Patent ID: 6880382

Claim:
A leakage detecting method for use in an oxidizing system of forming an oxide layer, the method comprising the steps of: (a) providing an oxidizing system having an oxidizing chamber and an oxygen concentration analyzer installed in a bypass of an exhaust pipe of said oxidizing chamber; (b) performing an oxidizing process on a test wafer in a test run under a specified operating condition in said oxidizing system by flowing an oxidizing gas through said oxidizing chamber containing said test wafer; (c) measuring an oxygen concentration of said oxidizing gas exiting said oxidizing chamber in said test run by said oxygen concentration analyzer; (d) measuring the oxide thickness of said test wafer after said test run; (e) repeating (b), (c), and (d) for a plurality of test runs to obtain a correlation between the measured oxygen concentration and the oxide thickness for the plurality of test runs to identify an acceptable oxygen concentration corresponding to a maximum acceptable oxide thickness, wherein an oxygen concentration greater than said acceptable oxygen concentration indicates gas leakage in said oxidizing system; (f) selecting a safety factor and multiplying said acceptable oxygen concentration with said safety factor to get a threshold oxygen concentration; (g) performing a general oxidizing process on a working wafer under said specified operating condition in said oxidizing system; wherein while said oxygen concentration analyzer starts to measure an oxygen concentration of said oxidizing gas exiting said oxidizing chamber, if said measured oxygen concentration is greater than said threshold oxygen concentration, an indication of gas leakage exists in said oxidizing system.