Preparation And Properties Of Hyperbranched Low Dielectric Polycarbosilane Benzocyclobutene Resin

The development of large-scale integratiod circuits is an important driving force for the progress of the present era,but the speed and size of transmission limit its development speed.In order to further increase the transmission speed and higher integration of large-scale integratiod circuits,it is necessary to use low-k materials.The low-k materials must also meet the requirements of thermodynamic,mechanical,and chemical properties.The route via the cross-linking of hyperbranched polymers has potential advantage to construct low dielectric constant（low-k）resins owing to the enhanced molecular free volume in hyperbranched structure.However,it is still a challenge to prepare hyperbranched resins with good film-forming property and low-k.1.Three low-dielectric hyperbranched polycarbosilane resins were designed and synthesized methyldipropylene silane and Polydiallyl（methyl）silane benzocyclobutene（P1）,Methyldistyryl silane and polymethylbis（4-vinylphenyl）silane benzocyclobutene（P2）,Methyldihexene Silane and polydienehexyl（methyl）silane benzocyclobutene（P3）.Dielectric constant and T₅ were2.75,436°C.2.49,430°C.and 3.10,393°C,respectively.Three similar monomers were designed to synthesize hyperbranched polymers,which indicated that in hyperbranched polycarbosilane,different space groups would affect the dielectric constant of the material.Phenyl groups are more polar than propenyl groups,which increases the dielectric constant of the material.However,a series of test results show that the chain mobility of the phenyl group with higher rigidity is lower,so the orientation polarization of P2 is suppressed,which is beneficial to reduce the dielectric constant.So the dielectric constant of P2 is lower.2.Polymethylbis（4-vinylphenyl）silane（P4）was synthesized using methyldiphenylvinylsilane and hydrosilylation,then the BCB synthesized H-P2 with polymer by Heck reaction.The double bonds are retained for curing.The dielectric constant of H-P2 is2.23,and T₅ is at 473°C,and the increase of cross-linking points improves the thermodynamic properties of the polymer.Moreover,different cross-linking methods will also have a certain influence on the dielectric constant of similar polymers.3.Traditional photoresists mostly contain highly polar bonds.Due to steric effects,a large number of double bonds remain on P2,which can be used for UV curing and impart a certain pattern,and the pattern will not be significantly deformed during the subsequent thermal curing process.Moreover,the double bond of H-P2 is preserved,and can also be patterned by UV curing.The resulting pattern has a high resolution,and the pattern will not be significantly deformed during the subsequent thermal curing process.In this paper,three hyperbranched polycarbosilanes with reactive benzocyclobutene（BCB）groups were synthesized via hydrosilylation reaction to avoid the generation of Si-O bonds for enabling the low polarity of chemical bonds.The spacing groups including phenyl or ethylene were incorporatiod into the hyperbranched structures,and the effect of the spacing groups on the physicochemical properties of hyperbranched polycarbosilane derived resins were investigated.The phenyl groups were found to effectively decrease the dielectric constant（k）,while endowing the resins with good film forming ability and thermostability.The UV/Thermally cured phenyl group resin owing to dual crosslinked structure,the patterns would not be deformed significantly during thermally cured process.Both hyperbranched polycarbosilane derived resins could be potential photoresists.The polymer is mainly composed of Si-C and C-H bonds,which can satisfy the low dielectric and have low dielectric loss and excellent thermodynamic properties.