Buffer cap layer to improve mim structure performance

Abstract

The present disclosure relates to method of forming a MIM (metal-insulator-metal) structure having a buffer cap layer that reduces stress induced by an overlying stress-inducing protective layer, and an associated apparatus. The method is performed by forming a lower conductive layer over a semiconductor substrate, forming a dielectric layer over the lower conductive layer, and forming an upper conductive layer over the dielectric layer. A buffer cap layer is formed over the upper conductive layer and a stress-inducing protective layer is formed onto the buffer cap layer. The buffer cap layer reduces a stress induced onto the upper conductive layer by the stress-inducing protective layer, thereby reducing leakage current between the lower and upper conductive layers.