STM breakthrough for computer chips
STM image of structured silicon substrate showing brighter flat terraces and darker edges, [Osaka University].
Claiming a world first, Japan-based researchers have used scanning tunnelling microscopy to image the atomically flat, vertical side-surfaces of 3D silicon crystals.
Striking STM images prove that such side-surfaces can be fabricated and spell good news for semiconductor manufacturers developing smaller, faster and more energy-efficient chips.
Spatial-derivative STM image; flat terraces become brighter and edges darker. The downstairs direction runs from left ((110) top-surface) to right ((-1-10) back-surface). [Osaka University]
Designing next generation computer chips requires new knowledge of the atomic structures of the side-surfaces.
With this in mind, researchers at Osaka University and the Nara Institute of Science and Technology used reactive ion etching, wet-etching and flash-annealing to fabricate a 3D vertical side-surface structure on a silicon wafer.
The side surface was then studied in atomic scale with STM, as well as atomic force microscopy, scanning electron microscopy and low-energy electron diffraction.
AFM and SEM revealed flat and smooth vertical side-surfaces without scallops while STM indicated that an atomically-flat structure had been realised.
Spatial-derivative STM image of atomically flat and ordered vertical side surfaces on 3D silicon substrate
“Our study is a big first step toward the atomically resolved evaluation of transistors designed to have 3D-shapes,” highlights Professor Azusa Hattori from the Nanoscience and Nanotechnology Centre, Osaka University.
“Our ability to directly look at the side-surfaces using STM proves that we can make artificial 3D structures with near-perfect atomic surface ordering,” adds Hidekazu Tanaka, from the Nanoscience and Nanotechnology Centre.
Research is published in Japanese Journal of Applied Physics.