United Microelectronics Corp.

Kuen-Syh Tseng

Shu-Jen Chen

Ming-Shing Chen

Jy-Hwang Lin

Ruoh-Haw Chang

A multi-film capping layer having a cobalt layer, a barrier layer, and a stuffing layer is disclosed, wherein the barrier layer isolates the cobalt layer from the stuffing layer. The multi-film capping layer is formed on a gate transistor and applicable to a self-aligned silicide (salicide) process, so that a sheet resistance of the salicide layer on conductive regions of the gate transistor is significantly reduced. The stuffing layer further prevents entry of oxygen or moisture to the salicide layer, thus no cobalt oxide is formed when RTP is performed. Without formation of the cobalt oxide, the salicide process is free from the bridging issue and the filament issue.

Multi-film capping layer for a salicide process

A method for forming silicide on a semiconductor wafer. The semiconductor wafer includes a doped silicon layer on a predetermined area of the semiconductor wafer, a metal layer positioned on the doped silicon layer, and a barrier layer covering the metal layer. A first rapid thermal processing (RTP) step is performed to make portions of the metal layer react with silicon inside the doped silicon layer so as to form a transitional silicide. The barrier layer and the portions of the metal layer that have not reacted with silicon are then removed. A dielectric layer is formed on the transitional silicide. Finally, a second rapid thermal processing (RTP) step is performed to make the transitional silicide react with portions of the doped silicon layer so as to form the silicide.

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Pingtung, Taiwan

Kuen-Syh Tseng