Vertical heat treatment apparatus

A vertical heat treatment apparatus for processing at least one semiconductor wafer, the heat treatment apparatus comprising:

• a heat treatment furnace provided with a furnace inlet at a lower end thereof allowing the at least one semiconductor wafer to be transported into and out of the furnace inlet;
• a cover unit configured to cover the furnace inlet of the heat treatment furnace;
• a cover unit opening/closing mechanism configured to support the cover unit and to position the cover unit away from the furnace inlet when the at least one semiconductor wafer is being processed within the furnace or is being transported into or out of the furnace, and to position the cover unit to cover the furnace inlet at other times;
• and
• an auxiliary mechanism comprising a toggle clamp with an extendible mechanism section, link plate, and auxiliary mechanism arm unit, the auxiliary mechanism configured to vertically rotate the auxiliary mechanism arm unit about a pivot point when the extendible mechanism section extends and rotates the link plate, such that the auxiliary mechanism arm unit will then clamp the cover unit against the furnace inlet.