Kim Eungchul, Hong Jiah, Seok Hyunho, Kim Taesung
School of Mechanical Engineering, Sungkyunkwan University, Suwon, 16419, South Korea.
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 16419, South Korea.
Sci Rep. 2022 Jan 31;12(1):1613. doi: 10.1038/s41598-021-03866-9.
The effects of photo-oxidative degradation of polyacids at various concentrations and with different durations of ultraviolet (UV) irradiation on the photo-reduction of ceria nanoparticles were investigated. The effect of UV-treated ceria on the performance of chemical mechanical polishing (CMP) for the dielectric layer was also evaluated. When the polyacids were exposed to UV light, they underwent photo-oxidation with consumption of the dissolved oxygen in slurry. UV-treated ceria particles formed oxygen vacancies by absorbing photon energy, resulting in increased Ce ions concentration on the surface, and when the oxygen level of the solution was lowered by the photo-oxidation of polymers, the formation of Ce ions was promoted from 14.2 to 36.5%. Furthermore, chain scissions of polymers occurred during the oxidation process, and polyacids with lower molecular weights were found to be effective in ceria particle dispersion in terms of the decrease in the mean diameter and size distribution maintaining under 0.1 of polydispersity index. With increasing polyacid concentration and UV irradiation time, the Ce concentration and the dispersity of ceria both increased due to the photo-oxidative degradation of the polymer; this enhanced the CMP performance in terms of 87% improved material removal rate and 48% lowered wafer surface roughness.
研究了不同浓度的多元酸在不同紫外线（UV）照射时长下的光氧化降解对氧化铈纳米颗粒光还原的影响。还评估了经紫外线处理的氧化铈对介电层化学机械抛光（CMP）性能的影响。当多元酸暴露于紫外光下时，它们会发生光氧化反应，消耗浆料中的溶解氧。经紫外线处理的氧化铈颗粒通过吸收光子能量形成氧空位，导致表面铈离子浓度增加，并且当聚合物的光氧化作用使溶液中的氧含量降低时，铈离子的形成从14.2%提高到36.5%。此外，在氧化过程中聚合物发生链断裂，发现分子量较低的多元酸在氧化铈颗粒分散方面是有效的，这表现为平均直径减小且多分散指数保持在0.1以下。随着多元酸浓度和紫外线照射时间的增加，由于聚合物的光氧化降解，氧化铈的铈浓度和分散性均增加；这在材料去除率提高87%和晶圆表面粗糙度降低48%方面提高了化学机械抛光性能。
