Backside Contact Placeholder Alignment in Nanoribbon Transistors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
State-of-the-art approaches to forming backside contacts for transistors, particularly non-planar transistors like nanoribbon-based devices, face limitations in alignment and integration due to their complex architecture.
Innovation Solution
A method involving the use of a placeholder for backside contact formation, where a dielectric placeholder is used to align contacts correctly during the manufacturing of nanoribbon-based transistors, allowing for the subsequent replacement with the actual backside contact after the support structure is transferred to a carrier wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional approaches are used to form backside contacts for non-planar transistors, then the manufacturing process can be completed, but alignment precision and integration quality deteriorate due to complex architecture
Solution Approach 1:
The patent introduces a placeholder structure as an intermediary element that simplifies the formation of backside contacts. The placeholder is formed on the front side of the substrate before transistor fabrication, serving as a reference marker that guides subsequent backside contact alignment. This intermediary structure mediates between the complex non-planar transistor architecture and the contact formation process, enabling precise alignment without directly complicating the transistor structure itself.
Solution Approach 2:
The placeholder structure is formed in advance during front-side processing, before the substrate is flipped for backside contact formation. This preliminary action establishes alignment references that simplify subsequent processing steps. By preparing the alignment framework beforehand, the patent avoids the need for complex real-time alignment procedures during backside contact formation.
2Productivity
If backside contacts are formed without a placeholder, then the process steps can be reduced, but contact alignment and integration quality worsen
Solution Approach 1:
The placeholder acts as a mediating reference structure that enables precise alignment without adding significant process complexity. By providing fixed alignment markers on the front side, the placeholder allows for straightforward backside contact formation using standard alignment techniques, thus maintaining manufacturing efficiency while achieving high precision.
Solution Approach 2:
The alignment function is segmented from the contact formation process itself. The placeholder structure separately provides alignment references, while the backside contact formation proceeds independently using these references. This segmentation allows each function to be optimized separately, maintaining productivity while achieving precision.
3Manufacturing precision
If placeholder structures are used for backside contact formation, then alignment precision improves, but device structure complexity increases
Solution Approach 1:
The placeholder is an intermediary structure that exists temporarily during fabrication but does not become part of the final device. It mediates the alignment process without permanently complicating the device structure. After serving its alignment purpose, the placeholder is removed, leaving no trace in the final device architecture.
Solution Approach 2:
The placeholder structure is discarded after serving its alignment function. It is formed temporarily to enable precise alignment, then removed through selective etching or other removal processes. This temporary presence allows precision improvement without permanent addition to device complexity.
Data Source
AI summary
Methods for fabricating a transistor arrangement of an IC structure by using a placeholder for backside contact formation, as well as related semiconductor devices, are disclosed. An example method includes forming, in a support structure (e.g., a substrate, a chip, or a wafer), a dielectric placeholder for a backside contact as the first step in the method. A nanosheet superlattice is then grown laterally over the dielectric placeholder, and a stack of nanoribbons is formed based on the superlattice. The nanoribbons are processed to form S/D regions and gate stacks for future transistors. The dielectric placeholder remains in place until the support structure is transferred to a carrier wafer, at which point the dielectric placeholder is replaced with the backside contact. Use of a placeholder for backside contact formation allows alignment of contact from the backside to appropriate device ports of a transistor arrangement.