The substrate is etched using {HEAD ~ reactive ion etching}, creating {TAIL ~ a coil shaped trench} in the substrate 
creating
The substrate is etched using { HEAD ~ reactive ion etching } , creating { TAIL ~ a coil shaped trench } in the substrate
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH