Transmission small-angle X-ray scattering metrology system

A method comprising:

• illuminating a measurement target formed on a wafer surface with a beam of x-ray radiation generated by an illumination source at an energy level of 15 kiloelectronvolts or higher;
• detecting an intensity associated with a plurality of diffraction orders of an amount of radiation scattered from the measurement target in response to the incident beam, wherein two or more of the plurality of diffraction orders spatially overlap on a surface of a detector that detects the intensities, and wherein an optical path length between the illumination source and the detector is less than three meters;
• determining an intensity of each of the overlapping diffraction orders based on a beam shape of a zeroth diffraction order;
• and
• determining a value of a parameter of interest associated with the measurement target based on the intensities of the plurality of diffraction orders.

A metrology system comprising:

• an x-ray illumination source configured to generate an amount of x-ray radiation;
• an x-ray illumination optics subsystem configured to illuminate a measurement target formed on a wafer surface with an incident focused beam of the amount of x-ray radiation;
• an x-ray detector configured to detect an intensity associated with each of a plurality of diffraction orders of an amount of radiation scattered from the measurement target in response to the incident focused beam, wherein an optical path length between the illumination source and the detector is less than three meters, and wherein two or more of the plurality of diffraction orders spatially overlap on a surface of the x-ray detector;
• and
• a non-transitory, computer-readable medium, comprising:
• code for causing a computing system to determine an intensity of each of the overlapping diffraction orders based on a beam shape of a zeroth diffraction order;
• and
• code for causing the computing system to determine a value of a parameter of interest associated with the measurement target based on the determined intensities of the plurality of diffraction orders.