Composite Hard Mask Etching Profile for Preventing Pattern Collapse in High-Aspect-Ratio Trenches

摘要

High-aspect ratio trenches in integrated circuits are fabricated of composite materials and with trench boundaries having pencil-like etching profiles. The fabrication methods reduce surface tension between trench boundaries and fluids applied during manufacture, thereby avoiding pattern bending, bowing, and collapse. The method, further, facilitates fill-in of trenches with suitable selected materials.

主权项

1. A method, comprising:
providing a semiconductor film stack having a hard mask layer disposed above oxide/polysilicon (OP) layers, a silicon nitride (SIN) layer, and one or more dielectric layers; performing an OP etch that forms a plurality of high-aspect-ratio trenches in the OP layers; trimming the hard mask layer to expose portions of the SIN layer; performing a critical dimension (CD) trim operation, whereby exposed portions of the SIN layer are etched by plasma; and performing one or more strip operations to remove hard mask material, thereby forming a pencil-like bit line (BL) profile in the OP layers, whereby collapse of the high-aspect-ratio trenches is avoided and fill-in of the high-aspect-ratio trenches is facilitated.