Tohru Satake

Electron beam inspection system for semiconductor wafer based on projection electron microscopy: II

Optical inspection systems and/or electron beam inspection systems are quite useful tools for the yield management in the semiconductor process. However, they have some issues of difficulties for the application to the yield management after 100nm-technology node generation. Optical inspection systems have a resolution limit by diffraction phenomena. On the other hand, electron beam inspection systems based on scanning electron microscopy (EBI-SEM) have the limit of inspection speed. Both limits are serious matter for the application to yield management after 100nm-technology node generation. We have developed the electron beam inspection system based on projection electron microscopy (EBI-PEM), having both performances of inspection speed of optical types and spatial resolution of EBI-SEM. The system has been improved on the signal electron collection efficiency and transmittance of the electron optical system. We also have developed high rate and sensitive signal detection system. Then we considered that the inspection speed of several times faster than the conventional EBI-SEM is feasible at the spatial resolution less than 100nm.

Inspection performances of the electron beam inspection system based on projection electron microscopy

The production prototype of an electron beam inspection system based on projection electron microscopy (EBI-PEM) has been developed. Inspection performances of the EBI-PEM were evaluated using the programmed defect standard wafer delivered by SELETE. We confirmed the EBI-PEM had the same inspection speed, 9 cm2/h, as the conventional electron beam inspection system based on scanning electron microscopy (EBI-SEM) under the following conditions: pixel size of 50 nm and defect capture rate of more than 80%. Furthermore, the EBI-PEM achieved an inspection speed of 36 cm2/h. This inspection speed is four times higher than that of the EBI-SEM. The EBI-PEM would be an effective tool for inspection subsequent to the 90 nm technology node generation.

Fast atom beam bombardment secondary ion mass spectrometry: FAB-SIMS

Abstract FAB-SIMS is a surface analysis method that uses bombardment by a fast atom beam as the probe instead of a conventional ion beam. Because FAB carries no electric charge, this method is particularly effective for insulator analysis. An apparatus for FAB-SIMS consists of a FAB source, a secondary ion detector with an energy filter, and a quadrupole mass filter. The FAB source is operated under a DC diode discharge. This source has useful characteristics for controlling the energy and density of the FAB. The ion energy filter is composed of four wire electrodes and has been investigated through experiments and numerical simulations. Because the filter can separate positive and negative ions, attaching the filter on the stage next to the quadrupole mass filter enables simultaneous detection of positive and negative secondary ions in the FAB-SIMS apparatus.