A silicon shelf tower for batch thermal processing of silicon wafers in a vertical furnace. The tower includes at least three silicon legs joined to bases and having a vertical arrangement of slots. Silicon shelves are detachably loaded by sliding therm through the slots in the side legs and into the slot of the back leg. A interlocking mechanism detachably locks the shelves to the back leg while the slots in the two side legs laterally constrains the shelves. The shelves include cutouts to allow a robot paddle to load and unload wafers to the shelves. Circular holes in the shelves relieve stress and prevent wafer sticking Preferably, the shelves are formed from randomly oriented polycrystalline silicon. The shelves and towers can alternatively be made of other materials such as quartz and silicon carbide.