Since the second half of the twentieth century, the semiconductor industry has conducted a frantic search to reduce the size of the components used in these circuits. This makes it possible to increase operating frequency by reducing transit times, and to increase component density, thereby multiplying computing power. During this seminar, I described the main technologies used to achieve these goals. In particular, I showed how optical lithography, thought to be limited to reproducing structures of the order of the wavelength used, can now reach a size up to almost ten times smaller than the wavelength. Nevertheless, for the next generation of integrated circuits, new optical techniques using very short wavelengths, from soft X to hard X, are now being explored. I have described these techniques and pointed out the difficulties in implementing them. I have also presented other lithography techniques that can go down to below 10 nm (the diameter of a human hair is of the order of 50,000 nm), using beams of charged particles such as electrons or ions. As we have seen, these techniques cannot yet meet the mass production requirements of the semiconductor industry. They do, however, make it possible to manufacture transistors with gate widths of less than 10 nm, proving that silicon still has a few years ahead of it. They are also widely used by the scientific community, which does not have the yield constraints of the semiconductor industry. These so-called top-down technologies have enabled nanoscience to flourish, as they not only enable the fabrication of extremely small objects, but also the construction of a set of structures that can be used to individually measure a nanostructure. They are, for example, very useful for chemists who use bottom-up synthesis to manufacture their nano-objects, and who generally only have access to the collective properties of their nanoparticles. I've outlined some possible ways of making these techniques compatible with industrial requirements.
Finally, I've talked about nanoimprinting, a very economical alternative to the previous techniques that enables high resolution at high throughput, but still requires considerable technological development. It is nevertheless a feasible technique for reproducing simple nanostructures on large surfaces, with important applications in photovoltaics, smart materials, etc
I concluded this seminar with a description of the transfer techniques that enable engraving to be carried out in compliance with the lithography drawing rule. These are reactive ion etching techniques that can achieve very high aspect ratios while maintaining very vertical sidewalls.
