Segmented Word-Line Contacts Prevent Short Circuits in DRAM
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Solution Overview
Problem
In semiconductor devices like DRAM, the increasing fineness of circuit features and reduction in word-line spacing lead to challenges in accurately positioning contact electrodes, resulting in potential short circuits with neighboring word-lines due to misalignment.
Innovation Solution
The semiconductor device employs a configuration where word-lines are arranged with specific portions missing or offset, allowing for misalignment tolerance by using projections and patterns in the resist layers to form trenches and word-line contacts, ensuring that even if contacts are misaligned, they do not short with adjacent word-lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of the repeating pitch of wiring and the distance between word-lines are reduced to increase data storage capacity, then the data storage capacity is improved, but the positioning accuracy of contact electrodes deteriorates leading to potential short circuits
Solution Approach 1:
The word-line is divided into multiple segments with gaps between them. Specifically, the word-line is segmented such that contact electrodes can be positioned in the gap regions without risking short circuits to adjacent word-lines. This segmentation allows independent positioning of contact electrodes while maintaining electrical isolation between word-line segments.
Solution Approach 2:
The harmful portion (potential short circuit risk) is extracted by removing material to create gaps in the word-line structure. These gaps are strategically positioned to accommodate contact electrodes, effectively separating the word-line into isolated segments that cannot short to neighboring word-lines even with positioning variations.
2Area of stationary object
If the distance between word-lines is reduced, then the integration density is improved, but the risk of short circuit between adjacent word-lines increases
Solution Approach 1:
By segmenting the word-line into multiple isolated sections with gaps, the patent reduces the continuous conductive path length. This segmentation ensures that even when word-lines are closely spaced, the gaps provide sufficient isolation to prevent short circuits between adjacent word-lines, thereby maintaining reliability while achieving high integration density.
Solution Approach 2:
The gaps in the word-line structure act as intermediary isolation regions. These gap regions serve as mediators that electrically isolate adjacent word-line segments, preventing direct contact and potential short circuits between neighboring word-lines while allowing the word-lines to be positioned in close proximity for high density.
3Device complexity
If contact electrodes are positioned closer to word-lines to reduce misalignment, then the manufacturing complexity is reduced, but the short circuit risk increases
Solution Approach 1:
The word-line is segmented with gaps that are wider than the maximum expected positioning error. This segmentation allows contact electrodes to be positioned in these gap regions with relaxed tolerance requirements, reducing positioning complexity while the gaps themselves provide the necessary isolation to prevent short circuits to adjacent word-lines.
Data Source
AI summary
A semiconductor device includes a substrate, a memory cell region, a peripheral region adjacent to the memory cell region, a plurality of word-lines extending across the memory cell region and the peripheral region, and a plurality of contacts connected to edge portions of even numbered ones of the plurality of word-lines in the peripheral region, respectively.