The semiconductor industry is growing at an annual rate of 6.9%, and the production of semiconductor devices is increasing accordingly. Currently, device manufacturing using Extreme Ultraviolet (EUV), referred to as 2 nm technology, has begun for AI and mobile phone devices. On the other hand, the production of devices using >90nm technology, known as mainstream, for the automobile industry and sensing devices, including power, analog, and discrete, is also increasing, leading to an increase in the production of photomasks. However, the reality is that the production of photomasks for the relevant technology is using outdated equipment, and there is a need for equipment with high productivity. In this study, we investigate how e-beam masks for devices used in the mainstream technology compares to masks manufactured with current high-productivity DUV laser equipment and will focus on the following aspects and provide a comprehensive report. Comparison with manufactured masks based on current technologies in terms of CDU, Registration, resolution, printability and so on.
EUV Lithography is an important technology that drives semiconductor device miniaturization. It is currently undergoing high volume manufacturing (HVM) of 3 nm logic node and development of 2 nm node by leading-edge semiconductor manufacturers. EUV mask technology is becoming increasingly important factor for EUV lithography. Mask resolution requirement is under 25nm for 2nm node Technology node. DNP has developed the EUV mask process with using the low-sensitivity-high-resolution resist and multi beam mask writer (MBMW) and This process shows promising capability on the resolution for 2nm Logic technology. For A14 Technology need more high resolution mask, In this paper, we present a comprehensive study on mask processes that possess a resolution of 20nm or below and techniques aimed at enhancing lithography contrast.
In semiconductor manufacturing for the 3nm node, 2nm node and beyond generations, Extreme ultraviolet lithography (EUVL) is an essential technology, and within that, photomask technology plays an important role. Currently, photomasks for EUVL are manufactured with a multi beam mask writer (MBMW) that uses over 200,000 electron beams to achieve high efficiency and high precision. However, it is said that the chemical amplification resist for EB lithography has already reached its limit, and forming a 10nm pattern on a mask is extremely difficult. Last year, We reported mask development using Ultra High Resolution CAR resists. In this report, we present the latest mask development status using chemical amplification resists and alternative resists to achieve even higher resolution.
We have been researching new mask blank materials for the next generation lithography (NGL) and developed
a new mask blank with low-k phase shifter [1] [2]. The low-k phase shifter consists of only Si and N. In our previous
work, we reported the advantages of developed SiN phase shift mask (PSM) [2]. It showed high lithographic
performance and high durability against ArF excimer laser as well as against cleaning. In this report, we further verified
its high lithographic performance on several types of device pattern. The SiN PSM had high lithographic performance
compared with conventional 6% MoSi PSM. Exposure latitude (EL) and mask enhancement factor (MEEF) were
especially improved on originally designed Gate, Metal and Via patterns.
The retardation of the development of NGL techniques causes the extension of ArF immersion lithography for 1x-nm node. We have been researching the new phase shift mask's (PSM) material for the next generation ArF lithography. In this reports, we developed the low-k, high transmission PSM and evaluate it. The developed new PSM shows good lithographic performance in wafer and high ArF excimer laser durability. The mask processability were confirmed such as the CD performance, the cross section image, the inspection sensitivity and repair accuracy.
New process with hard-mask (HM) blanks was evaluated as one of candidates for photomasks beyond 45nm-node.
Through the fabrication of gate-layer photomasks, aptitude of the HM process for practical use was confirmed from the
view of controllability on CDs and defects. Although conventional process for attenuated PSM was shown to have
critical CD error which belongs to the "patterns" in bright-field masks, experimental data proved effectiveness of the
HM process to control CDs after process optimization. With the HM blanks, remarkable reduction of CD error more
than 80% of conventional process was confirmed. In this report, peculiar opaque defects are also shown to be a critical
issue on the HM process. From results of design of experiment (DOE), combining the proper means to prepare the HM
blanks with the optimized HM etching condition, these defects were proved to be controlled within the tolerance for
production. Through the investigations, validity of the HM process on practical use for mask fabrication of 45nm-node
and beyond is considered as conclusions.
The CD requirements for the 45nm-node will become tighter so as it will be difficult to achieve with 65nm node
technologies. In this paper, a method to improve resolution by using DRECE (Dry-etching Resistance Enhancement
bottom-Coating for Eb) will be described. After all, DRECE has five times as high dry-etch resistance than the EB resist,
and this enables to accept higher anisotropic dry etching condition. By optimizing dry etching conditions, the CD
iso-dense bias dropped to 1/3 and the CD shift was reduced to 1/2. Also, there was no negative effect to CD uniformity.
From these results, we propose the use of DRECE for the 45nm-node technology.
The mask-making process for 45nm-node and beyond demands higher resolution and CD accuracy. To meet the requirements, the multi-layer resist system is developed as one of the solutions. BIL (Bottom Insulating Layer) can correct the profile of CAR (Chemically Amplified Resist). CAR shows profile degradation by photo-acid loss at the boundary of chrome and resist. The photo-acid loss induces excess footing in positive-tone CAR and under-cutting in negative-tone CAR. BIL reduced the profile degradation to less than half of the conventional resist system. BIL requires no extra mask process steps. Final CD linearity of isolated lines was improved by BIL. It is very beneficial for the patterning of sub-resolution assist features. Moreover, BIL with a hard-mask layer showed superior dry-etching bias performance.
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