High throughput scanning probe metrology for high-NA EUV photoresist profiling

Improved resolution of the High-NA EUV technology comes with thinner photoresist and smaller aspect-ratio requirements. Trade-offs include more stringent process control needs for resist loss and line roughness. Traditional metrologies like OCD or CD-SEM lose sensitivity due to diminishing interaction volume. A metrology technique that thrives in this regime is Scanning Probe Microscopy: thinner resist allows for higher scanning speed, and smaller aspect ratio for higher measurement accuracy. Here we propose a High-Throughput SPM technique as key enabler for High-NA EUV process control. Detailed, high-density full wafer measurements of resist loss, CD and roughness are enabled by a high-throughput, 4-head SPM toolset, and compared for different resist thicknesses down to 10nm. Sampling schemes consistent with scanner throughput are considered.