Abstract: Image-formation methods and photosensitive materials used in such methods are disclosed that form very high-resolution patterns. The photosensitive materials comprise an ingredient that is triggered by a radical to undergo a latent-image-forming reaction. The radicals are produced by photons from an illumination light. Alternatively, the ingredient is triggered by a reactive-intermediate compound that is activated by the exposure-produced radical. The photosensitive materials possess a non-linear sensitivity characteristic in which the latent-image reaction density increases according to the mth power (m>1) of the incident light intensity. The photosensitive material can be applied to a sensitive substrate for exposure. Multiple exposures of the sensitive substrate are performed using a projected mask pattern in the presence of a radical deactivator.