3D Semiconductor Layout With Wordline Staircase Overlap
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Solution Overview
Problem
The packing density of two-dimensional semiconductor devices is limited by the area occupied by individual storage units, and the development of three-dimensional semiconductor devices requires efficient use of layout space to increase storage density without mutual interference between functional components.
Innovation Solution
A semiconductor structure and manufacturing method that arranges transistor and capacitor structures along a first direction, with a wordline staircase structure extending along the same direction and intersecting a second direction, allowing for electrical connection and optimized layout to reduce total structural length and increase packing density by utilizing the layout space effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two-dimensional or planar semiconductor device layout is used, then manufacturing process is simple, but packing density is limited due to area occupied by each storage unit
Solution Approach 1:
The patent transitions from two-dimensional planar layout to three-dimensional vertical stacking. Multiple storage units are stacked along the vertical direction (third direction) to form a columnar structure, thereby increasing packing density without complicating the manufacturing process. The transistor and capacitor structures are extended vertically with multiple active regions stacked above each other, utilizing the third dimension to achieve higher integration density.
2Quantity of substance
If three-dimensional semiconductor device structure is adopted to improve packing density, then storage density increases, but layout optimization becomes complex due to mutual interference of functional components
Solution Approach 1:
The patent segments the storage unit into distinct functional components: transistor structure, capacitor structure, and bit line structure, arranged in separate vertical columns. This segmentation allows each component to be independently optimized and positioned, reducing mutual interference while maintaining high packing density. The wordline structures are also segmented into multiple levels (first wordline, second wordline) that can be independently routed.
Solution Approach 2:
The patent resolves layout complexity by utilizing the vertical dimension (third direction) to separate functional components that would otherwise interfere with each other in the planar view. Transistors, capacitors, and bit lines are distributed across different vertical levels and horizontal positions, creating a three-dimensional arrangement that minimizes interference while maximizing space utilization.
3Reliability
If wordline structure is extended to cover transistor projection area, then electrical connectivity is ensured, but layout space is reduced
Solution Approach 1:
The patent resolves the conflict between connectivity and space utilization by extending wordline structures in the vertical dimension. The first wordline and second wordline are positioned at different vertical levels and can pass through or alongside transistor projections without occupying additional planar area. This vertical stacking of wordlines ensures electrical connectivity to transistors at multiple levels while maintaining compact layout footprint.
Solution Approach 2:
The wordline structures are nested within the vertical columnar structure of the storage unit. The first wordline and second wordline are positioned within the same horizontal footprint as the transistor and capacitor structures, effectively nesting the wordlines within the existing layout boundaries rather than requiring additional area.
Data Source
AI summary
A semiconductor structure includes: a transistor structure and a capacitor structure that are arranged along a first direction, where the capacitor structure extends along the first direction; and a wordline staircase structure extending along the first direction, where the wordline staircase structure and the transistor structure are disposed along a second direction intersecting with the first direction. A plane perpendicular to the second direction is used as a reference plane. An orthographic projection of the transistor structure on the reference plane is a first projection. An orthographic projection of the capacitor structure on the reference plane is a second projection. An orthographic projection of the wordline staircase structure on the reference plane is a third projection. The third projection covers the first projection, and the third projection partially overlaps the second projection.