Wide-Spectrum Ellipsometry Measurement Based on Two Parallel Channels

Abstract

To solve the problem of a single light source, phase compensator, and detector, amongst others—which cannot meet the ellipsometry measurement requirements over a wide spectral range (from visible light (VIS) to short-wave infrared (SWIR) and even mid infrared (MIR; 400–3200 nm))—a wide-spectrum thin-film ellipsometry measurement solution based on two parallel channels was proposed. Full spectral coverage was achieved through a combination of the VIS-SWIR (400–2100 nm) and SWIR-MIR (2100–3200 nm) dual-band ellipsometry—that is, the ellipsometry measurements in the VIS-SWIR and SWIR-MIR bands were integrated in the same system. Consequently, the ellipsometry parameters for full spectral coverage could be obtained using a single measurement. An SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thin-film sample on a Si substrate of thickness 103.2 nm was used to evaluate the proposed ellipsometry system. The results showed that the thin-film thickness measurement accuracy was high (±0.5 nm in the range of 400–3200 nm), the thickness repeatability measurement accuracy was 0.03 nm, the refractive index repeatability measurement accuracy was 0.003, and the measurement time was approximately 0.5 s/λ, the proposed system having the advantages of high integration, simple operation, and high measurement speeds.