Abstract:
An optical semiconductor module including an optical semiconductor component that has a front face including an optical sensor. Encapsulation, defining a cavity in which the optical component is disposed, includes external electrical connections for the optical semiconductor component, and includes a window allowing light to pass through it toward the optical sensor. An optical lens ( 17 ) is disposed in the cavity ( 6 ) between the optical sensor ( 10 ) and the window ( 5 ). A support structure ( 18 ) supports the optical lens. This optical semiconductor module may also include a shield ( 24 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/FR02/01689 filed on May 17, 2002, which is based upon and claims priority from prior French Patent Application No. 0106553 filed May 18, 2001, the entire disclosure of which is herein incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to optical semiconductor packages. 
     2. Description of Related Art 
     Prior art optical semiconductor packages include a sealed cavity into which is fixed an optical semiconductor component whose front face includes an optical sensor; the cavity is partly delimited by a window in front of the optical sensor. Fixing a lens-carrier fitted with a lens in front of the optical sensor over the window on the outside of the cavity is also known in the art. Given cumulative manufacturing tolerances, it is obligatory to make provision adjusting the focal distance between the lens and the optical sensor. To this end the lens is fixed into a ring and the ring is screwed adjustably into a passage in the lens-carrier. 
     This kind of package includes many components that are complex to fabricate and necessitates adjustment of the lens, after assembly, and fixing it in the adjusted position, with the result that its fabrication cost is relatively high. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to propose an optical semiconductor package of simpler structure requiring no adjustment. 
     Another object of the present invention is to improve the quality of electrical signals delivered by the optical semiconductor component. 
     The optical semiconductor package according to the invention includes an optical semiconductor component, which has a front face including an optical sensor, and encapsulation means which delimit a cavity in which said optical component is disposed, have external electrical connection means of said optical semiconductor component, and include a window allowing light to pass through it toward said optical sensor and further includes an optical lens disposed in said cavity between said optical sensor and said window and support means ( 18 ) for supporting said lens. 
     According to the invention said lens support means are fixed to the front face of said optical component externally of said optical sensor. 
     According to the invention, a joining ring ( 18   a ) is preferably disposed between a front rim of said support means and said encapsulation means. 
     According to the invention, said lens support means preferably include a ring into which said lens is fixed and whose rear end is fixed to the front face of said optical component externally of said optical sensor. 
     According to the invention, said lens support means preferably include a joining ring disposed between the front rim of said annular ring and said encapsulation means. 
     According to the invention, said encapsulation means preferably include a diaphragm. 
     In one embodiment of the invention said encapsulation means include electrically conductive material electromagnetic shielding means which can be connected externally and are electrically insulated from said electrical connection means of said optical component. 
     According to the invention, said encapsulation means preferably include a support and a glazed cover fixed to a front face of said support, which delimits a cavity between them, said optical component is fixed to said support, and said support includes an external electrical connection network of said optical component. 
     According to another embodiment of the invention said support is in the form of a plate and said glazed cover is in the form of a cup whose peripheral rim is fixed to the front face of said plate and has an opening obstructed by said window. 
     According to another embodiment of the invention said support has a hollow part surrounded by an annular part and to the bottom of which said optical component is fixed and said glazed cover includes a glazed plate whose peripheral part is fixed to the front face of said annular part of said support. 
     According to the invention said support and said glazed cover include electrically conductive material shielding parts connected to each other in the area of the front face of said support. 
     According to the invention said shielding parts of said glazed cover preferably delimit a diaphragm. 
     According to the invention said support preferably includes an integrated electrically conductive material shielding plane under said optical component and integrated electrically conductive material shielding columns opening onto its front face and said glazed cover includes an electrically conductive material shielding part or layer electrically connected to said shielding columns of said support. 
     According to the invention said glazed cover is preferably fixed to said support by an electrically conductive adhesive making the electrical connection between them. 
     In one embodiment of the invention said glazed cover includes an electrically conductive material cup. 
     In another embodiment of the invention said glazed cover includes a window one face of which is at least partly covered by a shielding layer of an electrically conductive material except for an opening in front of said optical sensor. 
     In another embodiment of the invention said glazed cover includes an electrically conductive material plate which has an opening in front of said optical sensor and obstructed by a window. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood after studying various optical semiconductor packages described by way of non-limiting example and shown in the drawings, in which: 
         FIG. 1  shows a first optical semiconductor package in accordance with the present invention in section; 
         FIG. 2  is a top view of the optical semiconductor package shown in  FIG. 1  with the window removed; 
         FIG. 3  is a top view of the optical semiconductor package shown in  FIG. 1 ; 
         FIG. 4  shows a second optical semiconductor package in accordance with the present invention in section; 
         FIG. 5  is a top view of the optical semiconductor package shown in  FIG. 1  with the window removed; 
         FIG. 6  shows a third optical semiconductor package in accordance with the present invention in section; and 
         FIG. 7  shows a fourth optical semiconductor package in accordance with the present invention in section. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIGS. 1 to 3  show an optical semiconductor package  1  which includes a flat parallelepiped-shaped support  2  with a recess  3  in one face; the support  2  therefore has an annular front face  4  around the recess. 
     The optical package  1  further includes a glazed cover consisting of a transparent window  5 ; the periphery of the latter&#39;s rear face bears against and is fixed to the front face  4  of the support  2 , for example by means of an adhesive. The support  2  and the window  5  therefore delimit a sealed encapsulation cavity  6 . 
     An optical semiconductor component  8  is disposed in the cavity  6 . A rear face of the optical component  8  is fixed to the back  7  of the recess  3  in the support  2 , for example by means of an adhesive, and its front face  9 , which is at a distance from and parallel to the window  5 , has in its central part an optical sensor  10  covering a square area, for example. 
