3D NAND Tiered Stack Pillars for Precise Slit and Opening Formation
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Solution Overview
Problem
The challenge in forming 3D NAND memory devices lies in retaining the structural integrity of insulating materials during the removal of sacrificial materials and replacement of conductive materials, as conventional methods may cause material expansion or bending, affecting the design and formation of openings in the stack.
Innovation Solution
The formation of conductive structures for select gate drains is done before creating openings in the stack, ensuring they provide additional material and structural integrity, preventing expansion or bending during slit formation, and allowing for precise patterning of openings near neighboring features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sacrificial materials are removed and conductive materials are replaced in conventional methods, then the memory device structure is formed, but material expansion or bending occurs affecting the design and formation of openings
Solution Approach 1:
The conductive structures for select gate drains are formed before creating openings in the stack. This preliminary action ensures that the conductive structures provide additional material and structural integrity during subsequent opening formation processes, preventing material expansion or bending that would otherwise affect opening precision.
2Ease of manufacture
If openings are formed in the stack before conductive structures are in place, then opening formation is simpler, but material expansion or bending occurs during slit formation
Solution Approach 1:
The conductive structures are formed in advance before the openings are created. This sequencing allows the conductive structures to be present during opening formation, providing structural support that prevents material expansion or bending, thereby maintaining precise patterning of openings near neighboring features.
3Device complexity
If conventional formation methods are used, then the fabrication process is simpler, but structural integrity of insulating materials is compromised
Solution Approach 1:
The conductive structures for select gate drains are formed beforehand to provide additional material and structural integrity. This preliminary formation ensures that insulating materials maintain their structural integrity during subsequent processing steps, preventing expansion or bending that would compromise reliability.
Data Source
AI summary
Methods for forming microelectronic devices include forming lower and upper stack structures, each comprising vertically alternating sequences of insulative and other structures arranged in tiers. Lower and upper pillar structures are formed to extend through the lower and upper stack structures, respectively. An opening is formed through the upper stack structure, and at least a portion of the other structures of the upper stack are replaced by (e.g., chemically converted into) conductive structures, which may be configured as select gate structures. Subsequently, a slit is formed, extending through both the upper and lower stack structures, and at least a portion of the other structures of the lower stack structure are replaced by a conductive material within a liner to form additional conductive structures, which may be configured as access lines (e.g., word lines). Microelectronic devices and structures and related electronic systems are also disclosed.