Backside Power Network Landing Pad Structure for Nanosheet Contacts
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Solution Overview
Problem
As nanosheet technology scales down, devices interfere with each other, and forming connections to a backside power network becomes increasingly difficult due to their smaller size and proximity.
Innovation Solution
A semiconductor structure is developed with a sacrificial layer between substrate layers, featuring a dielectric landing pad and a frontside contact with sections extending through the landing pad, allowing for effective connection to the backside power network by forming alternating layers, shallow trench isolation, and recessing the sacrificial layer to create a uniform surface for the landing pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nanosheet devices are scaled down to smaller sizes and placed closer together, then device density and integration are improved, but device interference increases and connection formation becomes more difficult
Solution Approach 1:
The dielectric landing pad is formed in advance within the sacrificial layer before the actual connection etching process. This preliminary structure provides a pre-defined landing zone that guides subsequent etching operations, making connection formation easier despite the scaled-down device dimensions and closer spacing.
Solution Approach 2:
The dielectric landing pad acts as an intermediary structure between the through-silicon via and the backside power network. This intermediate dielectric feature provides a controlled interface that facilitates reliable electrical connection while accommodating the challenges of miniaturized device geometry.
2Ease of manufacture
If conventional connection methods are used in scaled-down nanosheet devices, then manufacturing simplicity is maintained, but connection reliability deteriorates due to over-etching risks and interference
Solution Approach 1:
The dielectric landing pad is formed in advance to prevent over-etching during the connection etching process. By providing a physical and chemical barrier within the sacrificial layer, it counteracts the tendency for etching to penetrate too deeply, thereby protecting the underlying structures and ensuring reliable connections without complicating the manufacturing process.
3Device complexity
If the sacrificial layer is not recessed to create a landing pad void, then manufacturing steps are reduced, but a uniform surface for the landing pad cannot be achieved
Solution Approach 1:
The sacrificial layer is recessed to create a landing pad void before forming the dielectric landing pad. This preliminary cavity creation ensures that when the dielectric material is deposited, it forms a uniform, planar surface at the correct depth, providing consistent electrical characteristics and reliable connections.
Data Source
AI summary
A semiconductor including a first sacrificial layer located directly between a first substrate layer and a second substrate layer, where the first sacrificial layer has a first thickness. The second substrate layer has a second thickness and where the second thickness is larger than the first thickness. A source/drain located on top of the second substrate layer and a dielectric landing pad located within the first sacrificial layer. A frontside contact comprised of a first section and a second section. The first section of the frontside contact is located on top of the source/drain. The second section of the frontside contact is a via that extends downwards past and through the dielectric landing pad.