Method for making y-shaped multi-fin stacked capacitors for dynamic

Abstract

An array of DRAM cells having Y-shaped multi-fin stacked capacitors with increased capacitance is achieved. A planar first insulating layer is formed over the semi-conductor devices on the substrate. Polycide bit lines are formed on the first insulating layer, and a second insulating layer and a silicon nitride (Si.sub.3 N.sub.4) etch-stop layer are conformally deposited. A multilayer, composed of a alternating insulating and polysilicon layers, is conformally deposited over the bit lines. Capacitor node contact openings are etched in the multilayer and in the underlying layers to the substrate. A fourth polysilicon layer is deposited sufficiently thick to fill the node contact openings and to form the node contacts. The multilayer is then patterned to leave portions over the node contacts, and an isotropic etch is used to remove the insulating layers exposed in the sidewalls of the patterned multilayer to provide Y-shaped multi-fin capacitor bottom electrodes over the bit lines. These Y-shaped multi-fin capacitors increase the capacitance by 37% over T-shaped multi-fin capacitors. The DRAM capacitors are then completed by forming an interelectrode dielectric layer on the bottom electrodes and by depositing a fifth polysilicon layer to form the capacitor top electrodes.