3D Flash Memory Word Line Segmentation for Etching and Fringing Fields
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Solution Overview
Problem
The existing 3D flash memory devices face challenges in securing an etching profile due to difficulty in gas flow into channel holes and suffer from fringing field issues caused by large word line areas, leading to performance limitations and potential short circuits.
Innovation Solution
The implementation of vertical connecting trenches and patterns that connect channel holes, allowing for simultaneous formation with vertical channel structures, and the use of separation films to divide word lines and improve etching profiles, while also addressing fringing field effects and short circuit risks through shape-modified mask patterns and optical proximity correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If channel holes are arranged in a staggered pattern to increase integration, then device density is improved, but etching gas flow into channel holes becomes difficult resulting in poor etching profile
Solution Approach 1:
The patent divides the continuous channel hole structure into segmented regions by introducing filling patterns between adjacent channel holes. This segmentation allows etching gas to access channel holes through multiple pathways while maintaining the staggered arrangement for high density. The filling patterns create discrete zones that facilitate controlled material deposition and etching processes.
Solution Approach 2:
The patent introduces filling patterns as intermediary structures between channel holes. These filling patterns serve as mediators that enable etching gas flow and material deposition while maintaining the close spacing required for high device density. The filling patterns act as intermediate zones that resolve the conflict between tight packing and process accessibility.
2Device complexity
If word lines are shared within one block to simplify structure, then device complexity is reduced, but fringing field affects adjacent memory cell strings causing performance degradation
Solution Approach 1:
The patent segments the continuous word line structure by introducing separation films between adjacent memory cell strings. This segmentation divides the word line into isolated sections for each string, preventing fringing field interference while maintaining structural simplicity. Each word line segment serves a specific memory cell string independently.
Solution Approach 2:
The patent extracts the problematic fringing field effect by removing the continuous connection between word lines serving different memory cell strings. Separation films are introduced to take out the harmful electromagnetic coupling while preserving the essential word line functionality for each individual string.
3Reliability
If vertical connecting patterns are formed separately to connect channel holes, then connectivity is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent merges the formation of filling patterns and vertical connecting patterns into a single manufacturing process step. By combining these two functions into one pattern structure formed through the same process, the patent achieves both channel connectivity and material filling without increasing process complexity. The unified pattern serves dual purposes simultaneously.
Solution Approach 2:
The patent creates universal patterns that perform multiple functions: filling the space between channel holes and providing vertical connectivity. This multi-functional pattern design eliminates the need for separate processing steps, as the same structure achieves both spatial filling and electrical connection objectives.
Data Source
AI summary
A 3D flash memory for improving integration and the influence of a fringing field due to a word line formed in one large area in a stack structure and a method for manufacturing the 3D flash memory are disclosed.