Abstract:
A semiconductor package includes a mounting and electrical connection plate, and a semiconductor component having front and rear surfaces and including a sensor. The rear surface of the semiconductor component is attached to the mounting and electrical connection plate and the front surface is attached to the sensor. An insert is adjacent the front face of the semiconductor component and the sensor and has an access passage for exposing the sensor. A plug is in the access passage of the insert. A body of encapsulation material surrounds the mounting and electrical connection plate, the semiconductor component and the insert.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the field of semiconductor packages having a sensor, and in particular, to an optical, chemical or displacement sensor operating remotely or by contact. 
   BACKGROUND OF THE INVENTION 
   Semiconductor components having a sensor are generally mounted in packages that are externally accessible. In the majority of cases, these sensors need to be protected. 
   Semiconductor components with optical sensors are generally installed in the bottom cavity of their encapsulation packages. These encapsulation packages often have an attached lid made of a transparent material. The bottom wall of the encapsulation packages are used to make electrical connections external the semiconductor component. Such arrangements require a large number of fabrication steps, and are not multi-functional. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to improve and simplify semiconductor devices having a sensor, and to provide a corresponding method for fabricating such devices. 
   This and other objects, advantages and features in accordance with the present invention comprises placing in an injection mold cavity a semiconductor component, a rear face of which is attached to a front face of mounting and electrical connection means and a front face of which is attached to a sensor. The semiconductor component may further comprise an insert that includes an open passage in front of the sensor, and is provided with a plug for closing the open passage. The insert may have an end bearing on the front face of the component and around the sensor, and a front face bearing against a bottom of the cavity. The method may further comprise injecting an encapsulation material into the cavity for encapsulating the mounting and electrical connection means, and peripherally the semiconductor component and insert. 
   The method may further comprise placing an annular seal forming a spacer between the insert and the semiconductor component. The insert may be fitted with centering fins for centering the insert in the injection mold cavity, and the insert may be fitted with a plug installed in the passage thereof. The plug may be a transparent plug that is installed in the passage after demolding. 
   Another aspect of the present invention is directed to a semiconductor package obtained by implementing the above described method. The semiconductor package may comprise a semiconductor component, a rear face of which is attached to a front face of mounting and electrical connection means and a front face of which is attached to a sensor. The semiconductor package may further comprise an insert bearing on the front face of the optical component around the sensor, and includes an open passage in front of the sensor. A plug may be installed in the passage of the insert. The mounting and electrical connection means, the semiconductor component and the insert may be encapsulated with an encapsulation material. 
   The insert may bear on the front face of the optical component via an annular seal forming a spacer. The insert may advantageously be attached to the front face of the optical component by adhesive bonding. The plug may be transparent, and the plug may advantageously be integrated in the insert. The insert may comprise, in its front face, an annular groove. 
   The mounting and electrical connection means may comprise a gate having a platform or plate for mounting the semiconductor component, and electrical connection leads extending external the encapsulation material. The mounting and electrical connection means may comprise a mounting and electrical connection plate. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The present invention will be better understood on studying semiconductor packages fitted with a sensor and their fabrication method, described by way of non-limiting examples and illustrated by the drawings in which: 
       FIG. 1  is a cross-sectional view of a first embodiment of a semiconductor package being fabrication in accordance with the present invention; 
       FIG. 2  is a top view of the semiconductor package illustrated in  FIG. 1  after fabrication; 
       FIG. 3  is a cross-sectional view of the semiconductor package illustrated in  FIG. 1  after fabrication; 
       FIG. 4  is a cross-sectional view of a second embodiment of a semiconductor package being fabrication in accordance with the present invention; 
       FIG. 5  is a cross-sectional view of a third embodiment of a semiconductor package being fabrication in accordance with the present invention; and 
       FIG. 6  is a top view, partially in cross-sectional, of the semiconductor package illustrated in  FIG. 5  after fabrication. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIGS. 1 to 3 , a semiconductor package  1  comprises a metal gate  2  which has a central platform  3  and peripheral electrical connection leads  4 . The rear face of a semiconductor component  5  is attached to the front face of the platform  3  via a layer of adhesive  6 . This semiconductor component  5  has, in the central part of its front face  7 , a sensor  8  such as an optical sensor, for example. At the periphery of this sensor  8  are electrical connection pads  9  which are selectively connected to the electrical connection leads  4  by metal wires  10 . 
   In addition, the semiconductor package  1  comprises an insert  11  made of metal or plastic, for example, which has an annular body  12  placed perpendicularly to the semiconductor component  5 . One end  13  of the insert  11  bears against the front face  7  of the semiconductor component  5  in its region lying between the sensor  8  and the pads  9 . The insert  11  thus determines an access passage  14  opposite the sensor  8 . The insert  11  has, at the periphery of its end opposite the semiconductor component  5 , an annular cover  15  which is extended radially by four oppositely paired fins  16  and distributed at 90° around the body  12 . 
