Laterally Perforated Support Pillars for 3D Memory Word Line Contacts
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming word line contact via structures due to high reactive ion etching requirements, which limits the number of word lines and memory cell layers, increases process complexity, and can lead to word line leakage failures.
Innovation Solution
The implementation of laterally perforated support pillar structures surrounding layer contact via structures, which reduces the need for reactive ion etching, allows for a higher number of word lines and memory cell layers, decreases process complexity, and minimizes word line leakage failures by creating interconnected support cavities and using fill materials to form contact via structures directly on topmost electrically conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional methods are used to form word line contact via structures, then contact via structures can be formed, but high reactive ion etching requirements limit the number of word lines and memory cell layers
Solution Approach 1:
The support pillar structure is segmented with lateral openings at different heights, dividing the single etching process into multiple localized contact regions. This segmentation allows contact via structures to be formed at different levels without requiring extensive reactive ion etching through the entire stack, thereby enabling more word lines and memory cell layers.
Solution Approach 2:
The invention transitions from a conventional vertical contact approach to a laterally perforated support pillar structure. By adding lateral openings at different heights in the support pillars, the contact via structures can access electrically conductive layers through horizontal paths rather than requiring deep vertical etching, thus reducing reactive ion etching requirements and enabling higher density.
2Ease of manufacture
If conventional contact via formation methods are used, then contacts can be established, but process complexity increases
Solution Approach 1:
The support pillar structures with lateral openings are formed preliminarily before the contact via structures. This preliminary structuring creates predefined pathways and cavities that guide subsequent material deposition and contact formation, simplifying the overall process by eliminating the need for complex multi-step etching and alignment procedures.
Solution Approach 2:
The laterally perforated support pillar structures serve as intermediary elements between the contact via structures and the electrically conductive layers. These support pillars with lateral openings provide a structured interface that facilitates contact formation without requiring direct complex etching through the entire stack, thereby reducing process complexity.
3Reliability
If extensive reactive ion etching is performed, then contact via structures can be formed, but word line leakage failures occur
Solution Approach 1:
The support pillar structures have localized lateral openings at specific heights rather than continuous vertical channels. This local quality approach creates discrete contact regions that minimize exposure of word lines to potential leakage paths, while still providing adequate contact access. The selective positioning of lateral openings ensures contact functionality without compromising word line integrity.
Solution Approach 2:
The laterally perforated support pillars act as intermediary structures that mediate between the contact via structures and the electrically conductive layers. By providing a structured interface with lateral openings, they enable contact formation without requiring extensive reactive ion etching that could compromise word line insulation, thus preventing leakage failures.
Data Source
AI summary
A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers, memory stack structures vertically extending through the alternating stack, a retro-stepped dielectric material portion overlying stepped surfaces of the alternating stack, a laterally perforated support pillar structure vertically extending through the alternating stack and the retro-stepped dielectric material portion, and a layer contact via structure laterally surrounded by the laterally perforated support pillar structure and contacting a top surface of a topmost electrically conductive layer within an area of the laterally perforated support pillar structure. Each electrically conductive layer within the area of the laterally perforated support pillar structure extends through the lateral openings.