Self-Aligned Dielectric Pillars in 3D Memory Arrays
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming self-aligned dielectric pillar structures within alternating stacks of insulating and conductive layers, which are crucial for enhancing memory density and performance.
Innovation Solution
A method involving the formation of alternating stacks of insulating and sacrificial material layers, followed by the creation of trenches and cavities, and subsequent replacement of sacrificial layers with conductive materials to form dielectric pillars and through-memory-level conductive via structures, allowing for precise and aligned integration of memory stack structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form dielectric pillar structures in three-dimensional memory devices, then the manufacturing process is simpler, but the memory density and performance are insufficient
Solution Approach 1:
Sacrificial material layers are deposited between the insulating layers during the initial stack formation process, before any trenching or cavity formation occurs. These sacrificial layers serve as pre-positioned templates that define the future locations of dielectric pillars, ensuring precise alignment without requiring complex alignment steps during subsequent processing
Solution Approach 2:
The patent employs nested trenches where an outer trench and an inner trench are formed concentrically, with the inner trench located within the outer trench. This nested structure allows sequential formation of cavities at different levels, enabling the creation of three-dimensional dielectric pillar structures with precise spatial relationships while maintaining manufacturing control
2Productivity
If self-aligned dielectric pillar structures are formed to enhance memory density, then the memory performance improves, but the manufacturing process becomes more complex
Solution Approach 1:
The alternating stack structure serves multiple functions simultaneously: it provides the memory cell structure with insulating and conductive layers, incorporates sacrificial material layers that template future dielectric pillar locations, and creates the nested trench geometry. This multi-functionality increases memory density without proportionally increasing manufacturing complexity
Solution Approach 2:
The sacrificial material layers within the alternating stack self-align to form the dielectric pillar structures. During processing, these sacrificial layers remain in place to define cavity locations, and are subsequently removed to create the final dielectric pillar positions, eliminating the need for separate alignment operations
3Manufacturing precision
If nested trenches are formed around memory stack structures, then precise alignment is achieved, but the manufacturing steps increase
Solution Approach 1:
The formation of outer trenches and inner trenches is combined into a single continuous manufacturing sequence. The outer trench is formed first, then the inner trench is formed within it using the same processing equipment and methodology, allowing both trenches to be completed in one operational cycle rather than requiring separate alignment and formation steps
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 creation of dense and efficient three-dimensional memory devices with improved memory density and performance by forming self-aligned dielectric pillars and conductive via structures, enhancing the integration of memory elements within the device.
Implementation Method 1
removing the at least one patterned remaining portion of the alternating stack using at least one etchant while preventing access of the at least one etchant to the pair of backside trenches
Data Source
AI summary
An alternating stack of insulating layers and spacer material layers is formed over a substrate. Memory stack structures are formed through the alternating stack. A pair of backside trenches and a set of nested trenches are simultaneously formed through the alternating stack. Each trench within the set of nested trenches is spaced from any other trench within the set of nested trenches by at least one patterned remaining portion of the alternating stack having a respective shape of an enclosing wall. The at least one patterned remaining portion of the alternating stack is removed from inside to outside using sequential etch processes. A dielectric pillar structure is formed within the pillar-shaped cavity. The sacrificial material layers are replaced with electrically conductive layers. A through-memory-level conductive via structure is formed through the dielectric pillar structure.