Impact of residual stress on the deflection of extreme ultraviolet pellicles

2023

Materials

Defect control of extreme ultraviolet (EUV) masks using pellicles is challenging for mass production in EUV lithography because EUV pellicles require more critical fabrication than argon fluoride (ArF) pellicles. One of the fabrication requirements is less than 500 μm transverse deflections with more than 88% transmittance of full-size pellicles (112 mm × 145 mm) at pressure 2 Pa. For the nanometer thickness (thickness/width length (t/L) = 0.0000054) of EUV pellicles, this study reports the limitation of the student’s version and shear locking in a commercial tool-based finite element method (FEM) such as ANSYS and SIEMENS. A Python program-based analytical-numerical method with deep learning is described as an alternative. Deep learning extended the ANSYS limitation and overcame shear locking. For EUV pellicle materials, the ascending order of transverse deflection was Ru<MoSi2=SiC<SiNx<ZrSr2<p-Si<Sn in both ANSYS and a Python program, regardless of thickness and pressure. According to a neural network, such as the Taguchi method, the sensitivity order of EUV pellicle parameters was Poisson’s ratio<Elastic modulus<Pressure<Thickness<Length.

Section: Results Of Deep Learningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Transverse Deflection for Extreme Ultraviolet Pellicles

2023

Materials

“…Tensile residual stress and gravity were applied to the EUV pellicle before applying the temperature load during the structural analysis. 27 The wrinkle profile of the EUV pellicle was simulated at different emissivity values (0.025, 0.05, 0.1, 0.2, and 0.4) and CTEs (0.5 × 10 −5 , 1 × 10 −5 , 2 × 10 −5 , and 4 × 10 −5 K −1 ). 17,[28][29][30][31] The CTE range was set according to the change in the CTE due to heating and oxidation.…”

Section: Fem Simulation Of a Wrinkle In The Slit Area Of The Euv Pelliclementioning

confidence: 99%

Impact of thermal expansion coefficient on the local tilt angle of extreme ultraviolet pellicle

J. Micro/Nanopattern. Mats. Metro.

Ahn

2022

Self Cite

Background: A local tilt angle of <300 mrad results in a critical dimension uniformity (CDU) impact below 0.1 nm when a pellicle is used for extreme ultraviolet (EUV) lithography. However, the thermomechanical property guidelines satisfying this specification have not yet been established. Aim:We present the thermomechanical property guidelines that yield a CDU impact below 0.1 nm.Approach: The peak temperature ranges of the EUV pellicle, as a function of the emissivity, were calculated through experimental, numerical, and finite element method analyses. The wrinkle profiles were evaluated as a function of the coefficient of thermal expansion (CTE) within these temperature ranges. The emissivity and CTE values satisfying the specifications were obtained using the CDU impact caused by the wrinkled EUV pellicle. Results:The wrinkle amplitude in the EUV pellicle exhibited 45% attenuation with a twofold decrease in the CTE. The maximum local tilt angles for the 17, 16, and 15 nm half-pitch patterns were 290.2, 286.1, and 272.3 mrad, respectively. CTE below 2 × 10 −5 K −1 and emissivity above 0.1 are suggested for the EUV pellicle. Conclusions:The CTE and emissivity guidelines satisfying the CDU impact specifications can be used for developing next-generation EUV pellicles.

“…The EUV pellicle requires a transmittance higher than 90% at a 13.5-nm wavelength to minimize the loss of throughput caused by the absorption of EUV photons by the pellicle. In addition, the mechanical, chemical, and thermal durability of the pellicle is essential inside an EUV scanner [5][6][7][8][9]. In particular, excess heating due to the absorption of EUV photons can destroy the pellicle membrane due to thermal stress, which is fatal to the availability of an EUV scanner [10].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Resistivity and Emissivity of a Pellicle Membrane for EUV Lithography

Jang

et al. 2022

Membranes

Self Cite

A pellicle is a thin membrane structure that protects an extreme ultraviolet (EUV) mask from contamination during the exposure process. However, its limited transmittance induces unwanted heating owing to the absorption of EUV photons. The rupture of the EUV pellicle can be avoided by improving its thermal stability, which is achieved by improving the emissivity of the film. However, the emissivity data for thin films are not easily available in the literature, and its value is very sensitive to thickness. Therefore, we investigated the dependence of emissivity on structural parameters, such as thickness, surface roughness, and grain size. We found a correlation between resistivity and emissivity using theoretical and experimental approaches. By changing the grain size of the Ru thin film, the relationship between resistivity and emissivity was experimentally verified and confirmed using the Lorentz–Drude model. Finally, we present a method to develop an EUV pellicle with better thermal stability that can withstand high-power EUV light sources.