A photoelectric method to determine lateral distribution of the effective contact potential difference in MOS structures

摘要

The most accurate method of determination of contact potential difference in MOS structure is photoelectrical method. Some important limitations of this method are caused by the UV light source. Application of argon laser with frequency doubler allows getting high power density light spot with theoretical diameter below micrometer. This way both structures with optically thick gate and MOS structure parameters lateral distribution could be investigated. Measurements of contact potential difference lateral distribution on MOS structure show significant difference in values on single structure. The lowest values are in the corner of squared structure, the higher on the middle of the edge and the highest at the structure center. The origin of these differences could be mechanical stress or different conditions for chemical diffusion under metallic gate.