Accurate ultrafine patterns are formed using a multiple exposure technique comprising implementing an OPC procedure to form an exposure reticle to compensate for distortion of an overlying resist pattern caused by an underlying resist pattern. Embodiments include forming a first resist pattern in a first resist layer over a target layer using a first exposure reticle, forming a second exposure reticle by an OPC technique to compensate for distortion of a second resist pattern caused by the underlying first resist pattern, depositing a second resist layer on the first resist pattern, forming the second resist pattern in the second resist layer using the second exposure reticle, the first and second resist patterns constituting a final resist mask, and forming a pattern in the target layer using the final resist mask.