3D Integrated Circuit Layout for Mixed-Height Cell Density
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to achieve higher cell density and better computing performance within a limited area, particularly in layouts with mixed cell heights, where existing designs suffer from area penalties due to white spaces when cells of different heights abut each other.
Innovation Solution
The solution involves a layout design where cells of varying heights are arranged such that active areas of different conductivity types are aligned and overlapping, allowing for the inclusion of additional active areas between cells of the same conductivity type, eliminating white spaces and enhancing cell density and layout flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cells of different heights are arranged in mixed layout to increase cell density, then computing performance and area utilization improve, but white spaces are generated between abutting cells causing area penalties
Solution Approach 1:
The patent transitions from two-dimensional planar arrangement to three-dimensional stacked arrangement by placing active areas in multiple layers (first layer and second layer). This vertical stacking eliminates white spaces between cells of different heights while maintaining proper electrical isolation, effectively utilizing the third dimension to resolve the area penalty issue.
Solution Approach 2:
The patent implements nested structures where active areas are positioned within vertical columns that span multiple layers. The active areas in the second layer are nested within the same vertical column structure as the active areas in the first layer, allowing compact integration without white spaces while maintaining electrical independence through the gate structure.
2Quantity of substance
If additional active areas are added to increase computing performance, then functional capability improves, but layout complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the active areas into distinct groups located in different vertical layers. By dividing the active areas into a first plurality in the first layer and a second plurality in the second layer, the design achieves higher functional density while maintaining manageable complexity through systematic organization and electrical isolation between layers.
Solution Approach 2:
The gate structure serves multiple functions simultaneously: it provides electrical isolation between active areas in different layers, acts as a barrier to prevent unwanted interactions, and enables the vertical stacking architecture. This multi-functional element reduces overall layout complexity while supporting increased numbers of active areas.
Data Source
AI summary
An integrated circuit includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The first transistor includes a first active area extending in a first direction in a first layer. The second transistor includes a second active area that is disposed in a second layer below the first layer and overlaps the first active area. The third transistor includes at least two third active areas extending in the first direction in the first layer. In the first direction, a boundary line of one of the at least two third active areas is aligned with boundary lines of the first and second active areas. The fourth transistor includes at least two fourth active areas that are disposed in the second layer and overlap the at least two third active areas.