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ARUN R. SRIVATSA, CARLOS L. YGARTUA AND DUNCAN W. MILLS,
KLA - Tencor Corporation, Milpitas, CA, USA

ABSTRACT

Many new materials are being considered as potential candidates for low dielectric constant (low k) applications. It is envisioned that such materials will be used in multiple layer filmstacks based on Cu and dual damascene processes using CMP. Some of these materials are birefringent, i.e. the optical properties are not isotropic. Critical to the success of these materials is the ability to non-destructively measure the thickness and quality of the films. Recently, we conducted a study on the optical characterization and measurement of several polymeric low k materials. The results of this study are discussed in this paper. The materials studied were benzocyclobutene polymers (BCB) and SiLKT M from Dow Chemical and parylene (AF-4) from Novellus. Parylene AF-4 is highly birefringent. A special algorithm was developed at KLA - Tencor for the measurement and characterization of such anisotropic, birefringent films.