A group of cyclolinear polycarbosilanes (CLPCS), which contain strained 1,3-disilacyclobutane (DSCB) rings imbedded in the ring-chain structure, have been shown to possess many of the prerequisites for use as a source of low-k dielectric films in the back end of line (BEOL) electronics processing [1]. These CLPCS have the general formula, [cyclo-{(CH3)Si(CH2)2Si(CH3)}-(CH2)x-]n, where x = 4-8, and are prepared by addition-metathesis (ADMET) polymerization using Grubbs or Schrock catalysts [2]. In addition to the ADMET polymerization method, we have found that Grignard coupling reactions can also be used to prepare these CLPCS, albeit in lower molecular weight form and with higher polydispersities. This Grignard reaction employs dibromo- or dichloro-terminated -(CH2)n- hydrocarbons and the corresponding 1,3-dichloro-1,3-dimethyl-1,3-disilacyclobutane and, as such, can be easily extended to other hydrocarbon linking groups, such as 1,4-dibromobenzene. We report here the synthesis of the resultant [–{cyclo-(CH3)Si(CH2)2Si(CH3)}-Y–]n Y = C6H4, etc. (Figure 1) CLPCS with aromatic linkers and the investigation of its unusual photochemically driven cross-linking reaction, which allows the direct photolithographic patterning of carbosilane films with excellent thermal and dielectric properties. [1] Matsuda, Y; Rathore, J.S.; Interrante, L.V.; Dauskardt, R.H.; Dubois, G.; 2012, ACS Appl. Mater. Interfaces, 4, 2659-2663. [2] Wu, Z.Z.; Papandrea, J.P.; Apple. T.; Interrante, L.V.; Macromolecules, 2004, 37, 5257-5264.

Synthesis and photochemical crosslinking of cyclolinear polycarbosilanes

251st National Meeting (2016)

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