     The support  2  is made from a multilayer ceramic or organic material, for example, and includes an internal electrical interconnection network  11 . The network  11  interconnects internal terminals  12  disposed and arranged on the wall of the recess  3  in the support  2 , at a distance from and at the periphery of the optical component  8 , and external terminals  13  for external electrical connections disposed and arranged on the rear face  14  of the support  2 . 
     The optical component  8  has front electrical connection terminals  15  on its front face  9 , near its periphery and at a distance from the optical sensor  10 . 
     The internal terminals  12  of the support  2  and the front terminals  15  of the optical component  8  are connected by electrical wires  16  whose ends are soldered to the terminals. The optical component  8  can thus be connected to an external electrical unit through the support  2 , via the network  11  and the electrical wires  16 . 
     The package  1  further includes an optical lens  17  disposed in the cavity  6 , between the window  5  and the optical sensor  10 . 
     The lens  17  is fixed into a ring  18  which is cylindrical, for example, whose axis is perpendicular to the front face  9  of the optical component  8 , and which has an annular rim  19  at its rear end fixed to the front face  9 , for example by means of an adhesive, between the area constituting the optical sensor  10  and the front terminals  15 ; an annular rim  20  at the front end of the ring  18  is near or in contact with the window  5 . 
     The front face of the window  5  is covered with an opaque layer  21  with an aperture  22  in the part thereof in front of the lens  17 , to constitute a diaphragm. 
     Thus external light passes through the diaphragm  22 , the corresponding part of the window  5  and the lens  17  inside the ring  18 , until it finally reaches the optical sensor  10 ; the optical component  8  is adapted to deliver the corresponding electrical signals to the external terminals  16  via the electrical wires  16  and the network  11  of the support  2 . 
     The optical semiconductor package  1  can be fabricated in the following manner. 
     The rear face of the optical semiconductor component  8  is fixed to the back  7  of the recess  3  in the support  2  using an appropriate adhesive. 
     The support  2  is electrically connected to the optical component  8  by soldering the ends of the wires  16  to the terminals  12  and  15 . 
     The ring  18  previously fitted with the lens  17  is fixed to the front face  9  of the optical component  8 , by means of a suitable adhesive, so that the required position of the lens  17  relative to the optical sensor  10  is obtained directly. 
     Finally, the window  5  with the layer  21  is installed on the front face  4  of the support  2  and fixed thereto using a suitable adhesive. 
       FIGS. 4 and 5  show an optical semiconductor package  23  that differs from the optical semiconductor package  1  described with reference to  FIGS. 1 to 3  only in that it includes electromagnetic shielding means  24  electrically insulated from the electrical connection network  11  of the support  2 . 
     To this end, the support  2  further includes an integrated electrically conductive material, for example metal, plane  25  parallel to its rear face  14  and a multiplicity of integrated electrically conductive material, for example metal, columns  26  arranged in the periphery volume of the support  2  and connected to the conductive plane  25 . The conductive columns  26  open onto the front face  4  of the support  2  and at least one column opens onto the rear face  14  of the support  2  to constitute at least one external electrical connection terminal  27 . 
     In the support  2 , the integrated conductive plane  25  and the integrated conductive columns  26  are arranged so that they are not in contact with the integrated interconnection network  11 . In particular, the interconnection lines of the network  11  pass through passages  28  through the conductive plane  25 . 
     The rear face of the window  5 , which faces toward the cavity  6 , carries an electrically conductive material layer  29  which is opaque except in the area in front of the lens  17 , to constitute the diaphragm  22 ; the external layer  21  of the previous example has been eliminated. 
     The periphery of the window  5  is advantageously fixed to the front face  4  of the support  2  using an electrically conductive adhesive so that the conductive layer  29  carried by the window  5  is electrically connected to the conductive columns  4  of the support  2 . 
     As a result, by connecting the external terminal  27  to ground, preferably one independent of the ground of the optical component  8 , the shielding means  24 , consisting of the conductive plane  25 , the conductive columns  26  and the conductive layer  29 , constitute a cage for electromagnetically isolating the optical semiconductor component  8 . 
     In this embodiment, a joining ring  18   a  is disposed around the diaphragm  22 , between the front annular rim  20  of the ring  18  and the rear face of the window  5 . 
       FIG. 6  shows an optical semiconductor package  30  which differs from the optical semiconductor package  23  described with reference to  FIGS. 4 and 5  only in that the window  5  with the conductive layer  29  is replaced by a glazed cover  31  which includes an opaque electrically conductive material, for example metal, plate  32  which has an opening  33  in front of the lens  17  and constituting the diaphragm  22  previously cited; the opening  33  is obstructed by a transparent window  34  whose periphery is glued to the plate  32 , for example. 
     As in the previous example, the periphery of the plate  32  is fixed to the front face  4  of the support  2  using a conductive adhesive, and is therefore electrically connected to the conductive columns  26 . 
       FIG. 7  shows a semiconductor package  35  that differs from those described in the previous examples in that its interconnection support  36 , corresponding to the interconnection support  2 , consists of a flat plate whose front face  37  carries the optical semiconductor component  8  and includes the internal terminals  15 . 
     This optical package  35  includes a glazed cover  38  in the form of a cup whose rim is fixed to the front face  37  of the plate  36  to delimit the sealed cavity  6 . 
     The bottom of the cup  38  consists of the plate  32  and the window  34  described with reference to  FIG. 6  and its lateral wall  39  consists of a peripheral extension of the plate  32  whose edge  40  is fixed to the front face  37  of the plate  36  by a conductive adhesive so that it is electrically connected to the conductive columns  26  integrated into the support  36 . 
     The present invention is not limited to the examples described hereinabove. Many different embodiments that do not depart from the scope of the invention as defined by the accompanying claims are feasible.