connection via  138  and the pad  140 . The connection via  138  can connected to the I/O terminal of the integrated circuit  120 , so that the I/O terminals are redistributed to the pad  140  for connection out. The structural dielectric layer  120  also includes the interconnect structure for connection to the integrated circuit  122  and coupling between sensing element  130  and integrated circuit  122 . In other words, the integrated circuit  122  can be connected out. The interconnection can be understood by one with the ordinary skill in the art. 
         [0080]    In this structure of MEMS package, the chamber  136  can provide a larger space for the acoustic sensing element  130  in sensing. The larger space shows higher mechanical compliance for acoustical sensing diaphragm indicating higher acoustic sensitivity. 
         [0081]    Based on the structure in  FIG. 2(   a ), several other structure options can be made, for example. In  FIG. 2(   b ), the second substrate  132  may have an aperture  142  for connecting the second chamber  136  to an environment. This aperture  142  can adjust the sensitivity in option or can be the 2 nd  aperture for the application of directional microphone. In  FIG. 2(   c ), a covering layer  144  may be formed over the substrate  124  to cover the first chamber  126  to protect the sensing element from particles or EMI. However, in this situation, an aperture  146  is in the covering layer  144  for coupling the first chamber  126  to the environment while the second chamber  136  is not coupled to the environment. In  FIG. 2(   d ) for alternative option, both the apertures  146  and  142  can be formed for the application of directional microphone. In one of applications as a microphone, for example, the aperture can receive the acoustic signal, and the diaphragm can sense the flow pressure. The two chambers  126 ,  136  locate at both sides of the sensing element  130 . 
         [0082]    Based on the same design principle from  FIG. 2 , in  FIG. 3 , another substrate  150 , serving as a covering layer  150 , can be formed on the first substrate  124 . As a result, the first chamber  126  can be covered by the covering layer  150 . However, the covered by the covering layer  150  can have an indent region and a side aperture  152  can be formed. The side aperture can connect the first chamber  126  to an environment. The aperture located on the side of microphone device can increase the feasibility for user application. In  FIG. 4 , alternatively, another substrate  154 , serving as cap function, can also be added. The substrate  154 , as the third substrate  154 , is disposed over the second substrate  132  with similar structure at the chip-size scale, for example. The third substrate  154  also has the interconnect structure, including a connection via  158  and a conductive pad  156  for electric connection out. However, the aperture  142  allows the two chambers  136  to be coupled together. In this situation, the volume of the back chamber can be expanded. 
         [0083]    In  FIG. 5 , alternatively, the second substrate  162  can be formed over the MEMS microphone device from the other structural dielectric layer  120 . In this embodiment, the second substrate  162 , serving as a cover  162  over the sensing element  130  and protecting the sensing element from damage during packaging, is not necessary to have the interconnect structure. However, the third substrate  160  can have the interconnect structure having the via  164  and conductive pad  166 , which can be coupled to the integrated circuit  122  electrically, such as the metal bump  168  like stud bump or conductive paste  168  like B-stage epoxy or solder paste. However, in order not to add thickness, the substrate  160  can have an indent region to adapt the second substrate  162 . The filling material  165  is filled in the gap between the structural dielectric layer  120  and the substrate  160  and seals the metal bump to provide the reliable package quality. In other words, the cover  162  is just used as the cover without interconnect structure. In  FIG. 6 , based on the structure in  FIG. 5 , the covering layer  144  can be further formed over the MEMS microphone device above the first chamber. The covering layer  144  has an aperture  146  for coupling the first chamber to the environment to protect the sensing element from particles. 
         [0084]    In  FIG. 7(   a ), the first substrate  124  of the MEMS microphone device has the opened chamber  137  downward and has the interconnect structure of via  138  and conductive pad  140 . In this situation, the MEMS package can be externally connected out from both sides to provide a feasible application to user. In  FIG. 7(   b ), further for example, in the application of MEMS device on user&#39;s PCB, the MEMS package can be coupled to the user&#39;s printed circuit board (PCB)  170  by the adhesive material  174 . The PCB  170  can have an aperture  172  as a sensing aperture, coupled to the first chamber  137 . In  FIG. 7(   c ), since the MEMS package allows the connection from both sides, the second substrate  132  of the MEMS package can be coupled to the PCB  176  while the chamber  137  remains opened. 
