Method of forming buried word line structure

摘要

A method of forming a buried word line structure is provided. A first mask layer, an interlayer and a second mask layer are sequentially formed on a substrate, wherein the second mask layer has a plurality of mask patterns and a plurality of gaps arranged alternately, and the gaps includes first gaps and second gaps arranged alternately. A dielectric pattern is formed in each first gap and spacers are simultaneously formed on sidewalls of each second gap, wherein a first trench is formed between the adjacent spacers and exposes a portion of the first mask layer. The mask patterns are removed to form second trenches. An etching process is performed by using the dielectric patterns and the spacers as a mask, so that the first trenches are deepened to the substrate and the second trenches are deepened to the first mask layer.

主权项

1. A method of forming a buried word line structure, comprising:
sequentially forming a first mask layer, an interlayer and a second mask layer on a substrate, wherein the second mask layer has a plurality of mask patterns and a plurality of gaps arranged alternately, and the gaps comprises first gaps and second gaps arranged alternately; forming a dielectric pattern in each first gap and simultaneously forming spacers on sidewalls of each second gap, wherein during the step of forming the dielectric patterns and the spacers, a first trench is formed between the adjacent spacers and exposes a portion of the first mask layer; removing the mask patterns to form second trenches; and performing an etching process by using the dielectric patterns and the spacers as a mask, so that the first trenches are deepened to the substrate and the second trenches are deepened to the first mask layer, wherein the second trenches are deepened with a greater etching rate than the first trenches.