Patent Publication Number: US-10326039-B2

Title: Proximity detector device with interconnect layers and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 15/668,138, filed on Aug. 3, 2017, which application is a divisional of U.S. patent application Ser. No. 14/259,344, filed on Apr. 23, 2014, and entitled “Proximity Detector Device with Interconnect Layers and Related Methods,” which application claims the benefit of Chinese Patent Application No. 201310158554X, filed on Apr. 28, 2013, which applications are hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of image sensor devices, and, more particularly, to a proximity detector device and related methods. 
     BACKGROUND 
     Typically, electronic devices include one or more image sensor modules for providing enhanced media functionality. For example, the typical electronic device may utilize the image sensor modules for photo capturing and video teleconferencing. Some electronic devices include additional image sensor devices used for other purposes, such as a proximity detector. 
     For example, the electronic device may use the proximity detector to provide object distances for providing focusing adjustment to the camera purposed image sensor modules. In mobile device applications, the proximity detector may be used to detect when the user&#39;s hand is nearby, thereby quickly and accurately waking the device from a power saving sleep mode. Typically, the proximity detector comprises a light source directing radiation to a potential nearby object, and an image sensor receiving the radiation reflected off of the nearby object. 
     For example, U.S. Patent Application No. 2009/0057544 to Brodie et al, assigned to the present application&#39;s assignee, discloses an image sensor module for a mobile device. The image sensor module comprises a lens, a housing carrying the lens, and a lens cap over the lens and housing. The image sensor module includes a barrel mechanism for adjusting the lens. During manufacture of an electronic device including one or more image sensor modules, there is a desire to manufacture the electronic device as quickly as possible, particularly in mass production runs. 
     The typical image sensor module is manufactured in a multi-step process. The first steps include semiconductor processing to provide the image sensor integrated circuit (IC). The next steps include some form of testing for the image sensor IC and packaging. The image sensor IC may be assembled into the image sensor module, along with a lens and movable barrel if needed. This assembly of the image sensor module may be performed manually or via machine. For example, in electronic devices that use surface mounted components, a pick-and-place (P&amp;P) machine may assemble the components onto a printed circuit board (PCB). A drawback to such singular packaging is that it may be relatively inefficient and also may require that each device be tested individually, adding to the manufacturing time. 
     An approach to an image sensor is disclosed in U.S. Patent Application Publication No. 2012/0248625 to Coffy et al., assigned to the present application&#39;s assignee. This image sensor comprises a transparent support, a pair of ICs on the transparent support, and encapsulation material on the transparent support and surrounding the pair of ICs. 
     Referring now to  FIG. 1 , a proximity detector  20 , as in the prior art, includes a dielectric layer  26 , an image sensor IC  24  on the dielectric layer, a light source device  22  also on the dielectric layer, and an adhesive material  25  between the image sensor IC and the dielectric layer. The proximity detector  20  includes a cap  21  positioned on the dielectric layer  26  and having a plurality of openings  31 ,  32   a - 32   b  therein, and transparent adhesive material  23  covering the light source device  22 . The proximity detector  20  also includes a lens  27  carried by the cap  21 , and a plurality of wire bonds  29   a - 29   c  coupling the image sensor IC  24  and the light source device  22  to electrically conductive traces on the dielectric layer  26 . The proximity detector  20  also includes additional transparent adhesive material  28  between the image sensor IC  24  and the lens  27 . A potential drawback to this proximity detector  20  includes a multi-step high precision assembly process using a P&amp;P device. Also, the proximity detector  20  may be less reliable and difficult to integrate into mobile devices, due to size constraints. 
     SUMMARY 
     In view of the foregoing background, it is therefore an object of the present disclosure to provide a proximity detector device that is efficient to manufacture. 
     This and other objects, features, and advantages in accordance with the present disclosure are provided by a proximity detector device comprising a first interconnect layer comprising a first dielectric layer, and a plurality of first electrically conductive traces carried thereby, an IC layer above the first interconnect layer and comprising an image sensor IC, and a light source IC laterally spaced from the image sensor IC. The proximity detector may comprise a second interconnect layer above the IC layer and comprising a second dielectric layer, and a plurality of second electrically conductive traces carried thereby. The second interconnect layer may have first and second openings therein respectively aligned with the image sensor IC and the light source IC. Each of the image sensor IC and the light source IC may be coupled to the pluralities of first and second electrically conductive traces. The proximity detector may comprise a lens assembly above the second interconnect layer and comprising first and second lenses respectively aligned with the first and second openings. Advantageously, the proximity detector may be manufactured using robust wafer level processing techniques and have a reduced size. 
     In particular, the IC layer may comprise encapsulation material laterally surrounding the image sensor IC and the light source IC. The encapsulation material may comprise a plurality electrically conductive vias, each coupled between a respective aligned pair of the pluralities of first and second electrically conductive traces. 
