Pump liner for process chamber

A pump liner for a process chamber, the pump liner comprising:

• a ring-shaped body having an upper portion and a lower portion separated by an annular partition having an inner diameter surface defining an inner diameter of the annular partition, an outer diameter surface defining an outer diameter of the annular partition, a top surface and a bottom surface defining a thickness of the annular partition, the inner diameter surface of the upper peripheral wall concentric with the inner diameter surface of the annular partition;
• the upper portion of the ring-shaped body having an upper peripheral wall and a top wall, the upper peripheral wall having an inner diameter surface defining an inner diameter of the upper peripheral wall and an outer diameter surface defining an outer diameter of the upper peripheral wall, the top wall having a bottom surface and a top surface defining a thickness of the top wall, the upper peripheral wall having in a range of from 4 to 256 circumferentially spaced apertures extending through a thickness of the upper peripheral wall from an opening in the inner diameter surface to an opening in the outer diameter surface;
• an upper channel formed in the upper portion of the ring-shaped body, the upper channel defined by the top surface of the annular partition, the outer diameter surface of the upper peripheral wall and the bottom surface of the top wall;
• the lower portion of the ring-shaped body having a lower peripheral wall and a bottom wall, the lower peripheral wall having an inner diameter surface defining an inner diameter of the lower peripheral wall and an outer diameter surface defining an outer diameter of the lower peripheral wall, the bottom wall having an outer diameter surface defining an outer diameter of the bottom wall, a top surface and a bottom surface defining a thickness of the bottom wall, the inner diameter of the lower peripheral wall being greater than the inner diameter of the upper peripheral wall;
• a lower channel formed in the lower portion of the ring-shaped body, the lower channel defined by the bottom surface of the annular partition, the outer diameter surface of the lower peripheral wall and the top surface of the bottom wall, the lower channel in fluid communication with the upper channel through at least one passage in the annular partition, a portion of the bottom surface of the annular partition inside the inner diameter of the lower peripheral wall, the at least one passage comprising an arc-shaped segment with a concave surface;
• and
• a slit valve opening in the lower portion of the ring-shaped body extending from the inner diameter surface of the lower peripheral wall to the outer diameter surface of the lower peripheral wall, the slit valve opening extending in a range of from 100 degrees to 140 degrees of the ring-shaped body.