The processing characteristics of a negative resist (CPMS) exposed with a x‐ray exposure system are studied by a comparison between developed profiles and calculated results of absorbed energy in the resist. In fine lines, reduction in volume is caused by vertical and horizontal shrinkage. In patterns which cover large areas, where the resist is fixed to the substrate by the adhesion between the resist and the substrate, the reduction in volume is mainly caused by the vertical shrinkage, while the horizontal shrinkage causes deformation of the profile at the pattern edge. This fact means that the normalized thickness for the large patterns agrees with the volume reduction ratio for the fine lines. These results are applied to a simulation program to estimate the profiles of the negative resist exposed with a x‐ray exposure system. The program is based on the sensitivity curve of the resist. The theoretical results calculated with the program agree well with the experimental results in the case where penumbral shadows due to mask to wafer gap exist.