     The proximity detector device may further comprise transparent adhesive material in the first and second openings of the second interconnect layer. In some embodiments, the lens assembly may further comprise a molding compound surrounding the first and second lenses, and having first and second openings aligned with respective ones of the first and second lenses. 
     Additionally, the proximity detector device may further comprise a plurality of contacts coupled respectively to the plurality of first electrically conductive traces. For example, the plurality of contacts may comprise a plurality of ball grid array (BGA) contacts. The first lens may comprise a filter lens. The light source IC may comprise a light emitting diode. 
     Another aspect is directed to a method of making a proximity detector device. The method may comprise forming a first interconnect layer comprising a first dielectric layer, and a plurality of first electrically conductive traces carried thereby, forming an IC layer above the first interconnect layer and comprising an image sensor IC, and a light source IC laterally spaced from the image sensor IC. The method may include forming a second interconnect layer above the IC layer and comprising a second dielectric layer, and a plurality of second electrically conductive traces carried thereby. The second interconnect layer may have first and second openings therein respectively aligned with the image sensor IC and the light source IC. Each of the image sensor IC and the light source IC may be coupled to the pluralities of first and second electrically conductive traces. The method may also include forming a lens assembly above the second interconnect layer and comprising first and second lenses respectively aligned with the first and second openings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic cross-sectional view of a proximity detector device, according to the prior art. 
         FIG. 2  is a schematic cross-sectional view of a proximity detector device, according to the present disclosure. 
         FIG. 3  is a flowchart of a method for making the proximity detector device of  FIG. 2 . 
         FIGS. 4-13  are schematic cross-sectional views of steps for making the proximity detector device of  FIG. 2 . 
         FIGS. 14-16  are schematic cross-sectional views of steps for making another embodiment of the proximity detector, according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the present disclosure are shown. This present embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present embodiments to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments. 
     Referring initially to  FIG. 2 , a proximity detector device  40  according to the present disclosure is now described. The proximity detector device  40  illustratively includes a first interconnect layer  41  comprising a first dielectric layer  45 , and a plurality of first electrically conductive traces  48   a - 48   b  carried thereby. The proximity detector device  40  illustratively includes an IC layer  42  above the first interconnect layer  41  and comprising an image sensor IC  56 , and a light source IC  55  laterally spaced from the image sensor IC. The light source IC  55  may comprise a light emitting diode (LED), such as an infrared LED. 
     The proximity detector device  40  illustratively includes a second interconnect layer  43  above the IC layer  42  and comprising a second dielectric layer  46 , and a plurality of second electrically conductive traces  51   a - 51   b  carried thereby. The second interconnect layer  43  illustratively includes first openings  62   a - 62   b  and a second opening  61  therein respectively aligned with the image sensor IC  56  and the light source IC  55 . Each of the image sensor IC  56  and the light source IC  55  is coupled to the pluralities of first  48   a - 48   b  and second  51   a - 51   b  electrically conductive traces. 
     In the illustrated embodiment, the first openings  62   a - 62   b  are illustratively aligned with the image sensor IC  56 . The pair of first openings  62   a - 62   b  provides the imaging sensor IC  56  with access to the first and second lenses cavities. 
     The proximity detector device  40  illustratively includes a lens assembly  44  above the second interconnect layer  43 . The lens assembly  44  illustratively includes first  53  and second  52  lenses respectively aligned with the first openings  62   a - 62   b  and the second opening  61 . 
     In particular, the IC layer  42  includes encapsulation material  47  laterally surrounding the image sensor IC  56  and the light source IC  55 . The encapsulation material  47  illustratively includes a plurality electrically conductive vias  50   a - 50   b  passing therethrough. Each electrically conductive via  50   a - 50   b  is coupled between a respective aligned pair of the pluralities of first  48   a - 48   b  and second  51   a - 51   b  electrically conductive traces. 
     The proximity detector device  40  illustratively includes transparent adhesive material  54   a - 54   b  in the first openings  62   a - 62   b  and the second opening  61  of the second interconnect layer. In the illustrated embodiment, the lens assembly  44  includes a molding compound  57  surrounding the first  53  and second  52  lenses. The lens assembly  44  illustratively includes first openings  59   a - 59   b  and a second opening  58  aligned with respective ones of the first  53  and second  52  lenses. In the illustrated embodiment, the first openings  59   a - 59   b  are aligned with the first lens  53 . 
     Additionally, the proximity detector device illustratively includes a plurality of contacts  49   a - 49   b  ( FIG. 16 ) coupled respectively to the plurality of first electrically conductive traces  48   a - 48   b . For example, the plurality of contacts  49   a - 49   b  ( FIG. 16 ) may comprise a plurality of BGA contacts. The first lens  53  may comprise a filter lens (e.g. glass filter or transparent sheet with filter coating). The first lens  53  may also comprise a focusing element in addition or alternatively. 
