Manufacturing method of an electronic device including overmolded mems devices

Abstract

A method manufactures an electronic device comprising a MEMS device overmolded in a protective casing. The MEMS device includes an active surface wherein a portion of the MEMS device is integrated, and is sensitive, through a membrane, to chemical/physical variations of a fluid. Prior to the molding step, at least one resin layer is formed on at least one region overlying the active surface in correspondence with the membrane. After, at least one portion of at least one resin layer is removed from at least one region, so that in the region an opening is formed, through which the MEMS device is activated from the outside of the protective casing.

1 . A method, comprising
 forming a MEMS device having a membrane sensitive to chemical or physical variations of a fluid;   forming a resin layer on said membrane;   removing at least a first portion of said resin layer from said membrane, so that an opening is formed over the membrane; and   molding a protective casing on the MEMS device after forming the resin layer, the protective casing being in contact with the resin layer.   
     
     
         2 . A method according to  claim 1 , wherein said opening is central with respect to an active surface of the MEMS device. 
     
     
         3 . A method according to  claim 1 , wherein forming the resin layer comprises depositing the resin layer simultaneously on said membrane, on a peripheral region overlying of an active surface of the MEMS device, and on a first and a second region of said active surface that are adjacent to said membrane. 
     
     
         4 . A method according to  claim 3 , wherein said step of removing at least the first portion of said resin layer comprises etching simultaneously said resin layer from said membrane and from said peripheral region and leaving said at least one resin layer on said first and second regions. 
     
     
         5 . A method according to  claim 1 , wherein said forming the resin layer comprises depositing the resin layer limitedly on said membrane without depositing the resin layer on peripheral areas of an active surface of the MEMS device. 
     
     
         6 . A method according to  claim 1 , wherein said opening formed by removing at least the first portion of said resin layer is an opening in said resin layer. 
     
     
         7 . A method according to  claim 1 , wherein said step of removing at least the first portion of said resin layer is performed prior to molding said protective casing. 
     
     
         8 . A method according to  claim 1 , wherein said step of removing at least the first portion of said resin layer is performed after molding said protective casing. 
     
     
         9 . A method according to  claim 1 , wherein said step of forming said resin layer comprises depositing said resin layer with a spin coating technique. 
     
     
         10 . A method according to  claim 1 , wherein said step of forming said resin layer comprises depositing said resin layer with a screen printing technique. 
     
     
         11 . A method according to  claim 1 , wherein said step of forming said resin layer comprises depositing said resin layer with a stencil printing technique. 
     
     
         12 . A method according to  claim 1 , wherein said step of forming said resin layer comprises depositing said resin layer with a dispensing technique. 
     
     
         13 . A method according to  claim 12 , wherein depositing said resin layer with the dispensing technique comprises forming a resin ovoidal region. 
     
     
         14 . A method according to  claim 13 , wherein said resin ovoidal region is subjected to a curing process. 
     
     
         15 . A method according to  claim 1 , wherein said step of forming said resin layer comprises depositing said resin layer through photo-lithography. 
     
     
         16 . A method according to  claim 1 , wherein said resin layer is photo-sensitive to near-UV radiation. 
     
     
         17 . A method according to  claim 1 , wherein said resin layer is an SU-8 resin layer. 
     
     
         18 . A method according to  claim 1 , wherein said resin layer has a thickness greater than 20 μm. 
     
     
         19 . An electronic device comprising:
 a MEMS device having an active surface and a membrane, sensitive to chemical/physical variations of a fluid;   first and second resin layer portions defining opposite sides of an opening over said membrane; and   a protective casing surrounding the MEMS device.   
     
     
         20 . The device of  claim 19  wherein the protective casing is positioned on top surfaces of the resin layer portions and has an opening aligned with the opening defined by the first and second resin portions. 
     
     
         21 . The device of  claim 19  wherein the protective casing laterally surrounds the resin layer portions and leaves exposed top surfaces of the first and second resin portions. 
     
     
         22 . The device of  claim 19  wherein the resin layer includes:
 a first resin layer positioned directly on the active surface of the MEMS device and having a first opening over the membrane; and   a second resin layer positioned directly on the first resin layer and having a second opening aligned with the first opening.   
     
     
         23 . The device of  claim 19  wherein the MEMS device includes a cavity underlying the membrane and an access opening allowing fluid communication between the cavity and the opening. 
     
     
         24 . An electronic device, comprising:
 a monolithic body of semiconductor material having a lower surface and an upper surface;   a buried cavity extending below said upper surface and delimiting, with said upper surface, a flexible membrane;   an access opening fluidically communicating with said buried cavity;   a protective casing comprising an opening suitable for putting said electronic device in communication with an external fluid;   a first resin layer, overlying said active surface laterally with respect to said flexible membrane, the first resin layer including first and second portions delimiting a channel region overlying said flexible membrane; and   a second resin layer having a first portion and a second portion separated from each other by a space communicating below with said channel region and above with said opening of the casing, wherein said channel region communicates with said cavity through said access opening.   
     
     
         25 . The device of  claim 24 , wherein said resin layers are SU-8 resin layers. 
     
     
         26 . The device of  claim 24 , wherein said second resin layer has a thickness greater than 20 μm.