Abstract:
Embodiments discussed herein relate to sensor devices and processes of producing them. Some embodiments include a sensor device with a substrate with a sensing element mounted above the substrate, with a heating element, mounted substantially coplanar to the sensing element; and with a heat spreading element, the heat spreading element thermally coupling the sensing element and the heating element.

Description:
TECHNICAL FIELD 
       [0001]    The various embodiments described herein relate to the manufacture and structure of sensor devices in general and with magnetic sensor devices in particular. 
       TECHNICAL BACKGROUND 
       [0002]    The subject matter described herein deals with heat management in sensor devices. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a schematic cross section of some embodiments of the invention; 
           [0004]      FIG. 2  shows a schematic cross section of some embodiments of the invention; 
           [0005]      FIG. 3  shows a schematic cross section through some embodiments of the invention; 
           [0006]      FIG. 4  shows a schematic top-view of an some embodiments of the invention; and 
           [0007]      FIG. 5  shows a block diagram of a some embodiments of a method for manufacturing the sensor device. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]      FIG. 1  shows a schematic cross section through some embodiments of a sensor device  1 . A heating element  3 , a sensing element  11 , and a heat spreading element  5  are shown mounted above a substrate  2 . In some embodiments the sensing element  11  and the heating element  3  are mounted substantially coplanar to each other above an isolation layer  4   a . In some embodiments, at least one heating element  3  is thermally coupled to a sensing element  11 . 
         [0009]    The isolation layer  4   a  is interposed between a lower surface of the sensing element  11  and a lower surface of the heating element  3  on the one hand and an upper surface of the heat spreading element  5 . 
         [0010]    In some embodiments portions of an intermediate layer  4  are interposed between and enclose the sensing element  11  and the heating element  3 . In some embodiments shown in  FIGS. 1-4  the intermediate layer  4  at least partially encloses the sensing element  11  and the heating element  3 . In some embodiments, an oxide or a nitride layer is used as the intermediate layer  4 . In an embodiment, intermediate layer  4  is a layer of SiO2. 
         [0011]    In some embodiments, the substrate  2  is a silicon substrate having a semiconductor active area  6  with at least one element of semiconductor circuitry adjacent to an upper surface  2   a  of the semiconductor substrate  2 . In some embodiments, semiconductor substrates such as GaAs or Ge can be used. 
         [0012]    A heat spreading element  5  provides thermal coupling between the heating element  3  and the sensing element  1 . In some embodiments, heat spreading element  5  has thermal conductivity exceeding that of the intermediate layer  4 . In some embodiments the heat spreading element  5  is formed above an insulating layer  8  which is formed above the substrate  2  and positioned below the sensing element  11  and the heating element  3 . In some embodiments, the heat spreading element  5  lies adjacent to the upper surface  2   a  of the substrate  2 . In some embodiments, the heat spreading layer  5  is formed from aluminium, aluminium-copper or polycrystalline silicon. 
         [0013]    In some embodiments, the sensing element  1  is a magnetoresistive sensing element having at least one magnetic layer  11   a ,  11   c  and at least one non-magnetic layer  11   b  interposed between the magnetic layers  11   a ,  11   c . Depending on type of the magnetoresistive sensing element, different geometries and materials for the magnetic and non-magnetic layers  11   a ,  11   b ,  11   c  can be used. In some embodiments, the non-magnetic layer  11   b  is formed from one or more materials selected from a group consisting of copper, aluminium, or their alloys. In some embodiments the magnetic layers  11   a ,  11   c  are formed from one or more of a group consisting of iron, nickel, cobalt, and of their alloys. In some embodiments the non-magnetic layer  11   b  separates vertically two magnetic layers  11   a ,  11   c . In some embodiments the non-magnetic layer  11   b  separates horizontally two magnetic layers  11   a ,  11   c.    
         [0014]    In some embodiments, sensing element  11  comprises one or more magnetoresistive sensing elements selected from the group consisting of an anisotropic magnetoresistive sensing element, a giant magnetoresistive sensing element, colossal magnetoresistive sensing element, an extraordinary magnetoresistive sensing element, and a tunnel magnetoresistive sensing element, depending on the application of the sensing element. 
