Buried word line structure and method of forming the same

Abstract

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.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of Invention[0002]The present invention relates to a semiconductor structure and a method of forming the same, and more generally to a buried word line structure and a method of forming the same.[0003]2. Description of Related Art[0004]Non-volatile memories provide the property of multiple entries, retrievals and erasures of data, and are able to retain the stored information even when the electrical power is off. As a result, non-volatile memories are widely used in personal computers and consumer electronic products.[0005]As the degree of integration of a non-volatile memory is getting higher, the critical dimension of the same is getting smaller. A buried word line structure is often employed in sub-28 nm memory technology or below to meet demands for scaling down the devices.[0006]In order to effectively integrate active areas with isolation areas, for example, in a buried-WL DRAM structure, a portion of buried word lines can serve as ac...

AI Technical Summary

Benefits of technology

[0007]Accordingly, the present invention provides a method of forming a buried word line structure, in which active areas and isolation areas can be effectively integrated with the existing process steps (e.g. a logic process).

[0029]In view of the above, extremely narrow isolation word line trenches that are even deeper than wider active word line trenches can be easily realized with the method of the present invention. Therefore, the cell size shrinkage can be achieved and the cell density can be accordingly increased.

Problems solved by technology

However, it has been difficult to effectively form such structure with the existing process steps.

Images