In extreme-ultraviolet (EUV) lithography, the development of a review apparatus for the EUV mask pattern at an exposure wavelength of 13.5 nm is required. The EUV mask is composed of an absorber pattern and a Mo/Si multilayer on a glass substrate. This mask pattern has a three-dimensional (3D) structure. The 3D structure would modulate the EUV reflection phase, which would cause focus and pattern shifts. Thus, the review of the EUV phase image is also important. We have developed a coherent EUV scatterometry microscope (CSM), which is a simple microscope without objective optics. The EUV phase and intensity images were reconstructed with diffraction images by ptychography. For a standalone mask review, the high-harmonic-generation (HHG) EUV source was employed. In this study, we updated the sample stage, pump-laser reduction system, and gas-pressure control system to reconstruct the image. As a result, an 88 nm line-and-space pattern and a cross-line pattern were reconstructed. In addition, a particle defect of 2 µm diameter was well reconstructed. This demonstrated the high capability of the standalone CSM, which can hence be used in factories, such as mask shops and semiconductor fabrication plants.

To increase the sensitivity of extreme-ultraviolet (EUV) resist, the method of adding high absorption material in base resin of the resist such as hafnium or zirconium metal has been developed. Since the EUV absorption of the base resin increases, the secondary electron emissions would increase to have a highresist-exposure sensitivity. Thus to achieve the high sensitive EUV resist, it is important to evaluate EUV absorption of the EUV resist precisely. We have developed a novel transmittance measurement method to evaluate EUV resist absorption with high precision at BL10 beamline of NewSUBARU synchrotron light facility. In this novel method, a sample resist was coated on an EUV photodiode directly. The EUV transmittance of the resist was measured with photodiode signals before and after the coating. The resist thickness uniformity coating on a photodiode has much smaller value compared to that coating on a freestanding membrane. By novel method, the measurement precisions of the resist thickness and the EUV transmittance were significantly improved. As the result, the high measurement precision of absorption coefficient of 1% was achieved. This novel method will help the development of high sensitive EUV resist with the high-absorption material.

Since the resist thickness in EUV lithography of which base material mainly consists of an organic material is thin, the EUV photon energy is not be used efficiently for the EUV chemical reaction. In order to increase chemical reaction incidence in the EUV photon energy, a resist having a high-absorption material compounds for the EUV photons has been developed. It has been studied to increase the absorption including high-absorption materials such as hafnium and zinc, tin oxide, tellurium. For the development of the next-generation high sensitive resist materials, since it is significant to measure the EUV absorption coefficient accurately, it is necessary to measure the transmittance and resist thickness to obtain the absorption coefficient accurately. Thus, we have developed to evaluate the absorption coefficient of the EUV resist at BL 10 beamline of NewSUBARU synchrotron hlight facility. In the previous paper, we measured the EUV resist transmittance on a freestanding membrane. However, since it was very difficult to coat resist on a membrane with high uniformity, the transmittance could not be measured accurately. Thus, we have developed the precise transmittance measurement method by coating resist on a photodiode directly, and the resist thickness on a photodiode was measured by XRR accurately instead on conventional method. Finally, the accurate measurement of EUV resist absorption coefficient was achieved.

No abstract