EUV lithography is the most promising technology for semiconductor device manufacturing of the 10nm node and
beyond. The image border is a pattern free dark area around the die on the photomask serving as transition area between
the parts of the mask that is shielded from the exposure light by the Reticle Masking (REMA) blades and the die. When
printing a die at dense spacing on an EUV scanner, the reflection from the image border overlaps edges of neighboring
dies, affecting CD and contrast in this area. This is related to the fact that EUV absorber stack reflects 1-3% of actinic
EUV light. To reduce this effect several types of image border with reduced EUV reflectance (<0.05%) have been
proposed; such an image border is referred to as a black border. In particular, an etched multilayer type black border was
developed; it was demonstrated that CD impact at the edge of a die is strongly reduced with this type of the black border
(BB). However, wafer printing result still showed some CD change in the die influenced by the black border reflection. It
was proven that the CD shift was caused by DUV Out of Band (OOB) light from the EUV light source. New types of a
multilayer etched BB were evaluated and showed a good potential for DUV light suppression.
In this study, a novel BB called ‘Hybrid Black Border’ (HBB) has been developed to eliminate EUV and DUV OOB
light reflection by applying optical design technique and special micro-fabrication technique. A new test mask with HBB
is fabricated without any degradation of mask quality according to the result of CD performance in the main pattern,
defectivity and cleaning durability. The imaging performance for N10 imaging structures is demonstrated on
NXE:3300B in collaboration with ASML. This result is compared to the imaging results obtained for a mask with the
earlier developed BB, and HBB has achieved ~3x improvement; less than 0.2 nm CD changes are observed in the
corners of the die. A CD uniformity budget including impact of OOB light in the die edge area is evaluated which shows
that the OOB impact from HBB becomes comparable with other CDU contributors in this area. Finally, we state that
HBB is a promising technology allowing for CD control at die edges.
EUV lithography is the most promising technology for semiconductor device manufacturing of the 10nm node and beyond. The EUV mask is a key element in the lithographic scanner optical path. The image border is a pattern free dark area around the die on the photomask serving as transition area between the parts of the mask that is shielded from the exposure light by the Reticle Masking (REMA) blades and the die. When printing a die at dense spacing on an EUV scanner, the EUV light reflection from the image border overlaps edges of neighboring dies, affecting CD and contrast in this area. To reduce this effect an etched multilayer type black border was developed, and it was demonstrated that CD impact at the edge of a die is strongly reduced with this type of the black border (BB). However, wafer printing result still showed some CD change influenced by the black border reflection. It was proven that the CD shift was caused by DUV Out of Band (OOB) light which is emitted from EUV light source. New types of a multilayer etched BB were evaluated and showed a good potential for DUV light suppression. In this study, a novel black border called Hybrid Black Border has been developed which allows to eliminate EUV and DUV OOB light reflection. Direct measurements of OOB light from HBB and Normal BB are performed on NXE:3300B ASML EUV scanner; it is shown that HBB OOB reflection is 3x lower than that of Normal BB. Finally, we state that HBB is a promising technology allowing for CD control at die edges.
We demonstrate a high quality 3D image reproduced by a full-color, full-parallax holographic stereogram (HS) with
high-density light-ray recording. The full-parallax HS is produced by a holographic 3D printer, which is an electronic
controlled optical system for automatic recording. The HS consists of a 2D array structure of volume type elementary
holograms, and full-parallax 3D image can be observed under white-light illumination. But the quality of the
reconstructed image from the HS affected by the array structure which obstructs the reconstructed image. Then, in order
to suppress the array structure, the size of elementary holograms is reduced to 50 × 50 micrometers as an invisible size.
If the size of elementary holograms is reduced, however, the number of reproducible light-rays is decreased due to the
diffraction limit. Thus we evaluate the light-ray density reconstructed by the full-parallax HS with the measurement of
the angular resolution of diffracted light, and demonstrate the visual image quality of reconstructed 3D image when
high-density light-rays are recorded.
In the experiments, we prepared samples of HSs in which sizes of elementary holograms are from 50 to 400 micrometers,
and measured the angular resolution of diffracted light. Moreover we synthesized HSs of 3-D artificial images, and
visually evaluated their image quality. As a result, decrease in angular resolution was observed as the element size was
reduced, though the angular resolution of reproduced light-rays is 1.08 degrees when the element size is 50 × 50
micrometers. But the image quality of 50 micrometers pitch HS was confirmed to be high enough to suppress the array
structure when the depth of the reconstructed image is not very deep.
In conventional LED backlight as that used in mobile liquid crystal displays (LCDs), typically the structure consists of a
light guide, a diffusing sheet, prism sheets and so on. In this work we would like to propose a novel light guide where we
have applied a special diffraction grating technology which provides a high performance with a thinner backlight. The
special designed diffraction gratings on the light guide redirects incident light by diffraction to the front direction without
the utilization of prism sheets. For testing the performance we made a diffraction grating light guide suited for a 2.4 inch
backlight with 4 LEDs in a trial. As a result, the backlight that consisted of a diffraction grating light guide, with either a
single or none prism sheet achieved equivalent performance to conventional backlights.
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