Polyhedral Oligomeric Silsesquioxanes Based Ultralow‐k Materials: The Effect of Cage Size

• Published in: Advanced functional materials Vol. 31; no. 31
• Main Authors: Zhou, Dai‐Lin, Li, Jiang‐Hui, Guo, Qing‐Yun, Lin, Xiong, Zhang, Qin, Chen, Feng, Han, Di, Fu, Qiang
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.08.2021
• Subjects: cage size; Cages; Chemical composition; Dielectric properties; High temperature; hybrid materials; insulators; Integrated circuits; low‐dielectric‐constant materials; Materials science; Polyhedral oligomeric silsesquioxane
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202102074

Polyhedral oligomeric silsesquioxanes (POSS) are of considerable interest as building blocks for preparing low‐k materials. To date T8 POSS has been extensively investigated while the potential of larger POSS cages remain an unexplored area. Herein, the first known contribution to map the role of POSS cage size on the dielectric and other comprehensive properties of hybrid materials with identical chemical compositions is described. First, three vinyl POSS (T8, T10, and T12) species are isolated from a commercial POSS mixture. Then, they are converted to benzocyclobutene functionalized and thermo‐crosslinked hybrid materials. It is found that the cage size can strongly affect their k values, more importantly, showing a linear decrease while increasing the cage volumes (k = 2.24, 2.02, and 1.83 for c‐T8B8, c‐T10B10, and c‐T12B12, respectively). This finding highlights a profound influence of POSS cage changes on dielectric properties and could be used to predict ultralow‐k (1.5–1.1) materials by extrapolating to larger T14, T16, and T18 POSS cages. Meanwhile, varying the cage size has no obvious effect on the materials’ other properties, and all of them exhibit good comprehensive properties. Moreover, such low‐k values can persist at high temperature and high humidity conditions, which affords some promising (ultra)low‐k dielectrics for modern integrated circuit development. A series of hybrid (ultra) low‐k materials are achieved based on T8, T10, and T12 polyhedral oligomeric silsesquioxanes (POSS). The results show that the POSS cage can strongly affect the materials’ k values, more importantly, showing a linear decrease with increasing the cage volumes. Moreover, varying the cage size has no obvious effect on the materials’ other properties and all of them show excellent thermal stability and mechanical performance, low surface roughness, high transparency, and hydrophobicity.