Backside Power Rail Contact Structure for Lower Contact Resistance
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Solution Overview
Problem
Integrated circuit devices face challenges in achieving low contact resistance and efficient power distribution due to limitations in backside power distribution network (BSPDN) structures, particularly in the middle-of-line (MOL) and back-end-of-line (BEOL) portions of device fabrication.
Innovation Solution
The integration of a power contact structure with a lower portion within the power rail structure, featuring a curved interface and direct contact with a metal layer without an intervening barrier layer, enhances electrical connectivity and reduces contact resistance in the BSPDN structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power contact structure with a barrier layer is used, then the structural integrity and fabrication simplicity are maintained, but the contact resistance between the power contact and power rail is higher
Solution Approach 1:
The patent removes the barrier layer from the power contact structure, extracting this intermediate layer that was previously present between the power contact and power rail. This elimination of the barrier layer directly reduces contact resistance while simplifying the overall structure, as the power contact now makes direct contact with the power rail without the intervening barrier material.
Solution Approach 2:
Instead of having the power contact sit on top of the power rail with a barrier layer in between, the patent inverts the configuration by having the lower portion of the power contact structure extend into the power rail structure. This inverted arrangement creates direct intimate contact between the conductive materials, eliminating the barrier layer effect and reducing contact resistance.
2Reliability
If the power contact structure is simplified without a barrier layer, then contact resistance is reduced, but the interface between power contact and power rail becomes more challenging to fabricate with precision
Solution Approach 1:
The patent employs a curved interface between the power contact and power rail structures. The lower portion of the power contact has a curved bottom surface that conforms to the top surface of the power rail, creating a curved contact interface. This curvature increases the contact area and provides manufacturing tolerance, as the curved surfaces can accommodate variations in fabrication while maintaining good electrical contact.
Solution Approach 2:
The power contact structure is nested within the power rail structure, with the lower portion of the power contact extending into the power rail. This nested configuration ensures that the power contact is surrounded by the power rail material, maximizing the contact interface area and providing mechanical support, which facilitates precise alignment during fabrication.
3Productivity
If integration density is increased, then operational speed improves, but contact resistance becomes a more significant limiting factor
Solution Approach 1:
The patent transitions from a conventional planar contact interface to a three-dimensional configuration where the power contact extends vertically into the power rail structure. This dimensional change creates a larger contact area in the vertical dimension, reducing contact resistance even as devices are scaled down and integrated more densely in the lateral dimensions.
Data Source
AI summary
Integrated circuit devices and methods of forming the same are provided. The integrated circuit devices may include a lower insulating structure, a transistor on the lower insulating structure, the transistor including a source/drain region, a power rail structure in the lower insulating structure, and a power contact structure that is on the power rail structure and electrically connects the source/drain region to the power rail structure. The power contact structure may include a lower portion that is in the power rail structure.