Semiconductor Dummy Patterns for Layout Uniformity
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Solution Overview
Problem
In semiconductor devices, the light proximity effect and microloading effect during exposure and etching lead to differences in processing dimensions between sparse and dense pattern areas, causing current unbalance and deterioration of transistor characteristics due to non-uniform layout.
Innovation Solution
A semiconductor device is designed with a dummy pattern, including a dummy active region and a dummy word line that overlaps part of the dummy active region, ensuring electrical connection with a bit line to maintain uniform voltage application and prevent floating, thereby improving layout uniformity and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If word lines are patterned with various widths and spaces to accommodate different transistor requirements, then device functionality is improved, but processing dimension uniformity deteriorates due to light proximity effect and microloading effect
Solution Approach 1:
The patent applies local quality by introducing dummy patterns specifically in sparse pattern areas where uniformity deteriorates. These dummy patterns are strategically placed to provide local compensation without affecting the functional transistors. The dummy word lines and dummy active regions are configured to have different properties than functional elements, creating localized correction zones that address the specific uniformity problems in sparse areas while maintaining the required variability in functional transistor dimensions.
Solution Approach 2:
The patent implements preliminary anti-action by pre-compensating for the expected light proximity effect and microloading effect through carefully designed dummy patterns. The dummy patterns are configured in advance to counteract the anticipated dimensional variations, effectively neutralizing the harmful effects before they manifest in the final device characteristics. This proactive approach prevents current unbalance and transistor characteristic deterioration.
2Manufacturing precision
If dummy patterns are added to improve layout uniformity, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the dummy pattern system into distinct functional components: dummy word lines and dummy active regions. These segmented elements can be independently designed and optimized for their specific functions. The dummy word lines provide gate control functionality while dummy active regions provide channel formation, allowing each segment to address specific uniformity requirements without unnecessary complexity.
Solution Approach 2:
The patent implements universality by designing dummy patterns that serve multiple functions simultaneously. The dummy word lines and dummy active regions not only improve layout uniformity but also provide electrical connections, form power capacitors, and prevent floating effects. This multi-functionality reduces the need for separate compensation structures, thereby limiting the increase in device complexity while achieving comprehensive uniformity improvement.
3Reliability
If dummy word line extends beyond dummy active region, then electrical connection is improved, but layout uniformity deteriorates due to floating effect
Solution Approach 1:
The patent applies preliminary action by ensuring the dummy word line is pre-configured to extend beyond the dummy active region boundary during the design stage. This preliminary extension establishes proper electrical connections before device operation, preventing floating effects and ensuring reliable voltage application. The extension is carefully controlled to achieve electrical connectivity while maintaining layout uniformity through proper positioning and dimensional control.
Data Source
AI summary
A semiconductor device to improve layout uniformity may include an active region formed in a substrate, a dummy active region formed in the substrate and separated from the active region, a word line crossing over the active region, and a dummy word line. The dummy word line is formed over the dummy active region to overlap at least part of the dummy active region and may have an end positioned within the dummy active region.