For a recent replacement metal gate (RMG) technology using a SOI substrate, residue from the dummy gate formed a defect that affected the RMG formation. In this FINFET technology, the high aspect ratio of the gate makes removing the dummy gate very difficult. Residue is left behind, especially in multi-fin structures. This residue was poorly detected by existing Broad-Band-Plasma inspection and thus required Electron Beam Inspection. However, this physical inspection is challenging due to high aspect ratio of the gate and an insulating wafer surface. The defect was verified using TEM, and careful sample prep is shown to be critical to verify the defect. The high aspect ratio and insulating sample in a charged-particle inspection is investigated with Monte-Carlo (MC) simulations.

E-beam Inspection (EBI) is used for in-line detection of defects in semiconductor manufacturing. This paper highlights a physical defect mode application where traditional defect inspection techniques, such as broadband plasma and dark field inspection were ineffective in finding the defects of interest. It describes the inspection setup and verification with failure analysis and the application of the technique. This inspection was implemented as a process monitor to detect excursions. The amount of process "ON" time after an etch-chamber part's change was identified as the main factor in MOAT defectivity. The correlation between EBI defect detection and leakage at in-line electrical test was further investigated by looking at each individual die and the leakage associated with the MOAT only. It was observed that the increased leakage could be due to another process factor in the process than a MOAT etch or a MOAT defect that was missed during the EBI inspection.

In-line E-beam inspection may be used for rapid generation of failure analysis (FA) results for low yielding test structures. This approach provides a number of advantages: 1) It is much earlier than traditional FA, 2) de-processing isn’t required, and 3) a high volume of sites can be processed with the additional support of an in-line FIB. Both physical defect detection and voltage contrast inspection modes are useful for this application. Voltage contrast mode is necessary for isolation of buried defects and is the preferred approach for opens, because it is faster. Physical defect detection mode is generally necessary to locate shorts. The considerations in applying these inspection modes for rapid failure analysis are discussed in the context of two examples: one that lends itself to physical defect inspection and the other, more appropriately addressed with voltage contrast inspection.