A method for manufacturing a semiconductor device includes forming a photoresist layer including a photoresist composition over a substrate. The photoresist layer is selectively exposed to actinic radiation to form a latent pattern and the latent pattern is developed by applying a developer to the selectively exposed photoresist layer to form a patterned photoresist. The photoresist composition includes a photoactive compound and a resin comprising a radical-active functional group and an acid labile group.