For the reactive ion etching of nanoscale semiconductor devices, it is very important to maintain uniform etch rates over the wafer surface to the near- edge of the wafer, and, for the enhanced etch uniformity, a focus ring which surrounds the silicon wafer is used. However, due to the continuous et...
For the reactive ion etching of nanoscale semiconductor devices, it is very important to maintain uniform etch rates over the wafer surface to the near- edge of the wafer, and, for the enhanced etch uniformity, a focus ring which surrounds the silicon wafer is used. However, due to the continuous etching (that is, eroding) of the focus ring during the use of the etch system, the wafer etch characteristics are drifted and particles are generated on the wafer surface. In this study, the effects of structure and materials of the focus ring on the etch characteristics of the focus ring were investigated to improve the lifetime of the focus ring. Among the materials investigated such as polytetrafluoroethylene (PTFE), alumina (Al2O3), zirconia (ZrO2), quartz (SiO2), and yttrium oxide (Y2O3), the material which as the lowest dielectric constant exhibited the lowest etch rate. In addition, when the materials were fabricated to contain more air gap in the structure, therefore, to have less overall dielectric constant, less etching of the materials was obtained. The lowest etch rates observed for the material with the lowest dielectric constant and for the structure with the lowest dielectric constant structure were related to the lowest sheath potential developed over the focus ring materials, therefore, the lowest ion bombardment energy to the focus ring surface. It is believed that, by designing the lowest dielectric material/structure as the focus ring body with the lowest sputter yield materials as the surface materials of the focus ring, the longest lifetime of the focus ring for nanoscale semiconductor processing could be achieved.
For the reactive ion etching of nanoscale semiconductor devices, it is very important to maintain uniform etch rates over the wafer surface to the near- edge of the wafer, and, for the enhanced etch uniformity, a focus ring which surrounds the silicon wafer is used. However, due to the continuous etching (that is, eroding) of the focus ring during the use of the etch system, the wafer etch characteristics are drifted and particles are generated on the wafer surface. In this study, the effects of structure and materials of the focus ring on the etch characteristics of the focus ring were investigated to improve the lifetime of the focus ring. Among the materials investigated such as polytetrafluoroethylene (PTFE), alumina (Al2O3), zirconia (ZrO2), quartz (SiO2), and yttrium oxide (Y2O3), the material which as the lowest dielectric constant exhibited the lowest etch rate. In addition, when the materials were fabricated to contain more air gap in the structure, therefore, to have less overall dielectric constant, less etching of the materials was obtained. The lowest etch rates observed for the material with the lowest dielectric constant and for the structure with the lowest dielectric constant structure were related to the lowest sheath potential developed over the focus ring materials, therefore, the lowest ion bombardment energy to the focus ring surface. It is believed that, by designing the lowest dielectric material/structure as the focus ring body with the lowest sputter yield materials as the surface materials of the focus ring, the longest lifetime of the focus ring for nanoscale semiconductor processing could be achieved.
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