Thin tin oxide films can be used in semiconductor device manufacturing. In one implementation, a method of processing a semiconductor substrate includes: providing a semiconductor substrate having a plurality of protruding features residing on an etch stop layer material, and an exposed tin oxide layer in contact with both the protruding features and the etch stop layer material, where the tin oxide layer covers both sidewalls and horizontal surfaces of the protruding features; and then completely removing the tin oxide layer from horizontal surfaces of the semiconductor substrate without completely removing the tin oxide layer residing at the sidewalls of the protruding features. Next, the protruding features can be removed without completely removing the tin oxide layer that resided at the sidewalls of the protruding features, thereby forming tin oxide spacers.