Formation of ULSI Copper Minute Wiring by Copper Electro-deposition Process Using the Pre-adsorption of Additive

In the basic concept of conventional electroplating, the additive, which determines the properties of the de-posited film, is included in the bath. However, it is difficult to solve the problems related to copper minute wiring as long as one clings to this concept. In this report, ULSI copper minute wiring formation by a new process, which consists of the pre-adsorption of the additive and copper electrodeposition from an acid copper sulfate bath without an additive, will be described. A copper layer of 1μum thickness was deposited from a basic bath on the copper electrode on which the additive had been pre-adsorbed, and the catholic polarization in the basic bath which does not contain an additive was then measured. The continuance of the efficacy of the additiveafter the copper electrodeposition was confirmed. The copper electrodeposition was done using an insoluble anode in the basic bath without an additive after the silicon wafer which formed the copper seed had pre-adsorbed the additive. In the method utilizing pre-adsorption., a minute hole can be filled with copper without causing voids and seams due to the effect of the pre-adsorbed additive.