Method and system for evaluating a height of structures

A system for measuring a height difference (H) between a extremum portion of a microscopic structure and a background element, the system comprises:

• a sensor arranged to detect, first and second interference patterns by a sensor;
• wherein the first interference patterns are generated by wherein the first interference patterns are generated by illuminating an area of a sample by a first light beam and directing towards the sensor a first reference light beam of a first wavelength (w1) and light of the first wavelength (w1) that is either reflected from the area or passes through the area;
• wherein the second interference patterns are generated by illuminating the area of the sample by a second light beam and directing towards the sensor a second reference light beam of a second wavelength (w2) and light of the second wavelength (w2) that is either reflected from the area or passes through the area;
• wherein the second wavelength (w2) differs from the first wavelength (w1);
• wherein the area comprises the extremum portion of the microscopic structure;
• wherein the height different H is smaller than half of a synthetic wavelength (ws) that equals a ratio between (w1×w2) and a difference between w1 and w2;
• wherein H exceeds w1 and w2;
• and a processor, arranged to:
• generate, in response to the first and second interference patterns, first and second wavelength phase information about the microscopic structure;
• detect, in the first and second wavelength phase information, first and second wavelength extremum portion information;
• and
• calculate the height of the extremum portion of the microscopic structure based on the first and second wavelength extremum portion information.

A computer program product that comprises a non-transitory computer readable medium that stores instructions for measuring a height difference (H) between a extremum portion of a microscopic structure and a background element, the instruction comprise instructions for:

• detecting, by a sensor, first and second interference patterns by a sensor;
• wherein the first interference patterns are generated by illuminating an area of a sample by a first light beam and directing towards the sensor a first reference light beam of a first wavelength (w1) and light of the first wavelength (w1) that is either reflected from the area or passes through the area;
• wherein the second interference patterns are generated by illuminating the area of the sample by a second light beam and directing towards the sensor a second reference light beam of a second wavelength (w2) and light of the second wavelength (w2) that is either reflected from the area or passes through the area;
• wherein the second wavelength (w2) differs from the first wavelength (w1);
• wherein the area comprises the extremum portion of the microscopic structure;
• wherein the height different H is smaller than half of a synthetic wavelength (ws) that equals a ratio between (w1×w2) and a difference between w1 and w2;
• wherein H exceeds w1 and w2;
• generating, in response to the first and second interference patterns, first and second wavelength phase information about the microscopic structure;
• detecting, in the first and second wavelength phase information, first and second wavelength extremum portion information;
• and
• calculating the height of the extremum portion of the microscopic structure based on the first and second wavelength extremum portion information.