Deep grave capacitor buried electrode plate and insulation collar

A term used in a trench DRAM deep grave capacitor includes a buried plate and an insulation collar. The deep trench (100) is bottle-shaped, and the insulation collar (122) is formed in the upper portion of the wider region of the bottle-shaped trench. The buried plate (132) surrounds the lower portion of the wider part of the bottle-shaped trench, and polysilicon (130) with hemispherical grain lines the walls of at least the lower portion of the wider part of the trench. A Nitridlinerschicht lines the inner walls of the oxide collar and prevents diffusion of dopant through the oxide collar in the substrate when the HSG polysilicon and the doped buried plate are formed. The area of ​​the buried plate is self-aligned to the insulation collar. The depth of the top surface of the wider part of the bottle shape and the depth of the bottom of the insulation collar are determined by successive Lackabscheidungs- and -Ausnehmungsschritte.