Sidewall Collar Pillar Isolation for Memory Stability
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Solution Overview
Problem
The challenge in fabricating memory devices lies in the instability of memory cell pillars during formation, which can lead to leaning or contact with adjacent pillars, resulting in defective memory arrays due to the lack of effective structural support and electrical isolation.
Innovation Solution
The implementation of an insulating sidewall collar around each memory cell pillar, made from materials like silicon nitride or silicon carbide, provides additional structural support and electrical isolation, preventing pillar instability and misalignment issues during the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If memory cell pillars are formed without additional structural support, then the fabrication process is simpler, but the pillars become unstable and may lean or contact adjacent pillars
Solution Approach 1:
An insulating collar is introduced as an intermediary structure around the memory cell pillar. This collar provides mechanical support to prevent pillar leaning and instability during fabrication, while also providing electrical isolation. The collar acts as a mediator that simultaneously addresses both structural stability and electrical isolation requirements without fundamentally changing the pillar formation process.
Solution Approach 2:
The support structure is segmented into a collar form that wraps around the pillar rather than requiring complete restructuring of the pillar itself. This segmentation allows the support function to be added independently to existing pillar structures, reducing the complexity increase while providing the necessary stability.
2Reliability
If insulating collars are added around memory cell pillars, then electrical isolation and structural support are improved, but the device complexity increases
Solution Approach 1:
The insulating collar is designed to perform multiple functions simultaneously: it provides electrical isolation between adjacent memory cell pillars and mechanical support to prevent pillar leaning. By combining these two functions into a single structure, the solution improves reliability without proportionally increasing device complexity, as one component accomplishes what would otherwise require multiple separate elements.
3Productivity
If memory cell pillars are formed closely spaced to increase density, then productivity is improved, but pillars are more prone to contact and misalignment
Solution Approach 1:
The insulating collar serves as a protective intermediary between closely spaced pillars, preventing direct contact and reducing misalignment issues. This allows pillars to be positioned closer together for higher density while maintaining manufacturing precision through the protective and stabilizing presence of the collars during fabrication.
4Manufacturing precision
If additional structural support is provided to prevent pillar leaning, then manufacturing precision is improved, but the ease of manufacture decreases
Solution Approach 1:
The insulating collar is formed using self-aligned processes where the collar material is deposited conformally on the pillar sidewalls and then planarized. This self-service approach uses the pillar itself as the alignment reference, eliminating the need for separate alignment steps and maintaining ease of manufacture while achieving high positioning precision.
Data Source
AI summary
A method of forming a memory cell is provided. The method includes forming a steering element pillar having a first stiffness and a sidewall, forming a sidewall collar along at least a portion of the sidewall of the steering element pillar, the sidewall collar having a second stiffness, wherein the second stiffness is greater than the first stiffness, and forming a memory element coupled to the steering element pillar. Numerous other aspects are provided.