Film interposer for integrated circuit devices

Abstract

In one embodiment, a stack device comprising a film interposer of a polyimide film material, for example, is assembled. In accordance with one embodiment of the present description, a front side of the film interposer is attached to a first element of the stack device, which may be an integrated circuit package, an integrated circuit die, a substrate such as a printed circuit board, or other structure used to fabricate electronic devices. In addition, a back side of the film interposer is attached to a second element which like the first element, may be an integrated circuit package, an integrated circuit die, a substrate such as a printed circuit board, or other structure used to fabricate electronic devices. Other aspects are described.

1 . A method, comprising:
 attaching a first side of a film interposer having columnar interconnects to a first element selected from a group consisting of an integrated circuit package, an integrated circuit die, and a substrate, wherein said first side attaching includes optically aligning a photonic component of said film interposer with a photonic component of the first element; and   attaching a second side of the film interposer to a second element selected from a group consisting of an integrated circuit package, an integrated circuit die, and a substrate.   
     
     
         2 . The method of  claim 1  wherein the photonic component of the film interposer includes a first optical cavity and wherein the optical aligning includes optically aligning the photonic component of the first element with the first optical cavity of the film interposer so that an optical signal may propagate between the photonic component of the first element and the first optical cavity of the film interposer. 
     
     
         3 . The method of  claim 2  wherein the first optical cavity includes a reflector oriented to reflect the optical signal from the first optical cavity of the film interposer through a waveguide of the film interposer, to a second optical cavity of the film interposer having a reflector oriented to reflect the optical signal from the second optical cavity, wherein the method further comprises attaching the first side of the film interposer to a third element selected from a group consisting of an integrated circuit package, an integrated circuit die, and a substrate, wherein said first side attaching of said third element includes optically aligning the reflector of the second optical cavity to a photonic component of the third element, so that an optical signal may propagate between the photonic component of the first element and the photonic component of the third element, through the first optical cavity, the waveguide and the second optical cavity of the film interposer. 
     
     
         4 . The method of  claim 2  wherein the first optical cavity includes a reflector oriented to reflect the optical signal from the first optical cavity of the film interposer through a waveguide of the film interposer, to a second optical cavity of the film interposer having a reflector oriented to reflect the optical signal from the second optical cavity, wherein the second side attaching includes optically aligning the reflector of the second optical cavity to a photonic component of the second element, so that an optical signal may propagate between the photonic component of the first element and the photonic component of the second element, through the first optical cavity, the waveguide and the second optical cavity of the film interposer. 
     
     
         5 . The method of  claim 2  wherein the film interposer is a first film interposer, and wherein the first optical cavity includes a reflector oriented to reflect the optical signal from the first optical cavity of the first film interposer through an internal waveguide of the first film interposer, the method further comprising optically coupling the internal waveguide of the first film interposer to an external waveguide optically coupled to a photonic component of an external third element selected from a group consisting of an integrated circuit package, an integrated circuit die, a substrate, and a second film interposer, and spaced from the first film interposer and first and second elements, so that an optical signal may propagate between the photonic component of the first element and the photonic component of the third element, through the external waveguide, and the internal wave guide and the first optical cavity of the first film interposer. 
     
     
         6 . The method of  claim 2  wherein the first optical cavity passes entirely through the body of the film interposer and wherein the second side attaching includes optically aligning the first optical cavity to a photonic component of the second element, so that an optical signal may propagate between the photonic component of the first element and the photonic component of the second element through the optical cavity of the film interposer, which is optically aligned with both of the photonic components of the first and second elements. 
     
     
         7 . The method of  claim 1  wherein the first side attaching includes bonding electrical contacts disposed on the first side of the film interposer to electrical contacts on the first element; and wherein the second side attaching includes bonding electrical contacts disposed on the second side of the film interposer to electrical contacts on the second element;
 wherein the first element is electrically coupled to the second element through the columnar interconnects which pass at least partially through the body of the film interposer. 
 
     
     
         8 . The method of  claim 1  further comprising bonding electrical contacts of the first element to electrical contacts of the second element, through a cavity defined by the body of the film interposer. 
     
     
         9 . The method of  claim 1  wherein film interposer is flexible so that said first side attaching includes conforming the shape of the flexible film interposer to the shape of the first element, and wherein said second side attaching includes conforming the shape of the flexible film interposer to the shape of the second element. 
     
     
         10 . The method of  claim 1  further comprising propagating input/output signals between electrical contacts of a first density on the first side of the film interposer and electrical contacts of a second density different from the first density on the second side of the film interposer. 
     
     
         11 . The method of  claim 1  wherein the body of the film interposer includes at least one layer of polyimide material. 
     
     
         12 . The method of  claim 11  further comprising propagating input/output signals through a layer of electrical contacts on the first side of the film interposer, a columnar interconnect layer of columnar electrical interconnects passing through the at least one layer of polyimide material, a routing layer of lateral electrical interconnects disposed on the at least one polyimide layer, and a layer of electrical contacts on the second side of the film interposer. 
     
     
         13 . The method of  claim 12  wherein said first side attaching includes bonding electrical contacts disposed on the first side of the film interposer using solder disposed in a solder mask layer of said film interposer, to electrical contacts of the first element; and wherein said second side attaching includes bonding the film interposer second side to the second element using adhesive in an adhesive layer of the film interposer. 
     
     
         14 - 38 . (canceled)