Recently, much attention has been paid on nanoimprint lithography (NIL) because of its capability for fabricating device
at a low cost without multiple patterning. It is considered as a candidate for next generation lithography technology. NIL
is one to one lithography and contact transfer technique using template. Therefore, the lithography performance depends
greatly on the quality of the template pattern. And there are some challenges to be solved for defect repair of template
because pattern size of template is as same as that of wafer.
In order to realize the defect repair of template using electron beam (EB) repair tools, it is necessary to control the EB
irradiated area and dose amount of EB repair process more accurately. By optimizing these conditions, EB repair process
for template has been improved.
In this paper, we evaluated etching repair of a master template and the imprinting to replica. Programmed missing defects
on master template were repaired by changing parameters of EB repair tool. It was confirmed that the relationship of
critical dimension (CD) and depth of etching repair process for master template and the influence on replica imprinting.
As a result, the repair process for master template with hole pattern enables the corresponding CD error of the replica
template to be less than ±10% of the target CD.
UV nano imprint lithography (UV-NIL) has high-throughput and cost-effective for complex nano-scale patterns and is
considered as a candidate for next generation lithography tool. In addition, NIL is the unmagnified lithography and
contact transfer technique using template. Therefore, the lithography performance depends greatly on the quality of the
According to ITRS 2013, the minimum half pitch size of Line and Space (LS) pattern will reach 1x nm level within
next five years. On the other hand, in hole pattern, half pith of 2x nm level will be required in five years. Pattern shrink
rate of hole pattern size is slower than LS pattern, but shot counts increase explosively compared to LS pattern due to its
data volume. Therefore, high throughput and high resolution EB lithography process is required.
In previous study, we reported the result of hole patterning on master template which has high resolution resist
material and etching process. This study indicated the potential for fabricating 2xnm hole master template .
After above study, we aim at fabricating the good quality of 2xnm master template which is assured about defect, CD
uniformity(CDU), and Image placement(IP). To product high quality master template, we develop not only high
resolution patterning process but also high accuracy quality assurance technology. We report the development progress
about hole master template production.
Nano imprint lithography (NIL) is one to one lithography and contact transfer technique using template. Therefore, the lithography performance depends greatly on the quality of the template pattern. In this study, we investigated the resolution and the defect level for hole patterning using chemical amplified resists (CAR) and VSB type EB writer, EBM9000. To form smaller pattern with high quality, high resolution resist process and high sensitivity etching process are needed. After these elements were optimized, we succeeded to form 24 nm dense hole pattern on template. In general, it is difficult to suppress the defect density in a large area because of fogging effect and process loading and so forth. However, from the view point of defect quality, 26 nm hole pattern is achieved to form with practical level in a large area. Therefore, we indicate the capability of forming 26 nm hole master template which will be required in 2019 from ITRS2013. These results show that this process is possible to obtain less than 30 nm hole pattern without enormous writing time. As future work, we will imprint master to replica template and check the printability.
Nanoimprint lithography (NIL) technology is in the spotlight as a next-generation semiconductor manufacturing technique for integrated circuits at 22 nm and beyond. NIL is the unmagnified lithography technique using template which is replicated from master templates. On the other hand, master templates are currently fabricated by electron-beam (EB) lithography. In near future, finer patterns less than 15nm will be required on master template and EB data volume increases exponentially. So, we confront with a difficult challenge. A higher resolution EB mask writer and a high performance fabrication process will be required. In our previous study, we investigated a potential of photomask fabrication process for finer patterning and achieved 15.5nm line and space (L/S) pattern on template by using VSB (Variable Shaped Beam) type EB mask writer and chemically amplified resist. In contrast, we found that a contrast loss by backscattering decreases the performance of finer patterning. For semiconductor devices manufacturing, we must fabricate complicated patterns which includes high and low density simultaneously except for consecutive L/S pattern. Then it’s quite important to develop a technique to make various size or coverage patterns all at once. In this study, a small feature pattern was experimentally formed on master template with dose modulation technique. This technique makes it possible to apply the appropriate exposure dose for each pattern size. As a result, we succeed to improve the performance of finer patterning in bright field area. These results show that the performance of current EB lithography process have a potential to fabricate NIL template.
ArF immersion lithography combined with double patterning has been used for fabricating below half pitch 40nm devices. However, when pattern size shrinks below 20nm, we must use new technology like quadruple patterning process or next generation lithography (NGL) solutions. Moreover, with change in lithography tool, next generation mask production will be needed. According to ITRS 2013, fabrication of finer patterns less than 15nm will be required on mask plate in NGL mask production 5 years later . In order to fabricate finer patterns on mask, higher resolution EB mask writer and high performance fabrication process will be required. In a previous study, we investigated a potential of mask fabrication process for finer patterning and achieved 17nm dense line pattern on mask plate by using VSB (Variable Shaped Beam) type EB mask writer and chemically amplified resist . After a further investigation, we constructed higher performance mask process by using new EB mask writer EBM9000. EBM9000 is the equipment supporting hp16nm generation's photomask production and has high accuracy and high throughput. As a result, we achieved 15.5nm pattern on mask with high productivity. Moreover, from evaluation of isolated pattern, we proved that current mask process has the capability for sub-10nm pattern. These results show that the performance of current mask fabrication process have the potential to fabricate the next-generation mask.
Photomask used for optical lithography has been developed for purpose of fabrication a pattern along with finer
designed rules and increase the productivity. With regard to pattern fabrication on mask, EB (Electron beam) mask
writer has been used because it has high resolution beam. But in producing photomask, minimum pattern size on mask is
hits a peak around 40nm by the resolution limit of ArF immersion systems. This value is easy to achieve by current EB
writer. So, photomask process with EB writer has gotten attached to increase turnaround time.
In next generation lithography such as EUV (Extreme ultraviolet) lithography and Nano-imprint lithography, it is
enable to fabricate finer pattern beyond the resolution limit of ArF immersion systems. Thereby the pattern on a mask
becomes finer rapidly. According to ITRS 2012, fabrication of finer patterns less than 20nm will be required on EUV
mask and on NIL template. Especially in NIL template, less than 15nm pattern will be required half a decade later. But
today’s development of EB writer is aiming to increase photomask’s productivity, so we will face a difficulty to fabricate
finer pattern in near future.
In this paper, we examined a potential of mask production process with EB writer from the view of finer pattern
fabrication performances. We succeeded to fabricate hp (half-pitch) 17nm pattern on mask plate by using VSB (Variable
Shaped Beam) type EB mask writer with CAR (Chemically Amplified Resist). This result suggests that the photomask
fabrication process has the potential for sub-20nm generation mask production.