Backside Contact Isolation for Dense Nanosheet Source/Drain Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As nanosheet technology scales down, it becomes challenging to form separate backside contacts with sufficient surface contact for source/drains due to increased device density and interference between adjacent devices.
Innovation Solution
A microelectronic structure is developed with a shared backside contact connected to both source/drains, which is then separated into multiple backside contacts. This structure includes shallow trench fill layers and a backside isolation pillar to isolate the contacts and maintain adequate surface contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device density is increased to scale down nanosheet technology, then productivity is improved, but manufacturing precision deteriorates due to interference between adjacent devices
Solution Approach 1:
The patent applies segmentation by dividing the backside contact formation process into multiple stages: first forming a shared backside contact structure that spans multiple source/drains, then selectively separating it into individual contacts. This segmentation approach allows precise control over each contact formation step, preventing interference between adjacent devices while maintaining high device density.
Solution Approach 2:
The patent employs preliminary action by first forming a shared backside contact structure before separation into individual contacts. The shared structure serves as a preliminary configuration that ensures proper alignment and spacing, and subsequent separation maintains the precision established in this preliminary stage, preventing manufacturing defects in high-density configurations.
2Reliability
If separate backside contacts are formed for each source/drain in high-density configurations, then reliability is improved, but device complexity increases due to interference between adjacent devices
Solution Approach 1:
The patent applies merging by combining multiple source/drains under a single shared backside contact structure before separation. This merged approach simplifies the overall contact structure formation process, reducing device complexity while ensuring that each source/drain ultimately receives reliable individual contact through the controlled separation step.
Solution Approach 2:
The patent utilizes another dimension by forming the shared backside contact structure that extends across multiple source/drains in the lateral dimension, then separating it vertically to create individual contacts. This dimensional approach allows the contact structure to accommodate high device density without increasing lateral complexity, as the separation occurs in the vertical dimension rather than requiring complex lateral patterning.
Data Source
AI summary
A microelectronic structure including a first nanosheet transistor that includes a first source/drain. A second nanosheet transistor that is adjacent to the first nanosheet transistor and the second nanosheet transistor includes a second source/drain. A first backside contact connected to a backside surface of the first source/drain. A second backside contact connected to a backside surface of the second source/drain. A first shallow trench fill layer located between the first backside contact and the second backside contact. A second shallow trench fill layer located adjacent to the first backside contact. The second shallow trench fill layer is located on the opposite side of the first backside contact than the first shallow trench isolation layer. A backside isolation pillar located on top of the first shallow trench isolation fill layer. A top surface of the backside isolation pillar is coplanar with a top surface of the first and second backside contact.