A salt represented by the formula :wherein Q1 and Q2 each independently represent a fluorine atom or a C1-C4 perfluoroalkyl group,X1 represents a single bond etc. The primary electron beam is radiated on a reticle, and an observation image of the reticle is obtained using the electrons secondarily released. The cover is pivotally connected to the base with a pivotal tab integrally formed between and connected to the base and the cover. The structure further includes a first spacer region on a first side wall of the gate electrode region.