超高分解能FE-SEM

ultra-high resolution FE-SEM, ultra-high resolution SEM

[目次：装置]

1990年代後期に開発された、電界放出電子銃（FE電子銃、FEG）とインレンズ方式の対物レンズを組み合わせたSEM（インレンズ型FE-SEM）が、30kVの加速電圧で1nmを上回る分解能を実現し、超高分解能SEMと呼ばれた。ただし、このタイプでは、試料が対物レンズのポールピース内に置かれるので、試料の周辺の空間が狭く、数mm角で1～2mmの厚さの小さな試料しか扱うことができない。
その後、このような欠点を補うために、大きな試料も扱えるセミインレンズ方式の対物レンズや、セミインレンズ方式の対物レンズと静電レンズを組み合わせた低収差対物レンズが考案された。セミインレンズ型FE-SEM も含めて、FE電子銃を組み合わせることで1nm以上の分解能が得られるSEMを超高分解能SEMと呼んでいる。

The ultra-high resolution SEM, called the inlens type FE-SEM, is a SEM which achieves a resolution better than 1 nm at an accelerating voltage of 30 kV. This type of SEM was developed in the late 1990s combining a field emission gun (FEG) and an inlens objective lens. However in this type of SEM, as a specimen is placed inside the polepiece of the objective lens, only a narrow space is available for a specimen, that is, only a small specimen of a few mm squares and 1 to 2 mm thick can be handled.
Entering into the 2000s, in order to overcome this limitation (disadvantage), a semi-inlens objective lens and a low-aberration objective lens that combines a semi-inlens objective lens and an electrostatic lens were developed. The SEMs providing a resolution better than 1 nm, including not only an inlens FE-SEM but also a semi-inlens FE-SEM are currently called the ultra-high resolution SEM.