Furnace annealing is a process used in semiconductor device fabrication which consist of heating multiple semiconductor wafers in order to affect their electrical properties.

The damage caused can be repaired by subjecting the crystal to high temperature.

Furnace anneals are performed by equipment especially built to heat semiconductor wafers.

This is due to the relatively long thermal cycles of furnaces that causes the dopants which are being activated, especially boron, to diffuse further than is intended.

RTP or RTA fixes this by having thermal cycles for each wafer that is of the order of minutes rather than hours for furnace anneals.