In accordance with the present invention, a method is provided for shrinking critical dimension in semiconductor processes. This method comprises a step of performing an over-exposure process to a photosensitive layer to form a patterned photosensitive layer on a substrate by using a patterned reticle. Due to the unexposed region of the photosensitive layer being diminished by over-exposure the critical dimension is shrunk. Then, a sacrificial layer is applied for the purpose of pattern reverse-transferring. Next, the patterned photosensitive layer is removed such that the pattern is transferred to the sacrificial layer with a shrunk critical dimension. In cooperation of the present exposure technology with the present invention, the shrinkage of a critical dimension is accomplished, for example, using an I-line exposure light source in a critical dimension of 0.25 &mgr;m process, or using a deep UV (ultraviolet) exposure light source in a critical dimension of 0.13 &mgr;m process.