Abstract:
A microelectromechanical sensor module includes a sensing mechanism for measuring an acceleration, pressure, air humidity or the like, a control mechanism for controlling the sensing mechanism, an energy supply mechanism for supplying the sensor module with energy, and a transmission mechanism for transmitting signals of the sensing mechanism. At least three of the mechanisms are integrated at the chip level in at least one chip in each case. A corresponding method is implemented to produce the microelectromechanical sensor module.

Description:
This application is a 35 U.S.C. §371 National Stage Application of PCT/EP2011/068003, filed on Oct. 14, 2011, which claims the benefit of priority to Serial No. DE 10 2010 062 559.0, filed on Dec. 7, 2010 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND 
     The disclosure relates to a microelectromechanical sensor module and a corresponding method for producing a microelectromechanical sensor module. 
     Microelectromechanical sensor modules are used for numerous applications, for example for measuring accelerations, angular rates, magnetic fields, temperature, pressure or the like. 
     One field of use of such microelectromechanical sensors, for example in the case of angular rate sensors, is automobiles, in which these sensors are used as part of the electronic stability program (ESP) in order to match a yaw rate of the automobile to angular rates of different wheels of the automobile. 
     DE 10 2005 041 539 B4 discloses connecting sensing means and an application specific integrated circuit at the wafer level.  FIG. 6  shows a connection of this type: a first chip  3 , which contains a sensing means  3   a,  is arranged on a printed circuit board  2 . On this chip is arranged a further chip  4  comprising an application specific integrated circuit  4   a.  Vias  10   a  enable the connection between the chip  4  and the chip  3 , whereas wire bonds  10   b  are used to connect the chip  3  to the printed circuit board  2  in order to make electrical contact. 
     SUMMARY 
     According to the disclosure, a microelectromechanical sensor module includes sensing means for measuring an acceleration, pressure, air humidity or the like, a control means for controlling the sensing means, power supply means for supplying power to the sensor module, and transmission means for transmitting signals from the sensing means, wherein at least three of the means are integrated at the chip level, each in a chip. 
     According to the disclosure, a method for producing a microelectromechanical sensor module includes the steps,
     arranging sensing means for measuring an acceleration, pressure, air humidity or the like,   arranging a control means for controlling the sensing means,   arranging power supply means for supplying power to the sensor module, and   arranging transmission means for transmitting signals from the sensing means,   wherein at least three of the means are arranged such that they are integrated at the chip level, each in a chip.   

     One of the achieved advantages is that of enabling a greater integration density. A further advantage is that this facilitates smaller constructions, and thereby makes it easier to convert or upgrade and also to retrofit existing installations/buildings or even objects with electronic open-loop and closed-loop control by means of the microelectromechanical sensor module. In all, it also enables cheaper fabrication. 
     Of course the respective means can be arranged on the respective chips for optimum use of space to minimize the volume of the respective chip. Furthermore, the chips can also be arranged with respect to one another so as to minimize the installation space of the sensor module. The chips can be arranged here side by side and/or one above the other. 
     The subclaims describe further advantageous embodiments and features of the disclosure. 
     According to an advantageous development of the disclosure, all the means are integrated at the chip level, each in a chip. This enables a sensor module that is both autonomous and fully integrated at the chip level, i.e. the sensor module does not depend on an external power supply and has a high integration density combined with a small construction. 
     According to a further advantageous development of the disclosure, the power supply means comprise a battery, in particular a thin-film battery, and/or an environment energy converter, in particular a solar cell. This achieves the advantage of enabling a fully autonomous microelectromechanical sensor module. The environment energy converter enables recharging of the battery, which is used to supply power to the microelectromechanical sensor module. This increases the autonomous operating life of the microelectromechanical sensor module. 
     According to a further advantageous development of the disclosure, the transmission means comprise a radio frequency interface and/or an antenna. This achieves the advantage of being able to dispense with costly wiring of the microelectromechanical sensor module and enabling simple integration or retrofitting in existing applications. 
     According to a further advantageous development of the disclosure, at least two of the means are arranged on a common chip, in particular two of the means on each chip. This enables even greater integration and hence an even smaller construction of the microelectromechanical sensor module. 
     According to a further advantageous development of the disclosure, vias are arranged for making contact between the chips and/or between the chips and a printed circuit board. This achieves the advantage that the contact-making elements can also be integrated into individual chips, which increases the integration density even further. At the same time, vias are also less prone to environmental influences than wire bonds. This increases the operating life of the micro-electromechanical sensor module. 
