Vertical batch furnace assembly

A vertical batch furnace assembly for processing wafers comprising:

• a cassette handling space provided with a cassette storage configured to store a plurality of wafer cassettes provided with a plurality of wafers, and a cassette handler configured to transfer wafer cassettes between the cassette storage and a wafer transfer position;
• a wafer handling space provided with a wafer handler configured to transfer wafers between a wafer cassette in the wafer transfer position and a wafer boat in a wafer boat transfer position;
• an internal wall separating the cassette handling space and the wafer handling space and provided with a wafer transfer opening adjacent the wafer transfer position for a wafer cassette from or to which wafers are to be transferred,
• wherein the cassette storage comprises two cassette storage carousels, wherein the vertical batch furnace assembly has a removable top cover extending above the horizontal plane at the height of around 2.8 meter above the bottom side, which top cover closes off a top opening in a top wall of the vertical batch furnace assembly through which top opening extend wafer cassettes which are placed at a top platform stage of at least one cassette storage carousel of the two cassette storage carousels.