         [0085]    In  FIG. 8 , the MEMS package can be used in other applications, such as the apparatus for inertial sensor, e.g. acceleration. In this situation, the MEMS package has the first substrate  200  with the sensing element  202 , e.g. moveable proof mass, which is a mass-source for sensing the acceleration, for example. This application does not need to receive the acoustic signal and therefore the cover  208  seals the chamber  206  and the substrate  214  is adhered to the MEMS device by the adhesive  212 , which may also be usual paste or conductive paste. The chamber  216  at the other side of the sensing element  202  can be formed. Similarly, the integrated circuit  204  in the structural dielectric layer  210  can be interconnected out by the via  218  and the conductive pad  220 . Both chambers  206 ,  216  are hermetic to isolate from the outside environment and allows the proof mass to move freely. The hermetic package in  FIG. 8  can be used in other MEMS package in which the hermetic package is needed, e.g. RF, actuator and etc. 
         [0086]    Further embodiment in  FIG. 9(   a ), it is a top view.  FIG. 9(   b ) and  FIG. 9(   c ) are the cross-sectional views at the Y cutting line and X cutting line in  FIG. 9(   a ). In structure of  FIG. 9 , the MEMS microphone device includes a first substrate  232  and a structural dielectric layer  240 , in which an integrated circuit  244  is formed inside. The acoustic sensing element  248  is coupled to the first chamber  250 . In this embodiment, the second substrate  230  is formed over the structural dielectric layer  240  to form a second chamber  252  at one side of the sensing element  248 . Likewise, the interconnect structure with the via  237  and conductive pad  236  in the second substrate  230  is used to connect I/O terminals of the integrated circuit  244  out with the bonding structure  242 , such as the metal bump or conductive paste. The adhesive material  234  is used to adhere the MEMS microphone device with the second substrate  230 . However, in order to allow the chamber  252  to receive the external acoustic signal, a ditch  238  is formed. In  FIG. 9(   c ) at the X cross-sectional view, the ditch  238  indeed provides the path for receiving the acoustic signal from sides. The cover layer  246  can be just a cap to cover the chamber  250  with expanded volume. As a result, the MEMS package can be formed. 
         [0087]    Similarly to  FIG. 9 , in  FIG. 10 ,  FIG. 10(   a ) is a top view.  FIG. 10(   b ) and  FIG. 10(   c ) are cross-section views in  FIG. 10(   a ) at the cutting line Y and cutting line X. In this embodiment, the ditch  238  in  FIG. 9  is not formed. In other words, the gap between the structural dielectric layer  240  and the substrate  230  is serving as the second chamber while all of the side aperture can receive the acoustic signal. 
         [0088]    In  FIG. 11 , other embodiments are further shown. In  FIG. 11(   a ), the MEMS package is similar to the structure in  FIG. 10 . However, the substrate  230  can be fully adhered to the MEMS microphone device without side aperture. The chamber  252  is coupled to the environment by the aperture  258  in the substrate  230 . In  FIG. 11(   b ), further, the substrate  230  can have the indent region to expand the chamber  252  into the chamber  252 ′. In  FIG. 11(   c ), the cover layer  246  can also have the aperture  260  for coupling the first chamber  250  to the environment for the application of directional microphone. 
         [0089]    In  FIG. 12 , other embodiments are further shown. In  FIG. 12(   a ), as previously described, the MEMS microphone device has the opened chamber  137  which the second substrate  132  can be just a cap  132  to seal a chamber  136  over the sensing element  130 . The interconnect structure of via  138  and conductive pad  140  is formed in the substrate  124  for outer electric connection. In  FIG. 12(   b ), the second substrate  132  has an aperture  240  for coupling the chamber  136  to the environment for the application of directional microphone. In  FIG. 12(   c ), another substrate  242  can be further formed on the substrate  124 . In this situation, the substrate  242  has an aperture  244  for coupling the chamber  137  to the environment which is the chamber  136  is sealed by the cap  132 . 
         [0090]    In  FIG. 13 , other embodiments are further shown. In  FIG. 13(   a ), the substrate  246  is not fully cover the chamber  137  of the substrate  124 . In this situation, a side gap  248  as an aperture is formed for receiving acoustic signal. In  FIG. 13(   b ), alternatively, the substrate  246  fully seals the chamber  137  and has the indent region  262  to expand the volume of the chamber  137 . In  FIG. 13(   c ), the substrate  146  can also have the indent region and the side gap  264 . 
