Local shape deviation in a semiconductor specimen

A computerized method of detecting local shape deviation of a structural element in a semiconductor specimen, the method performed by a processing and memory circuitry (PMC) and comprising:

• obtaining an image comprising an image representation of the structural element;
• extracting, from the image, an actual contour of the image representation;
• estimating a reference contour of the image representation indicative of a standard shape of the structural element, wherein the reference contour is estimated based on a Fourier descriptor representative of the reference contour, the Fourier descriptor being estimated using an optimization method based on a loss function specifically selected to be insensitive to presence of local shape deviation of the actual contour;
• and
• performing one or more measurements representative of one or more differences between the actual contour and the reference contour, the measurements being indicative of whether a local shape deviation is present in the structural element.

A non-transitory computer readable storage medium tangibly embodying a program of instructions that, when executed by a computer, cause the computer to perform a method of detecting a local shape deviation of a structural element in a semiconductor specimen, the method comprising:

• obtaining an image comprising an image representation of the structural element;
• extracting, from the image, an actual contour of the image representation;
• estimating a reference contour of the image representation indicative of a standard shape of the structural element, wherein the reference contour is estimated based on a Fourier descriptor representative of the reference contour, the Fourier descriptor being estimated using an optimization method based on a loss function specifically selected to be insensitive to presence of local shape deviation of the actual contour;
• and
• performing one or more measurements representative of one or more differences between the actual contour and the reference contour, the measurements being indicative of whether a local shape deviation is present in the structural element.