Wafer thickness, topography, and layer thickness metrology system
OwnerWojciech Jan Waleckiinventor
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Abstract
The invention describes a metrology system allowing for the reduction of the errors caused by vibration of the production floor and allowing for measurements of the thickness of wafers in motion. This is accomplished by performing simultaneous measurements of spectra containing interference signals containing distance information using a plurality of probes positioned on both sides of the measured wafer on the same detector at the same time or by means of plurality of synchronized detectors. System is also able to measure thickness of the individual optically accessible layers present in the sample.
Claims3
A Tool for measurement of semiconductor wafer comprising two probes equipped with reflectors positioned on opposite sides of the semiconductor wafer,
- where both probes are connected to 2×2 optical coupler to computer-controlled spectrograph, and to a low coherence light source,
- where an upper probe is placed at a distance from the semiconductor wafer,
- where the distance between the upper probe and semiconductor wafer defined as optical path length from 2×2 coupler through the first probe to the semiconductor wafer is different than a distance between the lower probe from the semiconductor wafer where the distance between the lower probe and semiconductor wafer is defined optical path length from 2×2 coupler through the lower probe to the semiconductor wafer
- by more than two coherence lengths of radiation emitted by the low coherence light source, and a computer-controlled spectrograph where computer is equipped with a computer Fourier transform program filtering and separating Fourier transform frequency peaks originating from top and bottom probes.
Dependencies are inferred from the claim text.