Uniform Conductive Loops for NAND Wordline Contact Formation
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Solution Overview
Problem
Conventional NAND memory device architectures with 'shark jaw' layouts for wordlines result in non-uniform patterns, complicating photolithography and leading to difficulties in forming contacts and increasing the risk of shorting, due to varying spacings between conductive material portions.
Innovation Solution
The formation of loops of conductive material with a uniform pattern using a pitch multiplication process, allowing for easier etching and contact formation without the need for complex masks, by maintaining consistent distances between parallel and perpendicular portions of the conductive material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional shark jaw layout is used for wordlines, then contact space is provided, but photolithography complexity increases and manufacturing precision deteriorates
Solution Approach 1:
The patent applies asymmetry by intentionally designing non-uniform spacings in the wordline pattern. Specifically, certain regions have wider spacings to accommodate contact landing pads and contacts, while other regions maintain narrower spacings. This asymmetric design allows contact formation in specific areas without requiring complex photolithography masks, as the non-uniform pattern naturally creates the necessary contact spaces.
2Ease of manufacture
If non-uniform spacing is used to provide contact space, then contacts can be formed, but shorting risk increases and reliability deteriorates
Solution Approach 1:
The patent applies local quality by providing different spacings in different regions of the wordline pattern. Wider spacings are localized to areas where contacts are formed, while narrower spacings are maintained in regions where shorting risks are lower. This localized differentiation allows contact formation where needed while maintaining reliability in other areas, as each region's spacing is optimized for its specific function.
3Ease of manufacture
If complex masks are used to etch wordlines, then contact landing pads and contacts can be formed, but device complexity increases
Solution Approach 1:
The patent applies the extraction principle by removing the need for complex photolithography masks. Instead of using multi-layer masks with multiple alignment steps, the design extracts the contact formation requirement and accommodates it through the inherent non-uniform spacing of the wordline pattern. This allows contact landing pads and contacts to be formed using simpler, single-step photolithography processes, significantly reducing device complexity.
Data Source
AI summary
Methods of forming semiconductor device structures are disclosed. One method comprises forming a plurality of loops of a conductive material. Each loop of the plurality of loops comprises a uniform pattern. In one embodiment, a portion of the conductive material is removed from at least one location in each loop of the plurality of loops. Contacts are formed to the conductive material. A semiconductor device structure is also disclosed.