Stairless 3D Memory Word Line Contacts Over Dielectric Support Pillars
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Solution Overview
Problem
Existing three-dimensional memory devices face challenges in efficiently forming stairless structures with reliable word line contact via structures over support features, which affect the integrity and performance of the memory device.
Innovation Solution
The method involves forming an alternating stack of insulating and sacrificial material layers, creating memory openings and support openings, and then replacing sacrificial material with conductive layers and insulating fins to create layer contact via structures and dielectric support pillars, ensuring stable word line contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional stairless structure formation methods are used, then manufacturing complexity is reduced, but word line contact reliability deteriorates
Solution Approach 1:
A dielectric support pillar structure is introduced as an intermediary element between the word line contact via structure and the underlying layers. This mediator provides mechanical support and ensures reliable electrical contact while maintaining the stairless configuration, resolving the contradiction between manufacturing simplicity and contact reliability.
Solution Approach 2:
The dielectric support pillar structure is formed in advance before the word line contact via structures are created. This preliminary action establishes a stable foundation that ensures subsequent contact formation is reliable, preventing contact issues while maintaining the simplified stairless approach.
2Reliability
If dielectric support pillars are added to improve contact reliability, then structural integrity is improved, but device complexity increases
Solution Approach 1:
The dielectric support pillar structure serves multiple functions simultaneously: it provides mechanical support for the word line contacts, maintains the stairless configuration, and ensures electrical connectivity. This multi-functionality justifies the added structural element by delivering multiple benefits rather than a single function, thereby improving reliability without proportionally increasing complexity.
3Reliability
If insulating fins are formed around contact via structures, then contact stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The insulating fins are formed through a self-aligned process where the fins naturally position themselves around the contact via structures during the formation of the alternating insulating and conductive layers. This self-alignment mechanism reduces the need for additional precise alignment steps, thereby improving contact stability without proportionally increasing manufacturing precision requirements.
Data Source
AI summary
A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers, a memory opening vertically extending through the alternating stack, a memory opening fill structure located in memory opening and including a vertical stack of memory elements located at levels of the electrically conductive layers and a vertical semiconductor channel, and a layer contact via structure contacting a first electrically conductive layer. The layer contact via structure overlies one or more support features.