| 摘要 |
PURPOSE: To reduce the undercut of heat oxide and to reduce etching time dependency by raising the temperature of wafer to a prescribed set value and exposing the wafer under HF/H2 O steam. CONSTITUTION: A wafer 14 is heated to the specified temperature by infrared radiations from a heating system 16. Pressure in a reaction chamber 12 is regulated to a prescribed set value. When the HF/H2 O steam is passed into the reaction chamber 12, the top face of wafer 14 is exposed under the vapour. During the period of exposure, the aqueous membrane of HF and H2 O is condensed on the surface of wafer 14. Because of the rise of wafer temperature, etching speed is decelerated and the incubation period of heat oxide is prolonged as well. When etching is performed with desired uniformity or all the phosphorus silicate glass is removed, etching is completed. Because of a method for exposing the wafer under the HF/H2 O steam by letting the temperature of wafer rise to the prescribed set value, the undercut of heat oxide is reduced and etching time dependency can be reduced. |
