According to the IEEE Spectrum website, from late February to early March, a laboratory was created on the basis of the Belgian center Imec together with the American company KMLabs to study problems with semiconductor photolithography under the influence of EUV radiation (in the ultra-hard ultraviolet range). It would seem, what is there to study? No, there is a subject for study, but why establish a new laboratory for this? Samsung started producing 7nm chips half a year ago with partial use of EUV range scanners. TSMC will be joining soon. By the end of the year, both of them will start risky production with 5 nm standards, and so on. And yet there are problems, and they are serious enough to look for answers to questions in laboratories, and not in production.
The main problem in EUV lithography today remains the quality of the photoresist. The source of EUV radiation is plasma, not laser, as is the case with older 193nm scanners. The laser vaporizes a drop of lead in a gaseous medium and the resulting radiation emits photons, the energy of which is 14 times higher than the energy of photons in scanners with ultraviolet radiation. As a result, the photoresist is destroyed not only in those places where it is bombarded by photons, but also random errors occur, including due to the so-called fractional noise effect. The energy of photons is too high. Experiments with EUV scanners show that photoresists, which are still capable of working with 7 nm standards, demonstrate a critically high level of rejects when fabricated in 5 nm circuits. The problem is so serious that many experts do not believe in the early successful launch of the 5nm process technology, not to mention the transition to 3nm and below.
The problem of creating a new generation photoresist will be solved in the joint laboratory of Imec and KMLabs. And they will solve it from the point of view of a scientific approach, and not by selecting reagents, as has been done in the last thirty-something years. To do this, scientific partners will create a tool for a detailed study of the physical and chemical processes in the photoresist. Usually, synchrotrons are used to study processes at the molecular level, but Imec and KMLabs are going to create projection and measurement EUV equipment based on infrared lasers. KMLabs is just a specialist in laser systems.
Based on the KMLabs laser facility, a platform for generating high harmonics will be created. Usually, for this, a high-intensity laser pulse is directed into a gaseous medium, in which very high frequency harmonics of the directed pulse occur. With such a conversion, a significant power loss occurs, so that a similar principle of generating EUV radiation cannot be used directly for semiconductor lithography. But this is enough for experiments. Most importantly, the resulting radiation can be controlled both by pulse duration ranging from picoseconds (10-12) to attoseconds (10-18), and by wavelength from 6,5 nm to 47 nm. For a measuring tool, these are valuable qualities. They will help to study the processes of ultrafast molecular changes in the photoresist, ionization processes and exposure to high energy photons. Without this, industrial photolithography with standards less than 3 and even 5 nm remains in question.
Source: 3dnews.ru