There are few topics in lithography for which there are dedicated conferences outside of SPIE’s Advanced Lithography and Patterning Symposium. However, for one topic – masks – there are remarkably three conferences: Photomask Technology, Photomask Japan (PMJ), and the European Mask and Lithography Conference (EMLC). Of these conferences, Photomask Technology is the largest, and it is the oldest one, having descended from the BACUS Symposium, which was first held in 1981. For nearly two decades, BACUS took place in Silicon Valley, but in the late 1990s the conference organizers made the inspired decision to move the meeting to Monterey, California, which has proven to be a nice location for a lithography conference. Along with the move to Monterey, the conference also formally lost the BACUS title, although it remains under sponsorship of the BACUS technical group, and many lithographers continue to this day to refer to the Photomask Technology Conference as BACUS. Another enhancement came to this event in 2017, when the International Conference on Extreme Ultraviolet Lithography co-located with the Photomask Technology Conference in Monterey.

A few years after the first BACUS Symposium, EMLC was first held. Considering the amount of critical lithographic technology that is generated in Europe, it is appropriate that there be a lithography conference held regularly in Europe. Since 1993 EMLC has been chaired by Dr. Uwe Behringer. Unquestionably, the continuing success of this conference has owed much to his energy and commitment over the years. Next year will be the 40^th anniversary of EMLC, but the conference will have new leadership, as Dr. Behringer has decided to retire from chairing EMLC. For your many years of service to the international lithography community, thank you, Uwe!

The last of the lithography conferences concentrating on mask technology to be established was Photomask Japan, which was first held in 1994. Many materials used in mask-making, particularly resists and mask blanks, are made in Japan, and numerous tools for mask-making are supplied by Japanese companies. It is natural for an annual conference that is focused on mask technology to be held in Japan. Since PMJ is typically held in April, it also gives visitors to Japan the opportunity to view beautiful cherry blossoms.

SPIE publishes the proceedings papers from all three of these mask-centric conferences, as well as the International Conference on Extreme Ultraviolet Lithography. Presenters at all lithography conferences supported by SPIE are also encouraged to submit manuscripts to JM³ based on material that was first presented at these conferences.