Analysis of Residual Stress in Thin Film Using Laser Scanning Method
The residual stresses in a polymeric thin film deposited on Si wafer induced during cooling from a cure temperature down to room temperature are investigated. The laser scanning method and the boundary element method (BEM) are employed to investigate the residual stresses. A 3 μm thick polyimide film is deposited on a relatively thick Si wafer. The normal stress across thickness of the thin film is estimated from wafer curvature measurements to be 20MPa . The boundary element method is employed to investigate the whole stresses in the film. The numerical result for the normal stress across thickness of the film, σ xx , shows good agreement with the experimental result obtained by using the laser scanning method. The singular stress is observed near the interface corner. Such residual stresses are large enough to initiate interface delamination to relieve the residual stresses.
Seung-Seok Lee, Joon Hyun Lee, Ik Keun Park, Sung-Jin Song, Man Yong Choi
S. S. Lee and M. H. Yi, "Analysis of Residual Stress in Thin Film Using Laser Scanning Method", Key Engineering Materials, Vols. 321-323, pp. 1377-1380, 2006