Process development and impurities analysis for the bottom antireflective coating material

The optical behavior of semiconductor bottom antireflective coating (BARC) material was investigated by both the measurement and simulation methods. The effects of spin-coating rate, interface reflection, BARC layer thickness and photoresist layer thickness were studied. Our results indicated that the 62.5 nm of BARC layer had strong effect on suppressing the light reflection of wavelength of 248 nm from the wafer surface, irrespective of the photoresist layer thickness. Based on the gravimetric method, a high throughput and one-step microwave digestion procedure was developed for the BARC materials. The digestion efficiency increased with the digestion duration and the temperature. By following the established one-step microwave digestion method and inductively coupled plasma mass spectrometry determination, the detection limits obtained for Cr, Ni, Cu, Zn and Pb were in 0.1 to 1.11 ppb levels. The spike recoveries of the metallic impurities were in the range 86-102% for the BARC materials. The analytical results of the BARC samples were found to be in reasonably good agreement with our previous method, and the analytical throughput can achieve up to 20 samples per hour for the analysis of 5 elements.