No abstract

This study is concerned with variations of the concentration of active boron dopant in the near surface region of silicon wafers. Boron can be deactivated by pairing with hydrogen or metals, particularly Cu and Fe, all of which may originate from the surface polishing process. The temperature dependence of boron activation is studied using the surface charge profiling method. Based on the determined activation energy of 1.28 eV it was concluded that in the p-type wafers used in this study initially observed boron deactivation was dominated by its interaction with hydrogen introduced during wafer polishing.

In contrast to most wet cleans, cleaning reactions in the gas phase may be significantly affected by the surface hydration of the incoming wafer. Additionally, effective termination of the cleaning reaction, which in wet cleans is accomplished through a deionized water rinse, is not as straightforward in the case of dry cleaning processes. In this experiment, UV/ nitrogen exposure and slight oxide etching (30 Å) were found to control the initiation of gas-phase oxide etching reactions by reducing the level of physisorbed and chemisorbed moisture on the oxide surface, respectively, while UV exposure, pressure, temperature, and ambient composition were used to control termination of surface reactions following silicon surface exposure to the UV/Cl 2 treatment.

The SPV-based method of Surface Charge Profiling (SCP) is discussed, and its applications in silicon surface monitoring in IC manufacturing are reviewed. The SCP method shows high sensitivity to changes in the condition of the Si surface (e.g. surface cleaning operations) and a very thin near-surface region (e.g. variations of active dopant concentration near the surface).

No abstract