         [0091]    In  FIG. 14 , other embodiments are further shown. In  FIG. 14(   a ), in this embodiment, the I/O terminal of the integrated circuit  122  can be exposed to the environment. The second substrate  132 ′ can be just a cap and does not cover all portion of the I/O terminal. In this situation, the MEMS package allows several different packaging process later. In  FIG. 14(   b ), in packaging process, for example, the metal bump  280 ′ can be formed on the pad of the integrated circuit  122  by the technology of stud bumping or B-stage conductive epoxy. In  FIG. 14(   c ), when the additional acoustic path is needed, the aperture  282  can be formed for the application of directional microphone. In  FIG. 14(   d ), different from  FIG. 14(   c ), the metal bump  280 ′ can be formed on the pad of the integrated circuit  122  by the technology of stud bumping or B-stage conductive epoxy. 
         [0092]    In  FIG. 15 , other embodiments are further shown. In  FIG. 15(   a ), an additional covering layer  284  can be further formed over the substrate  124  and cover the chamber  288 . The covering layer  284  has an aperture  286  for coupling the chamber  288  to the environment. The cap  132  also forms the chamber  290 . In  FIG. 15(   b ), the covering layer  284  does not have aperture. However, instead, the covering layer  132  has the aperture  292 . These are the choices according to the actual need. 
         [0093]    In  FIG. 16 , other embodiments are further shown. In  FIG. 16(   a ), the packaging structure can be further included. The substrate  294  is formed one the substrate  124  to form the chamber  288 , which is coupled to the environment by the aperture  296 . The substrate  294  also has the interconnect structure with via  297  and conductive pad  298 . The interconnect structure in the substrate  294  can be connected to the integrated circuit  244  by the bonding wire  302 . The molding compound  300  can be formed to seal the bonding structure. In  FIG. 16(   b ), as previously described, the chamber  288  and the chamber  290  can be adjusted in volume, in which the aperture  304  allows the chamber  290  to be coupled to the environment. In  FIG. 16(   c ), the molding compound  300  can be replaced with a cover  310 . The chamber  288  can be connected to the environment by the aperture  296  in the substrate  294 . 
         [0094]    In  FIG. 17 , the applications of  FIG. 14  used in circuit substrate are shown. In  FIG. 17(   a ), the MEMS device  400  is coupled to the circuit substrate  406  by the bonding structure  402  like Flip chip application. The substrate  406  has the indent region  404  to adapt the cover  408  of the MEMS device  400  without adding the thickness. A filling material is filled in the gap between the MEMS device  400 , the circuit substrate  406  and a cap and seals the bonding structure  402 . In  FIG. 17(   b ), the additional cover  414  can be formed to fully seal the chamber  416 . The aperture  412  of the cover  408  and the aperture  410  of the substrate  406  allow the front chamber to couple to the environment. However, the substrate  406  can, for example, further have the subs indent region in coupled with the aperture  412 . A filling material  401  is filled in the gap between the MEMS device  400 , the circuit substrate  406  and a cap and seals the bonding structure  402 . 
         [0095]    In  FIG. 18 , the applications of  FIG. 14  used in user&#39;s PCB are further shown. In  FIG. 18(   a ), the MEMS package  550  is mounted on the circuit board  502 . The MEMS device  550  includes the substrate  500  having the chamber  504  and the integrated circuit  508 , which is connected to the circuit board  502  by, for example, the bonding wire  510  from the I/O terminal of the integrated circuit  508 . The chamber  504  is coupled to the environment through the aperture  506  in the circuit board  502 . In  FIG. 18(   b ), depending on the operation direction, the MEMS microphone device  552  is also mounted on the circuit board  502 ′. However, the aperture  512  is in the cover for receiving acoustic signal from the upper side of the circuit board  502 ′. In this situation, the chamber  504 ′ is sealed by the circuit board  502 ′ as a back chamber in operation. However, in order to have larger volume of the back chamber  504 ′, the circuit board  502 ′ has the indent region to expand the chamber  504 ′. 
         [0096]    In  FIG. 19 , other embodiments are further shown. In  FIG. 19(   a ), in other applications not for microphone, the MEMS device does not need to receive the acoustic signal. For example, the MEMS device is used to detect inertial force, and then the structural substrate  600  has the sensing element  602  as the mass source in response to inertial force, for example, acceleration. The integrated circuit  612  has the I/O pad  614 , which is exposed without being covered by the cover  606 . The cover  606  covers the sensing element to have the upper chamber  610 . At the other side of the structural substrate  600 , another cover layer  604  covers over the lower chamber  610 . The both upper and lower chambers  610  do not couple to the environment. In  FIG. 19(   b ), the bounding structure  614 ′ such as metal bump can be further formed on the I/O pad  614  by the technology of stud bumping or B-stage conductive epoxy. The hermetic package in  FIG. 19  can be used in other MEMS device in which the hermetic package is needed, e.g. RF MEMS or MEMS actuator. 
