Extreme-UV lithography (EUVL) is the most promising candidate of next generation technology for hp20nm node device manufacturing and beyond, however there are many critical issues to solve in the light source, tools, mask and photo resist. Regarding the development of a photo resist, it is necessary for high volume manufacturing (HVM) to improve LWR, resolution limit and sensitivity. Additionally, concerning about deterioration of a patterning performance by Out-of-Band (OoB) light existing in the EUV light, and contamination problem of exposure tool due to the photo resist outgassing are the key issues which have
to be resolved toward HVM by EUVL. Especially, the outgassing problem can become a significant issue for fine patterning under high dose exposure condition. This paper proposes the novel solution for these critical issues with the application of a top coat material which is named OBPL (Outgassing & out-of-Band Protection Layer) on photo resist. The key characteristics of OBPL material are to have a role in protection against the OoB adverse effect to keep up the photo resist performance, to suppress the outgassing from photo resist as a barrier layer and to enhance the lithographic performance such as photo resist profile and process window. In designing the OBPL material, the optical property needs having not only the high absorbance of DUV (Deep-UV) light in OoB range but also high transmittance for 13.5nm wavelength to prevent the sensitivity loss. Furthermore, it is found that the polymer backbone affects the outgassing barrier capability in previous evaluation. Based on these investigations, a state-of-the-art OBPL achieves quite a positive lithographic result with sufficient OoB absorption and outgassing suppression. Moreover, this material has applicability to all types of photo resist including NTD (Negative-Tone Development) process. This paper describes the result of the feasibility study for OBPL and the lithography performance with EUV full field
scanner.
Resists, underlayers, and new rinse processes were evaluated for negative tone development (NTD) using extreme ultraviolet (EUV) lithography. The most recently developed resists show resolution and sensitivity improvements. High remaining-film thickness was also achieved for better etching resistance. The underlayers smoothed the line width roughness (LWR) and prevented pattern collapse. In addition, the proposed NTD-compatible rinse process further assisted to prevent pattern collapse. The best NTD performance at EIDEC till date was achieved: 22 nm line and space (L/S) resolution, 5.4 nm LWR, and 16.8 mJ/cm2 sensitivity with annular illumination for a small-field exposure tool (SFET). Furthermore, an ultimate resolution of 17 nm L/S was achieved with x-dipole illumination of SFET. The lithographic performance of the best NTD resist is comparable to the typical positive tone development resist.
KEYWORDS: Extreme ultraviolet, Extreme ultraviolet lithography, Etching, System on a chip, Roentgenium, Photomasks, Line width roughness, Lithography, Chromophores, Silicon
Tri-layer process is the one of the key technique both for lithography and etching around Hp20nm patterning. In
applying for tri-layer process, we are focusing on inorganic type under layer which mainly containing Si atoms. This Si
type hard mask (Si-HM) can perform not only as the Lithography performance enhancement layer for fine pitch, but also
as the etching hard mask against bottom layer (spin on carbon : SOC). In this paper, we propose our new Si-HM
concepts to achieve high sensitivity, wide process window and good line edge roughness for hp 1Xnm generation. The
key point of our concepts is EUV sensitive unit in Si-HM. Our EUV sensitive unit strongly promotes acid generation
from PAG of EUV photo resist. Especially, for EUV NTD lithography process, EUV sensitive unit can perform as the
adhesion enhancer between Si-HM and photo resist at EUV exposed area.
As this result, hp18nm L/S pattern and hp24nm C/H pattern were successfully achieved by applying the EUV
sensitive Si-HM in EUV PTD process. Especially, as compared to organic UL, the 4th generation EUV sensitive Si-HM
showed 5~10% higher sensitivity and 10~25% wider process window (DOF and EL) with keeping LER. Moreover this
EUV-sensitive Si-HM could also enhance the ultimate resolution to Hp22nm L/S in EUV NTD process. On the other
hand, from the view point of etching hard mask, around hp 19 nm Si-HM L/S pattern could be transferred to SOC layer
successfully. We will present the high resolution concepts and performances of our latest EUV sensitive Si-HM for 1X
nm generation in EUV lithography.
