In situ electrical characterization of dielectric thin films directly exposed to plasma vacuum-ultraviolet radiation

Abstract

In this article we report a method for in situ electrical characterization of dielectric thin films under direct exposure to plasma in an electron-cyclotron-resonance etcher. This method is based on the development of a special test structure that allows for the measurement of the influence of plasma vacuum-ultraviolet (VUV) radiation on the electrical conductivity of thin dielectric layers. Results show that the measured conductivity of SiO2 layers temporarily increases during exposure to argon and oxygen plasmas, with controlled VUV emission. Based on the measurements made through this method, a model of the VUV-induced conductivity of SiO2 is developed. These measurements are very important for plasma processing of semiconductor devices, because the temporary increase in the conductivity of these layers upon exposure to processing plasmas can decrease the plasma-induced charging of these dielectric layers depending on the intensity of the plasma VUV emission. This can have an impact on the properties and reliability of processed devices. © 2000 American Institute of Physics.