Semiconductor Memory Device Sacrificial Member Etching Control
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Solution Overview
Problem
The manufacturing of semiconductor memory devices faces challenges in processing three-dimensionally stacked memory cell arrays, particularly in coupling circuits below and interconnects above the memory cell array, due to the difficulty in forming holes with metal word lines, which increases manufacturing costs and can lead to etching-induced defects.
Innovation Solution
The implementation of a penetration region with sacrificial members not replaced by conductors in the stacked interconnect replacement process, allowing for easier formation of contacts and reducing the number of processing steps, and using oblong support pillars in an alternating arrangement to control etching advancement and maintain sacrificial member breadth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If holes are formed with metal word lines in three-dimensionally stacked memory cell arrays, then circuit coupling below and interconnects above the memory cell array is achieved, but manufacturing cost increases and etching-induced defects occur
Solution Approach 1:
The patent applies preliminary action by forming sacrificial members in advance at the positions where metal word lines will eventually be placed. These sacrificial members serve as placeholders that guide the subsequent formation of actual metal word lines. This preliminary structuring allows for easier hole formation and reduces etching complexity, thereby lowering manufacturing costs while maintaining coupling reliability between circuits below and interconnects above the memory cell array.
2Reliability
If holes are formed with metal word lines in three-dimensionally stacked memory cell arrays, then circuit coupling below and interconnects above the memory cell array is achieved, but etching-induced defects occur
Solution Approach 1:
The patent uses sacrificial members as intermediary structures that facilitate the formation of holes and metal word lines. These sacrificial members act as mediators between the etching process and the final metal word line structure. By providing a temporary, easily removable structure, they enable precise hole formation without directly exposing metal word lines to harsh etching conditions, thus reducing etching-induced defects while ensuring reliable circuit coupling.
Solution Approach 2:
The sacrificial members are designed as temporary, disposable structures that are formed, used to guide hole formation and metal deposition, and then removed. This approach is more cost-effective and defect-reducing than attempting to form holes directly with metal word lines in place. The sacrificial members can be made from inexpensive materials and are intentionally designed to be short-lived, serving their purpose during manufacturing and then being eliminated to reveal the final structure.
3Ease of manufacture
If the number of processing steps is reduced by not replacing sacrificial members with conductors, then manufacturing cost decreases, but the ability to form interconnects may be compromised
Solution Approach 1:
The patent applies the taking out principle by selectively removing sacrificial members from specific regions where metal word lines are not needed, while retaining them in regions where they continue to serve as structural support or spacing elements. This selective extraction allows the manufacturing process to proceed without the full replacement step, reducing cost and complexity, while still achieving proper interconnect formation in the necessary areas. The sacrificial members are taken out only where their function is no longer needed.
Data Source
AI summary
A first region includes a memory cell transistor. A second region is adjacent to the first region in a first direction, and includes first and second subregions aligned in a second direction. First members include a portion extending along the first direction, and are provided in the first subregion. The first members are arranged in such a manner that the first members aligned in the second direction in an n-th row and an (n+1)-th row, counted from a side of the second subregion, are shifted in the first direction. The first members adjacent to each other in the second direction are arranged in such a manner that portions extending in the first direction face each other.