Chemical‐state‐resolved in‐depth profiles of gate‐stack structures on Si studied by angular‐dependent photoemission spectroscopy

Abstract

We have investigated chemical-state-resolved in-depth profiles of SiO 2 /SiN stack films using angular-dependent photoemission spectroscopy and maximum-entropy method (MEM). MEM enables to reproduce the gate-stack structure from angulardependence of core-level spectra, and it is utilized to determine atomic concentration of the interfacial layer. In-depth profile of the SiO 2 /SiN stack film reveals that the SiO 2 layer is distributed in the surface region and that the SiN layer is partly oxidized, which is well related to nitrogen bonding states analyzed by angular-dependence of N 1s core-level spectra.

Scanning photoelectron microscope for nanoscale three-dimensional spatial-resolved electron spectroscopy for chemical analysis

“…MEM has proven to be a powerful tool for constructing concentration versus depth profiles from angleresolved photoemission measurements. 9,12 The key concept of this method is that it minimizes artificial correlations within the data by proposing a reconstruction that agrees with the data but has the minimum amount of information. In order to find this reconstruction, the problem can be described mathematically as one in which a regularization function must be maximized.…”

“…The angular distribution corresponds to the probing-depth dependence of the photoelectron spectra and can be converted into the depth profiling information (z direction) using maximumentropy methods (MEM). 9 Thus, we can obtain the threedimensional x, y, and z distribution of the electronic structure and chemical bonding states of the samples on a nanometer scale. Figure 2 shows the schematic illustrations of the 3D nano-ESCA system.…”

Application of Maximum Entropy Method to Semiconductor Engineering

“…For determining α, there are also historical condition [26] and optimization methods [20], although the former significantly overestimates the experimental data and the latter needs long computing time. Although the validity of the classical MEM condition is still under debate, I have used it in this paper.…”

“…Although not many reports have been issued in this regard, MEM is gradually becoming popular as a powerful analyzing tool. The most popular application in this field may be the extraction of the depth distribution of atoms inside ultrathin films [16][17][18][19][20]. In using MEM to analyze angle resolved X-ray photoelectron spectroscopy (ARXPS) data, Chang et al reconstructed nitrogen depth distribution in nitrided silicon oxide films (SiON) and concluded that MEM enables nondestructive determination of depth distribution [19].…”

“…In using MEM to analyze angle resolved X-ray photoelectron spectroscopy (ARXPS) data, Chang et al reconstructed nitrogen depth distribution in nitrided silicon oxide films (SiON) and concluded that MEM enables nondestructive determination of depth distribution [19]. Moreover, MEM made it possible to determine even the chemical-state-resolved depth distribution [19,20]. This information cannot be obtained using other conventional methods such as medium energy ion scattering or secondary ion mass spectroscopy, which evidences the advantages of MEM.…”