Product wafer measurements of MOS gate dielectric quality with a small diameter elastic probe.

A new metrology method has been developed for the monitoring of advanced gate dielectric processes associated with 0.1 µm technology. Unlike previous techniques that involved corona or Hg gate based methods, this technique measures all gate dielectric parameters on product as well as monitor wafers. This is accomplished with a specially designed small area elastic pressure probe contacting the gate oxide within the scribe lines of 200 or 300 mm wafers. The elastic probe method utilizes a semiconductor compatible material, which is specially conditioned to produce a nondamaging, highly repeatable contact. Extensive damage evaluations have been performed and indicate that no observable physical or electrical damage is introduced into the silicon by these pressure contacts. Critical parameters such as equivalent oxide thickness (EOT), threshold voltage, channel doping profile, oxide and interface trap charge, and leakage current can be determined with high precision and accuracy. For example, EOT repeatabilities of less than 0.3% (one sigma) have been obtained. The technique is also highly useful for process development, especially in the area of ultra-thin gate oxides and advanced gate dielectrics. [ABSTRACT FROM AUTHOR]