EUV lithography (EUVL) is the most promising candidate of next generation technology for hp20nm node device manufacturing and beyond. However, the power of light source, masks and photo resists are the most critical issues for driving the EUVL. Especially, concerning about deterioration of the patterning performance by Out-of-Band (OoB) light existing in the EUV light, and contamination problem of exposure tool due to the resist outgassing are the key issues which have to be resolved in the material view point toward the high volume manufacturing by EUVL. This paper proposes the solution for these critical issues by applying the top coat material. The key characteristics for top coat material are the protection of the OoB effect, the prevention of the outgassing from resist as a barrier layer and enhancement of photo resist performance, like resist profile and process window. This paper describes the material design and performance. The optical property needs having the high absorbance of DUV light in OoB range and high transmittance for 13.5nm wavelength. Outgassing barrier property needs high broking property against non contamination chemical species from photo resist outgassing. The study of TOF-SIMS analysis indicates how much the polymer chemistry can impact for outgassing barrier property. The dependency of material design and lithography performance is also discussed.
For below Hp22nm generation, Hard-mask strategy is one of the key issues to achieve the good balance for
Lithography and Etching performance.
The thickness of resist should be thicker enough to obtain the etching margin for the substrate etching. However,
the thickness of photo resist (PR) needs to be thinner to obtain the good pattern collapse margin and resolution. In
order to solve this tread-off, the spin-on hard mask (HM) technology can be applied.
On the other hand, the ultra thin organic Underlayer (UL) being combined with the CVD-HM film stack is also
one of the processes for EUV lithography. In order to avoid the film loss of resist during UL open, the thickness of
UL must be thinner and the etch rate need to be faster. We studied the effect of UL design and thickness for the
EUV lithography performance.
For EUV lithography, the electron generation effect from UL is one of the key factors to improve the patterning
performance of resist. In this paper, we studied the suitable functional group for the Silicon containing HM(Si-HM)
for multilayer process and Org.-UL, which has high potential to generate 2nd electron and enhance the resist
performance, and discuss the material design and performance.
For the next generation lithography (NGL), several technologies have been proposed to achieve the 22nm-node devices
and beyond. Extreme ultraviolet (EUV) lithography is one of the candidates for the next generation lithography. In EUV
light source development, low power is one of the critical issue because of the low throughput, and another issue is Out
of Band (OoB) light existing in EUV light. OoB is concerned to be the cause of deterioration for the lithography
performance. In order to avoid this critical issue, we focused on development of the resist top coat material with OoB
absorption property as Out of Band Protection Layer (OBPL). We designed this material having high absorbance
around 240nm wavelength and high transmittance for EUV light. And this material aimed to improve sensitivity,
resolution and LWR performance.
For the next generation lithography (NGL), several technologies have been proposed to achieve the 22nm-node devices
and beyond. Extreme ultraviolet (EUV) lithography is one of the candidates for the next generation lithography. For
lithography processes, the Line width roughness (LWR) and the pattern collapse of resist are the most critical issues for
NGL, because of the small target critical dimension (CD) size and high aspect ratio. In this study, we design the new
concept of EUV Under layer (UL) material to meet these requirements and study the impact of polymer design for
pattern collapse behavior, pattern profile and LWR control by using EUV exposure tool.
Double patterning process with ArF immersion lithography has been developed as one of the most promising candidate
for hp32 node and beyond. However complicated process flow and cost of ownership are the critical issue for this
process. LELE (Litho-Etch-Litho-Etch) is the one of the standard process, but in order to reduce the process and cost,
that LFLE(Litho-Freezing-Litho-Etch) and LLE (Litho-Litho-Etch) process have been investigated as the alternative
process. In these processes, Organic Bottom-Anti-Reflective coating (BARC) is used two times with same film in both
1st Litho and 2nd Lithography process. In 2nd Lithography process, resist pattern will be printed at space area where
exposed and developed in 1st lithography process. Therefore, organic BARC needs to have process stability in Photo and
development step to keep good litho performance between 1st and 2nd lithography in LFLE / LLE process.
This paper describes the process impact of 1st exposure and development for organic BARC, and the LFLE / LLE
performance with optimized organic BARC will be discussed.
193nm immersion and Hyper NA lithography are used at 45nm and beyond. The next generation of lithography will use a new technology such as Double Pattering, EUV or EB. Double patterning is one of the currently acceptable technologies.
Three common double pattern techniques are Litho-Etch-Litho-Etch (LELE), freezing, and sidewall (spacer) process. From a technical standpoint LELE is a very promising process, except for the second litho alignment. However, the cost of ownership will be very high because LELE will cost about twice as much as the current single litho patterning process. In order to build up a suitable double patterning technique, many device makers are developing unique processes. Two of these processes are freezing and sidewall. Flash memory makers are diligently investigating the sidewall process by CVD. This is because of the lack of a second litho alignment step, even with its high cost. The high cost of the CVD process can be reduced if a spin on material is used.
One of the goals of this paper is to reduce the cost of ownership by using spin on coatings for the sidewall process. Currently we are investigating this approach to control the sidewall width, profile and other properties.
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