Single Staircase 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 formation of mirror image stair step structures, which occupy space that could be used for more desirable purposes.
Innovation Solution
A method 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, eliminating the formation of opposing stair step structures and optimizing space utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional methods are used to form stair step structures, then electrical connections can be established, but opposing mirror image stair step structures are formed that waste space and reduce device efficiency
Solution Approach 1:
The patent applies asymmetry by forming only a single stair step structure at one lateral end of the stack structure rather than forming opposing mirror image structures at both ends. This asymmetric approach eliminates the wasted space from the opposing structure while maintaining all necessary electrical connection functions, thereby improving space utilization without significantly complicating the manufacturing process.
2Manufacturing precision
If photoresist is trimmed and etching is performed repeatedly to form stair step structures, then contact regions are created, but the process is time-consuming and reduces productivity
Solution Approach 1:
The patent applies preliminary action by forming a single masking structure that defines the stair step structure in advance, before any etching operations begin. This preliminary masking approach allows for precise contact region formation while reducing the number of repeated trimming and etching cycles needed, thereby improving both manufacturing precision and productivity.
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.