Raman Imaging of Stress Distribution in Silicon Wafer

4種RBMの分布重ね合わせ

Laser wavelength   : 532nm
Objective lens  : x100、NA=0.90
Grating   : 2400gr/mm
Number of spectra : 60,000(400x150)
Total measurement time   : 20min

 

The top image shows the distribution of peak shift of Si substrate. Raman imaging is a powerful tool to analyze the spatial distribution of stress around the boundary of thin film on Si substrate by quantifying the Raman peak shift.

 

▼ Magnified image
Line profile of the shift of Raman peak

The right figure shows the shift of Si peak along the dot line. RAMANtouch can determine peak position more precisely than 0.1cm -1.

  ▼ Line profile of the shift of Raman peak
Line profile of the shift of Raman peak


(Supplement)Spectral resolution and the precision of peak determination

  ▼ Spectral resolution
Spectral resolution

Methods 785nm 1200gr/mm


  ▼ Precision of peak determination
Precision of peak determination

Methods 532nm 2400gr/mm

 
Spectral resolution is frequently misunderstood. "Spectral resolution" is fundamentally defined as the ability to separate close peaks. "Spectral resolution" depends on various factors such as focal distance of spectrometer, grating, and width of excitation laser. One can directly characterize the spectral resolution of a Raman microscope by measuring the width of Reilygh light. On the other hand, measurement of stress requires the precision of peak determination, which can be evaluated by the deviation of the peak positions of repeated measurements.