Corona – Kelvin characterization of semiconductor materials is now a common technique that is used as a non-contact replacement of contact CV measurements [1,2]. Traditionally it is applied to planar structures such as an oxide – semiconductor structure or similar. Deposition of corona charge ΔQ_CORONA causes a change in surface voltage, ΔV = ΔV_SB + ΔV_D, which includes voltage drop across the semiconductor space charge layer, ΔV_SB, and across the dielectric layer, ΔV_D. The differential capacitance is calculated as C = ΔQ_CORONA/ΔV. The incremental charging-measuring cycle gives the non contact CV characteristic and also charge-voltage characteristic, QV, where Q = ΣΔQ, and V = ΣΔV.

In this work we applied the Kelvin-corona method to a patterned structure, which represents a grid of 2 or more locally adjacent elements having different properties (Figure 1). Elements of the structure can constitute a planar structure (Figure 1A) or a non-planar three dimensional structure (Figure 1B). In both cases, the elements of the structure have dimensions smaller than the size of the Kelvin probe, such that at least one cycle of the pattern structure is within the Kelvin probe diameter.

A model based analysis of corona charge – Kelvin probe data (QV data) was developed which is based on the geometrical dimensions, electrical parameters of elements of the patterned structure, and response of each element to corona charging. The effective voltage measured by the Kelvin probe follows: V_eff=Σ(a_iV_i)/Σ(a_i), where a_i is the area of an element i, and V_i is the voltage in the area a_i. The surface voltage for each element of the structure depends on electrical properties of the structure, Vi=f(φ_MS, C_D, Q_D, D_IT), and responds to corona charging according to its electrical properties.

Examples of experimental and simulated data will be presented for a type 1B structure. The simulated data allow quantification of electrical parameters of each element of the structure such as interface properties at the SiO₂ / silicon interface, including the interface trap density, D_IT, and the flat band voltage, V_FB.

The results are of importance for the rapid characterization of 3D structures, such as STI, FinFET, etc. where the electrical properties vary between elements of the structure. The model based QV method enables extraction of electrical parameters that are different for the elements of the structure.

References.

1. K. Schroder, Meas. Sci. Technol., 12, R16 (2001).
2. Wilson, D. Marinskiy, A. Byelyayev, J. D’Amico, A. Findlay, L. Jastrzebski, and J. Lagowski, ECS Trans., 3(3), 3 (2006).