The Increasing Importance of the Use of Ozone in the Microelectronics Industry

The effects of oxygen plasma on the chemical composition and morphology of the Ru capping layer of the extreme ultraviolet mask blanks

“…3,4 However, oxygen plasma is known to etch Ru metal. 5 Removal of the Ru capping layer from the EUV reflecting coating reduces the durability of the EUV mask.…”

“…This significant amount of subsurface oxygen is incorporated into the Ru lattice that absorbs EUV radiation, reducing the reflectivity of the EUV mask. 4,6,7 It is, therefore, important to understand the mechanism of the corrosive gas phase-surface interactions to improve existing cleaning processes and Ru-based capping layer of the EUV mask. This is part of a broader effort in the investigation of surface changes of Ru-based capping layer in various cleaning chemistries under different conditions Oxidation of Ru is a complex process; chemisorbed oxygen is found together with dissolved oxygen in the Ru lattice.…”

Improved oxidation resistance of Ru/Si capping layer for extreme ultraviolet lithography reflector

“…Ultraviolet radiation can also be used for polymer surface modification, with applications in photolithography, nanocatalysis, and bioengineering. 17,18,[22][23][24] Si 2p, Ru 3d, and O 1s XPS spectra comparison of samples with the same thickness ͑6 nm͒ before oxidation or UV treatment is shown in Figs. 1͑a͒-1͑c͒, respectively.…”

“…14,18 A significant amount of subsurface oxygen is incorporated into the Ru lattice that absorbs EUV radiation, reducing the reflectivity of the EUV mask. 1,14,18,26 Figures 1͑d͒-1͑f͒ show XPS spectra in the Si 2p, the Ru 3d, and the O 1s regions of the XPS spectra, respectively, of 6 nm capping layers on the EUV lithography mask/mirror after UV/ozone treatment for 100 min. To make a qualitative comparison of the chemical durability of the four different capping layers, we conducted UV/ozone treatment experiments where all samples are treated at identical experimental conditions by placing all samples in the cleaning chamber simultaneously.…”

“…[7][8][9][10][11][12] Current processes for cleaning EUV lithography reflectors involve many corrosive and oxidizing environments, including acids, bases, UV/ozone, and plasma. 5,6,[13][14][15][16][17][18] However, cleaning processes that involve corrosive chemicals cause surface oxidation of the Ru capping layers, 19 resulting in surface corrosion and deterioration of the EUV reflector. Therefore, it is necessary to develop new types of capping layers that exhibit higher chemical and oxidation resistance.…”