Methods and systems for semiconductor metrology based on wavelength resolved soft x-ray reflectometry

Abstract

Methods and systems for measuring structural and material characteristics of semiconductor structures based on wavelength resolved, soft x-ray reflectometry (WR-SXR) at multiple diffraction orders are presented. WR-SXR measurements are simultaneous, high throughput measurements over multiple diffraction orders with broad spectral width. The availability of wavelength resolved signal information at each of the multiple diffraction orders improves measurement accuracy and throughput. Each non-zero diffraction order includes multiple measurement points, each different measurement point associated with a different wavelength. In some embodiments, WR-SXR measurements are performed with x-ray radiation energy in a range of 10-5,000 electron volts at grazing angles of incidence in a range of 1-45 degrees. In some embodiments, the illumination beam is controlled to have relatively high divergence in one direction and relatively low divergence in a second direction, orthogonal to the first direction. In some embodiments, multiple detectors are employed, each detecting different diffraction orders.