Reduced electromigration and stressed induced migration of copper wires by surface coating
    4.
    发明授权
    Reduced electromigration and stressed induced migration of copper wires by surface coating 有权
    通过表面涂层减少电迁移和应力诱导的铜线迁移

    公开(公告)号:US07468320B2

    公开(公告)日:2008-12-23

    申请号:US11183773

    申请日:2005-07-19

    IPC分类号: H01L21/44

    摘要: The idea of the invention is to coat the free surface of patterned Cu conducting lines in on-chip interconnections (BEOL) wiring by a 1-20 nm thick metal layer prior to deposition of the interlevel dielectric. This coating is sufficiently thin so as to obviate the need for additional planarization by polishing, while providing protection against oxidation and surface, or interface, diffusion of Cu which has been identified by the inventors as the leading contributor to metal line failure by electromigration and thermal stress voiding. Also, the metal layer increases the adhesion strength between the Cu and dielectric so as to further increase lifetime and facilitate process yield. The free surface is a direct result of the CMP (chemical mechanical polishing) in a damascene process or in a dry etching process by which Cu wiring is patterned. It is proposed that the metal capping layer be deposited by a selective process onto the Cu to minimize further processing. We have used electroless metal coatings, such as CoWP, CoSnP and Pd, to illustrate significant reliability benefits, although chemical vapor deposition (CVD) of metals or metal forming compounds can be employed.

    摘要翻译: 本发明的想法是在沉积层间电介质之前,通过1-20nm厚的金属层将芯片上互连(BEOL)布线中的图案化Cu导线的自由表面涂覆。 该涂层足够薄,以便消除对通过抛光进行附加平面化的需要,同时提供了防止氧化和表面或Cu的扩散的保护,这已经被本发明人鉴定为导致金属线路故障的主要贡献者通过电迁移和热 压力消除。 此外,金属层增加了Cu和电介质之间的粘合强度,从而进一步增加寿命并且有助于工艺产量。 自由表面是在镶嵌工艺中的CMP(化学机械抛光)或通过图形化Cu布线的干蚀刻工艺的直接结果。 提出通过选择性方法将金属覆盖层沉积到Cu上以最小化进一步的加工。 尽管可以使用金属或金属形成化合物的化学气相沉积(CVD),但我们已经使用了无电金属涂层,例如CoWP,CoSnP和Pd来说明显着的可靠性优点。