Method for manufacturing image sensor

Methods of forming a microlens for an image sensor are provided. In one embodiment, the microlens can be oxide film microlens fabricated by forming an oxide film on a substrate; forming a first photoresist pattern on the oxide film; performing a plasma processing with respect to the oxide film using the first photoresist pattern as a mask; removing the first photoresist pattern; and performing an isotropic etching of the plasma processed oxide film. In another embodiment, the oxide film microlens can be fabricated by forming an oxide film on a substrate; forming a first photoresist pattern on the oxide film; implanting ions into the oxide film using the first photoresist pattern as a mask; removing the first photoresist pattern; and performing an isotropic etching of the ion implanted oxide film. Convex shaped microlens can be provided as a result of the etching selectivity to the oxide film.