SEMICONDUCTOR-SUBSTRATE DIFFUSION FURNACE

PROBLEM TO BE SOLVED: To provide a semiconductor-substrate diffusion furnace of a simple structure, capable of forming an even sheet resistance on the surface of a diffused substrate, and moreover with the even sheet resistance from the jet orifice of a diffusion-furnace gas to a furnace-gate door, using process gas of requisite amount.SOLUTION: The semiconductor-substrate diffusion furnace includes a furnace-core tube closed by the furnace-gate door with a blocked one end and an openable another end to thermally diffuse dopant onto the diffused substrate, and a diffused-substrate boat with the substrate mounted thereon to feed into and take out of the furnace-core tube from its substrate gateway by opening the furnace-gate door. Further in the diffusion furnace, a process-gas jet nozzle for diffusing the dopant is disposed hermetically through a blockade in one end of the furnace-core tube, to blow out the process gas towards each of the substrates mounted on the boat; or a plurality of gas-guiding tubes are disposed to blow out the process gas from a jet nozzle to each of the substrates through a gas-guiding tube, together with the jet nozzle through an introducing tube. The process gas is reliably supplied to the diffused substrate, resulting in getting the substrate with the even sheet resistance.