Effects controlling initiation and termination of gas-phase cleaning reactions

In contrast to most wet cleans, cleaning reactions in the gas phase may be significantly affected by the surface hydration of the incoming wafer. Addi tionally, effective termination of the cleaning reaction, which in wet clea ns is accomplished through a deionized water rinse, is not as straightforwa rd in the case of dry cleaning processes. In this experiment, UV/ nitrogen exposure and slight oxide etching (30 Angstrom) were found to control the i nitiation of gas-phase oxide etching reactions by reducing the level of phy sisorbed and chemisorbed moisture on the oxide surface, respectively, while UV exposure, pressure, temperature, and ambient composition were used to c ontrol termination of surface reactions following silicon surface exposure to the UV/Cl-2 treatment. (C) 1999 The Electrochemical Society. S0013-4651 (98)03-043-2. All rights reserved.