A Novel High-Resolution Scanning Electron Microscope for the Surface Analysis of High-Aspect-Ratio Three-Dimensional Structures

概要

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A scanning electron microscope (SEM) with an immersion-type objective lens has been developed. The objective lens generates a strong axial magnetic field of about 0.17 T at a wafer surface and has a very short focal length of about 2.5 mm. The SEM realizes an image resolution of 30Å at 0.7 kV accelerating voltage. The capability to observe the bottom of a trench with a 5.3 μm depth and 0.55 μm width and that of a hole with a 0.46 μm diameter and 1.6 μm depth has been demonstrated at a low accelerating voltage of 0.5〜1.5 kV. A good measurement reproduceability of 5 nm /3σ(σ: standard deviation) has been achieved in the measurement of the 0.55 μm SiO_2 line pattern on the bottom of a trench of 0.55 μm width and 5.3 μm depth. The SEM has been applied to the observation of 64MDRAM cell patterns with a 0.4 μm design rule.
社団法人応用物理学会の論文
1991-09-15