Evaluation and reduction of electron shading damage in high temperature etching

The effect of wafer temperature on electron shading damage has been studied using an ECR plasma etcher. The gate oxide breakdown frequency was found to increase in proportion to exp(-E/kT), where E reflects the activation energy of Q_bd. The electron shading damage in high temperature etching is dramatically reduced by reducing the ion saturation current and/or reducing the electron temperature. The effect of the small Q_bd at high temperature was found to be completely eliminated by changing the etching temperature from high to low before the open area clears. Consequently, the increase in the gate oxide failure at high temperature has been completely suppressed