   Having previously installed a plug  17  in the passage  14  of the insert  11 , for example by screwing until the latter comes to bear against an annular shoulder  14   a  provided in the passage  14 , the assembly described above is placed in the flat cavity  18  formed between a lower part  19  and an upper part  20  of an injection mold  21  as illustrated in  FIG. 1  and as readily understood by those skilled in the art. 
   The rear face of the platform  3  of the gate  2 , and the front face  22  of the insert  11  formed by the front face of the body  12 , the front face of the cover  15  and the front face of the fins  16  are respectively in contact with the parallel bottoms  23  and  24  of the cavity  17 . The parallel bottoms  23  and  24  are formed respectively in the lower part  19  and the upper part  20  of the mold  21 . The front face of the plug  17  may also be in contact with the bottom  24 . 
   The pads  4  of the gate  2  are held between the lower and upper parts  19  and  20  of the mold  21 , and protrude into the cavity  18 . The ends of the fins  16  are placed in the corners of the cavity  18  adjacent its bottom wall  24 , and they position the insert  11  with respect to the semiconductor component  5 . The distance between the bottoms  23  and  24  of the cavity  18  determines the pressing force of the rear face  13  of the insert  11  on the front face  7  of the semiconductor component  5 . The front face  22  of the insert  11  has an annular groove  25 . 
   In one variation, the rear face  13  of the insert  11  could be adhesively bonded to the front face  7  of the component  5 . The layer of adhesive provides flexibility in positioning the insert  11  in the cavity  18 , and control of the pressing force of the insert  11  on the component  5 . In another variation, the cover  15  and the fins  16  could be omitted. 
   The injection of an encapsulation material  26  into the cavity  18  of the mold  21  is then undertaken to carry out an encapsulation operation, as readily understood by those skilled in the art. The encapsulation material  21  surrounding the platform  3  of the gate  2 , the semiconductor component  5  and the insert  11  embeds the inner part of the leads  4  of the gate  2  and the wires  10 . 
   By virtue of the insert  11  fitted with its plug  17 , the passage  14  lying in front of the sensor  8  is protected against any introduction of encapsulation material during the injection operation. In addition, the annular groove  25  forms a reservoir in case of frontal seepage. 
   In the semiconductor package  1  being produced, it is then possible to remove the plug  17  to free the passage  14  so that the sensor  8  is then accessible from the outside. The sensor  8  may be an optical sensor, for example, as shown in  FIG. 3 . It is then possible to install a transparent protective plug  27 , which could in addition form an optical lens in the passage  14  instead of the plug  17 . 
   With reference to  FIG. 4 , a semiconductor package  28  in the process of being fabricated is shown, which is placed in the cavity  29  of an injection mold  30 . In this variation, the semiconductor component  31  is attached by a layer of adhesive  32  to the front face of a mounting and electrical connection plate  33 . 
   The insert  34  is differentiated from the insert  11  of the previous example in that its fins  35  move away from the bottom  36  of the cavity  29  corresponding to the bottom  24  of the mold  21  of the previous example. The fins  35  come to rest in the corners of the cavity  29  at a distance from its bottom  36 . 
   In addition, an annular seal  40  forming a spacer is inserted between the rear face  37  of the body  38  of the insert  34 , corresponding to the rear face  13  of the insert  11  of the previous example, and the front face  39  of the semiconductor component  31 . This seal  40  is preferably adhesively bonded against the face  37  and against the face  38 , and provides a degree of flexibility in positioning the insert  34 . 
   During injection of an encapsulation material  41  in the cavity  29  of the mold  28 , as in the previous example, this encapsulation material is prevented from entering the passage  42  of the insert  34  by a plug  43  installed in this passage  42  and by the seal  40 . The seal  40  also makes it possible to reduce and to control the pressing force of the insert  34  on the semiconductor component  31 . In this variation, the fins  35  of the insert  34  are embedded in the encapsulation material  41 . 
   With reference to  FIGS. 5 and 6 , a semiconductor package  44  is shown, which is only differentiated from the semiconductor package  1  described with reference to  FIGS. 1 and 2  in that its insert  45  has a slot  46  made radially in its body  47  and open from one side. A plate  48 , for example made of glass, is installed in the slot  46  of the insert  45  and forms a plug obstructing the passage  49  of this insert, thus replacing the plug  17  of the previous example. After injection of the encapsulation material, which is carried out in the same way as in the previous example, the plate  48 , mounted in a sealed manner, is finally installed in the semiconductor package  44 . 
   The present invention is not limited to the examples described above. Many embodiments are possible without departing from the scope defined by the appended claims.