Patent ID: 11885609
Assignee: nan
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 1:
2. A method of measuring thickness of slab of the material using the tool for measurement of thickness of semiconductor wafer as described in claim 1, comprising following steps:
recording a set of three spectra using spectrograph including a first spectrum when two probes illuminate the semiconductor wafer;
recording a second spectrum when only first probe produces interference fringes while the second probe is removed by distance larger than three (3) times the coherence length from position, where second probe produces largest observed amplitude interference fringes;, recording a third spectrum when only second probe produces interference fringes while the first probe is removed by distance larger than three (3) coherence length from position where the first probe produces largest observed amplitude interference fringes;, analyzing the second spectrum and finding a first frequency of fringes caused by the radiation reflected through the first probe;, analyzing third spectrum and finding a second frequency of fringes caused by radiation propagating through the second probe;, analyzing the first spectrum using and finding simultaneously recorded two distinct frequencies corresponding to interference fringes produced by radiation propagating through two probes and attributing frequency peaks to radiation propagating through the first and the second probe using frequencies identified in the analysis of the second and the third spectra and using the simultaneously measured frequencies to calculate thickness of the wafer.