Integrated circuit package method

Abstract

A method of forming a packaged electronic device includes fabricating a MEMS structure, such as a BAW structure, on a first semiconductor wafer substrate; forming a cavity in a second semiconductor wafer substrate; and mounting the second substrate on the first substrate such that the MEMS structure is positioned inside the cavity in the second substrate using epoxy die attachment film. A wafer level assembly and an integrated circuit package are also described.

What is claimed is: 
     
         1 . A method of forming a wafer level package comprising:
 fabricating a BAW structure on a first semiconductor wafer substrate;   forming a cavity in a second semiconductor wafer substrate; and   mounting the second substrate on the first substrate such that the BAW structure is positioned inside the cavity in the second substrate using epoxy die attachment film.   
     
     
         2 . The method of  claim 1  further comprising thinning the first substrate. 
     
     
         3 . The method of  claim 2  wherein said mounting the second substrate comprises rigidly bonding portions of a second substrate of proper size, thickness and configuration to sufficiently stabilize the first substrate during thinning to prevent cracking and warping of the first substrate. 
     
     
         4 . The method of  claim 1  further comprising forming a hole through the first substrate that exposes the BAW structure. 
     
     
         5 . The method of  claim 1  further comprising mounting the first substrate on a die pad of a leadframe and connecting at least one bond pad on the first substrate to at least one lead of the leadframe with at least one bond wire. 
     
     
         6 . The method of  claim 5  further comprising covering the first and second substrates, the at least one bond wire, and at least a portion of the leadframe with encapsulant. 
     
     
         7 . The method of  claim 1  wherein said forming a cavity comprises etching a cavity. 
     
     
         8 . The method of  claim 1  further comprising removing a lateral portion of the second substrate at a location proximate the cavity. 
     
     
         9 . The method of  claim 7  wherein said removing a lateral portion of the second substrate comprises etching the second substrate. 
     
     
         10 . The method of  claim 2  wherein said thinning the first substrate comprises etching the first substrate. 
     
     
         11 . The method of  claim 4  wherein said forming a hole through the first substrate that exposes the BAW structure comprises etching the hole that exposes the BAW structure. 
     
     
         12 - 20 . (canceled)