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This presentation by Angelina Lao, a Principal Engineer at Micron Semiconductor Singapore, highlights the advantages of Optical Photothermal Infrared Spectroscopy (O-PTIR) for analyzing microelectronic failures and contamination.
Micron acquired their first O-PTIR system in 2021, and spent a year studying this technology before implementing it in their failure analysis workflow. The O-PTIR technique addresses fundamental limitations of conventional analytical methods like Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy.
The key advantages of O-PTIR include:
1. Superior spatial resolution (0.5 micrometer/500 nanometer spot size) compared to conventional FTIR’s 25+ micrometer limitation
2. Non-contact technique that eliminates sample damage and cross-contamination issues
3. Point analysis rather than area analysis, providing IR wavelength independent measurements
4. No autofluorescence impact, unlike Raman spectroscopy
5. Minimal sample preparation requirements
The presentation showcases two successful case studies:
First, O-PTIR enabled effective cross-section analysis of subsurface delamination in microelectronic specimens. While conventional FTIR required sample pry-open preparation (which risks removing the foreign material causing delamination), O-PTIR could directly analyze mechanical cross-sections with its 500nm spot size. This revealed polymer resin and chemical solvent residues at the delamination interface, identifying underfill material flowing into unintended areas as the root cause. O-PTIR even detected cotton fiber residues from cleaning cloths used during sample preparation, demonstrating its remarkable sensitivity.
Second, O-PTIR successfully analyzed sub-10 micrometer particles on silicon dies that were impossible to characterize with conventional FTIR. The example showed two visually similar particles that O-PTIR revealed to have completely different chemical compositions (silica vs. urea), highlighting the importance of chemical analysis over visual inspection.
The system accommodates samples up to 7cm × 7cm with 22mm height. For samples easily damaged by Raman lasers, O-PTIR can operate at reduced green probe power (tens of microwatts) with an avalanche photodiode detector while maintaining excellent signal-to-noise ratios. The technique works effectively on metal substrates and rough surfaces, with the latter benefit stemming from its monochromatic light detection that eliminates wavelength-dependent scattering artifacts.
In conclusion, O-PTIR technology provides semiconductor failure analysts with a powerful tool for non-destructive chemical analysis at submicron resolution, enabling more accurate root cause determination with minimal sample preparation requirements.
