Rikimaru Sakamoto

Dry development rinse process (DDRP) and material (DDRM) for novel pattern collapse free process

Because the pattern pitch is getting smaller and smaller, the pattern collapse issue in the lithography process have been getting the sever problem. Especially, pattern collapse is one of the main reasons for minimizing of process margin at fine pitch by EUV lithography. The possible major cause of pattern collapse is the surface tension of the rinsing liquid and the shrinkage of resist patterns surface in the process of drying the rinsing liquid. The influence of surface tension for very small pitch pattern is particularly severe. The one of the most effective solution for this problem is thinning of the resist film thickness, however this method is reaching to its limits in terms of substrate etching process anymore. The tri-layer resist process or hard mask processes have been used, but there is a limit to the thinning of resist film and there is no essential solution for this problem. On the other hand, the supercritical drying method has been known as an ultimate way to suppress the pattern collapse issue. The supercritical drying method is a dry process advanced to the vapor phase from the liquid phase via supercritical, and the supercritical drying method can dry the rinsing liquid without making the vapor-liquid coexistence state. However, this process is not applied to the mass production process because it requires the introduction of the special equipment. We newly developed the novel process and material which can prevent the pattern collapse issue perfectly without using any special equipment. The process is Dry Development Rinse Process (DDRP), and the material used in the process is Dry Development Rinse Material (DDRM). DDRM is containing the special polymer which can replace the exposed and developed part. And finally, the resist pattern will be developed by Dry etching process without any pattern collapse issue. In this paper, We will discuss the approach for preventing the pattern collapse issue in PTD and NTD process, and propose DDRP and DDRM as the solution.

The novel spin-on hard mask and ultrathin UL material for EUVL

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.

Backexposure Effect in Chemically Amplified Resist Process upon Exposure to Extreme Ultraviolet Radiation

With the progress in the resist development toward the realization of 22nm high volume production using extreme ultraviolet (EUV) lithography, practical issues such as defects, filtering, and etching durability have recently attracted much attention. The side wall profile of resist pattern si s among such issues. Although EUV radiation is hardly reflected at the resist-underlayer boundary, secondary electrons generated in the underlayer sensitize acid generators in the resist. In this study, the backexposure effect on the side wall profile of line-and-space patterns was theoretically investigated. The potential difference between the resist and the underlayer and the absorption coefficient of the underlayer significantly affected the sidewall profile. The image quality at the bottom of the resist layer was also improved by increasing the absorption coefficient of the underlayer. # 2011 The Japan Society of Applied Physics

Development of reverse materials for double patterning process

Materials and processes for double patterning using 193nm immersion lithography has been developing for the 32/22 nm node device generations. As for double patterning , some patterning methods such as LELE (Litho Etch Litho Etch) process and LFLE (Litho Freeze Litho Etch) process have already been reported. LELE process is complicated and is a low throughput process compared to LFLE process. On the other hand, freezing process and freezing material are needed in LFLE process. Contact hole (C/H) and trench pattern resolution are limited by low aerial image contrast. Then, we examined the process and the material that was able to form a minute pattern without increasing the number of processes as much as possible. So image reverse process has one of technique to form the fine hole pattern and trench pattern. The pillar pattern is obtained by the X-Y double line exposures. Then, the reverse material is applied on the pillar pattern and the subsequent process (dry etching or wet etching process) converts the pillar pattern into a hole pattern. In this paper, we studied the reverse process and materials. Methyl isobutyl carbinol (MIBC) was selected as a slovent for the Si contained reverse material. MIBC solvent system has no damege for PR film and pattern. Plannarizaion of reverse material is important for image reverse and pattern transfer.

Approach to hp10nm resolution by applying Dry Development Rinse Process (DDRP) and Materials (DDRM)

EUV lithography has been desired as the leading technology for single nm half-pitch patterning. However, the source power, masks and resist materials still have critical issues for mass production. Especially in resist materials, RLS trade-off is the key issue. To overcome this issue, we are suggesting Dry Development Rinse Process (DDRP) and Materials (DDRM) as the pattern collapse mitigation approach. This DDRM can perform not only as pattern collapse free materials for fine pitch, but also as the etching hard mask against bottom layer (spin on carbon : SOC). In this paper, we especially propose new approaches to achieve high resolution around hp10nm. The key points of our concepts are 1) control PR profiles, 2) new solvent system to avoid chemical mixture, 3) high etching selective DDR materilas and 4) high planar DDR materials. This new DDRM technology can be the promising approach for hp10nm level patterning in N7/N5 and beyond.

