Second Harmonic Generation characterization of SOI wafers: Impact of layer thickness and interface electric field

Abstract

In this work, we investigate Second Harmonic Generation (SHG) as a nondestructive characterization method for Silicon-On-Insulator (SOI) materials. For thick SOI stacks, the SHG signal is related to the thickness variations of the different layers. However, in thin SOI films, the comparison between measurements and optical modeling suggests a supplementary SHG contribution attributed to the electric fields at the SiO2/Si interfaces. The impact of the electric field at each interface of the SOI on the SHG is assessed. The SHG technique can be used to evaluate interfacial electric fields and consequently interface charge density in SOI materials.

(Invited) Second Harmonic Generation: A Powerful Non-Destructive Characterization Technique for Dielectric-on-Semiconductor Interfaces

“…Therefore when thin Si films are used, SHG measurements allow accessing the interfacial electric field partially due to the interface trap density. Note that the interface of interest is the film-BOX, while the one that dominates the SHG is the top one (film-passivation or native oxide) (29). However if the SOI film thickness is below the absorption limit at the double frequency (~70 nm thickness for 380 nm wavelength of SHG), it is possible to develop a strategy to access the buried interface.…”

The study of interface quality in HfO2/Si films probed by second harmonic generation

“…Optical second harmonic generation (SHG) is a nonlinear optical phenomenon that serves as a sensitive probe for studying buried solids and interfacial properties [11]. The sensitivity of SHG to interfacial electrical properties, such as charge traps [12] and doping levels [13,14], makes it as a unique characterization technique. In the centrosymmetric materials, dipole contributions at the lowest order are typically prohibited, except the dipole contribution at the interface where inversion symmetry is disrupted due to material discontinuity as well as the interfacial electric field.…”