3D Memory Device Thinned Insulating Layers
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming vertical NAND strings with optimal insulating and conductive layer thicknesses, leading to suboptimal performance and reliability.
Innovation Solution
A method involving the formation of an alternating stack of insulating and sacrificial material layers over a substrate, followed by the creation of memory openings and fill structures with specific dielectric and charge storage layers, and subsequent etching processes to form backside recesses and conductive layers, ensuring word lines are thicker than insulating layers for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If insulating layers are made thinner to improve device performance and density, then data storage efficiency improves, but structural integrity and reliability deteriorate
Solution Approach 1:
The patent employs composite material structures where thin insulating layers are combined with specially engineered charge storage materials and blocking dielectric layers. The memory film comprises multiple functional layers including blocking dielectric, charge storage material, and tunneling dielectric, creating a composite structure that maintains reliability while enabling thinner overall insulating layer configurations for higher density.
Solution Approach 2:
The patent applies different material properties and thicknesses to different regions of the memory structure. The insulating layers have varying thicknesses at different locations, with thinner regions enabling higher density while thicker regions provide necessary structural support and reliability. The charge storage material is selectively positioned to optimize both density and performance locally.
2Reliability
If word lines are made thicker than insulating layers to improve conductivity and performance, then electrical performance improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent forms the alternating stack of insulating and sacrificial material layers first, establishing a precise reference structure before forming the memory openings and fill structures. This preliminary formation of the insulating layer stack provides a thickness reference that guides subsequent processing steps, ensuring that word lines are formed with appropriate thickness relative to the insulating layers while maintaining manufacturing feasibility.
Solution Approach 2:
The patent specifies that word lines be made thicker than insulating layers, representing a deliberate parameter change in the structure. This thickness relationship is maintained throughout the device to ensure adequate electrical performance and conductivity of the word lines while keeping insulating layers thin for density, creating an optimized parameter set that balances performance and manufacturability.
3Manufacturing precision
If complex alternating stacks of insulating and sacrificial material layers are formed to enable selective etching and precise structure formation, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent divides the memory structure into alternating segments of insulating material layers and sacrificial material layers. This segmentation enables selective removal of sacrificial materials through the insulating layers, creating precisely positioned memory openings and backside recesses. The segmented alternating stack provides a roadmap for selective etching processes, achieving high manufacturing precision through systematic division of the structure into functional segments.
Solution Approach 2:
The sacrificial material layers serve as intermediary elements that facilitate the formation of the final memory structure. These intermediate layers are deposited alternately with insulating layers, then selectively removed to create memory openings and backside recesses. The sacrificial materials act as temporary mediators that enable precise structure formation through selective etching, after which they are removed to reveal the final configuration.
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 enhances the structural integrity and performance of three-dimensional memory devices by allowing thicker conductive layers while maintaining thinner insulating layers, thereby improving data storage efficiency and reliability.
Implementation Method 1
expanding the backside recesses by isotropically etching surface portions of the insulating layers employing a remote-plasma-assisted dry etch process or a chemical dry etch process
Data Source
AI summary
A three-dimensional memory device includes an alternating stack of word lines and at least one insulating layers or air gaps located over a substrate, a memory opening fill structure extending through the alternating stack. The memory opening fill structure includes a memory film and a vertical semiconductor channel contacting an inner sidewall of the memory film. The word lines are thicker than the insulating layers or air gaps.