Stress Analysis for Semiconductor Raw Materials

Emerging display technologies demand high brightness, low power consumption and longer lifetime. Arrays, of self-emitting, micron-sized LEDs or Micro-LED (µLED), are considered a strong contender to replace current OLED or LCD displays.

Raman spectroscopy is an essential tool for the characterization of semiconductors. However, Raman spectroscopy's spatial resolution is limited by the diffraction limit to about 200-300 nanometers, which can be insufficient for analyzing the increasingly smaller features of modern electronic devices.

Raman spectroscopy enables precise, non-destructive stress analysis in 4H-SiC semiconductors. This study shows how peak shifts in Raman spectra reveal stress variations from surface treatments like cutting, lapping, and CMP—supporting quality control and process optimization in electronics.

Raman spectroscopy is a very well suited technique to determine both Ge fraction and strain in SiGe layers and Si cap layers. Moreover the possibility of using both UV and visible excitation lines on the same instrument is essential to study structures made up of a Silicon cap layer on top of a SiGe layer. The relative Ge content in the constant Si1-xGex layer is calculated from the visible Raman spectrum and the strain of the cap Si layer is derived from the UV Raman spectrum.

We have performed a complete Raman polarized study of a single GaN nanowire using a confocal microscope together with a high resolution stage. The high spatial resolution of our Raman confocal instrument together with a piezoelectric stage demonstrates unambiguously the possibility to image the optical properties of nano-objects with a resolution better than 200 nm keeping the fill advantage of the polarization control under a confocal microscope.