Polycrystalline Silicon Gettering Layers with Controlled Residual Stress

We report on a novel method of low pressure chemical vapor deposition of polycrystalline silicon layers used for external gettering in silicon substrate for semiconductor applications. The proposed method allowed us to produce layers of polycrystalline silicon with pre-determined residual stress. The method is based on the deposition of a multilayer system formed by two layers. The first layer is intentionally designed to have tensile stress while the second layer has compressive stress. Opposite sign of the residual stresses of the individual layers enables to pre-determine the residual stress of the gettering stack. We used scanning electron microscopy for structural characterization of the layers and intentional contamination for demonstration of the gettering properties. Residual stress of the layers was calculated from the wafer curvature.