A method for protecting a layer includes: providing a substrate having a target layer; depositing a protective layer on the target layer, which protective layer contacts and covers the target layer and is constituted by a hydrocarbon-based layer; and depositing an oxide layer on the protective layer so that the protective layer in contact with the oxide layer is oxidized. The hydrocarbon-based layer is formed by plasma-enhanced atomic layer deposition (PEALD) using an alkylaminosilane precursor and a noble gas without a reactant.