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