Texas Instruments Corporation

Adel El Sayed

Alfred J Griffin, Jr

John Paul Campbell

Clint Montgomery

Antonietta Oliva

A multilevel metal and via structure is described. The metal conductors include a base or seed layer, a bulk conductor layer, a capping layer, and a barrier layer, and the via structure include a seed layer, a diffusion barrier layer and a metal plug. The via seed layer is controlled to a thickness that discourages the reaction between the via seed layer and the bulk conductor layer. The reaction may result in the formation of harmful voids at the bottom of the vias and is caused by having the via seed metal coming in contact with the bulk conductor through openings in the barrier layer.

Method for forming a void free via

A process whereby elimination of metal extrusion through the via-barrier layer into the base of etched via holes is accomplished by controlling the process temperature of the via-barrier deposition to less than 400&deg; C., and preferably to about 380&deg; C. By eliminating the cause of metal extrusions, i.e., excessive thermally induced stresses on the metal confined biaxially by the dielectric via walls, the resulting defect-free vias are independent of the barrier thickness. The method is applicable to different metal stacks, and in turn, yield and reliability of the device is significantly enhanced.

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Adel El Sayed