In recent years, as represented by smart phone and head mounted device, high definition displays have been rapidly developed, and the importance of phase shift mask (PSM) to resolve high definition patterns is increasing. However, since the conventional PSM has high reflection characteristic, high reflection of PSM causes large line width distribution due to the influence of the standing wave on the resist pattern, which hinders the formation of high definition patterns. We have developed PSM with low reflectivity by using Cr and MoSi material. It has been confirmed that the developed PSM blanks show significant low reflection characteristics.
Half-tone masks are essential for process reduction and shape control of photo reactive organic material in FPD, the importance of half-tone masks is increasing in recent large sized and high resolution displays. Half-tone masks are categorized as top layer type and bottom layer type. Process reduction and short term mask production are possible in bottom layer half-tone mask. Therefore it is expected that the demand of bottom layer half-tone mask will be increasing in future. Ulvac coating has developed two types of bottom layer half-tone mask blanks which half-tone layers are composed in Cr material or MoSi material respectively. Since each bottom layer half-tone mask blanks has different advantage in process and characteristics, it is possible to select half-tone mask blank by customer requirement. We will discuss process and characteristics of two types bottom layer half-tone mask blanks in this meeting.
Semiconductor technology nodes are steadily miniaturizing. On the other hand, various efforts have
been made to reduce costs, mass production lines have shifted from 200 mmφ of Si wafer to 300 mmφ,
and technology development of Si wafer 450 mmφ is also in progress.
As a photomask, 6-inch size binary Cr mask has been used for many years, but in recent years, the use
of 9-inch binary Cr masks for Proximity Lithography Process in automotive applications, MEMS,
packages, etc. has increased, and cost reduction has been taken.
Since the miniaturization will progress in the above applications in the future, products corresponding
to miniaturization are also desired in 9-inch photomasks.
The high grade Cr - binary mask blanks used in proximity exposure process, there is a prospect of
being able to use it by ULVAC COATING CORPORATION's tireless research. As further demands for
miniaturization, KrF and ArF Lithography Process, which are used for steppers and scanners , there are
also a demand for 9-inch size Mask Blanks.
In ULVAC COATING CORPORATION, we developed a 9 - inch size KrF PSM mask Blanks
prototype in 2016 and proposed a new high grade 9 - inch photomask. This time, we have further
investigated and developed 9-inch size ArF PSM Mask Blanks corresponding to ArF Lithography
Process, so we report it.
The fine pattern exposure techniques are required for Flat Panel display applications as smart phone, tablet PC recently. The attenuated phase shift masks (PSM) are being used for ArF and KrF photomask lithography technique for high end pattern Semiconductor applications. We developed CrOx based large size PSM blanks that has good uniformity on optical characteristics for FPD applications. We report the basic optical characteristics and uniformity, stability data of large sized CrOx PSM blanks.