Oxygen-map image of 64-Mbit DRAM
Conventional TEM has mainly been used to observe the structures of microscopic regions. However, TEM-EELS-which excites inner-shell electrons of elements in a test specimen, disperses the electron beam (which loses energy), and forms an image-can create elemental maps and observe the state of chemical bonding.
Through development of an electron spectroscopic instrument using a scanning transmission electron microscope (STEM), it has become easy to observe elemental distributions in real time. By dispersing the energy of the electrons that pass through the sample while the electron beam is scanned over the sample surface, this instrument can create an elemental map in real time; accordingly, it is applicable to the development of processes such as fabrication of semiconductor devices.
TEM image (left) and nitrogen-map image (right)
of 64-Mbit DRAM
It main features are (a) spatial resolution of 1 nm; (b) selection of target elements as needed during observation and accurate identification of boundaries between heterogeneous elements; and (c) browsing fields of view and selection of magnification ratio during observation of elemental maps.
The figure shows high-resolution images of a 64-Mbit DRAM taken by this instrument. The configuration of the elemental map of capacitor sections and insulator sections can be clearly seen from the "oxygen map" image and "nitrogen map" images.
