In recent years, there have been a lot of studies on surface imaging techniques in which the single layer lithography process is utilized. They have advantages of capability of high resolution, wide focus latitude, small critical dimension (CD) variation on topography, as well as their process simplicity compared with multilayer lithography process. The DESIRE process, one of the surface imaging process, also has the same advantages. This process is based on the selective silylation which proceeds only in an optically exposed region of surface layer with use of vapor phase silylation. This paper describes the relation between resist profile and the silylation condition which may influence the silylated layer owing to the variation of diffusion characteristics of the silylation agent. We found that resist profile was strongly influenced by the silylation condition. In order to make the phenomenon clear, we studied the silylated profile of cross sectional view under various silylation conditions. As a result, it was found that the lower degree of silylation became, the less silicon diffusion depth was dependent on exposure energy and pattern size. Furthermore, the silylated profile having a gentle slope and thin shape tended to make a vertical sidewall profile after dry-development. It is discussed what characteristics of silylated profile have a significant effect on the final resist profile in the DESIRE process.