When observing a micro region of a sample in a magnified fashion, used is a typical charged particle beam device such as a SEM (Scanning Electron Microscope) or a TEM (Transmission Electron Microscope). In observation via a SEM or a TEM, a sample targeted for observation is put in a sample room of which entire part is evacuated, and a micro region of the sample is observed in high vacuum.
Meanwhile, there is a great demand for observing a micro region of a sample under atmospheric pressure in use of a SEM or a TEM. For example, Patent Literatures 1 and 2 disclose an example of a SEM which achieves observation of a micro region of a sample in a state that most of the sample is exposed to atmospheric pressure.
Regarding the SEM disclosed in Patent Literature 1, a sample room is not particularly provided, while instead a cylindrical shroud covering the lens barrel unit of the SEM is provided. Here, the cylindrical shroud is configured so that one side (or upper side) thereof is closed, while the other side (or lower side) thereof is open. The lens barrel unit is arranged on the closed upper side in the shroud. Hereby, if a sample targeted for observation is placed to close the open lower side of the shroud, the inside of the shroud becomes a closed space. This allows the inside of the shroud to be kept at a certain degree of vacuum when evacuating therein. Accordingly, under the above condition, it is possible to observe a micro region of the sample surface via irradiating an electron beam from the lens barrel unit to the sample surface. That is, according to the SEM disclosed in Patent Literature 1, it is possible to observe a micro region of the sample facing the inside of the shroud even in a state that most of the sample is exposed to atmospheric pressure.
Here, the SEM of Patent Literature 2 is slightly different in the structure from the SEM of Patent Literature 1. That is, the shroud (i.e., vacuum container) of Patent Literature 2 has a semi-spherical shape. However, both SEMs are essentially almost the same for observing a sample exposed to atmospheric pressure. Accordingly, in the SEM of Patent Literature 2, it is also possible to observe a micro region of a sample facing the inside of the shroud in a state that most of the sample is exposed to atmospheric pressure.