Non‐destructive Characterizing of Lateral Doping Effects

As channel lengths decrease, device performance becomes increasingly sensitive to lateral doping effects. We report on methods of non‐contact measurement of lateral diffusion and implant straggle using a combination of a bar mask pattern and Carrier Illumination™ measurements, in which one laser beam generates excess carriers and a second laser beam reflects from the excess carrier distribution. Doped region width is extracted from measurements in structures with a range of pitches and fills from 0 to 100%. The method may be applied to both pre‐ and post‐annealed structures, with orthogonal bar patterns used to determine the vector components of lateral doping. Lateral resolution of 0.5 nm is demonstrated. Both vertical and lateral diffusion distance are obtained. Data presented shows that the ratio of lateral to vertical diffusion depends on implant and anneal conditions. Measurements of high‐current single‐wafer implants show implant angle uniformity of better than ±1°.