When manufacturing a semiconductor device having a three-dimensional structure, grasping the positional relationship between the upper and lower structures is important. Our “Dig & See” technology using GFIS-SIM enables such a device to be processed and its lower layers observed by quickly switching ion beams. With this technology, the digging of only the narrow areas of interest expedites delayering. Moreover, the structure of the lower layer can be exposed by top-down delayering and observed without using another tool. Unlike with other methods, the position of the lower layer can be determined with reference to the upper layer position.
In recent years, miniaturization and multilayering have been key technologies in order to improve performance and integration of semiconductor devices. For a fine dimension control of semiconductor devices, the critical-dimension scanning electron microscope (CD-SEM) has been widely used. In addition to this technique, the recent advent of 3D semiconductor devices has created a strong demand for new dimension control method. We have developed a scanning ion microscope with a gas field ion source (GFIS-SIM) to meet this demand. The GFIS has almost the same brightness as a field emission type electron source, and it is possible to switch from a light-element ion used for observation to a heavy-element ion used for processing. In this way, we can achieve a high degree of freedom in the sample chamber (regarding sample size and inclination), an observation resolution of better than 1 nm, and the sample processing function with one identical ion source and beam column. We succeeded in observing the internal structure of several samples using this technique. We dug each sample with 2 kV neon ions to expose the internal structure, switched the ion beam, and successfully observed its internal structure with a hydrogen ion beam of 30 kV.