Interview: Sorin Cristoloveanu, IMEP-LAHC

Sorin Cristoloveanu, IMEP-LAHC:

« SHG gives us a new SOI wafer characterization technique »

US-based equipment manufacturer FemtoMetrix has just installed its first-ever Second Harmonic Generation (SHG) instrument at IMEP-LAHC. Read on to learn more about this innovative prototype.
SHG is a surface and interface characterization technique for thin layer materials. Here is how it works: A femtosecond laser is focused on the surface of the material. The second harmonic of the signal reflected delivers information like the presence of metal contaminants, imperfections in the interfaces, parasitic charge, and the local electrical field.
The technique is particularly suitable for SOI substrates, whose ultra-thin layers (measuring just nanometers thick) raise challenges like not knowing to which interface the signals measured should be attributed when traditional measurement methods are used.

What spurred FemtoMetrix to set up the prototype in Grenoble?
Grenoble is a hub for SOI R&D. And our lab had worked with FemtoMetrix and Vanderbilt University in Tennessee for more than two years. There was SHG theory, of course, and there had been some informal lab experimentation, but we had to overcome some major hurdles to produce a prototype that could one day become an industrially-manufactured product.

Who gets to use the prototype and what for?
The equipment is at IMEP-LAHC, where it will be used for Ph.D. research starting in early 2015. We plan to characterize as many samples as we can, giving FD-SOI priority. The goal is to determine the metrology rules for the instrument. We are in talks with STMicroelectronics, Soitec, and Leti, and we are open to working with other interested organizations willing to send us their wafers.

Contact: ionica@minatec.grenoble-inp.fr

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