Optical and electrical evaluation methods of plasma-induced damage in InP substrates

Indium phosphide (InP) has been focused on as one of emerging materials that can be implemented in advanced semiconductor devices. We proposed optical and electrical characterization methods to evaluate plasma-induced physical damage (PPD)—ion bombardment damage—to InP substrates. By introducing a native oxide phase in an interfacial layer, we proposed an optical model of the damaged structure applicable for an in-line monitoring by spectroscopic ellipsometry. Gas species dependence was obtained, which suggested that the H2 plasma exposure formed a thicker damaged layer than Ar. An impedance spectroscopy (IS) under various biases (V b) was implemented to reveal the nature of damaged structures. Capacitive and conductive components assigned by the IS were confirmed to depend on incident species from plasma, indicating the difference of the energy profile of created defects. The presented methods are useful to characterize and control PPD in designing future high-performance InP-based devices.