1. A processing chamber, comprising:a chamber body having sidewalls, a bottom and a lid defining an interior volume of the chamber body;
a heat shield assembly disposed in the interior volume, the heat shield assembly comprising:
a heat shield member;
an annular preheat member having an inner circumference, wherein the annular preheat member is positioned below the heat shield member;
a susceptor disposed in the interior volume and configured to support a substrate thereon, the susceptor positioned within the inner circumference of the annular preheat member; and
an annular opening between the susceptor and the annular preheat member, wherein:
a first section of the annular opening proximate a gas inlet, the first section covered by the heat shield member, and
a second section of the annular opening proximate a gas outlet, the second section not covered by the heat shield member, wherein the second section is an arc that extends from a first edge and a second edge of the heat shield member.