the outlet gas nozzle 222 is open to the combustion chamber 221a for injecting the oxygen gas the inner tube member 223 is bent to have a u shape in the combustion chamber 221a and has an outlet gas nozzle 223a for injecting the hydrogen gas toward the outlet gas nozzle 222 in this instance both of the outer tube member 221 and the inner tube member 223 are formed of quartz while the gas supply sub system 210 is supplying the hydrogen gas and the oxygen gas into the combustion chamber 221a the hydrogen gas is mixed with the oxygen gas and is burnt in the oxygen gas high temperature steam is generated through the combustion and is exhausted through the wafer chamber 230 by means of the exhausting sub system 240 the loading sub system 250 loads the boat 260 holding the semiconductor wafers 261 into the wafer chamber 230 and the high temperature steam oxidizes the surface portions of the semiconductor wafers 261 though not shown in the drawings the controlling sub system 265 includes various monitoring sensors and optimizes the oxidation of the semiconductor wafers 261 as will be better seen in fig5 the furnace system according to the present invention further comprises a guard member 270 provided.