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