This article describes a chemical amplification electron beam (EB) positive resist, and associated overcoat process with an acidic film. The EB resist consists of three components; the modified poly(p-vinylphenol), a dissolution inhibitor, and an acid generator. Polymer containing a sulfonic acid group is used as the overcoat material. A 0.16-mum lines-and-spaces pattern is successfully fabricated at 14.6 muC/cm2 using 50 keV EB. The process latitude on EB exposure for 0.3-mum lines and spaces exceeds +/- 10% of the standard dose. The acceptable delay time between resist coating and EB exposure exceeds 200 h, and the acceptable delay time between EB exposure and postexposure bake is as much as 38 h. The limitation of the latter delay time is not restricted by the generation of surface insoluble layer but by the acid catalyzed reaction at room temperature. It is experimentally confirmed that the acidic overcoat film is effective for both protecting a surface of EB resist against airborne contaminants and dissolving the surface insoluble layer.