3D Memory Word Line Contacts With Expanded Support Openings
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Solution Overview
Problem
Current methods for forming three-dimensional memory devices with expanded support openings and double spacer word line contacts face challenges in achieving precise and efficient formation of structures that ensure reliable electrical isolation and structural integrity.
Innovation Solution
The method involves forming alternating stacks of insulating and sacrificial material layers, creating support pillar structures, and replacing sacrificial layers with conductive layers, while using dielectric spacers to isolate electrically conductive layers and form contact via structures through a series of etching and deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to form support openings and word line contacts, then the fabrication process is simpler, but electrical isolation and structural integrity are insufficient
Solution Approach 1:
The support structure is divided into two distinct components: support pillars formed in support openings and dielectric spacers formed in expanded support openings. This segmentation allows each component to perform its function optimally - support pillars provide structural support while dielectric spacers provide electrical isolation, thereby improving reliability without requiring a complete redesign of the fabrication process
Solution Approach 2:
The dielectric spacers are formed within expanded support openings that contain the support pillars. This nested structure allows the dielectric spacers to be positioned precisely relative to the support pillars, ensuring proper electrical isolation while maintaining structural integrity. The nested approach also enables a systematic fabrication process where each structure is formed in sequence
2Reliability
If standard spacer formation is used, then the manufacturing process is easier, but electrical isolation between conductive layers is insufficient
Solution Approach 1:
The dielectric spacers are formed preliminarily before the final conductive layer deposition. By forming the dielectric spacers in the expanded support openings early in the fabrication process, the electrical isolation structure is established before subsequent processing steps, ensuring that electrical isolation is maintained throughout the remaining fabrication steps without requiring additional isolation steps later
Solution Approach 2:
The support openings are laterally expanded to create expanded support openings with increased horizontal dimensions. This dimensional change provides sufficient space to form dielectric spacers that completely fill the expanded openings, ensuring thorough electrical isolation between adjacent conductive layers while maintaining compatibility with standard fabrication processes
3Reliability
If support openings are not laterally expanded, then the fabrication process is simpler, but dielectric spacers cannot provide adequate electrical isolation
Solution Approach 1:
The dielectric spacers act as intermediary structures formed in the expanded support openings between the support pillars and the conductive layers. These intermediary dielectric spacers provide the necessary electrical isolation while the lateral expansion of the support openings enables the formation of these spacers using standard fabrication techniques, maintaining fabrication efficiency
Solution Approach 2:
The support openings undergo lateral expansion to change their dimensional parameters, creating expanded support openings with larger cross-sectional areas. This parameter change enables the formation of dielectric spacers with sufficient volume to provide adequate electrical isolation, while the expansion process itself can be integrated into existing fabrication workflows to maintain productivity
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 enables the formation of three-dimensional memory devices with enhanced electrical isolation and structural support, improving the reliability and efficiency of memory device fabrication.
Implementation Method 1
performing an isotropic etch process that etches a material of the dielectric spacer material layer selective to a material of the tubular sacrificial spacer
Implementation Method 2
forming a layer stack of a dielectric spacer material layer and a sacrificial spacer material layer in the first via cavity and over the first alternating stack
Data Source
AI summary
A memory device includes at least one alternating stack of respective insulating layers and respective electrically conductive layers and memory stack structures vertically extending through the at least one alternating stack. A layer contact via structure contacts a top surface of one of the electrically conductive layers, and is laterally surrounded by at least one dielectric spacer, which may include a plurality of dielectric spacers, and optionally by a plurality of dielectric support pillar structures. Additionally or alternatively, the layer contact via structure may comprise a convex surface segment that is adjoined to a straight sidewall segment.