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This report describes a new process for ULSI minute copper-wiring formation. It relies on microcontact printing [μCP] of polyethylene glycol bis(1,2,3-benzotriazolylether) [PBTA]—synthesized from polyethylene glycol and benzotriazole—to the surface of copper seed layer, with preferential copper electrodeposition in PBTA-free regions (contact hole and trench) using an acid copper sulfate bath. The copper electrodeposition was done using an insoluble anode in the basic bath without additives. The microcontact printed PBTA on the copper seed-layer surface strongly inhibits copper electrodeposition. Using this process, because of the effect of site-selective printing of PBTA, a minute contact hole can be filled completely with copper without causing voids and seams.

In the basic concept of conventional electroplating, the additives, which determine the properties of the deposited film, are included in the plating bath. In this report, ULSI copper minute wiring formation by a new process is described. The process relies on the pre-adsorption of the polyethylene glycol bis (1, 2, 3-benzotriazolylether) [PBTA] synthesized from polyethylene glycol and benzotriazole, and copper electrodeposition from an acid copper sulfate bath without additives. The copper electrodeposition was done using an insoluble anode in the basic bath without additives after PBTA was pre-adsorbed on the silicon wafer with copper seed. The adsorbed PBTA on the surface of the copper seed strongly inhibited copper electrodeposition. In this process, a minute hole can be filled with copper without causing voids and seams due to the effect of site-selective adsorption of PBTA.

The formation of LSI copper minute wiring by the electroless plating process is expected to become a dominant process for LSI interconnection because of the advantages in obtaining a film of uniform thickness on a dielectric film. Moreover, there is a possible application in three-dimensional wiring and three-dimensional mounting, which use the ball chip technology. However, the conformal deposition of metal basically takes place in electroless plating. The copper electroless deposition was done using neutral electroless plating after the copper seed layer of the sillicon wafer surface had pre-adsorbed PEG 4000 under the condition of coexistence with chloride ions. In the method utilizing pre-adsorption, a minute contacthole can be filled with copper without causing a seam due to the effect of the pre-adsorbed additive. The copper film obtained from this process is advantageous in electromigration (EM) resistance, because the priority orientation the (111) plane, which is the close-packed plane of the fcc structure, is shown and the crystallite size is 37nm. The specific resistance of the copper film is 1.85μΩ·cm.

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.