Protective bondline control structure

Abstract

In described examples, a bondline structure is arranged along a periphery of a cavity. The bondline structure extends from a first substrate and is configured to bond with an interposer arranged on a second substrate. A diffusion barrier is arranged on the first substrate for contacting the interposer. The diffusion barrier is arranged to impede a contaminant against migrating from the bondline structure and entering the cavity.

What is claimed is: 
     
         1 . Apparatus, comprising:
 a first substrate that delimits a surface of a cavity.   a bondline structure arranged along a periphery of the cavity, wherein the bondline structure extends from the first substrate and is configured to bond with an interposer arranged on a second substrate; and   a diffusion barrier arranged on the first substrate for contacting the interposer, and wherein the diffusion barrier is arranged to impede a contaminant against migrating from the bondline structure and entering the cavity.   
     
     
         2 . The apparatus of  claim 1 , comprising the interposer, and comprising the second substrate. 
     
     
         3 . The apparatus of  claim 2 , wherein the diffusion barrier includes a portion of the first substrate adjacent to the bondline structure. 
     
     
         4 . The apparatus of  claim 2 , wherein the diffusion barrier is coupled to the second substrate via a barrier extension formed between the interposer and the second substrate. 
     
     
         5 . The apparatus of  claim 1 , wherein the barrier extension is deformable. 
     
     
         6 . The apparatus of  claim 2 , wherein the bondline structure includes a gold layer and an indium layer formed in contact with the gold layer, wherein the indium layer includes an intermetallic species, and wherein the contaminant includes a reactive species of indium outgassing from the indium layer. 
     
     
         7 . The apparatus of  claim 6 , wherein the gold layer is a first gold layer, wherein the first gold layer is formed on the first substrate, wherein a second gold layer is formed on the interposer, and wherein the interposer is further coupled to the second substrate independently of the bondline structure via the first gold layer and at least one barrier extension formed between the interposer and the second substrate. 
     
     
         8 . The apparatus of  claim 2 , wherein the diffusion barrier includes a first barrier extension formed on the first substrate, wherein the first barrier extension is coupled to a second barrier extension formed on the interposer. 
     
     
         9 . The apparatus of  claim 8 , wherein at least one of the first and the second barrier extensions includes a structure that is pliantly deformable in response to a coupling of the first and second barrier extensions. 
     
     
         10 . The apparatus of  claim 9 , wherein the pliantly deformable structure includes an internal closed aperture. 
     
     
         11 . The apparatus of  claim 9 , wherein the pliantly deformable structure includes an internal open aperture. 
     
     
         12 . The apparatus of  claim 2 , wherein the first substrate includes silicon and the second substrate includes glass. 
     
     
         13 . The apparatus of  claim 1 , further comprising a microelectromechanical system (MEMS) element arranged within the cavity. 
     
     
         14 . An apparatus, comprising:
 a first substrate that delimits a first boundary of a headspace;   a second substrate that delimits a second boundary of the headspace, wherein the second boundary is arranged opposite to the first boundary;   an interposer extending from the second substrate and that delimits a peripheral boundary of the headspace;   a bondline structure extending between the first substrate and the interposer and that is arranged to bond the first substrate to the second substrate; and   a diffusion barrier arranged between the interposer and the first substrate and arranged to impede a contaminant from the bondline structure against contacting an element within the headspace.   
     
     
         15 . The apparatus of  claim 14 , wherein the element is a microelectromechanical system (MEMS) element. 
     
     
         16 . The apparatus of  claim 14 , wherein the diffusion barrier extends along the peripheral boundary of the headspace. 
     
     
         17 . The apparatus of  claim 14 , wherein the interposer includes a recess that includes a first gold layer formed thereupon, wherein the interposer include an indium layer formed on the first gold layer, and wherein a bond for bonding the first and second substrates is formed by compressing the indium layer against a second gold layer formed on the first substrate. 
     
     
         18 . The apparatus of  claim 17 , wherein the recess of the interposer is arranged to limit sideways extrusion of indium in response to the compressing the indium layer against a second gold layer formed on the first substrate. 
     
     
         19 . A method, comprising:
 arranging an interposer extending from a first substrate and that delimits a peripheral boundary of a cavity;   arranging a bondline structure extending between a second substrate and the interposer;   bonding the first and second substrates along the bondline structure; and   arranging a diffusion barrier between the interposer and the first substrate.   
     
     
         20 . The method of  claim 19 , wherein the diffusion barrier is arranged to impede a contaminant from the bondline structure against contacting an element within the cavity formed by the first and second substrates and the diffusion barrier.