Support Pillar Structure Layout for Vertical Memory Stack Alignment
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Solution Overview
Problem
The increasing memory density in vertical memory arrays leads to issues such as block bending, tier shrinkage, over/under etching, and electrical shorting due to the tensile stress of support pillar structures like tungsten, causing misalignment and electrical issues in microelectronic devices.
Innovation Solution
The use of first support pillar structures with a dielectric liner and polysilicon, electrically isolated from the source structure, and second support pillar structures with a conductive material in electrical communication with the source, reducing tensile stress and misalignment by employing bridge structures and different material compositions in specific regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If support pillar structures are filled with materials like tungsten to provide structural support, then the mechanical strength and stability of the stack structure are improved, but tensile stress causes block bending, tier shrinkage, and misalignment
Solution Approach 1:
The patent changes the material parameter of support pillars from high-tensile-stress materials like tungsten to low-tensile-stress materials such as polysilicon or silicon nitride. This parameter change maintains structural support functionality while eliminating the harmful tensile stress that causes block bending and misalignment, thereby resolving the contradiction between strength and manufacturing precision.
Solution Approach 2:
The patent employs composite material structures where support pillars are formed with multiple layers including polysilicon, silicon nitride, and oxygen-rich dielectric materials. These composite materials provide both mechanical support and stress management, preventing block bending while maintaining structural integrity, thus resolving the contradiction between strength and alignment precision.
2Quantity of substance
If the number of tiers in vertical memory arrays is increased to improve memory density, then storage capacity is improved, but the stack structure becomes more susceptible to bending and misalignment
Solution Approach 1:
By changing the material parameter of support pillars to low-tensile-stress materials, the patent enables the construction of higher-tier stacks without proportional increases in structural defects. The reduced tensile stress allows taller, denser memory structures to maintain reliability, resolving the contradiction between memory density and structural stability.
3Ease of manufacture
If conventional materials are used in support pillar structures, then fabrication is simplified, but electrical shorting and capacitive coupling issues arise
Solution Approach 1:
The patent uses composite material structures including polysilicon, silicon nitride, and oxygen-rich dielectric materials in support pillars. These materials provide both mechanical support and electrical isolation properties, preventing electrical shorting and reducing capacitive coupling while remaining compatible with standard fabrication processes, thus resolving the contradiction between ease of manufacture and electrical performance.
Solution Approach 2:
The patent introduces oxygen-rich dielectric materials as intermediary layers within support pillar structures. These intermediary materials provide electrical isolation between conductive components, preventing electrical shorting and reducing capacitive coupling, thereby resolving the contradiction between fabrication simplicity and electrical performance.
Data Source
AI summary
A microelectronic device comprises a stack structure comprising alternating conductive structures and insulative structures arranged in tiers, the tiers individually comprising one of the conductive structures and one of the insulative structures, first support pillar structures extending through the stack structure within a first region of the microelectronic device, the first support pillar structures electrically isolated from a source structure underlying the stack structure, second support pillar structures extending through the stack structure within a second region of the microelectronic device, the second support pillar structures comprising an electrically conductive material in electrical communication with the source structure, and bridge structures extending between at least some neighboring first support pillar structures of the first support pillar structures. Related memory devices, electronic systems, and methods are also described.