Method of and system for determining an overlay or alignment error between a first and a second device layer of a multilayer semiconductor device

Abstract

The present document relates to a method of determining an overlay or alignment error between a first and a second device layer of a multilayer semiconductor device () using an atomic force microscopy system (). The system comprises a scan head () including a probe (). The probe includes a cantilever and a probe tip (). The method comprises moving the probe tip and the semiconductor device relative to each other for scanning of the surface of the semiconductor device with the probe tip, wherein the probe tip is intermittently or continuously in contact with the surface during scanning. During scanning a signal application actuator () applies an acoustic input signal to the substrate, and motion of the probe tip is monitored with a tip position detector for obtaining an output signal, to be analyzed for mapping subsurface structures in different device layers. The signal application actuator includes a shear wave actuator to apply a shear acoustic wave () in the substrate. The output signal () is indicative of torsional deflection of the probe tip. The document further describes a system.