Electron-microscope image of a CNT
"Carbon nanotubes" (CNTs) are cylindrical crystals of carbon with length of several tens of micrometers and diameter of 1-10 nanometers. By using CNTs as the probe in an atomic force microscope, it is possible to evaluate true surface metrology and high-level reproducibility over the long term.
An atomic force microscope used for semiconductor inspection is a device used in the fabrication process for LSIs for measuring three-dimensional deformation of fine circuit patterns formed on silicon wafers and for inspecting the end results. A key issue, however, is quickly identifying defects according to these inspection results and performing sensitive control as countermeasures.
In regards to measurements of next-generation LSIs, namely, LSIs with processed trench linewidth of 45 nm, the probe must have an extra-fine diameter; that is, 20 nm.
Electron-microscope
image of CNT probe
With a diameter of around 20 nm, the CNT probe developed by Hitachi can accommodate devices with processed gap linewidth of 45-32 nm. Moreover, the diameter of the CNT is constant from root to tip, and its abrasion resistance is outstanding; consequently, true surface metrology over the long term and high-level reproducibility are evaluated. As a result of combining this CNT with "StepInTM mode" (namely, few contacts between the probe and the measurement target), the operational lifetime of the probe is extended to an equivalent of measuring more than 1000 images.
