In-Situ Growth Of Organic Insulation Film On Silicon Surface And Its Application In Through-Silicon Via Interconnection

As the feature sizes of integrated circuits approach the physical limit,three-dimensional packaging technology and system integration technology with the representative through-silicon via(TSV)have become attractive methods to beyond Moore's Law,which can reduce the package size and achieve functional integration.TSV technology has also become a research hotspot in resent years.In order to reduce the package size and meet the social needs,TSV technology towards to be small size and high aspect ratio.However,it is difficult to prepare insulation films with high step coverage in TSVs,which has become one of the major problems that hindering the development of TSV technology.We have proposed a chemical grafting method to in-situ graft organic films with high step coverage in TSVs,and have successfully prepared poly(methyl methacrylate)and poly(acrylic acid)organic insulation layers.To expand the kinds of organic films,improve the performance and further expand the choice of monomers,an in-depth and systematic study was carried out about the grafting of single monomer,the grafting of binary monomers,the mechanism of the grafting process,the heat treatment process of the grafted films,and the properties of the films.The application of chemical grafting technology in high aspect ratios TSVs with the diameter of 3 ?m and the depth of 30 ?m and wafer-level large area were also studied.We have made important progress in many aspects such as preparation processes,film formation theories,modification of performance,and the application exploration.The specific research contents and main conclusions of this study are as follows:(1)In order to overcome the water vapor,weak bonds and unstable structures in the water-phase chemically grafted organic insulation films,a heat treatment process was proposed to improve the stability of grafted films.First,the influence of components for chemically grafting poly(methacrylic acid)film was studied,and the optimized grafting parameters were obtained.Then the organic film was heat-treated that prepared under the optimized grafting parameters.During the heat treatment,the carboxyl group and the amino group in the organic film were dehydrated to an amide group,and the excess carboxyl groups were decarboxylated to ketone groups.The formed amide and ketone groups both had cyclic and cross-linked structures.After the heat treatment,the thickness of the organic films was reduced,but the films became denser,the stability of the films is increased,and the films showed excellent comprehensive performance.(2)In order to expand the scope of the chemically grafting methods,improve the single structure and the poor stability of the grafted film,a multi-monomer chemically co-grafting method was proposed to improve the properties.The co-grafting of acrylonitrile and methacrylic acid was studied to figure out the influencing factors and chemical reaction mechanism.The hydrolysis of cyano groups into amide groups in the organic film during the grafting process was found.In the heat treatment process,a dehydration reaction happed between the carboxyl group and the amide group with the generation of cross-linked and cyclic imide structures.The imide structures improved the dielectric properties and breakdown field strength of the organic film,which indicating that the multi-monomer chemically cografting was an excellent method for film modification.(3)In order to overcome the limitation of the monomer types for the water-phase solvent and further expand the application of the chemical grafting organic method,a chemical grafting method in mixed solvent was proposed.Three kinds of aromatic monomers,including cinnamic acid,cinnamyl alcohol,and coumarin,were successfully grafted to prepare aromatic films in a mixed solvent of water and ethanol.During the heat treatment process,cross-linking structures were formed in poly(cinnamic acid)and poly(cinnamyl alcohol)films.The reaction of poly(cinnamic acid)was similar with the poly(methacrylic acid)film.For poly(cinnamyl alcohol)film,the dehydration reaction happened between hydroxyl groups to form ether groups,and also happened between the hydroxyl and amino groups with the generation of amine groups.The grafting of aromatic monomers introduced a large number of aromatic rings into the organic film,which improved the heat resistance and reduced the thermal expansion coefficient of the organic film.The mixed solvent chemical grafting technology was beneficial for expanding chemical grafting with excellent properties.(4)The chemical grafting and heat treatment composite processes,the multi-monomer chemically co-grafting method,and the chemical grafting method in mixed solvent were applied on small size and high aspect ratio TSVs with the diameter of 3 ?m and the depth of 30 ?m.Compared with the aqueous solvent,the film prepared in the mixed solvent of water and ethanol in TSV was more uniform and defectless.The morphology of the grafted film in TSV was also affected by the concentration of components in the solution.Under the optimized grafting parameters,the step coverage of the organic film could be up to 100%.In addition,the organic films were sucessfully prepared on 4-inch flat Si wafer and 8-inch TSV wafer,which may be valuable for industrial production.