Method for Fabricating Array-Molded Package-On-Package

Abstract

A method and apparatus for fabricating a semiconductor device are disclosed. The method attaches semiconductor chips ( 130 ) on a sheet-like insulating substrate ( 101 ) integral with two or more patterned layers of conductive lines and vias and with contact pads ( 103 ) in pad locations. A mold is provided, which has a top portion ( 210 ) with metal protrusions ( 202 ) at locations matching the pad locations. The protrusions are shaped as truncated cones of a height suitable to approach the pad metal surface in the closed mold cavity. The substrate and the chip are loaded onto the bottom mold portion ( 310 ); the mold is closed by clamping the top portion onto the bottom portion so that the protrusions are aligned with the contact pads, approaching the pad surface. After pressuring encapsulation compound into the cavity, the mold is opened; the encapsulated device has apertures to the pad locations. Any residual compound formed on the pads is removed by laser, plasma, or chemical to expose the metal surface.

1 . A method for fabricating a semiconductor device comprising the steps of:
 providing a sheet-like insulating substrate integral with two or more patterned layers of conductive lines and vias, the substrate having a first surface with chip assembly sites and contact pads in pad locations, and a second surface;   providing semiconductor chips;   attaching a chip to each assembly site;   providing a mold having top and bottom portions, the top portion forming a cavity for holding semiconductor devices;   the top portion including protrusions at locations matching the pad locations, the protrusions shaped as truncated cones of a height suitable to approach the pad metal surface when the mold is in a closed form;   the bottom portion being without corresponding protrusions;   loading the substrate with the chips onto the bottom mold portion, resting the second substrate surface on the mold and positioning the first surface with the contact pads away from the bottom mold portion;   closing the mold by clamping the top portion onto the bottom portion so that the protrusions are aligned with the contact pads, approaching the pad surface;   pressuring molding compound into the cavity to fill the cavity, thereby creating an encapsulation;   opening the mold and removing the substrate together with the encapsulated chips from the mold, the encapsulation having apertures to the pad locations; and   removing any residual compound on the pads to expose the metal surface.   
   
   
       2 . The method according to  claim 1  wherein the protrusions approach the pad metal surface in the closed cavity to a distance between 0 and 100 μm. 
   
   
       3 . The method according to  claim 1  wherein the protrusion touches the pad metal surface in the closed mold. 
   
   
       4 . The method according to  claim 1  wherein the metal protrusions further include a ridge operable to create an aperture having a gas release channel in the aperture. 
   
   
       5 . The method according to  claim 1  wherein the step of removing residual compound from the pad surface is performed by the process of shining laser light into the encapsulation apertures, thereby depositing compound particles on the otherwise smooth sidewalls. 
   
   
       6 . The method according to  claim 1  wherein the step of removing residual compound from the pad surface is performed by a plasma clean-up process, thereby creating a roughened surface on the aperture sidewalls. 
   
   
       7 . The method according to  claim 1  wherein the step of removing residual compound from the pad surface is performed by a chemical etch process, thereby leaving etch structures on the aperture sidewalls. 
   
   
       8 . The method according to  claim 1  further including, before the step of loading the substrate, the step of placing a compliant film over the top portion loaded with the inserts. 
   
   
       9 . The method according to  claim 8  further including, after the step of opening the mold, the step of peeling the compliant film off the top portion. 
   
   
       10 . The method according to  claim 1  wherein the step of attaching the chip includes wire bonding. 
   
   
       11 . The method according to  claim 1  wherein the step of attaching the chip includes a flip-chip process. 
   
   
       12 . The method according to  claim 1  further including the step of attaching solder balls to the second substrate surface. 
   
   
       13 . The method according to  claim 1  further including the step of filling the encapsulation apertures to the pads with solder material. 
   
   
       14 . The method according to  claim 1  further including the step of singulating individual units from the sheet-like substrate. 
   
   
       15 . The method according to  claim 14  wherein the step of singulating is performed by a sawing process, thereby creating a surface with saw marks. 
   
   
       16 . The method according to  claim 15  further including the step of attaching another semiconductor device with solder balls to the first substrate surface of the singulated unit so that the exposed pad surfaces are contacted by the solder balls, thereby creating a package-on-package semiconductor assembly. 
   
   
       17 . The method according to  claim 1  wherein the pad metal surface has a layer including gold or palladium. 
   
   
       18 . An apparatus for the fabrication of a semiconductor device comprising:
 a mold having top and bottom portions, the top portion having a cavity for holding semiconductor devices, the device includes a semiconductor chip attached to a sheet-like insulating substrate integral with two or more patterned layers of conductive lines and vias, the substrate having contact pads in pad locations;   the mold operable to be closed by clamping the top portion onto the bottom portion;   the top portion including protrusions at locations matching the pad locations, the protrusions shaped as truncated cones of a height suitable to approach the pad metal surface in the closed mold; and   the bottom portion being without corresponding protrusions.   
   
   
       19 . A device comprising:
 a sheet-like insulating substrate integral with two or more patterned layers of conductive lines and vias, the substrate having a first surface with a chip assembly site and contact pads in pad locations, and a second surface;   a semiconductor chip attached to the assembly site; and   an encapsulated region on the first surface, extending to the edge of the substrate, enclosing the chip and having contact apertures at the pad locations for external communication with the metal surfaces, the apertures having a not-smooth sidewall surfaces.   
   
   
       20 . The device according to  claim 19  wherein the not-smooth aperture sidewall surfaces include laser spalled compound particles. 
   
   
       21 . The device according to  claim 19  wherein the not-smooth aperture sidewalls include a plasma-roughened surface. 
   
   
       22 . The device according to  claim 19  wherein the not-smooth aperture sidewall surfaces have chemically etched structures. 
   
   
       23 . The device according to  claim 19  wherein the semiconductor chip is attached to the substrate by wire bonding. 
   
   
       24 . The device according to  claim 19  wherein the semiconductor chip is attached on the substrate by a flip-chip process.