Abstract: The present document relates to a method to determine dimensions of features of a subsurface topography of a sample, the features having a spatial periodicity. The subsurface topography is obtained using scanning probe microscopy. The method includes obtaining measurement values of an acoustic output signal in at least N locations and generating a location dependent subsurface topography signal. The method further comprises providing an autocorrelation matrix by performing a cross-correlation of the subsurface topography signal in respect of each further location to yield the autocorrelation matrix having size N*N. Thereafter, the method includes performing an Eigenvalue decomposition for obtaining Eigenvalues of the matrix, and selecting a subset of Eigenvalues having the largest values. From these a frequency estimation function is constructed and at least one output value indicative of the spatial periodicity is obtained therefrom.

Abstract: The present document relates to a method of monitoring an overlay or alignment between a first and second layer of a semiconductor using a scanning probe microscopy system. The method comprises scanning the substrate surface using a probe tip for obtaining a measurement of a topography of the first and second layer in at least one scanning direction. At least one pattern template is generated which is matched with the topography of the first layer for determining a first candidate pattern. The first candidate pattern is matched with the measured second topography for obtaining a second candidate pattern to represent the measured topography of the second layer. Feature characteristics of device features are determined from both the first and second candidate pattern, and these are used to calculate one or more overlay parameters or alignment parameters.

Abstract: The present document relates to a method to determine dimensions of features of a subsurface topography of a sample, the features having a spatial periodicity. The subsurface topography is obtained using scanning probe microscopy. The method includes obtaining measurement values of an acoustic output signal in at least N locations and generating a location dependent subsurface topography signal. The method further comprises providing an autocorrelation matrix by performing a cross-correlation of the subsurface topography signal in respect of each further location to yield the autocorrelation matrix having size N*N. Thereafter, the method includes performing an Eigenvalue decomposition for obtaining Eigenvalues of the matrix, and selecting a subset of Eigenvalues having the largest values. From these a frequency estimation function is constructed and at least one output value indicative of the spatial periodicity is obtained therefrom.