Inferred measurement of subsurface nanosheet structures using scanning probe microscopy, solving the inverse problem

Metrology challenges surrounding nanosheet structures used in next generation semiconductor devices based around Forksheet and Gate-All-around Field Effect Transistors include procuring measurements in the planar directions, such as critical dimensions, as well as in the vertical direction, such as sheet and recess thicknesses. Subsurface Scanning Probe Microscopy (SSPM) can be used to distinguish and measure features that are buried beneath opaque layers. In this work, we investigate if SSPM can contribute to this challenge and can be used to solve the inverse problem. It is shown that qualitative agreement between modelling and experiments is good, when the experimental contact conditions are sufficient. Quantitative measurements, however, are still out of reach.