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

Abstract

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.

Improvement of the plasma‐induced defect generation model in Si substrates and the optimization design framework

“…The resultant plot of d dam versus D ion is depicted in Figure d. One can expect that the d dam value tends to saturate due to the characteristic feature of n dam ( x ) toward to a “saturation” phase, which is in good agreement with the results reported previously . We focus on this D ion dependence of d dam and improve the conventional PPD range theory by introducing the D ion dependence of the damaged layer formation as below.…”

“…The increasing rate increases with an increase in E ion . Equation is the main result of this paper, that is, progressive behavior is observable, which was reported previously . The improved PPD range theory includes the E ion and D ion dependences of d dam .…”

“…This model was confirmed to be valid for the PPD analysis in the present d dam range and is widely used for in‐line monitoring . The details of the PPD characterizations have been reported elsewhere …”

“…As seen, d dam increases rapidly with D ion at the early stage and then tends to saturate. The observed feature was empirically expressed by a simple damaged layer formation model as where is a material‐ and process‐dependent constant. As , B = A in Equation .…”

“…One can expect that the d dam value tends to saturate due to the characteristic feature of n dam (x) toward to a "saturation" phase, which is in good agreement with the results reported previously. [34] We focus on this D ion…”