Method for forming electromigration-resistant structures by doping

Abstract

A method for forming a copper conductor in an electronic structure by first depositing a copper composition in a receptacle formed in the electronic structure, and then adding impurities into the copper composition such that its electromigration resistance is improved is disclosed. In the method, the copper composition can be deposited by a variety of techniques such as electroplating, physical vapor deposition and chemical vapor deposition. The impurities which can be implanted include those of C, O, Cl, S and N at a suitable concentration range between about 0.01 ppm by weight and about 1000 ppm by weight. The impurities can be added by three different methods. In the first method, a copper seed layer is first deposited into a receptacle and an ion implantation process is carried out on the seed layer, which is followed by electroplating copper into the receptacle. In the second method, a copper seed layer is first deposited into a receptacle, a copper composition containing impurities is then electrodeposited into the receptacle and the electronic structure is annealed so that impurities diffuse into the copper seed layer. In the third method, a barrier layer is first deposited into a receptacle, dopant ions are then implanted into the barrier layer with a copper seed layer subsequently deposited on top of the barrier layer. An annealing process for the electronic structure is then carried out such that dopant ions diffuse into the copper seed layer. The present invention method may further include the step of ion-implanting at least one element into a surface layer of the copper conductor after the conductor is first planarized. The surface layer may have a thickness between about 30 Å and about 500 Å. At least one element may be selected from Co, Al, Sn, In, Ti and Cr.

Dependencies are inferred from the claim text.