         [0015]    In some embodiments shown in  FIG. 1 , two heating elements  3  are thermally coupled with the sensing element  1  above the heat spreading element  5 . The heat spreading element  5  lies between the upper surface  2   a  of the substrate  2  and the insulating layer  4   a . The lateral dimensions of the heat spreading element  5  are chosen in such a way that it has at least partial lateral overlap with the heating element  3 , i.e. a vertical projection of the heat spreading element  5  on a plane parallel to the upper surface of the semiconductor substrate  2  has at least partial overlap with a vertical projection of the heating element  3  on this plane. In some embodiments, the heat spreading element can have at least partial lateral overlap with the sensing element  11 . 
         [0016]    In some embodiments, tungsten plugs serve as thermal and electrical contact vias  7  in layers connecting the heating element  3  with the heat spreading element  5 . In another embodiment of the invention the contact vias are formed of good thermally and electrically conductive material other than tungsten, such as aluminium or copper. In some embodiments, contact vias  7  have higher thermal conductivity than intermediate layer  4   a.    
         [0017]    In other embodiments, not shown, there is no contact via connecting a sensing element with a heating element. A thermal path to thermally couple the heating element with the sensing element is provided directly through the insulating layer  4   a.    
         [0018]    In some embodiments, the heating element  3  is an electrically heatable element. In some embodiments the heating element  3  has substantially the same layered structure as the sensing element  11 . 
         [0019]    In some embodiments, a passivation layer, not shown, as a protection layer is formed on the top of the intermediate layer  4 . 
         [0020]      FIG. 2  shows a schematic cross section of some embodiments. It shows again a sensing element  11  and two heating elements  3 . A heat spreading element  5  is above the heating element  3  and the sensing element  11 . For the sake of simplicity, the inner structure of the sensing element  11  is not shown. In some embodiments shown in  FIG. 2 , contact vias  7  couple the heat spreading element  5  to the heating element  3  through the intermediate layer  4 . In some embodiments, contact vias  7  serve for thermal coupling of heat spreading element  5  to the heating element  3  through the intermediate layer  4 . In some embodiments, contact vias  7  couple thermally and electrically the heat spreading element  5  to the heating element  3  through the intermediate layer  4 . 
         [0021]    In some embodiments there is no contact via for coupling the sensing element  11  with the heating element  3 . The path of thermal coupling is through intermediate layer  4  from the heating element  3  to the heat spreading element  5  and from the heat spreading element  5  to the sensing element  11 . 
         [0022]      FIG. 3  shows some embodiments of the invention. It shows two heat spreading elements  5  formed above and below the intermediate layer  4 , in which the sensing element  11  and two heating elements  3  are embedded. Contact vias  7  are connecting the heating elements  3  with the heat spreading elements  5 . In some embodiments at least one contact via  7  is thermally connecting at least one heating element  3  with at least one heat spreading element  5 . 
         [0023]      FIG. 4  shows a top view of some embodiments shown in  FIG. 1 . In this view the layout of different elements for some embodiments is shown. It shows also a wiring  9  connected to at least one heating element  3 . The wiring  9  is used to apply electric current to heating element  3 . For simplicity neither the semiconductor substrate  2  nor a possible read-out circuitry of the sensing element  11  are depicted. 
         [0024]    In some embodiments, the heating current is applied through additional circuitry on the same semiconductor substrate  2  for controlling the heating current. In some embodiments, the heating current is applied over an external circuitry coupled to the semiconductor heating element  3  over at least one special contact  10   a ,  10   b . In some embodiments, not shown, the sensing element  11  itself is used for the heating. In this case the heating current is applied directly to the sensing element  11 . 
         [0025]    In some embodiments, read-out wiring, not shown, is also connected to the sensing element in order to measure its response to the external influence, such as a change in the magnitude or the direction of the external magnetic field. In some embodiments, wiring connects the sensing element to a circuitry for data processing. The circuitry can be at least partially implemented in the active area  6  of the semiconductor substrate  2 . 
