| With the widespread application of the third-generation semiconductors on superpower electronic component,it raises reliability and safety issues of interconnect material such as the resistance of high temperature,high pressure,and high frequency.The traditional interconnect material and process can't meet this requirement.The interconnect materials such as solder paste and conductive glue commonly used in the field of electronic packaging cannot meet the application requirements of high temperature and high pressure.Nano-metal is being to be used in this field due to small size,low melting point and be able to sinter under low-temperature.It can be widely applied in many fields based on its good capability and is expected to be used in electronic packaging field.At present,the main researched nano-metal materials include nano-silver and nano-copper,but the price of nano-silver is relatively high,and there is electromigration under high voltage conditions,which may lead to chip failure and not suitable for the working environment of the third-generation semiconductors.Nano-copper has lower cost,good anti-electromigration properties and the electrical and thermal conductivity of nano-copper is closed to nano-silver.However,the nano-copper is easily oxidized in air.The oxidization of copper will affect the formation of sintering neck between the particles which may reduce the interconnection performance.Therefore,it's important to study and work out a method to make antioxidant nano-copper to meet the requirements of packaging and interconnection material for the third-generation semiconductors.After the analysis the influence of different imidazole compounds on the appearance,dispersion and antioxidant properties of nano-copper,A general anti-oxidation nano-copper processing method is proposed;Finally,the nano-copper is configured into“copper paste”,and the sintering process properties of the copper paste are studied.In this thesis,the method of liquid phase deduction is used to make nano-copper particles,cupric acetate is used as copper source,ascorbic acid is used as deoxidizer,imidazole,2-methylimidazole,2-phenylimidazole,benzimidazole or benzothiazine are used as the protective agents.This experiment consisted of all of them,The experimental results showed that the average particle size of nano-copper made with imidazole compounds was under 500 nm.The nano-copper made by different imidazole compounds was having different antioxidant performance of nano-copper,and the antioxidant mechanism of nano-copper made by this method was analyzed.This thesis proposed a general method(Post-processing)to solve the oxidation issues of nano-copper with benzimidazole.Post-processing raises the antioxidation time of nano-copper from 30 to 45 days.In this thesis,copper paste made of nano-copper was used as interconnect material to explore the sintering properties of nano-copper based on different imidazole compounds.The research sintered nano-copper stored in the air for different periods of time,and found that the shear strength of the nano-copper stored in air for 30 days did not decrease significantly compared with that in air for 1 day,while the nano-copper made with the conventional method was placed in the air for only 6 days,the shear strength of the nano-copper will be significantly reduced.The nano-copper prepared by benzimidazole has good sintering properties with a shear strength of 32.634 MPa,which meets the requirements of the third-generation semiconductor package interconnection.This thesis studied the anti-oxidation problem of nano-copper and tested the sintering performance of nano-copper and conducted a series of researches on the strength of nano-copper from the aspects of shear strength and cross-sectional porosity.The research results had certain guiding significance for the third-generation semiconductor interconnection field. |
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