Offset Active Regions in Semiconductor Memory Devices
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Solution Overview
Problem
Conventional semiconductor memory devices with diagonal active regions face challenges in pattern design and optical stability due to the need for unique optical requirements and potential bridging issues, which increase fabrication time and complexity.
Innovation Solution
The semiconductor memory device incorporates bar-shaped active regions with a major and minor axis, arranged in columns and crossed by wordline pairs and bitlines, allowing for regular spacing and optical stability, with bitlines alternately connected to active regions and data storage elements positioned at opposite ends of wordline pairs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If diagonal active regions are used to reduce cell area, then integration density is improved, but fabrication complexity and optical requirements increase
Solution Approach 1:
The patent employs asymmetric active region configurations where adjacent active regions are offset from each other in the major axis direction. This asymmetric arrangement allows for reduced cell area while maintaining simplified fabrication processes by avoiding the need for complex optical systems required by diagonal configurations.
2Area of moving object
If diagonal patterns are used to define active regions, then area is reduced, but pattern stability and bridging risk worsen
Solution Approach 1:
The patent segments the active regions into discrete rectangular blocks arranged in columns with offsets. This segmentation approach maintains adequate pattern-to-pattern distances that prevent bridging during fabrication, while still achieving area reduction through the offset arrangement that allows tighter packing in the minor axis direction.
3Manufacturing precision
If unique optical aperture is used for diagonal patterns, then pattern formation is achieved, but manufacturing time and cost increase
Solution Approach 1:
The patent adopts a universal optical system configuration that can handle standard rectangular pattern exposure without requiring specialized diagonal aperture settings. The offset rectangular active regions can be formed using conventional optical lithography processes, making the manufacturing process multi-functional and compatible with standard fabrication equipment, thereby reducing both time and cost.
Data Source
AI summary
A semiconductor memory device may include a substrate having a plurality of active regions and a field isolation layer on the substrate surrounding the active regions of the substrate. Each of the plurality of active regions may have a length in a direction of a first axis and a width in a direction of a second axis, and the length may be greater than the width. The plurality of active regions may be provided in a plurality of columns of active regions in the direction of the second axis, and active regions of adjacent columns may be offset in the direction of the second axis.