Measurement And Control Of Wafer Tilt For X-Ray Based Metrology

A method comprising:

• illuminating a semiconductor wafer with an x-ray illumination beam at an x-ray measurement spot;
• detecting an amount of x-ray radiation from the semiconductor wafer in response to the incident x-ray illumination beam;
• illuminating the semiconductor wafer with an optical illumination beam over an orientation measurement spot on the semiconductor wafer;
• focusing an amount of light reflected from the semiconductor wafer in response to the incident optical illumination beam onto a photosensitive surface of a detector;
• detecting light reflected from the semiconductor wafer in response to the incident optical illumination beam at the photosensitive surface of the detector;
• estimating a change in orientation of the semiconductor wafer at the orientation measurement spot based on a change of a location of incidence of the light reflected from the semiconductor wafer on the photosensitive surface of the detector;
• and
• determining a value of a parameter of interest characterizing a structure disposed on the semiconductor wafer based on the detected amount of x-ray radiation.

A wafer orientation measurement system comprising:

• an optical illumination source configured to generate an illumination beam directed to an orientation measurement spot on a semiconductor wafer;
• an optical detector configured to detect light reflected from the semiconductor wafer in response to the incident optical illumination beam;
• one or more focusing optical elements configured to focus the light reflected from the semiconductor wafer in response to the incident illumination beam onto the detector, wherein the detector is located at or near a focal plane of the one or more focusing optical elements;
• and
• a computing system configured to estimate a change in orientation of the semiconductor wafer with respect to an x-ray illumination source at the orientation measurement spot based on a change of a location of incidence of the light reflected from the semiconductor wafer on the optical detector, wherein the x-ray illumination source is configured to generate an x-ray illumination beam incident on the semiconductor wafer at an x-ray measurement spot.