     According to a further advantageous development of the disclosure, the vias are arranged at the edge of the respective chip and/or at least some of the vias are designed as an antenna. This achieves the advantage of increasing the integration density even further, because the antenna structure can be realized by means of vias arranged at the chip edge. In addition, it is also possible to implement the antennas as fractal antennas or even antennas made of metamaterials. 
     According to a further advantageous development of the disclosure, the solar cell comprises a collector interconnection system, and the collector interconnection system is designed as transmission means, in particular as an antenna. This enables a particularly advantageous combination of the solar cell and the antenna. Since a solar cell normally requires a collector interconnection system, also known as a busbar, on its outside, this interconnection system can also be used as an antenna simultaneously or even partially, for example by dividing the period of use into different time segments. This increases the integration density even further and makes the installation space of the microelectromechanical sensor module even smaller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the disclosure are explained in greater detail in the following description and are shown in the drawing, in which: 
         FIG. 1  shows in cross-section a microelectro-mechanical sensor module according to a first embodiment of the present disclosure; 
         FIG. 2  shows in cross-section a microelectro-mechanical sensor module according to a second embodiment of the present disclosure; 
         FIG. 3  shows in cross-section a microelectro-mechanical sensor module according to a third embodiment of the present disclosure; 
         FIG. 4  shows in cross-section a microelectro-mechanical sensor module according to a fourth embodiment of the present disclosure; 
         FIG. 5  shows in cross-section a microelectro-mechanical sensor module according to a fifth embodiment of the present disclosure; 
         FIG. 6  shows in cross-section an already known sensor module. 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG. 1 , reference sign  1  denotes a microelectromechanical sensor module in cross-section, which is arranged on a printed circuit board  2 . The microelectromechanical sensor module  1  comprises a first chip  5 , which comprises a three-dimensional thin-film battery  5   a.  The chip  5  is arranged directly on the printed circuit board  2  and connected to same by means of a via  10   a,  which is arranged on the left-hand side of the chip  3 . On the first chip  5  is arranged a further chip  3 , which contains sensing means  3   a  for measuring an acceleration. These sensing means are connected to the underlying chip  5  by means of vias  10   a  on the left-hand side of the chip  3 . On the chip  3  is arranged a further chip  4 . The chip  4  comprises an application specific integrated circuit  4   b  and transmission means  4   a  in the form of a radio frequency interface. The chip  4  is connected on its left-hand side to the chip  3  and further to the chip  5  and the printed circuit board  2  by means of a via  10   a.  A further chip  6  comprising a solar cell  6   a  is arranged on the chip  4 . On the left-hand side of the microelectromechanical sensor module  1  shown in cross-section are arranged vias  10   a,  which connect the chip  6  to the chip  4  and further to the chip  3 , the chip  5  and finally the printed circuit board  2 .  FIG. 1  shows an autonomous microelectromechanical sensor module  1  that is fully integrated at the chip level and contains discrete chips  3 ,  4 ,  5 ,  6  for the individual functions. It is possible here to implement the radio frequency interface  4   a,  or radio interface, as part of the application specific integrated circuit  4   b.    
       FIG. 2  shows in cross-section a microelectromechanical sensor module according to a second embodiment of the present disclosure. In  FIG. 2 , reference sign  1  again denotes a microelectromechanical sensor module. The sensor module  1  comprises a printed circuit board  2 , which is arranged in a housing H. The printed circuit board  2  comprises on its left-hand upper face a chip  3 , which comprises a three-dimensional thin-film battery  5   a  on its lower face, and on its upper face comprises sensing means  3   a  for measuring an acceleration. The chip  3  is electrically connected to the printed circuit board  2  by means of vias  10   a  on the left-hand side of said chip  3 . On the right-hand side of the chip  3  is arranged a further via  10   a,  which is connected to a further chip  4  arranged on said chip  3 . The chip  4  comprises an application specific integrated circuit  4   a.  On its left-hand side, the chip  4  is likewise connected to the chip  3  by means of vias  10   a.  The chip  3  and the chip  5  are here arranged entirely inside the housing H. A further chip  6  having a solar cell  6   a  is arranged on the right-hand side of the chip  3 . The chip  6  is likewise arranged on the printed circuit board  2 . The housing H has a suitable opening A above the solar cell  6   a  in order that the solar cell  6   a  of the chip  6  can receive light, which the solar cell  6   a  converts into electrical energy. Overall, the embodiment of  FIG. 2  enables even greater chip-level integration. The microelectromechanical sensor module  1  shown in  FIG. 2  can be used, for example, as a photovoltaic energy converter or electromagnetic radiation energy converter, as an antenna for radio transmission, as a battery etc. 
