As the power of EUVL (extreme ultraviolet lithography) scanners increases, the thermal load and hydrogen plasma environment applied to the pellicle become harsher. If the core material of the pellicle membrane is unstable in the EUV environment, reliability depends on the top-most layer (capping). However, the loss of EUV transmission restricts the thickness of the capping and raises concerns related to hydrogen radicals or protons. In our previous report, we introduced molybdenum carbide (Mo2C) as a new pellicle material with high EUV transmittance (91.4 %), transmission uniformity (3σ=0.49 %, 5×5 mm2), and chemical stability against a hydrogen plasma. In this report, we demonstrate the stability against high-intensity (30 W/cm2) EUV irradiation and hydrogen plasma for Mo2C membranes. Large-area (≥5×5 cm2) Mo2C membranes with high EUV transmittance (≥88 %) were fabricated using MEMS technology. The membranes were tested for thermal load test using an 808 nm infrared laser under the same conditions producing up to 3000 wafers in the EUV scanner. The chemical properties of the membranes were evaluated using an inductively coupled plasma device in a high-temperature (<900 °C) hydrogen gas and plasma environment. Furthermore, the EUV transmittance for the Mo2C membrane and the difference after thermal load and hydrogen plasma evaluation were characterized by EUV coherence scattering microscopy. Consequently, we show the feasibility of high-volume manufacturing (HVM) Mo2C pellicles by fabricating the membrane over 5 × 5 cm2.
The power of EUVL (extreme ultraviolet lithography) scanner continues to increase, making the heat dissipation characteristics of EUV pellicles increasingly crucial. The thermal and chemical stability of the EUV pellicles, which have a multilayer thin film structure, relies on the capping layer, and the thermal stability of the capping layer is determined by its emissivity (ε). However, it is challenging to directly measure the ε of an ultrathin film, such as the capping layer of the EUV pellicle. Although a method to obtain the ε of a target material is employed which measure the ε of the whole layer with a target material on a support membrane having low ε, no approach has been proposed to exclude the measurement changes caused by the support membrane. In this study, a methodology for obtaining the ε of a multilayer nanomembrane is proposed. Ruthenium (Ru) with a high ε at nanoscale was deposited on SiNx membranes to have varying thicknesses. The ε of SiNx film and Ru deposited SiNx film were precisely characterized by infrared spectroscopy according to Kirchhoff's law. Based on transfer matrix method (TMM), the ε of Ru layers was theoretically calculated, fitting by DrudeLorentz oscillator model. Finally, reliability was verified by comparing the measurement results through a free-standing membrane without a support. In this way, if the contribution of a single element to the ε of a multilayer or composite membrane can be derived, engineering for a high-emissive layer that combines various components will be possible and used as EUV pellicle and further application research.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.