Low dielectric materials show great application potential in future microelectronic industry. In this study, benzocyclobutene-functionalized polycarbosilane derived block copolymer, poly(carbosilane-b-lactide), was synthesized via sequential anionic polymerization of silacyclobutene and ring-opening polymerization of lactide. The block copolymer revealed microphase-separation behavior to form a well-defined morphology. Simultaneously, the sacrifice of polylactide blocks by thermal decomposition and thermally-induced reaction of benzocyclobutene produces cross-linked nanoporous polycarbosilane (PBCS). The dielectric constant of this nanoporous material reaches to around 2.1.

One trend for low dielectric materials is to reach low dielectric constant values at as low porosity as possible. In this work, a lamellar porous material was prepared by spin-coating of poly(vinyl alcohol) (PVA)/manganese dioxide (MnO2) nanosheet composited film, followed by cross-linking of PVA and removing nanosheets. FTIR, XRD and TGA measurement results demonstrate that the templates were almost completely removed. SEM image shows that the etched PVA film has a lamellar porous structure. Dielectric test results indicate that at the porosity of only 17.5%, the dielectric constant of porous PVA is reduced to approximately half that of neat cross-linked PVA. The serial model shows a good consistence with experimental dielectric constant value. This explains well the high efficiency of lamellar porous structure in reducing dielectric constant.

Although general porous materials have a low dielectric constant, their uncontrollable opened porous structure results in high dielectric loss and poor barrier properties, thus limiting their application as interconnect dielectrics. In this study, polymeric nanoporous materials with well-controlled closed pores were prepared by incorporating polystyrene (PS) hollow nanoparticles into polyethylene (PE/HoPS). SEM images suggested a closed porous structure for PE/HoPS. In order to show the effect of the porous structure on dielectric properties, nanoporous materials with an opened or uncontrollable porous structure were prepared by etching SiO2/PE or PE/PS@SiO2 composites. PE/HoPSs composites showed an apparently lower dielectric constant and loss compared with the opened porous PE, demonstrating the advantages of a closed porous structure upon enhancing low-dielectric performance. The low dielectric performance of the PE/HoPS composites is linked with high water resistance owing to their closed porous characteristics. When incorporating 15.3 wt% HoPS (porosity: ∼6.9%), the dielectric constant reached 2.08. This value is lower than that calculated from the serial model. Our work revealed that the incorporation of HoPS not only reduces the porosity, but also alters the intrinsic properties of PE, as a result, leading to a greatly reduced dielectric constant.

One effective route to reduce the dielectric constant is to directly incorporate hollow silica (HoSiO2) microspheres into a polymeric matrix. However, the incompatibility between silica and hydrophobic polymers possibly results in interfacial defects and polarization, and thus a high dielectric loss. In this study, the HoSiO2 microspheres were coated by polystyrene using a surface-initiated ATRP method in order to enhance interfacial property. TGA results indicated that the weight percentage of polystyrene in resulting microspheres (HoSiO2@SI-PS) reached around 33 wt%. OM images showed that the thickness of the polystyrene layer reached around 2 μm. HoSiO2@SI-PS microspheres with a weight percentage of 25% were incorporated into polyethylene (PE) to prepare the composites. The dielectric measurement results indicated that the dielectric constant of the composites was reduced to 2.05, while maintaining low dielectric loss at the level of 10−4. In comparison, when HoSiO2@C-PS microspheres, which were prepared by conventional vinyl-initiated free radical polymerization, were incorporated into polyethylene, the dielectric loss was greatly elevated to 0.007. SEM images and water absorption experiments further revealed that the low dielectric loss of PE/HoSiO2@SI-PS was related to the dense interfacial structure, strong interfacial interaction and low water absorption ability.

With the development of microelectronic industry, low dielectric-constant insulating materials with high temperature performance and photopatternability have aroused interest. In this work, a kind of benzocyclobutene/vinylphenyl-introduced polycarbosilanes (PVBCS) were synthesized by H2PtCl6 catalyzed ring-opening copolymerization of 4-(1-methylsilacyclobutyl) benzocyclobutene (4-MSCBBCB) and 1-methyl-1-(4-vinylphenyl) silacyclobutane (1-MVPSCB). By directly introducing photo-active groups on the pendants of polycarbosilanes, the PVBCS was endowed with photopatternability without additionally using any photo-initiators or photo-crosslinkers. DSC and FTIR characterization demonstrated that the PVBCS was UV&thermally curable. The UV curing was conducted at ambient temperature and the thermally curing was performed above 200 °C. TGA curves of the cured PVBCS indicated that the 5% weight loss temperature is 473 °C, which is above the required temperature limit. The cured PVBCS also has low dielectric constant of 2.32–2.40 in the range of 1 k∼1 MHz. The high temperature performance and low-dielectric constant could be attributed to the polycarbosilane main-chain structure and the benzocyclobutene-based cross-linked structure.

A novel silicon-/phosphorus hybrid (SDPS) was synthesized by a condensation polymerization of diphenylhydroxysilane and spirocyclic pentaerythritol di(phosphate monochloride). The use of SDPS and the cooperative use of SDPS with P–N hybrid in flame retardant epoxy resin (EP) were investigated. Limiting oxygen index and cone calorimeter tests showed that the loading of SDPS and the cooperative use of SDPS and P–N hybrid in EP provided enhanced fire resistance. TGA, TG-FTIR and SEM measurements revealed that the enhancement in fire resistance was arising from the formation of a compact honeycomb carbonaceous structure hybridized by silica, the good char forming ability and the inhibition of flammable gas release. Further analysis from Raman spectra revealed that the compact carbonaceous layer may be originated from an increase in ordering of amorphous carbonaceous layer.

A series of benzocyclobutene-carbosilane thermosets derived from benzocyclobutene-containing oligomeric silylenephenylene (PBSEPs) were synthesized. DSC analysis results demonstrated that the reaction of PBSEPs presumably took place within the temperature range of 200–350 °C. FT-IR, 1H NMR and 13C NMR results demonstrated that this exothermic reaction was attributed to a [4 + 2] cycloaddition. DSC results further revealed that benzocylcobutene linked with silylene exhibited lower exothermic temperature compared with that linked with Si(CH3)2. Chemical simulation results attributed the lower temperature to lower steric hindrance and greater activity. DSC and TGA analysis of the thermosets showed high Tg and thermostability, and good pyrolysis yield.

Although general porous materials have a low dielectric constant, their uncontrollable opened porous structure results in high dielectric loss and poor barrier properties, thus limiting their application as interconnect dielectrics. In this study, polymeric nanoporous materials with well-controlled closed pores were prepared by incorporating polystyrene (PS) hollow nanoparticles into polyethylene (PE/HoPS). SEM images suggested a closed porous structure for PE/HoPS. In order to show the effect of the porous structure on dielectric properties, nanoporous materials with an opened or uncontrollable porous structure were prepared by etching SiO2/PE or PE/PS@SiO2 composites. PE/HoPSs composites showed an apparently lower dielectric constant and loss compared with the opened porous PE, demonstrating the advantages of a closed porous structure upon enhancing low-dielectric performance. The low dielectric performance of the PE/HoPS composites is linked with high water resistance owing to their closed porous characteristics. When incorporating 15.3 wt% HoPS (porosity: ∼6.9%), the dielectric constant reached 2.08. This value is lower than that calculated from the serial model. Our work revealed that the incorporation of HoPS not only reduces the porosity, but also alters the intrinsic properties of PE, as a result, leading to a greatly reduced dielectric constant.