METHOD AND DEVICE FOR PURGING BACK SURFACE OF SUBSTRATE IN CHEMICAL VAPOR PROCESSING

PROBLEM TO BE SOLVED: To prevent formation of an unrequited deposit, by a method wherein there is provided a substantially annular opening giving a slit, and the slit is structured and disposed so as to direct a purge gas flow to a direction in substantial parallel to a plane defined by a wafer and outwardly of a radial direction from the slit. SOLUTION: If a surface 22 and a back surface 26 are rotated, this gives a movement amount outwardly of a radial direction to a reaction gas 18 and purge gas 32. A rotation speed is sufficiently increased and the gas is made to flow outwardly of a radial direction to a margin part 36 of a wafer 10 by mutual operations of the wafer surfaces 22, 26 and the gases 18, 32. This flow outwardly of a radial direction prevents the purge gas 32 and the reaction gas 18 from being remarkably mixed on an upper surface 22 of the wafer. A processing profile is accelerated so that it is made the most uniform outside a peripheral portion of the upper surface 22 of the wafer 10.