Dry development rinse (DDR) process and material for ArF/EUV extension technique toward 1Xnm hp and beyond

Since the pattern pitch is getting smaller and smaller, the pattern collapse issue has been getting sever problem in the lithography process. Pattern collapse is one of the main reasons for minimizing of process margin at fine pitch by ArF-immersion or EUV lithography. The possible major cause of pattern collapse is the surface tension of the rinsing liquid and the shrinkage of resist pattern’s surface. These surface tension or shrinkage are occurred in the spin drying process of the rinsing liquid. The influence of surface tension against very small pitch pattern is particularly severe. One of the most effective solution for this problem is thinning of the resist film thickness, however this strategy is reaching to its limits in terms of substrate etching process anymore. Recently the tri-layer resist process or hard mask processes have been used, but there is a limit to the thinning of resist film and there is no essential solution for this problem. On the other hand, dry development process such a supercritical drying method or DSA patterning by dry etching have been known as an ultimate way to suppress the pattern collapse issue. However, these processes are not applied to the mass production process right now because these have some problems such a defect issue, requirement of the special equipment and so on. We newly developed the novel process and material which can prevent the pattern collapse issue perfectly without using any special equipment. The process is Dry Development Rinse process (DDR process), and the material used in the process is Dry Development Rinse material (DDR material). DDR material is containing the special polymer which can replace the exposed and developed part. And finally, the resist pattern is developed by dry etching process without any pattern collapse issue. In this paper, we will discuss the approach for preventing the pattern collapse issue in ArF and EUV lithography process, and propose DDR process and DDR material as the solution.

EUV sensitive Si containing hard mask (Si-HM) for PTD and NTD process in EUVL

Tri-layer process is the one of the key technique both for the 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. 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, we could resolve 22nm L/S=1/1 pattern on the EUV sensitive Si-HM by EUV NTD process even in the condition which hp40nm was the resolution limit with HMDS treated Bare-Si / PR stack. Moreover, from the view point of etching hard mask, 30nm dense L/S pattern and 20nm semi iso line pattern could be transferred to SOC layer successfully. We will present our latest Si-HM performance specialized for EUV lithography.

Spin-on-carbon-hardmask with high wiggling resistance

For the mass production of the advanced semiconductor device, the multi-layer process has been used for the essential technique {photoresist/ silicon contained hard mask (Si-HM)/ spin-on-carbon-hardmask (SOC)}. Spin -on-Carbon material plays a very important role during the etching process of substrates. The substrate etching process induces severe pattern deformations (called wiggling) especially with fine line/space patterns. Therefore, both the high etching resistances and the high wiggling resistance are demanded for SOC materials. In this study, we investigated the etching performances with several SOC materials. We found that the relationships between SOC properties and the resistance for wiggling generation. We will discuss the material design of novel SOC for high wiggling resistance.

Novel ArF extension technique by applying Dry Development Rinse Process (DDRP) and Materials (DDRM)

ArF lithography is still major process to develop N7/N5 devices. Especially in resist materials, DOF, roughness and CD uniformity are the biggest key parameters in fine pitches. To improve these issues, we newly propose to apply Dry Development Rinse Process (DDRP) and Materials (DDRM) as the ArF extension approach. In EUV lithography, DDRP is already one of the approaches to achieve high resolution. However, the performance of DDRP for ArF lithography was never demonstrated in detail. In this paper, we especially focus to improve DOF, CD uniformity and roughness by applying DDRP for ArF generation. Finally we succeeded to enhance every parameter at the same time by controlling DDRM etching condition. This new DDRP technology can be the promising approach for ArF extension stages in N7/N5 and beyond.

EUV lithography and etching performance enhancement by EUV sensitive Si hard mask (EUV Si-HM) for 1Xnm hp generation

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.