Raman Investigation of Stress for Shallow Trench
A trench is used as a storage capacitor in dynamic memory (DRAM) technologies (deep storage trenches), or as an isolation structure in CMOS, bipolar and BiCMOS technologies. But a shallow trench structure has also been shown to be a major factor in substrate defect generation during processing. Such defect generation is directly related to mechanical stresses existing around the trench. This stress can be monitored, using Raman spectroscopy, to a stress resolution of 10MPa and a spatial resolution of 0.2μm. In this paper, a trench structure is designed and fabricated, and the test results for local stresses within the trench are shown to be in good correspondence with theory.
David J. Fisher
S. B. Sang et al., "Raman Investigation of Stress for Shallow Trench", Defect and Diffusion Forum, Vol. 265, pp. 1-6, 2007