A Study on the Hydrogen Plasma induced material damage for EUV lithography Components and Material evaluation

In the ultra-fine semiconductor fabrication, the lithography process confronts a major change from deep ultraviolet (DUV) to extreme ultraviolet (EUV), introducing new challenges. Particularly, damage to components used in EUV system such as multi-layer mirrors, reticles, and pellicles within the lithography equipment due to EUV-induced hydrogen (H₂) plasma is a critical issue that directly impacts process yield and equipment lifespan. To resolve these issues, it is imperative to establish an environment which is similar to EUV-induced plasma and develop a method to assess the resulting damage. Accordingly, we developed an evaluation method of material damage by hydrogen radicals and ions in the inductively coupled plasma with H₂. In these system, the electron density was 5<!--[if gte msEquation 12]> style='font-size:11.0pt;mso-bidi-font-size:10.0pt;line-height:160%;font-family:
"Cambria Math",serif;mso-bidi-font-family:"Times New Roman";color:windowtext'> m:val="roman"/>× 10⁸ to 3.5<!--[if gte msEquation 12]> style='font-size:11.0pt;mso-bidi-font-size:10.0pt;line-height:160%;font-family:
"Cambria Math",serif;mso-bidi-font-family:"Times New Roman";color:windowtext'> m:val="roman"/>× 10¹⁰ cm^-3, the electron temperature was 1 to 4 eV, and the ion energy was several to tens of eV, which has similar environment of the EUV-induced hydrogen plasma. The damage of the Mo₂C, one of the possible candidate for EUV-pellicle material, samples was quantitatively analyzed by measuring the pore area fraction and chemical characteristics after plasma exposure under various H₂ plasma conditions such as electron density, gas pressure, and exposure time.