Incident ion dose evolution of damaged layer thickness in Si substrate exposed to Ar and He plasmas

The effect of ion flux on the formation of a damaged layer in a Si substrate was investigated in detail. An inductively coupled plasma source was used to control the flux (Γ ion ) and energy ( E ion ) of incident ions. The progressive behavior of the total damaged layer thickness ( d dam ) estimated by spectroscopic ellipsometry primarily depends on the total ion dose ( D ion = Γ ion × t pr , where t pr is the process time) and E ion . The evolution of d dam then saturates and becomes independent of D ion . The characteristic total ion dose ( D dam ) is defined, which distinguishes the progressive and saturation phases. Experimental results suggest that D dam is estimated to be in the range from 1 × 10 16 to 3 × 10 16 cm −2 , regardless of Ar and He plasmas in the present study. This D ion -dependent behavior was also confirmed by transmission electron microscopy and capacitance–voltage measurements. The interface thickness d IL of the damaged layer was found to be independent of D ion . This result confirms that d IL can be used as a measure of the E ion -dependent plasma-induced damage (PID) for in-line monitoring. The present D ion dependence can be implemented in the conventional PID range theory, particularly, in the designs of high-density plasma sources.