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As Hi NA EUV patterning Era is coming, here comes the defect inspection challenges status update from imec in 2022. The optical BF tools(KLA 2935 and 3925) and EBI(HMI eP5) were used in this study. As expected, when PR thickness down to <20nm, the faster and most advanced BF tools is nearly blind. To meet sensitivity, the throughput(1mm2/hr) of EBI tool is far out of inline monitoring requirement (to inspect one die of 850 mm2 needs 35 days. Full wafer takes ~ 5 years!!!). Can we use precise CD/Hotspot metrology tools and rigorously statistical sampling to predict defect rate and process window? or we need to wait for maturity of multiple ebeams inspector? Go for Metrology and Inspection experts in Hi NA EUV Era.
郭菓賢 HS Kuo, Technical Consultant, Taipei, Taipei City, Taiwan
Fred:
As you might know, when defect size down to less than 10nm, the defect capture rate of bright field(BF) inspection tool is getting lower and lower, but AEI is easier than ADI in inspection(sometimes ADI damage could happen for some wavelength and intensity). The light source used in BF is typically with wavelength larger than 190nm. By typical rule of thumb about sensitivity, which could be >1/10 of wavelength(or >20nm) to get higher capture rate. The statement of "BF tool is out of steam" has been talked for years but optical wafer inspection market still occupied ~50% market share of M&I. I would not say KLA3925( a leading tool) is ruled out, but definitely it faces sensitivity challenges.
Not sure what is your definition of electrical test vehicle. If you talked about Voltage Contrast application, it has been used for decades. It also been extended to validate overlay capability currently using pre-defined overlay shift pattern to detect actual overlay result in local and chip area.
To cover the smaller defect size(<10nm or even down to less than 5nm), ebeam inspection is adopted. There are typically two type inspection modes for so-call physical defects in EBI. One is continuous ebeam scan for larger area inspection but with less sensitivity. Another is "static or step-and-scan" for hotspots in smaller region and with higher sensitivity.
ASML/HMI eP5 here is typically for hotspot inspection or for large field inspection/metrology which is the grean field ASML wants to capture. eBeam application is a hot market and critical for advanced nodes. But it can not fit into inspection for 3D pattern like GAA. Just FYI.
Daniel:
Thanks for your sharing here.