       FIG. 3  shows in cross-section a microelectromechanical sensor module according to a third embodiment of the present disclosure. In  FIG. 3 , reference sign  1  again denotes a microelectromechanical sensor module. The microelectromechanical sensor module  1  of  FIG. 3  is constructed from the bottom upwards as follows: a chip  3  is arranged on a printed circuit board  2 . The chip  3  is connected by means of vias  10   a  on its left-hand side to the printed circuit board  2  and by means of further vias on the right-hand side to a chip  4 , which is arranged on the chip  3 . The chip  3  here comprises sensing means  3   a  for measuring a pressure, and a thin-film battery  5   a . The chip  4  here comprises an application specific integrated circuit  4   b  and a wireless radio interface  4   a.  Chip  4  is connected by means of vias  10   a  on its right-hand side to the chip  3 , more precisely to the thin-film battery  5   a,  and likewise by means of further vias  10   a  on its left-hand side to the chip  3 . A further chip  6 , which comprises a solar cell  6   a,  is arranged on the chip  4 . The solar cell  6   a  is here connected to the chip  3  by means of wire bonds  10   b.    
       FIG. 4  shows in cross-section a microelectromechanical sensor module according to a fourth embodiment of the present disclosure. In this case, the microelectromechanical sensor module  1  of  FIG. 4  has the following construction from the bottom upwards: a chip  3  is arranged on a printed circuit board  2 , which chip comprises a thin-film battery  5   a  on its lower face and an application specific integrated circuit  4 b on its upper face. The chip  3  is connected by means of vias  10   a  on its left-hand side to the printed circuit board  2  and to a chip  4 , which is arranged on the chip  3 . The chip  4  here comprises sensing means  3   a  for measuring a pressure. The chip  4  is connected by means of vias  10   a  on its left-hand side to the underlying chip  3  and to a chip  5  arranged on said chip  4 . The chip  5  comprises a wireless communications interface  4   a.  The chip  5  is connected by means of vias  10   a  to the underlying chip  4  and further to the chip  3  and the printed circuit board  2 . The chip  5  is also connected by means of vias  10   a  on its left-hand side to a further chip  6 , which is arranged on the chip  5 . The chip  6  comprises here a solar cell  6   a  on its upper face. The chip  6  is connected by means of vias  10   a  on its left-hand side to the underlying chips  5 ,  4 ,  3  and the printed circuit board  2 . An antenna  7 , which is embodied in the form of vias  10   a , is arranged at the edges of the solar cell  6   a.    
       FIG. 5  shows in cross-section a microelectromechanical sensor module according to a fifth embodiment of the present disclosure. The microelectromechanical sensor module  1  of  FIG. 5  has the following construction from the bottom upwards: a chip  3  is arranged on the printed circuit board  2 , which chip comprises a thin-film battery  5   a  on its lower face and on its upper face comprises sensing means  3   a  for measuring an acceleration. The chip  3  and thereby the thin-film battery  5   a  and the sensing means  3   a  are connected by means of vias  10   a  on the left-hand side of said chip to the printed circuit board  2 , and also to a further chip  6 , which is arranged on the chip  3 . The chip  6  comprises on its lower face an application specific integrated circuit  4   b  and a wireless interface  4   a.  On its upper face, the chip  6  comprises a solar cell  6   a.  The chip  6  and thereby the application specific integrated circuit  4   b,  the wireless communications interface  4   a  and the solar cell  6   a  are connected in an electrically conducting manner by means of vias  10   a  on the left-hand side of the chip  6  to the underlying chip  3  and further to the printed circuit board  2 . The microelectromechanical sensor module  1  shown in  FIG. 5  has a high integration density by integrating at least two functions on respectively connected chips  3  and  6 : thin-film battery  5   a  and sensing means  3   a  are arranged on a common chip  3 , and likewise application specific integrated circuit  4   b  together with wireless interface  4   a  and solar cell  6   a  or energy harvester are arranged in a second chip  6 . 
       FIG. 6  shows in cross-section an already known sensor module. In  FIG. 6 , reference sign  1  denotes a microelectromechanical sensor module  1 . The microelectromechanical sensor module  1  here comprises a printed circuit board  2 , on which is arranged a chip  3  comprising sensing means  3   a.  The chip  3  is here connected to the printed circuit board  2  by means of wire bonds  10   b.  On the upper face of the chip  3  is arranged a further chip  4 , which comprises an application specific integrated circuit  4   a.  The chip  4  is connected to the chip  3  by means of vias  10   a.    
     Although the present disclosure has been described above with reference to preferred exemplary embodiments, it is not limited to these embodiments but can be modified in numerous different ways.