         [0097]    It should be noted that all the provided embodiments can be properly combined to each other to have other embodiments. 
         [0098]    From the fabrication method, in order to protect the MEMS device, serving as the transducer, from being damaged during packaging process and dicing into singulated chip, the fabrication needs special consideration.  FIGS. 20-37  are cross-sectional views, schematically illustrating various fabrication processes for the MEMS device, according to embodiments of the present invention. 
         [0099]    In  FIG. 20A , the fabrication process includes forming several MEMS microphone units  1002  in continuous structure on the same structural substrate  1000 . The integrated circuit for each MEMS microphone unit is also formed. The fabrication is based on semiconductor fabrication technology. In  FIG. 20B , after the MEMS microphone units are accomplished, the MEMS microphone units are disposed on a supporting layer  1004 . In this situation the first chamber of the MEMS microphone unit is covered by the supporting layer  1004 . The metal bump  1008  for later use can be formed beforehand by using the technology of stud bumping for example. It should be noted that the supporting layer  1004  is, for example, used for fabrication in supporting and protection and not used as a part of the MEMS device. In  FIG. 20C , in order to fabricate the other substrate as described in previous structure embodiments, the adhesive material  1006  are, for example, formed on the structural substrate  1000 , e.g. conductive or nonconductive epoxy. 
         [0100]    In  FIG. 21A , the cover structure  1010  with the interconnect structure can be formed in separate units. However, the adhesive material  1006  can also be formed on the cover structure  1010  instead on the structural substrate  1000 . In  FIG. 21B , the metal bump or conductive paste  1012  may also formed on the metal pad of the interconnect structure by using the technology of stud bumping, conductive paste (B-stage conductive epoxy). In  FIG. 21C , the cover structure  1010  with the interconnect structure can be formed in separate units without adhesive material and bonding structure. 
         [0101]    Alternatively, in  FIG. 22A , the cover structures  1010  can be formed together at the same substrate  1024 . In the situation, there is a substrate portion  1014  between the cover structures  1010  for mechanical joining. However, the adhesive material  1006  can also be formed on the cover structure  1010  instead on the structural substrate  1000 . In  FIG. 22B , likewise, the metal bump or conductive paste can also be formed on the metal pad of the interconnect structure by using the technology of stud bumping or B-stage conductive epoxy. In  FIG. 22C , the cover structures  1010  with interconnect structure can be formed together at the same substrate  1024  without metal bump and adhesive material. This is depending one the actual arrangement. 
         [0102]    In  FIG. 23A , for the combination of MEMS units and cover structures, e.g.  FIGS. 20A-21B ,  FIGS. 20B-21A ,  FIGS. 20C-21C  or  FIGS. 20B-21B , several MEMS units  1020  are formed over the structural substrate  1000  of the MEMS device by the adhesive material. In  FIG. 23B , for the combination of the substrate  1024  of MEMS units and continuous cover structures, e.g.  FIGS. 20A-22B ,  FIGS. 20B-22A ,  FIGS. 20C-22C  or  FIGS. 20B-22B . For example, if the continuous structure in  FIGS. 22A-22B  is taken, then the joined MEMS units  1020 ′ are formed on the structural substrate  1000 . The electrical coupling between microphone units and covering units using metal bump or conductive paste. 
         [0103]    In  FIGS. 24A-24C , the top views are shown. In  FIG. 24A , the adhesive material  1006  is surrounding the MEMS chamber  1026 . The bonding structure on I/O metal pads  1012  is located within the adhesive material  1006 . However, in  FIG. 24B , the bonding structure on I/O metal pads  1012  can be located outside the adhesive material  1006 . The advantage of  FIG. 24B  is that if the metal bump is used in the electrical connection, the filling material is able to fill in the gap between MEMS units and cover structure and seals the metal bump to increase the reliability of package. Moreover, the adhesive material can protect the MEMS from damage by such liquid filling material, for example. 
         [0104]    Even further, the bonding structure on metal pads  1012  can be formed with the adhesive material  1006  as shown in  FIG. 24C  for example. The bonding structure includes a conductive paste, e.g. B-stage conductive epoxy. 
