Photoactive parameters of contrast enhancement material CEM 420 for Dill’s model were measured to analyze the contrast enhancement lithography (CEL) process. Then using the three‐dimensional photolithography simulator RESPROT, photoresist images in the CEL process were analyzed and compared with images got in a conventional process. The nature of the photosensitizer concentration distribution in contrast enhancement material (CEM) differs from that in conventional photoresist. The former has a higher contrast distribution. In the CEL process, the sidewall of the photoresist image has a steeper slope than that in the conventional one, and the depth of focus is improved 25% for the former. When defocus is 2.0 μm in the conventional process, the photoresist holes do not open but in the CEL process they do. The contrast of an aerial image in the photomask pattern is improved in the CEL process. For a three‐line pattern in the conventional process, the center photoresist line is narrow and low, but in the CEL process, all three lines have the same height and width. For a double elbow pattern in the conventional process, photoresist thicknesses differ inside and outside of the two elbow photoresist lines after development, however, they are the same in the CEL process.