Semiconductor Dummy Contact Plug Design for Misalignment Margin
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Solution Overview
Problem
Conventional semiconductor device manufacturing techniques, such as single photo/etch patterning and double patterning with sidewall spacers, struggle to ensure a sufficient process margin for contact holes with diameters less than 40 nm, leading to alignment issues and increased manufacturing costs due to the need for high-performance photolithography.
Innovation Solution
A semiconductor device design featuring line patterns with dummy and connecting portions, where contact plugs are electrically connected to the connecting portions, providing a sufficient process margin even if misaligned, allowing for the use of single photo/etch patterning and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If single photo/etch patterning is used, then manufacturing process is simple and cost-effective, but process margin is insufficient for contact holes with diameter less than 40 nm
Solution Approach 1:
The method performs preliminary patterning to form mandrels, then uses these mandrels as templates to define contact hole positions through spacer formation. This preliminary action establishes precise alignment references before the actual contact hole etching, enabling single photo/etch to achieve the required precision for sub-40nm contact holes.
Solution Approach 2:
Spacer structures are introduced as intermediary elements between the mandrel pattern and the final contact hole pattern. These spacers act as a mediating layer that transfers the pattern from the mandrel to the contact hole definition, allowing precise position transfer without requiring direct high-precision photolithography alignment.
2Manufacturing precision
If double patterning with sidewall spacer is used, then line width precision is improved, but contact hole formation still requires high-performance photolithography and sufficient process margin cannot be ensured
Solution Approach 1:
The patterning process is segmented into distinct stages: mandrel formation, spacer formation on mandrels, and contact hole etching using spacers as masks. This segmentation allows each stage to be optimized independently, with the spacer stage specifically addressing contact hole alignment precision without compromising line width control from the mandrel stage.
Solution Approach 2:
The spacer structure serves as an intermediary that decouples the line width definition (controlled by mandrel) from the contact hole position definition (controlled by spacer). This intermediary mechanism ensures that contact holes are precisely positioned relative to line patterns while maintaining the process margins needed for reliable manufacturing.
3Productivity
If contact hole diameter is reduced to less than 40 nm, then device integration density is increased, but alignment precision requirements and manufacturing difficulty increase
Solution Approach 1:
The method creates a copy of the mandrel pattern through spacer formation, where the spacer pattern replicates the mandrel geometry at the desired contact hole positions. This copying mechanism enables precise position transfer for sub-40nm contact holes using lower-precision photolithography, thereby increasing integration density without proportionally increasing alignment difficulty.
Data Source
AI summary
A semiconductor device or a memory which includes the same have a line pattern, and a contact plug, the line pattern including a first linear feature to which the contact plug is connected by design, and a second linear feature having a connecting portion and a dummy portion adjacent the location at which the contact plug is electrically connected to the first linear feature. A second contact plug is electrically connected to the connecting portion of the second linear feature of the line pattern. In the case of a misalignment error or the like, the first contact plug may also be electrically connected to the second linear feature of the line pattern but at the dummy portion thereof so as to not create a short circuit in that case. The dummy portion thus allows a sufficiently large process margin to be secured for the contact plug.