A novel technique for in-line monitoring of micro-contamination and process induced damage

The use of a simple, rapid (one minute) and nondestructive technique for inline monitoring of electrically active impurities introduced during wafer fabrication is reported. The technique is shown to have a resolution on the order of 1×10¹⁰/cm² , better than that of most spectroscopic techniques such as SIMS, XRF, and AES which are time consuming and destructive. It is based on the use of a surface charge analyzer as a tool for MOS capacitance-voltage measurements. The technique has been successfully applied for monitoring cleaning stations and diffusion furnaces; detection of contaminants is shown to correlate well with the electrical performance of thin dielectrics. Also demonstrated is the use of this surface-photovoltage-based technique for in-line monitoring of very low levels of plasma-induced damage in the SiO₂/Si system