A system and method is disclosed that prevents the formation of a vertical bird's beak structure in the manufacture of a semiconductor device. A polysilicon filled trench is formed in a substrate of the semiconductor device. A composite layer stack is formed over the trench that has a nitride layer as...http://www.google.com.au/patents/US7776708?utm_source=gb-gplus-sharePatent US7776708 - System and method for providing a nitride cap over a polysilicon filled trench to prevent formation of a vertical bird's beak structure in the manufacture of a semiconductor device
