Other Dielectric Layers Used in Microelectronics

OTHER DIELECTRIC LAYERS USED IN MICROELECTRONICS 5.8.1. Cap2, Bap2, and Srp2 Layers 

The freqnencies of the vlo absorption bands of these materials, determined from the LST law [Eq. (1.41)], lie at higher frequencies (e.g., 465 cm for CaF2). Therefore, the structural and chemical properties of this material can be easily analyzed using standard IR spectrophotometers operating in this spectral region. 

Examples of snch analyses are presented in Eig. 5.26. CaE2 layers with thicknesses ranging from 30 to 460 nm were obtained by molecular beam epitaxy on n-Si. The vlo band measured in /j-polarized radiation is a symmetric Gaussian with a maximum at 450 cm . The absorbance increases linearly with an increase in the thickness, while the maximum shifts from 452 cm for a 30-nm layer up to 472 cm for a 460-nm layer, and the EWHM decreases from 62 to 28 cm (Fig. 5.27). 

These changes in the absorption bands cannot be attributed to a chemical interaction between the layer and the silicon substrate because under molecular 

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