Noisy cracks, rough material

The acoustical waves emitted when a crack propagates in a material can change the crack’s trajectory. The waves create alternating smooth and rough textures on the changed surface of the material. The phenomenon was observed during research conducted by INAC, Leti, and Soitec on SOI wafers, which are made by cleaving silicon.

Small cavities, like dotted cutting lines, are made to control the cleavage plane. However, additional roughness (cavities of around 0.05 nm) also appears. We now know that this additional roughness is caused by the “noise” produced by the crack, whose phase speed is equal to the speed of the crack. The researchers will now try to eliminate this additional roughness to continue to improve Soitec’s substrates.

Contact: francois.rieutord@cea.fr

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