Wafer boat system, holder ring and use thereof

A wafer boat system comprising:

• a carrier;
• and
• a plurality of holder rings,
• wherein the carrier comprises a first end member at a first axial end of the carrier, a second end member at a second axial end of the carrier, and at least three mutually spaced apart axial rods;
• wherein each axial rod of the at least three mutually spaced apart axial rods connects the first end member with the second end member and comprises a series of rod projections extending inwardly and defining axially spaced apart holder ring positions;
• wherein each rod projection of the series of rod projections, of each of the at least three mutually spaced apart axial rods, is configured to support one of the plurality of holder rings in the carrier at one of the holder ring positions;
• wherein each holder ring of the plurality of holder rings is configured to support a wafer in the carrier;
• wherein each holder ring of the plurality of holder rings has an annular body and ring projections projecting from the annular body, the ring projections being arranged to be in contact with the wafer and to space the wafer apart from the annular body when the wafer is supported by the holder ring in the carrier;
• and
• wherein the annular body has a local surface area that varies along its circumferential periphery, wherein, at the ring projections, the local surface area of the annular body is smaller than a circumferential average or median of the local surface area of the annular body.