DRAM Contact Plug Layout to Prevent Dummy Region Shorts
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Solution Overview
Problem
In DRAM devices, electrical shorts can occur between neighboring structures due to remaining active patterns in the dummy region, leading to inefficiencies and potential device failure.
Innovation Solution
The semiconductor device incorporates specific structural elements such as capping patterns, contact plug structures, and an etch stop layer to prevent electrical shorts by isolating the dummy lower contact plug from the active patterns, ensuring proper alignment and separation of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If active patterns are formed in the cell region, then memory cells can be constructed, but remaining portions of active patterns in the dummy region cause electrical shorts between neighboring structures
Solution Approach 1:
The patent extracts and removes the harmful portions of active patterns from the dummy region through selective etching processes. The method separates the active pattern formation into two stages: first forming complete active patterns across both cell and dummy regions, then selectively removing the portions in the dummy region while preserving those in the cell region, thereby eliminating the source of electrical shorts
Solution Approach 2:
The patent segments the dummy region into multiple zones (first dummy region and second dummy region) with different handling requirements. Different etching conditions and parameters are applied to each segment, allowing precise control over which active pattern portions remain and which are removed, thus preventing electrical shorts while maintaining manufacturing efficiency
2Ease of manufacture
If conductive materials are formed on remaining active patterns in the dummy region, then electrical connections are established, but electrical shorts occur between neighboring bit line structures
Solution Approach 1:
The patent performs preliminary removal of active pattern portions in the dummy region before forming conductive materials. By conducting the selective etching process prior to conductive material deposition, the invention ensures that no conductive material is formed on removed portions, thereby preventing electrical shorts while maintaining ease of manufacture through a straightforward process sequence
3Reliability
If dummy region is used for isolation, then cell and peripheral circuit regions are separated, but active patterns remaining in dummy region create electrical connectivity issues
Solution Approach 1:
The patent applies different quality requirements to different locations within the dummy region. The first dummy region adjacent to the cell region undergoes complete active pattern removal, while the second dummy region may retain some patterns. This local differentiation allows the invention to achieve both effective isolation and acceptable manufacturing precision by adapting the removal criteria to each location's specific requirements
Data Source
AI summary
A semiconductor device includes a bit line structure, first and second capping patterns, first and second contact plug structures, and a capacitor. The bit line structure extends on a cell region and a dummy region. The first capping pattern is adjacent the bit line structure on the cell region. The second capping pattern is adjacent the bit line structure on the dummy region. The first contact plug structure is adjacent the bit line structure and the first capping pattern on the cell region, and includes a lower contact plug and a first upper contact plug sequentially stacked. The second contact plug structure is adjacent the bit line structure and the second capping pattern on the dummy region, and includes a dummy lower contact plug and a second upper contact plug sequentially stacked. The capacitor contacts an upper surface of the first contact plug structure on the cell region.