         [0105]    In  FIG. 25A , the continuous structural substrate with several MEMS units  1020  is subjected to a dicing process  1032  on the gap between the MEMS units  1020 . For the MEMS device, the supporting layer  1004  can protect the MEMS microphone device from, for example, water jet in dicing. Usually, in good protection, the supporting layer  1004  can be the porous layer, so that the chamber can still interact with the environment. In  FIG. 25B , if the supporting material  1004  is not porous, an aperture  1034  may be formed over the first chamber of MEMS microphone device so that the supporting layer can be a covering layer of first chamber after singulation. 
         [0106]    In  FIG. 26A , for another continuous substrate, the MEMS device units  1020 ′ are joined. The dicing process  1032  is performed to first dice the substrate portion and then the MEMS substrate. In  FIG. 26B , likewise, the supporting layer  1004  has the aperture  1034 . 
         [0107]    In  FIG. 27A , the separate MEMS device units  1020  are the structure having a covering layer with a plurality of apertures deposed on the substrate of MEMS units. Such the apertures on the substrate of MEMS units are over the first chambers of MEMS units. In this structure, the supporting layer  1036  can also be used. The dicing process  1032  is then performed. In  FIG. 28B , the MEMS device units  1020  are in continuous structure before dicing. The dicing process  1032  then dices the substrate portion first and then the MEMS substrate. 
         [0108]    Alternatively, in  FIG. 28A , before performing dicing process, the photoresist layer  1038  can be formed on the substrate  1024  and has an opening  1040  top expose the substrate  1024  at the joining portion. Then, the etching process can be performed to remove the exposed portion of the substrate  1024 . In  FIG. 28B , after etching process and striping the photoresist layer  1038 , the dicing process  1032  is performed. 
         [0109]    In  FIG. 29A , for another structure of the MEMS device with the substrate  1042 , it has the aperture  1044  for coupling the chamber to the environment. The supporting layer  1004  can also be used to support the MEMS units. In  FIG. 30B , the MEMS units can also be continuous by the substrate  1042 ′. 
         [0110]    In  FIG. 30A  and  FIG. 30B , another supporting layer  1048  can be formed over the substrate  1042  or the substrate  1042 ′. The supporting layer  1048  can also protect the aperture  1044  in dicing process. In  FIG. 31A  and  FIG. 31B , the dicing process is performed to singulate the MEMS chips. 
         [0111]    In  FIG. 32A , the MEMS device unit is the structure with the I/O pad being exposed. However, the supporting layer  1004  can also be used to support the separate MEMS device units with the covers  1015 , subjected to dicing process. In  FIG. 33B , for the continuous MEMS device units by the substrate  1024 , a dual-stage dicing process can also be performed. A first dicing process is to cut the joining portion of the substrate  1024 , and then another dicing process is to singulate the MEMS device units into chips. 
         [0112]    In  FIG. 33 , alternatively, the photoresist layer  1052  can be formed with the opening  1054  to expose the joining portion. In  FIG. 34 , after the joining portion of the substrate is etched and the photoresist layer  1052  is stripped, the dicing process  1056  is performed. 
         [0113]    For stacking the second substrate and the third substrate as described in various structures, there are several manners. In  FIG. 35 , the substrate  1058  is adhered with the cover substrate  1060 . In  FIG. 36A , the substrate  1062  is adhered to the substrate  1058 . The substrate  1062  has the aperture  1064  for coupling the front chamber to the environment. However, there is a gap  1066  between the MEMS device units. In  FIG. 36B , for another structure, the substrate  1062  can be continuous without the gap  1066  in  FIG. 37A . 
         [0114]    In  FIG. 37A , since the cover substrate is continuous, the supporting layer  1068  is used to protect the chamber that has the aperture  1064  in  FIG. 36A . The dual-stage dicing process of dicing process  1072  is performed and the dicing process  1070  is performed. In  FIG. 37B , it is corresponding the structure in  FIG. 36B  for the continuous cover substrate. 
         [0115]    Generally, the supporting layer for the MEMS device is essential because the chamber with the diaphragm should be protected from the dicing process, such as water jet, or from vacuum on the backside of MEMS devices during the wafer level stud bumping. 
         [0116]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing descriptions, it is intended that the present invention covers modifications and variations of this invention if they fall within the scope of the following claims and their equivalents.

Technology Category: 5