Fast foup swapping with a foup handler

A vertical batch furnace assembly for processing wafers comprising:

• a cassette handling space;
• a wafer handling space;
• and
• a first wall and separating the cassette handling space from the wafer handling space and having at least one wafer transfer opening in front of which, at a side of the first wall which is directed to the cassette handling space, a wafer transfer position for a wafer cassette is provided;
• wherein the cassette handling space comprises
• a cassette storage having a plurality of cassette storage positions each configured to store a wafer cassette provided with a plurality of wafers;
• and
• a cassette handler configured to transfer wafer cassettes between the cassette storage positions and the wafer transfer position, wherein the cassette handler comprises:
• a first cassette handler arm;
• and
• a second cassette handler arm.