     Another aspect is directed to a method of making a proximity detector device  40 . The method may comprise forming a first interconnect layer  41  comprising a first dielectric layer  45 , and a plurality of first electrically conductive traces  48   a - 48   b  carried thereby. The method may include forming an IC layer  42  above the first interconnect layer  41  and comprising an image sensor IC  56 , and a light source IC  55  laterally spaced from the image sensor IC. The method may include forming a second interconnect layer  43  above the IC layer  42  and comprising a second dielectric layer  46 , and a plurality of second electrically conductive traces  51 - 51   b  carried thereby. The second interconnect layer may have first openings  62   a - 62   b  and a second  61  opening therein respectively aligned with the image sensor IC  56  and the light source IC  55 , each of the image sensor IC and the light source IC being coupled to the pluralities of first  48   a - 48   b  and second  51 - 51   b  electrically conductive traces. The method may also include forming a lens assembly  44  above the second interconnect layer  43  and comprising first  53  and second  52  lenses respectively aligned with the first openings  62   a - 62   b  and the second opening  61 . 
     Referring now additionally to  FIGS. 3-16 , a flowchart  70  illustrates a method for making the semiconductor device  20  (Block  71 ). In the illustrated embodiments, a wafer level processing technique for making a pair of identical proximity detector devices  40  is shown, but it should be appreciated that typical processes would include the manufacture of a large number of proximity detector devices (sometimes including varying embodiments in a single manufacturing process, i.e. the illustrated adjacent proximity detectors need not be identical). The method includes forming a carrier layer  90 , and an adhesive layer  91  on the carrier layer ( FIG. 4  and Block  73 ). The method includes positioning image sensor ICs  56  and light source ICs  55  on the adhesive layer  91  ( FIG. 5  and Block  74 ). At this point, any other desired surface mount devices (e.g. capacitors) may also be positioned. The method includes forming an encapsulation material  47  on the image sensor ICs  56  and light source ICs  55  to define an IC layer  42  ( FIG. 6  and Block  75 ). 
     The method includes flipping the IC layer  42  on the carrier layer  90  by heating the adhesive layer  91  to detach the IC layer and reapplying the IC layer to the adhesive layer on an opposite face thereof ( FIG. 7  and Block  77 ). The method also includes forming a second interconnect layer  43  and a plurality of second electrically conductive traces  51   a - 51   b  carried thereby ( FIG. 8  and Block  78 ). 
     The method includes forming a transparent adhesive material  54   a - 54   b  in first openings  62   a - 62   b  and the second opening  61  of the second interconnect layer  43 . The method also includes positioning first  53  and second  52  lenses on the transparent adhesive material  54   a - 54   b  ( FIG. 9  and Block  79 ). 
     The method includes forming molding compound  57  on the first  53  and second  52  lenses to define a lens assembly  44  ( FIG. 10  and Block  80 ). In some embodiments, the forming of the molding compound  57  may be film assisted. The method includes flipping the IC  42  and second interconnect layers  43 , and lens assembly  44  on the carrier layer  90  ( FIG. 11  and Block  81 ) (again using a heating step to deactivate the adhesive layer  91 ). The method includes grinding a portion of the backside of the IC layer  42  ( FIG. 12  and Block  82 ). 
     The method includes forming a first interconnect layer  41  comprising a first dielectric layer  45 , and a plurality of first electrically conductive traces  48   a - 48   b  carried thereby ( FIG. 13  and Block  84 ). In this embodiment, the plurality of first electrically conductive traces  48   a - 48   b  defines LGA contacts. The method also includes a singulation step ( FIG. 15 ) (Blocks  84 - 86 ). 
     Advantageously, the proximity detector device  40  may be manufactured using robust wafer level processing techniques. Additionally, the proximity detector device  40  may be made in large quantities. Moreover, the structure is mechanically robust since the first  53  and second  52  lenses are tightly integrated with the lens assembly molding compound  57 . Also, the lens assembly  44  is tightly integrated with the first  41 , second  43  interconnect layers and the IC layer  43 , also adding mechanical rigidity. The packaging of the proximity detector device  40  is thinner than typical approaches, thereby permitting easier integration into mobile devices. Moreover, the proximity detector device  40  provides for good co-planarity for the image sensor and light source ICs  55 - 56 , thereby reducing the computational load of proximity detection calculations (i.e. from having adjacent source and receiver positions). 
     Referring now additionally to  FIGS. 14-16 , steps from another embodiment of the method for making the proximity detector device  40 ′ is now described. In this embodiment of the method for making the proximity detector device  40 ′, those steps and elements already discussed above with respect to  FIGS. 2-13  are given prime notation and most require no further discussion herein. This embodiment differs from the previous embodiment in that this method illustratively includes forming a plurality of ball grid array contacts  49   a ′- 49   b ′ on the plurality of first electrically conductive traces  48   a ′- 48   b ′ ( FIG. 14  and Block  85 ). The method illustratively includes a singulation step using a dicing blade  97 ′ ( FIGS. 15-16 ). 
     Many modifications and other embodiments of the present disclosure will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the present disclosure is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. 
     While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.