Backside Contact Structure for Scaled MOSFET Power Routing
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Solution Overview
Problem
The scaling down of metal-oxide-semiconductor field-effect transistors (MOS-FETs) in semiconductor devices leads to deterioration in operational properties, necessitating improvements in electrical characteristics and productivity.
Innovation Solution
A semiconductor device with a substrate, a lower power line buried in the substrate, a source/drain pattern, and a backside contact structure that includes a backside via pattern and a backside conductive contact. The backside conductive contact has a convex side surface and a width that increases as it moves away from the source/drain pattern, improving electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If MOS-FETs are scaled down to meet increasing demand for smaller pattern sizes, then device density and integration are improved, but operational properties and electrical characteristics deteriorate
Solution Approach 1:
The patent introduces a backside contact structure that extends vertically through the substrate, adding a third dimension to the electrical connection path. This allows power lines to be routed from the backside of the substrate rather than confined to the front-side planar layout, effectively decoupling the horizontal scaling constraints from the electrical connection requirements and enabling continued device scaling without compromising operational properties.
Solution Approach 2:
The power delivery network is segmented into multiple components: front-side power lines, backside via patterns, and backside conductive contacts. This segmentation allows each component to be independently optimized and positioned, enabling the backside contact structure to compensate for the electrical characteristic deterioration caused by front-side MOS-FET scaling.
2Ease of manufacture
If the backside contact structure uses a uniform width design, then manufacturing simplicity is maintained, but electrical connectivity and current carrying capacity are insufficient
Solution Approach 1:
The backside conductive contact is designed with non-uniform width, featuring a first width in the first region and a second width (greater than the first width) in the second region. This local quality variation optimizes electrical connectivity by providing increased current carrying capacity and reduced resistance in critical areas while maintaining adequate coverage in other regions, thereby improving overall electrical reliability without requiring complete redesign of the entire contact structure.
Data Source
AI summary
A semiconductor device may include a substrate, a lower power line buried in the substrate and extended in a first direction parallel to a bottom surface of the substrate, a source/drain pattern on the substrate, and a backside contact structure provided to penetrate the substrate and electrically connect the lower power line to the source/drain pattern. The backside contact structure may include a backside via pattern and a backside conductive contact, which are sequentially provided on the lower power line. A side surface of the backside conductive contact may be convex in an outward direction from an inner portion of the backside conductive contact toward an outside. A width of the backside conductive contact in the first direction may be the largest at a first level and may increase as a distance from the source/drain pattern increases in a direction toward the first level.