Backside Power Rail Structure for Dense IC Power Delivery
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Solution Overview
Problem
Existing integrated circuit devices face challenges in increasing integration density and simplifying the middle-of-line (MOL) and back-end-of-line (BEOL) portions of device fabrication, particularly in forming power distribution networks on the backside of the substrate.
Innovation Solution
The integration of a power contact that is formed during the front-end-of-line (FEOL) portion of device fabrication, allowing for the subsequent formation of a backside power distribution network (BSPDN) structure without increasing complexity in the MOL and/or BEOL portions, by replacing a placeholder in the substrate and forming a power rail that contacts both the power contact and the source/drain region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power distribution networks are formed using conventional front-end-of-line (FEOL) and middle-of-line (MOL) processes, then power delivery is achieved, but fabrication complexity increases and integration density is reduced
Solution Approach 1:
The patent inverts the conventional approach by forming the power distribution network on the backside of the substrate rather than integrating it within the front-side device layers. This involves etching openings in the backside substrate, forming power contacts that protrude through the substrate thickness, and creating power rails that contact these protruding contacts, thereby simplifying the MOL portion and increasing integration density
Solution Approach 2:
The patent transitions the power distribution network from a planar two-dimensional layout in the front-side device layers to a three-dimensional structure on the backside of the substrate. The power contacts protrude in the thickness direction (z-direction) beyond the backside surface, creating vertical interconnections that reduce lateral space requirements and simplify the overall fabrication process
2Ease of manufacture
If power contacts are formed after FEOL fabrication, then power distribution is established, but the number of fabrication steps increases
Solution Approach 1:
The patent performs preliminary action by forming the power contacts on the backside of the substrate before completing the FEOL fabrication process. The power contacts are formed by etching openings in the backside substrate and depositing conductive material, then the substrate is thinned to expose the lower surfaces of these pre-formed contacts, allowing subsequent power rail formation to occur after FEOL without adding significant complexity
Data Source
AI summary
Integrated circuit devices and methods of forming the same are provided. The integrated circuit devices may include a transistor including a channel region and a source/drain region contacting the channel region, a power rail that is configured be electrically connected to a power source and is spaced apart from the source/drain region in a first direction, and a power contact that is between the source/drain region and the power rail and contacts both the source/drain region and the power rail. The channel region may overlap the power contact in the first direction.