3D NAND Dummy Pillar Oxide Isolation to Prevent Twisting
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Solution Overview
Problem
In 3D NAND memory devices, dummy pillars with wider critical dimensions than memory pillars cause pillar twisting and ellipticity, leading to bridging and shorting issues due to their larger critical dimensions.
Innovation Solution
Forming oxide material in the central region of the upper deck after memory pillars are formed, which electrically isolates dummy pillars from the source and maintains their critical dimensions similar to memory pillars, reducing twisting and ellipticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dummy pillars are formed with oxide material in the central region, then electrical isolation is improved, but manufacturing complexity increases due to additional processing steps
Solution Approach 1:
The oxide material is formed in the central region of the upper deck before the dummy pillars are formed. This preliminary action ensures that the oxide material is already in place to provide electrical isolation, preventing potential shorting issues before they can occur during subsequent processing steps.
Solution Approach 2:
The upper deck is divided into a central region and other regions, with the central region filled with oxide material. This segmentation allows the dummy pillars in the central region to be electrically isolated from the source, while other regions maintain their normal structure and functionality.
2Ease of manufacture
If dummy pillars have wider critical dimensions, then filling is easier, but pillar twisting and ellipticity increase causing bridging and shorting
Solution Approach 1:
The oxide material is selectively placed in the central region where dummy pillars are located, creating a local environment that constrains the dummy pillars. This local quality change ensures that dummy pillars maintain critical dimensions similar to memory pillars, preventing twisting and ellipticity while still allowing easier filling.
3Ease of manufacture
If oxide material is formed after memory pillars, then memory pillar formation is simplified, but dummy pillar critical dimension control worsens
Solution Approach 1:
The oxide material is formed in the central region before the dummy pillars are formed, ensuring that the dummy pillars will be constrained by the oxide material during their formation process. This preliminary action maintains dummy pillar critical dimensions while allowing memory pillars to be formed using standard processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces pillar twisting and ellipticity, ensuring that the critical dimensions of memory and dummy pillars are substantially the same, preventing bridging and shorting, and improving the structural integrity of the memory device.
Implementation Method 1
the oxide material electrically isolates the dummy pillars from the source
Data Source
AI summary
An electronic device comprising lower and upper decks adjacent to a source. The lower and upper decks comprise tiers of alternating conductive materials and dielectric materials. Memory pillars in the lower and upper decks are configured to be operably coupled to the source. The memory pillars comprise contact plugs in the upper deck, cell films in the lower and upper decks, and fill materials in the lower and upper decks. The cell films in the upper deck are adjacent to the contact plugs and the fill materials in the upper deck are adjacent to the contact plugs. Dummy pillars are in a central region of the lower deck and the upper deck. The dummy pillars comprise an oxide material in the upper deck, the oxide material contacting the contact plugs and the fill materials. Additional electronic devices and related systems and methods are also disclosed.