Substrate supports for semiconductor processing systems

A reaction chamber, comprising:

• a chamber body with a hollow interior;
• a gas delivery arrangement including a silicon-containing precursor connected to the chamber body;
• and
• a substrate support arranged within the interior of the chamber body, the substrate support comprising a disc body having an upper surface and an axially opposite lower surface arranged along a rotation axis, the upper surface having:
• a circular concave portion extending about the rotation axis;
• an annular ledge portion extending circumferentially about the circular concave portion;
• an annular rim portion extending circumferentially about the annular ledge portion, the annular rim portion connected to the circular concave portion by the annular ledge portion of the disc body;
• and
• wherein the annular rim portion of the disc body comprises:
• a radially inner side wall extending upwards from the annular ledge portion of the disc body;
• an outer side wall radially outward of the radially inner side wall and extending circumferentially about the annular ledge portion of the disc body;
• and
• an upper rim surface connecting the outer side wall to the radially inner side wall, the upper rim surface being substantially orthogonal relative to the rotation axis, and axially offset from a seating apex of the annular ledge portion by a distance greater than a thickness of substrate seated on the seating apex,
• wherein the annular ledge portion of the disc body slopes downward in a direction radially inward from the rotation axis to seat a substrate on the disc body such that a beveled edge of the substrate is cantilevered above the annular ledge portion of the upper surface of the disc body, and
• wherein the seating apex extends circumferentially about the rotation axis, and wherein the upper rim surface is between 0.8 millimeters and 2 millimeters above the seating apex, or is between 0.8 millimeters and 1 millimeter above the seating apex.