CHEMICAL AMPLIFICATION ELECTRON-BEAM POSITIVE RESIST PROCESS FREE FROM SURFACE INSOLUBLE LAYER

This article describes a chemical amplification electron beam (EB) pos itive resist, and associated overcoat process with an acidic film. The EB resist consists of three components; the modified poly(p-vinylphen ol), a dissolution inhibitor, and an acid generator. Polymer containin g a sulfonic acid group is used as the overcoat material. A 0.16-mum l ines-and-spaces pattern is successfully fabricated at 14.6 muC/cm2 usi ng 50 keV EB. The process latitude on EB exposure for 0.3-mum lines an d spaces exceeds +/- 10% of the standard dose. The acceptable delay ti me between resist coating and EB exposure exceeds 200 h, and the accep table 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 re action at room temperature. It is experimentally confirmed that the ac idic overcoat film is effective for both protecting a surface of EB re sist against airborne contaminants and dissolving the surface insolubl e layer.