Word Line Layout With Alternating Conductive Patterns for Trench Stability
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Solution Overview
Problem
As integrated circuit devices undergo down-scaling, there is a risk of process defects such as leaning or collapse of structures defining trenches, particularly due to the fine-sizing of word lines and increased aspect ratios, which can compromise device reliability.
Innovation Solution
The integration of a specific structure in the integrated circuit device, featuring alternating first and second conductive patterns with varying separation distances and vertical levels, supported by a device isolation film, to prevent structural defects during fabrication, and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the integration level is increased to reduce device area, then the device area is reduced, but the word line widths become fine-sized and aspect ratios increase, leading to process defects such as leaning or collapse of trench structures
Solution Approach 1:
The word line is divided into multiple discrete conductive patterns (first conductive patterns and second conductive patterns) arranged in alternating sequence. This segmentation allows each individual pattern to have reduced width and lower aspect ratio, preventing structural collapse while maintaining the overall continuous word line function across active regions and device isolation films.
Solution Approach 2:
Different conductive patterns are positioned at different vertical levels: first conductive patterns are at a higher vertical level covering closely-spaced active regions, while second conductive patterns are at a lower vertical level covering widely-spaced active regions. This local differentiation optimizes structural support locally - higher patterns provide support where trenches are narrower and more prone to collapse, while lower patterns reduce resistance in regions with larger spacing.
2Productivity
If the word line width is reduced to increase integration density, then the device area is reduced, but the trench structures become unstable and may lean or collapse during fabrication
Solution Approach 1:
The conductive patterns are arranged at different vertical levels (height dimension) in addition to horizontal positioning. First conductive patterns are positioned at a higher vertical level than second conductive patterns. This vertical dimensionality allows the structure to maintain stability during fabrication by distributing the load and reducing the aspect ratio of individual patterns, while still achieving high horizontal integration density.
3Reliability
If alternating first and second conductive patterns are used with different vertical levels, then structural stability is improved, but the device complexity increases
Solution Approach 1:
The first and second conductive patterns are electrically connected to form a continuous word line structure that extends across both active regions and device isolation films. By merging these patterns into a single functional word line unit, the complexity of having separate structures is reduced, and the overall device design is simplified while maintaining the stability benefits of the alternating multi-level arrangement.
Data Source
AI summary
An integrated circuit device includes a word line on active regions and a device isolation film and extending in a first horizontal direction. The word line includes first conductive patterns spaced apart from each other in the first horizontal direction. Each of the first conductive patterns covers a pair of active regions that are immediately adjacent to each other in the first horizontal direction, and a first portion of the device isolation film between each active region of the pair of active regions. Second conductive patterns are arranged one-by-one between the first conductive patterns. Each of the second conductive patterns covers a second portion of the device isolation film. A first vertical distance from the substrate to a lowermost surface of each of the first conductive patterns is greater than a second vertical distance from the substrate to a lowermost surface of each of the second conductive patterns.