Various embodiments include methods and chemistries to etch metal-oxide films. In one embodiment, a method of etching tin oxide (SnO2) films includes using thionyl chloride (SOCl2) chemistry to produce an etch rate of the SnO2 films of up to 10-times higher as compared with Cl2 chemistry for similar flow-rates and process conditions, and gettering oxygen species from the SnO2 films by using the SOCl2, thereby forming volatile SO2 and volatile SnCl4 to provide human safety and machine safety and operations. Other methods, chemistries, and techniques are disclosed.