Pickup Cell Well Layout With Protruding Sections to Avoid LOD Breakage
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Solution Overview
Problem
The existing semiconductor manufacturing processes face challenges in efficiently integrating pickup cells with regular cells due to the LOD effect, which results in decreased silicon wafer utilization and increased complexity.
Innovation Solution
The design incorporates N and P wells with protruding and recessed sections, allowing continuous fins for both regular and pickup cells, thereby avoiding the breakage of active regions and reducing the impact of the LOD effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pickup cells are integrated with regular cells in standard cell designs, then device integration is improved, but the LOD effect causes active region breakage and manufacturing complexity increases
Solution Approach 1:
The pickup cell is nested within the regular cell structure by forming the pickup cell's active region inside the well region of the regular cell. The pickup cell's source/drain regions are formed within the well, and its gate is positioned above the well, creating a nested configuration that allows both cell types to coexist without breaking active regions.
Solution Approach 2:
The patent applies different doping concentrations and types in different regions: the well region has a first doping concentration and type, while the pickup cell's source/drain regions have a second doping concentration and type. This local differentiation allows the pickup cell to function properly within the regular cell structure without causing LOD effect-related breakage.
2Area of moving object
If pickup cells are made smaller to increase integration density, then area usage is improved, but the LOD effect impact increases and reliability decreases
Solution Approach 1:
By nesting the pickup cell within the regular cell's well region, the design achieves compact area usage while maintaining continuous active regions. The pickup cell's active region is formed within the well, eliminating the need for separate active regions that would be susceptible to LOD effect breakage.
Solution Approach 2:
The well region is formed with appropriate doping characteristics before forming the pickup cell's source/drain regions. This preliminary preparation of the well region ensures that the subsequent pickup cell formation does not cause active region breakage due to the LOD effect.
3Productivity
If continuous fins are used for both regular and pickup cells, then device integration is improved, but the LOD effect causes active region breakage
Solution Approach 1:
The patent implements local quality differentiation by forming the pickup cell's source/drain regions with a second doping concentration that differs from the well's first doping concentration. This local differentiation maintains continuous fins while preventing LOD effect-induced breakage by creating distinct electrical regions.
Solution Approach 2:
The continuous fin structure is segmented into different functional regions: the well region and the pickup cell's source/drain regions. This segmentation allows the fins to remain physically continuous while being electrically differentiated, preventing LOD effect breakage through proper doping profiles.
Data Source
AI summary
A semiconductor structure includes a substrate having a first well of a first conductivity type and a second well of a second conductivity type. From a top view, the first well includes first and seconds edges extending along a first direction. The second edge has multiple turns, resulting in the first well having a protruding section and a recessed section. The semiconductor structure further includes a first source/drain feature over the protruding section and a second source/drain feature over a main body of the first well. The first source/drain feature is of the first conductivity type. The second source/drain feature is of the second conductivity type. The first and the second source/drain features are generally aligned along a second direction perpendicular to the first direction from the top view.