An etching method is disclosed. The etching method comprises providing on a substrate a structure comprising a recess region formed therein. The recess region includes an inner part and a mouth part whose width is less than that of the inner part. The etching method further comprises performing a clean-then-etch process to remove at least a portion of etching object formed outside the recess region. The performing a clean-then-etch process comprises performing a cleaning process to fill at least a portion of the recess region with a cleaning solution, and performing a wet etch process to the substrate in a state that the cleaning solution remains in the recess region.