Apparatus and method to improve electromigration performance by use of

Abstract

An ion implant process is disclosed for forming an amorphous structure in a semiconductor metallization barrier layer, which barrier may be a pure metal barrier, such as titanium, tantalum, tungsten, or metal compound barrier, such as titanium nitride, or titanium-tungsten. The implant is preferably an ion of the barrier metal being used, which is implanted such that an amorphous (texture-less non-crystalline) layer is produced. Other implant species, such as nitrogen or noble gases, such as neon or argon may also be used. Subsequent deposition of the interconnect metallization (typically Al or Cu) results in an interconnect metal structure having a high degree of texture which is characterized by a very narrow distribution of crystallographic orientations in the Al or Cu film. The highly textured Al or Cu metallization results in optimizing the interconnect metal for maximum electromigration performance. The implant energy is chosen such that the tail of the Gaussian distribution of ion's stopping distances extends above the top of the barrier metal film. The ion implantation forms a non-crystalline metal structure in the metal barrier film such that there is no crystalline metal to act as a 'seed' for nucleation during the metallization deposition and subsequent processing. Thus, the final interconnect metallization texture (Al or Cu) will not be governed by the texture of the underlying metal barrier layer which results in an optimized interconnect metal structure with maximum electromigration performance characteristics.