depositing a thin cap layer on said diffusion source layer to prevent the outdiffusion of {TAIL ~ elemental constituents} comprising {HEAD ~ said structure}, 
depositing a thin cap layer on said diffusion source layer to prevent the outdiffusion of { TAIL ~ elemental constituents } comprising { HEAD ~ said structure } ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH