I. Introduction
Evolution of semiconductor material systems and device topologies calls for development of new noninvasive metrology methods to characterize and monitor quality and structural parameters. The use of nondestructive, noninvasive optical second harmonic generation (SHG) can support a class of these needs. The SHG process is very sensitive to characteristics of heterointerfaces, making the technique well suited to layered material structures such as gate-dielectric to semiconductor interfaces and silicon-on-insulator (SOI) structures. SHG has been previously investigated to detect defects in the SOI structure and to measure the bias dependence of the SHG signal in SOI wafers [1], and rotational dependency has been correlated to interface roughness in Si/ structures (none in SOI buried oxides) [2]. In this paper, we focus on the specific application of monitoring the subsurface quality parameters of SOI wafers in a noncontact, noninvasive manner, not requiring an applied bias. The work presented is not intended to be a comprehensive scientific study with qualitative models, but is intended to further evaluate and demonstrate the potential of SHG for application as a nondestructive SOI wafer metrology tool.