Ring-shaped element for etcher and method for etching substrate using the same

A ring-shaped element for an etcher, comprising:

• a body portion comprising an upper surface and a bottom surface spaced a distance from each other by an outer diameter surface connecting an outer contour line of the upper surface and an outer contour line of the bottom surface, and an inner diameter surface connected to an inner contour line of the upper surface;
• and
• a mounting portion comprising an upper surface comprising an outer diameter directly connected to the inner diameter surface of the body portion at a position lower than the upper surface of the body portion, a bottom surface connected to the bottom surface of the body portion, and spaced a distance from the upper surface by an inner diameter surface connecting an inner contour line of the upper surface and an inner contour line of the bottom surface,
• wherein the upper surface of the mounting portion is stepped from the upper surface of the body portion to constitute a substrate mounting portion thereon,
• wherein the surface or entire body of the ring-shaped element comprises necked boron carbide-containing particles, and
• wherein the thermal conductivity of the ring-shaped element at 400° C. is 27 W/m·K or less.