Measurement of spectral transmissivity of quartz plates used in rapid thermal processing

During the rapid thermal process, silicon wafers are heated using infrared lamps. Quartz plates are affected by wafer-related contaminants and heat, which alter their radiation characteristics. We investigated the transmissivity at various wavelengths: 635, 1310, and 2200 nm. The refractive indices of the contaminated quartz plates were analyzed using ellipsometry. The planar roughness of the quartz samples was determined by atomic force microscopy. The transmissivities of quartz plates with different contamination thicknesses were estimated using thin-film optical calculations. The errors in the contaminated thickness estimation at 2200 nm were within 31 %.