After a complete cancellation of the European Mask and Lithography Conference in 2020 and a virtual event with panel discussions in 2021, the 37th edition could again be held as a face-to-face event from 20 June to 22 June 2022 in Leuven (Belgium).
Impressive: The great variety of lectures
There were 41 papers presented, including 4 keynote, 15 invited, 8 student presentations and 9 posters. The content of the presentations reflected the developments of the last 3 years at the forefront of lithography technology. While 3 years ago there was still discussion about how EUV lithography (EUV = extreme ultraviolet light with a wavelength of 13.5 nm) would prove itself in semiconductor mass production, this has now become the norm. The issue now is how this technology can be used to push the limits of what is possible, both in terms of structure sizes and with new types of transistors - adapted to the superfine structures that are now possible.
We risked a brief look into the future …
This became particularly clear in the first keynote presentation by Luc van den Hove, President of the IMEC. In an outlook up to the year 2036, he illustrated how Moore's Law will be implemented: by further scaling up to the technology node 1nm (!), by new transistor types, starting with so-called nanosheet transistors, and by stacking the transistors into the 3rd dimension.
In the keynote by Frank Abboud (Intel) and in further 6 presentations, the tasks that have already been solved for the production of EUV masks applicable in mass production and which will be solved in the future were addressed directly and in detail. In contrast to conventional DUV masks, which have light shining through them, EUV masks are in principle mirrors with an absorber layer, which is then removed during mask production according to the desired geometries. Significant progress is still possible and can be expected in the design and materials of the mirror and absorber layers.
Especially in the production of masks, a new class of problems and corresponding solution approaches have emerged in recent years. The desire to create ever smaller structures on the wafer leads to an approach called "Inverse Lithography" (ILT) for all mask technologies. The diffraction of light when imaging small structures inevitably results in a different image on the wafer than that on the mask. However, in a computationally intensive process, it is possible to determine what the pattern on the mask would have to look like to produce the desired image on the wafer. The pattern on the mask then contains many additional small structures and these are no longer rectangular, like most of the structures to be created on the wafer, but have some kind of curvilinear edge.
Young talents, go ahead!
A cross-section of all the topics dealt with was also found in a format that was carried out for the first time at the EMLC: two sessions with exclusively student contributions, which was considered very successful by all participants and speakers. To support research activities in the student area, Carl-Zeiss AG has endowed the "Zeiss Award for Talents in Photomask Industry", which this year was awarded to Cansu Hanim Canpolat-Schmidt et al. from the TU and Fraunhofer ENAS Chemnitz respectively for their presentation on questions concerning the joint use of optical and electron beam lithography (see photo above).
Reinhard Galler, EQUIcon Software GmbH Jena
