Semiconductor Device Metal Silicide Formation Blocking Ions

The patent divides the semiconductor device into distinct first and second regions corresponding to N-type and P-type MOS transistors. Each region receives targeted ion implantation (blocking ions in the second region) and forms different metal silicide layers through selective diffusion control, allowing optimized electrical performance for each transistor type while managing process complexity through regional differentiation.

The patent applies local quality by doping the second region with blocking ions to prevent metal atom diffusion, while leaving the first region undoped or differently doped. This creates locally optimized conditions: the first region forms a first metal silicide layer with specific properties for N-type transistors, and the second region forms a second metal silicide layer with different properties for P-type transistors, achieving optimal Schottky barriers for each device type.

The patent merges the fabrication processes for N-type and P-type MOS transistors into a single integrated process. Both regions receive ion implantation and metal layer deposition simultaneously, followed by a unified annealing treatment that forms both metal silicide layers in one thermal processing step. The blocking ions in the second region selectively prevent diffusion only where needed, allowing both transistor types to achieve optimized Schottky barriers through a combined process rather than separate sequential processes.

The patent performs preliminary ion implantation of blocking ions into the second region before forming the metal layers. This preliminary action prepares the second region to selectively prevent metal atom diffusion during the subsequent annealing process, ensuring that the second metal silicide layer forms with the desired properties while the first metal silicide layer forms differently in the first region, all within a unified fabrication sequence.

The patent introduces blocking ions as an intermediary substance in the second doped region that mediates the diffusion process during annealing. These blocking ions act as a diffusion barrier, preventing metal atoms from the second metal layer from diffusing into the second metal silicide layer, while allowing controlled diffusion in the first region. This intermediary mechanism enables simplified unified processing while maintaining precise diffusion control through the blocking ion concentration and distribution.

The patent utilizes parameter changes by varying the blocking ion concentration in the second doped region to control diffusion characteristics. By adjusting the blocking ion dose and energy during ion implantation, the diffusion barrier strength is precisely controlled, enabling the second metal silicide layer to form with specific properties while preventing unwanted diffusion. This parameter control allows unified annealing processing to achieve different diffusion outcomes in different regions.