Atom probe is an analytical method capable of directly observing atomic arrangement/composition distribution of a leading end of a sample that has been processed so as to be needle-shaped, at an atomic scale. In the atom probe, a high direct current voltage is applied so as to cause the leading end of the needle-shaped sample to generate a high electric field. A pulse voltage is applied or a pulse laser is irradiated to the leading end so that field evaporation of an atom belonging to a first layer of a surface is induced. Then, mass of an ion that has field-evaporated is time-of-flight-measured so that a type of an element can be determined. Since the field evaporation progresses every atomic layer, atom probe analysis has resolution in a depth direction at an atomic level (refer to PTL 1).
A peculiar high electric field in an order of 1010 (V/m) due to a metal is required in order to evaporate the metal by an electric field. In the atom probe analysis, a sample should be a needle-shaped sample having a leading end diameter of 100 nm or less in order to achieve the high electric field. In a case where a portion to be observed, such as a bulk sample, is uniformly present over an entire sample, an electric-field polishing method is used for processing of making a leading end of the sample to be acute. In contrast, since a region to be analyzed should be positioned at a leading end of a needle in order to perform the atom probe analysis to a specific region of a semiconductor, an interface, or the like, processing for a needle shape is performed using a focused ion beam (hereinafter, referred to as the “FIB”).
Using the FIB enables easy processing of a sample in a needle-shape. However, only the FIB cannot often ascertain whether a leading end of the needle-shaped sample that has been completed actually includes a region to be analyzed. Thus, a sample that has been completed or a leading end of a needle-shaped sample that has been being processed, is sometimes observed by a transmission electron microscope (hereinafter, referred to as a “TEM”). In this case, processing and observation are alternately repeated in order to position a region to be analyzed at a leading end of a needle. Thus, a risk of damaging the sample increases. One holder is preferably shared and repeatedly used between the FIB and the TEM for purposes of a reduction of the risk that the sample is damaged and efficiency of work. PTL 2 describes a sample holder including an atmosphere-isolation mechanism that prevents a sample from altering by an atmospheric effect during a movement between an FIB and a TEM.