| 摘要 |
PURPOSE:To minimize a wafer cooling action and thereby to obtain the excellent uniformity of the temperature of a wafer, by preheating an ambient gas to be introduced into a chamber. CONSTITUTION:When a heater 8 is energized and a nitrogen gas is preheated thereby to a high temperature before it is introduced into a chamber, a wafer cooling effect by the nitrogen gas is sharply reduced. In the case when the temperature of gas is increased to 1,000 deg.C in a preheating chamber, the lowering of the temperature of a wafer is reduced to about 4 deg.C. It is because the temperature of gas itself lowers while the gas passes through a low-temperature piping 9 that the cooling effect still exists in spite that the gas is heated in the preheating chamber. In order to hold down further the wafer cooling effect by an introduced ambient gas so as to realize an optimum heating condition, accordingly, the temperature of gas in a preheating chamber 7 needs to be set at a temperature higher than 1,000 deg.C. |
