【作者】 刘立筠；

【导师】 李晓娜；

【作者基本信息】 大连理工大学 ， 材料物理与化学， 2012， 硕士

【摘要】 随着超大规模集成电路互连线特征尺寸的不断缩小,直接向Cu膜中掺杂少量合金元素来制备热稳定性高、电阻率低且自身带有扩散阻挡效果的Cu种籽层成为该领域新的研究热点。合金化Cu膜的方法有望解决Cu互连线中的若干实际问题。本论文研究利用稳定固溶体模型设计和制备无扩散阻挡层Cu三元合金薄膜,以及考察掺杂元素所形成的团簇对该铜膜微观结构和电学性能的影响。按照董闯等人提出的稳定固溶体模型：如果掺杂的第三组元M,与Ni具有负混合焓,与Cu具有正混合焓,则M更容易与Ni结合,而与Cu相排斥,最终形成Ni原子包围中心原子M的团簇,均匀分布在Cu晶格中。团簇固溶在Cu合金薄膜中,有望明显提高薄膜的稳定性。具体研究内容是利用磁控溅射的方法向Cu膜中掺杂一定比例的Ni、Sn元素和一定比例的Ni、Nb元素分别制备成Cu-Ni-Sn和Cu-Ni-Nb三元合金薄膜,并对其进行微结构和电学性能等的测量。研究表明,铜膜中掺杂少量的Ni-Sn或Ni-Nb元素可以增加铜膜的热稳定性。共掺杂一定比例的Ni-Sn或Ni-Nb要比单独添加某一种元素的铜膜具有更好的热稳定性和更低的电阻率,而且Ni-Sn或Ni-Nb元素的总掺杂量相对来说更少,这可以在更大程度上保留Cu的本征优良电学性能。Cu-Ni-Sn系统中：(Sn1.1/13.1Ni12/13.1)0.23Cu99.77薄膜在500℃退火后电阻率可低至2.73μΩ·cm。Sn在Cu晶格中主要以(Ni12Sn)团簇均匀分布在薄膜当中,降低了Cu与Si反应的化学反应活性,进而提高薄膜的热稳定性。多余的Sn会析出与Cu反应生成CuSn化合物,这种纳米量级的化合物在晶界处也会起到阻挡扩散的作用。同时增大的界面非晶层也可以增加薄膜的扩散阻挡作用,抑制Cu/Si之间的扩散及化合反应。Cu-Ni-Nb系统中：(Nb1.2/13.2Ni12/13.2)0.32Cu99.68薄膜电阻率最低可达2.73μQ·cm。Cu-Ni-Nb薄膜稳定性的主要是由(Nil2Nb1)团簇和过量难溶元素Nb在缺陷处的钉扎作用共同影响的。稳定团簇(Ni12Nb1)在晶体中固溶存在主要是晶内钉扎作用,降低Cu和Si反应的化学反应活性；而析出的Nb主要是阻塞扩散快速通道(晶界、界面和缺陷等),一定程度上阻碍晶粒长大。高稳定性Cu-Ni-Sn和Cu-Ni-Nb薄膜的制备成功为稳定固溶体团簇模型应用于Cu合金薄膜的设计领域提供了有力的证据,并对开发新型的铜互连线材料具有重大意义。更多还原

【Abstract】 As the feature size of interconnects continue to shrink, more attention has been paid to Cu seed layer by the method of alloying with elements, which could both inhibit the diffusion of Cu/Si and improve the properties of thin films. This method of Cu alloying is expected to solve some practical problems of Cu interconnects.The stable solid solution cluster model for Cu-Ni-alloy established by C. Dong and J. Zhang dissociates a structure into a cluster part and a glue atom part. The cluster refers to the nearest neighbor coordination polyhedron and is composed of elements with negative enthalpies of mixing, while the glue atoms refer to those atoms that situate outside the clusters in the structure and usually have weaker enthalpies of mixing with the cluster elements. A structure satisfying ideally the nearest neighbor configuration as demanded by the enthalpies of mixing between the constituent elements should naturally possess a high thermal stability.This study reports the thermal stability of NiSn-doped and NiNb-doped Cu films prepared by magnetron sputtering onto the barrierless Si(100) substrates, were enhanced, and exhibits higher thermal stability with a better electrical property than the Cu films doped only one element. And adding less Ni-Sn or Ni-Nb elements can keep the native resistivity of Cu films much better. Cu-Ni-Sn film systems showed:the film (Sn1.1/13.1Ni12/13.1)0.23Cu99.77had a resistivity of2.73μΩcm after annealing at500℃for1h. Sn exists evenly in Cu films by the way of (Ni12Sn) clusters, and reduces the reactivity of Cu and Si, improving thermal stability of the film. Those extra Sn precipitate out and react with Cu generating CuSn compounds, this kind of the nanometer level compounds can also play block diffusion effect in the grain boundary. Increasing interface amorphous layer can also block the diffusion of Cu/Si and restrain Cu/Si compound reactions.Cu-Ni-Nb film systems:The film (Nb1.2/13.2Ni12/13.2)0.32Cu99.68exhibited minimal resistivity of2.73μΩ·cm at500℃for1hour. thermal stabilities of this ternary solid solution Cu films were mainly due to the combined effects of the pinning effect of (Ni12Nb1) clusters and excess undissolved element Nb in the defects. stable (Ni12Nb1)clusters acted the pinning effect of grain interiors by solid-solution state, to reduce the reactivity of Cu and Si; But the precipitated Nb mainly blocked fast diffusion channels (grain boundaries, interface and defects, etc.), and inhibited grain growth to a certain extent。 The preparation of High stability Cu-Ni-Sn and Cu-Ni-Nb films provides tangible evidences for the application of Stable Solid Solution Cluster Model in the scheme of Cu alloy thin film, and has significant importance to developing new Cu interconnects更多还原