In recent years, a sputter neutral particle mass spectrometry apparatus using a focused ion beam device and a light beam oscillation device has been developed. In light beam post-ionized neutral particle mass spectrometry using a focused ion beam, an ion beam is irradiated on a sample to generate neutral particles, and a light beam is made incident horizontally on the surface of the sample to perform post-ionization a single time. Here, a secondary ion mass spectrometry apparatus is equipped with a light beam for post-ionization to improve detection sensitivity. Therefore, the measuring system is simplified to facilitate optimization of the timing for irradiating the light beam and the timing for drawing in ions.
In such neutral particle mass spectrometry, since the output of the light beam is small, it has been necessary to make the light beams converge at a particular position on the sample surface in order to secure sufficient detection sensitivity. Therefore, to prevent background noise caused by direct contact of the light beams with the sample from occurring, the optical axis of the light beam has been required to be designed horizontal to, and at a fixed distance from the sample surface. As a result, the light beam irradiation timing needed to be delayed, and thus density per unit volume of a sputter neutral particle group decreased, causing a decline in yield.
In recent years, objects to be analyzed by the sputter neutral particle mass spectrometry apparatus have become microscopic. Therefore, there is a need for a sputter neutral particle mass spectrometry apparatus which is capable of improving detection sensitivity by increasing the yield of any element in the region of analysis.