3D NAND Pillar Architecture with Inset Plugs for Stack Anchoring
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Solution Overview
Problem
The challenge in 3D NAND Flash storage devices is the 'lifting' of semiconductor pillars during manufacturing, which occurs as the vertical height increases, leading to defects and a weakened connection between the stack and the substrate, resulting in defective wafers.
Innovation Solution
The introduction of 'dummy' pillars etched deep into the silicon base substrate, combined with active channel pillars, and partially inset tungsten plugs to enhance skin friction and distribute load, preventing the stack from lifting off the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the vertical height of semiconductor pillars is increased to increase memory density, then the memory capacity is improved, but the stack lifts off the underlying substrate causing manufacturing defects
Solution Approach 1:
The invention divides the semiconductor structure into multiple functional segments: active pillars for memory storage, dummy pillars for mechanical support, and inset plugs for anchoring. This segmentation allows each component to serve its specific purpose - active pillars maintain memory capacity while dummy pillars prevent stack lifting, resolving the contradiction between density and reliability.
Solution Approach 2:
The invention introduces dummy pillars as intermediary elements that mediate between the stack and substrate. These dummy pillars act as mechanical mediators that transfer and distribute stress, preventing the stack from lifting off the substrate while allowing active pillars to maintain their memory function.
2Productivity
If conventional vertical memory array architectures are used to increase density, then more memory cells fit in unit area, but manufacturing defects increase due to stack lifting
Solution Approach 1:
The invention performs preliminary action by forming dummy pillars and inset plugs before completing the stack formation. This preliminary structural preparation ensures that when the full stack is built, the mechanical support is already in place to prevent lifting, thereby maintaining manufacturing precision throughout the process.
Solution Approach 2:
The invention creates a composite structural system combining active pillars (for memory function), dummy pillars (for mechanical support), and inset plugs (for anchoring). This composite approach integrates multiple material functions into a unified structure that simultaneously achieves high density and manufacturing precision.
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 solution strengthens the connection between the stack and the substrate, reducing defects and maintaining the integrity of the semiconductor pillars, thereby improving the reliability and density of 3D NAND Flash storage devices.
Implementation Method 1
partially inset tungsten plugs to enhance skin friction and distribute load
Data Source
AI summary
Disclosed is a three-dimensional memory device. In one embodiment, a device is disclosed comprising a source plate; plugs fabricated fabricated on or partially formed in the source plate; a stack formed on the substrate and plugs comprising alternating insulating layers and conductive layers and channel-material strings of memory cells extending through the insulating layers and conductive layers; a first set of pillars extending through the stack formed by a process including etching the alternating insulating layers and conductive layers and depositing a pillar material therein, wherein each pillar in the first set of pillars terminates atop a respective plug in the plurality of plugs; and a second set of pillars extending through the stack formed by a process including etching the alternating insulating layers and conductive layers and depositing a pillar material therein, wherein each pillar in the second set of pillars terminates in the source plate.