Baffled liner cover

A liner assembly for use in a thermal processing furnace, comprising:

• a generally tubular liner having sides extending along a central axis for accommodating a tower supporting a plurality of wafers in a horizontal orientation;
• and
• a cover over a top of the liner having passageways passing therethrough which occupy no more than 10% and at least 0.5% of an area of a top of the liner.

A baffled liner cover to be fit over the top of a tubular liner configured to accommodate within the liner a substrate support tower, comprising:

• a top plate extending in a plane about an axis and having peripheral edges to be supported on the liner and having a central aperture;
• a baffle assembly having a rim at its top fit to the aperture, a generally tubular wall open at its top in a plane of the top plate, extending parallel to the axis, and having horizontal holes therethrough, and supporting at its bottom a continuous floor extending perpendicularly to the axis.