【作者】 刘强；

【导师】 崔成强； 林挺宇；

【作者基本信息】 广东工业大学 ， 机械工程（专业学位）， 2022， 硕士

【摘要】 第三代半导体器件在高温等极端环境下保持长期稳定的运行,互连材料起着至关重要的作用,所以开发一种综合性能优异的互连材料极为重要。纳米铜颗粒具有表面效应和小尺寸效应等特点,能够在低温条件下烧结成高导电性、高导热性、高稳定性和耐电迁移性的块体结构,是非常理想的互连材料。但是,纳米铜材料具有易团聚、易氧化和产率低等难以解决的问题,这些问题限制了纳米铜材料在第三代半导体器件上的应用。为解决纳米铜存在的这些问题,本论文提出了一种新型原位铜膏制备工艺。此工艺将铜颗粒的合成和铜膏的制备同步进行,去掉多次干燥和分散的步骤,铜颗粒不直接暴露在空气中,有效地防止了团聚和氧化。而且,整个制备过程简单、高效、绿色环保,产率可达99%。运用甲酸铜、乙酸铜、乙酰丙酮铜和氢氧化铜等四种铜源可制备出四种原位铜膏,这四种原位铜膏中不含难以除去的杂质,在260℃、2 MPa的烧结条件下得到的互连接头剪切强度都在20 MPa以上,而且烧结层没有发生氧化,固含量在98%以上,说明得到了较为纯净的铜烧结层。其中,乙酸铜基原位铜膏烧结性能最好,互连接头的剪切强度为55.26 MPa,烧结层的电阻率为4.01×10^-8Ω·m。新型原位铜膏制备工艺不仅具有操作简便、成本低等优点,还能够根据性能需要在不同制备阶段加入分散剂、保护剂对原位铜膏的性能进行优化。为了得到具有超强抗氧化性能的原位铜膏,用乙酸铜作为铜源,分别在制备铜悬浊液之前和得到铜悬浊液之后,加入咪唑类化合物,依次得到前处理原位铜膏和后处理原位铜膏。通过XRD表征发现,这两种铜膏都具有超强的抗氧化性,在空气中放置四个月不氧化。其中,苯并咪唑包覆的前处理原位铜膏颗粒粒径最小、分散性最好,在260℃、2 MPa的烧结条件下,能得到剪切强度为83.45 MPa的互连接头,电阻率为4.16×10^-8Ω·m的烧结层。苯并咪唑包覆的后处理原位铜膏能得到剪切强度为48.89 MPa的互连接头,电阻率为8.63×10^-8Ω·m的烧结层,烧结性能仅次于不加苯并咪唑的乙酸铜基原位铜膏。而且这两种铜膏的烧结层没有发生氧化,固含量均在98%以上,说明加入苯并咪唑没有引入大量难以除去的杂质,大幅提高了铜膏的抗氧化性能。更多还原

【Abstract】 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.更多还原