Single Stair Step Stack Structure for Semiconductor Space Utilization
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Solution Overview
Problem
Conventional methods for forming stair step structures in semiconductor devices result in underutilization of space and inefficiencies due to the presence of mirrored stair step structures, which occupy space that could be used for more desirable purposes.
Innovation Solution
A method is described for forming a semiconductor device structure with a single stair step structure by using a masking structure and photoresist to selectively remove portions of the stack structure, thereby eliminating the formation of opposing stair step structures and optimizing space utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to form stair step structures, then electrical connections can be established, but opposing mirrored stair step structures are formed that occupy unnecessary space
Solution Approach 1:
The patent extracts and removes one of the two opposing stair step structures that are conventionally formed. By selectively eliminating the unnecessary mirrored structure, the invention reduces space occupation while maintaining the essential electrical connection function through the remaining single stair step structure.
Solution Approach 2:
The invention transitions from a symmetric configuration (opposing mirrored stair step structures) to an asymmetric configuration (single stair step structure). This asymmetry eliminates the redundant structure on one side, optimizing space utilization while preserving the required electrical connectivity.
2Manufacturing precision
If repeated trimming and etching acts are performed to form stair step structures, then contact regions are created, but the process becomes complex and time-consuming
Solution Approach 1:
The patent applies preliminary action by forming a single stair step structure directly through selective material removal, rather than repeatedly trimming and etching alternating structures. This preliminary formation approach simplifies the process by eliminating multiple iterative steps while achieving the required contact regions with precision.
Solution Approach 2:
The invention extracts the unnecessary repetitive trimming and etching acts from the conventional process. By removing the alternating structure formation steps and directly creating the single stair step structure, the process complexity is reduced while maintaining manufacturing precision for contact region formation.
3Ease of operation
If opposing stair step structures are formed, then electrical access is provided, but space that could be utilized for other purposes is occupied
Solution Approach 1:
The patent extracts and eliminates the unnecessary opposing stair step structure, retaining only the single structure required for electrical access. This extraction maintains the essential functionality while freeing up the space that would otherwise be occupied by the redundant structure for other device purposes.
Solution Approach 2:
The invention employs asymmetry by having electrical access provided by a single stair step structure rather than opposing mirrored structures. This asymmetric configuration maintains ease of operation for electrical connections while optimizing the available space for additional device functionality.
Data Source
AI summary
A method of forming a semiconductor device structure comprises forming a stack structure over a substrate, the stack structure comprising tiers each independently comprising a sacrificial structure and an insulating structure and longitudinally adjacent the sacrificial structure. A masking structure is formed over a portion of the stack structure. A photoresist is formed over the masking structure and over additional portions of the stack structure not covered by the masking structure. The photoresist and the stack structure are subjected to a series of material removal processes to selectively remove portions of the photoresist and portions of the stack structure not covered by one or more of the masking structure and remaining portions of the photoresist to form a stair step structure. Semiconductor devices and additional methods of forming a semiconductor device structure are also described.