| As the third-generation semiconductor devices bear a long-term and stable operation under extreme conditions like high temperature,interconnected materials play a vital part in it,so it is of great significance to develop a kind of interconnected material with excellent comprehensive performance.With the characteristics of surface effect and small size effect and the ability to be sintered into a block structure with high conductivity,high thermal conductivity,high stability and electromigration resistance at low temperatures,Cu nanoparticles are ideal interconnected materials.However,the nano-copper materials have some tricky issues such as easy agglomeration,easy oxidation and low yield,which limit the application of nano-copper materials in the third-generation semiconductor devices.In order to solve such problems,a new in-situ copper paste preparation process is proposed in this thesis.This process synchronizes the synthesis of copper particles with the preparation of copper paste,removing the steps of multiple drying and dispersion.Copper particles are not directly exposed to the air,effectively preventing agglomeration and oxidation.Moreover,the whole preparation process is simple,efficient and green,and the yield can reach99%.Made by formic acid copper,copper acetate,acetylacetone copper and copper hydroxide,the four kinds of in-situ copper pastes contain no impurities hard to remove.Under sintering conditions of 260°C and 2 MPa,the shear strength of the interconnection joints obtained is above 20 MPa,and no oxidation occurs in the sintered layer with the solid content above 98%,indicating the relatively pure copper sintered layer is obtained.Among the four kinds of in-situ copper pastes,the in-situ copper paste based on acetic acid shows the best sintering performance,in which the shear strength of the interconnection joint is 55.26 MPa,and the resistivity of the sintered layer is 4.01×10-8Ω·m.This new in-situ copper paste preparation technology not only has the advantages of simple operation and low cost,but also can be optimized by adding dispersants,protective agents and other organic substances at different preparation stages according to the performance requirements.In order to obtain the in-situ copper paste with super antioxidant property,using copper acetate as copper source,the imidazole compounds were added before preparing the copper suspension and after obtaining it,and pretreatment in-situ copper pastes and aftertreatment in-situ copper pastes were obtained respectively.Through XRD characterization,it was found that both kinds of copper pastes have super oxidation resistance,which will not be oxidized after four months in the air.Among them,the pretreatment in-situ copper pastes covered by benzimidazole have the smallest particle size and the best dispersion.Under the sintering condition of 260℃and 2 MPa,the shear strength of interconnection joint is 83.45 MPa,and the resistivity of sintering layer is 4.16×10-8Ω·m.The posttreatment in-situ copper pastes covered by benzimidazole can get interconnection joint with shear strength of48.89 MPa,and the resistivity of sintering layer is 8.63×10-8Ω·m.The sintering performance is second only to the in-situ copper paste without benzimidazole.Moreover,no oxidation occurs in the sintered layer with the solid content above 98%,indicating the addition of benzimidazole did not bring a lot of impurities that were difficult to remove,and the antioxidant performance of copper paste was greatly improved. |
