Patent ID: 7452423

Claim:
A diffusion system for forming a doping layer in a wafer, the system comprising: a bubbler generating a doping gas; a premixer premixing the doping gas with reactive gases to form a gas mixture and preheating the gas mixture; a main chamber, in which the gas mixture reacts with the wafer; a buffer case surrounding at least a portion of the main chamber and externally isolating an exhaust port and a door on the main chamber, wherein the wafer is loaded and unloaded via the buffer case and the door into and out of the main chamber; a waste gas exhaustion system exhausting waste gas after the reaction is finished in the main chamber; and wherein the door has a double insulation structure with a double sandwich structure with two elements with two surfaces combined to form a door, wherein the first element is formed of quartz and the second element is formed of graphite.