WARP OF CZOCHRALSKI WAFER WITH BACK-SURFACE POLYCRYSTALLINE SILICON FILM

Warp of Czochralski (CZ) Si wafers with back-surface polycrystalline s ilicon (BPS) film was measured with elevation of ambient temperature t o 620-680-degrees-C, using a film internal stress meter (ULVAC Corpora tion FIS-1000). For the first time, to the aurthors' knowledge, it was clarified that the wafers were warped because of film-induced stress occurring at the film deposition temperature. Film-induced stress is d ivided into temperature-dependent stress (thermal stress) and residual stress at room temperature. Thermal stress is quantified under the as sumption that warp depends on the apparent linear thermal expansion co efficients of the BPS film. Residual stress was measured by means of t he X-ray diffraction method.