         [0026]    In some embodiments, external circuitry other than that implemented in the active area  6  of the semiconductor substrate  2  is used. In some embodiments, at least one contacting via for connecting a wiring, not shown, with the sensing element  11  or with the heating element  3  is used. 
         [0027]    Some embodiments of the invention are processes of manufacturing the sensor device.  FIG. 5  shows a block diagram of some embodiments of methods for manufacturing a sensor device. In the first operation  501  a semiconductor substrate is provided. Afterwards a heat spreading element above the semiconductor substrate  2  is formed in operation  502 . For forming the heat spreading element a film deposition technique such as sputtering, evaporation, chemical vapour deposition, lamination with subsequent structuring can be used. For structuring photolithography with etching can be used. 
         [0028]    In some embodiments, an insulating layer  8  prior to forming the heat spreading element  5  is formed. In the next operation  503  an intermediate layer  4  having a sensing element  11  and a heating element  3  is formed above the semiconductor substrate  2 . In some embodiments, within operation  503  first the sensing element  11  and the heating element  3  are formed. Afterwards the intermediate layer  4  is deposited. For forming the sensing element and the heating element  3  any kind of film deposition technique such as sputtering, evaporation, chemical vapour deposition, lamination etc with subsequent structuring by photolithography and etching can be used. 
         [0029]    In some embodiments planarization techniques for planarization of the intermediate layer  4  and the insulating layers  4   a ,  8  are used. In an embodiment, for planarization chemical-mechanical polishing is used. In some embodiments, as intermediate layer  4  an amorphous borophosphosilicate glass is used. 
         [0030]    In some embodiments, not shown, the intermediate layer  4  having a sensing element  11  and a heating element  3  is formed prior to forming a heat spreading element  5  above the semiconductor substrate  2 . In some embodiments, an insulating layer  8  above the semiconductor substrate  2  prior to forming the heat spreading element  5  is formed. For creating the insulating layer  8  such deposition methods as chemical vapour deposition, dispensing or sputtering can be used. 
         [0031]    In some embodiments, at least one contact via  7  through the insulating layer  8  prior to forming the heat spreading element  5  is formed. Again different kinds of layer formation techniques can such as chemical vapour deposition, dispensing, sputtering etc. can be used. In some embodiments, an insulating layer  4   a  above the heat spreading element  5  prior to forming the intermediate layer  4  with the sensing element  11  and the heating element  3  is formed. 
         [0032]    In some embodiments, at least one contact via  7  through the insulating layer  4  prior to forming the intermediate layer  4  with the heating element  3  and the sensing element  11  is formed. In some embodiments, the semiconductor substrate has a semiconductor active area  6  with at least one element of semiconductor circuitry adjacent to an upper surface  2   a  of the semiconductor substrate  2 . 
         [0033]    In some embodiments, conductive wiring above the semiconductor substrate  2  is formed. In some embodiments, at least one contact via  7  for contacting the metal wiring with the sensing element  11  is formed. In some embodiments, at least one contact via  7  for contacting the heating element  3  with the heat spreading element  5  is formed. 
         [0034]    In some embodiments, the sensing element  11  in the intermediate layer  4  formed above the substrate is a magnetoresistive sensing element comprising at least one magnetic layer  11   a ,  11   c  and at least one non-magnetic layer  11   b.    
         [0035]    In some embodiments, the sensing element  11  in the intermediate layer  4  formed above the substrate is a sensing element selected from a group consisting of anisotropic magnetoresistive sensing element, giant magnetoresistive sensing element, colossal magnetoresistive sensing element, extraordinary magnetoresistive sensing element, and tunnel magnetoresistive sensing element. 
         [0036]    The accompanying drawings that form a part hereof show by way of illustration, and not of limitation, specific embodiments in which the subject matter may be practiced. The embodiments illustrated are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. This Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. 
         [0037]    Such embodiments of the inventive subject matter may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description. 
         [0038]    The Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.