Cross-bar fin formation for VTFET drive current
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Solution Overview
Problem
Current vertical transport field-effect transistors (VTFETs) face limitations such as lacking design flexibility, high parasitic capacitance, and low drive current, which hinder their performance and efficiency.
Innovation Solution
The development of a method to form cross-bar fins with any number of fins, utilizing a series of mask layers and spacer layers to create a fin structure with two orthogonal segments and sharp corners, compatible with conventional semiconductor manufacturing processes, allowing for improved device width and drive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional vertical transport FET structures are used, then the basic transistor function is achieved, but design flexibility is limited and parasitic capacitance is high
Solution Approach 1:
The fin structure is divided into multiple segments (three or more fins) arranged in a cross-bar configuration, where each fin acts as an independent current path. This segmentation allows for optimized current distribution and reduced parasitic capacitance while maintaining design flexibility through configurable fin arrangements
Solution Approach 2:
The invention transitions from traditional lateral or simple vertical FET structures to a multi-dimensional cross-bar fin configuration. The fins extend in multiple directions (orthogonal segments with sharp corners) to create a three-dimensional current transport path, enabling improved device width and drive current while reducing parasitic effects
2Power
If conventional FET structures are used, then manufacturing simplicity is maintained, but drive current is low
Solution Approach 1:
The cross-bar fin structure employs nested spacer layers (first spacer layer, second spacer layer, third spacer layer) that are formed sequentially around mandrel structures. Each spacer layer is deposited and patterned to create progressively more complex fin configurations, allowing sophisticated multi-fin structures to be built through iterative deposition processes compatible with conventional manufacturing
Solution Approach 2:
Mandrel structures are formed first as temporary templates that define the final fin geometry. The mandrels are positioned and patterned before the spacer layers are deposited, allowing the complex fin structure to be predetermined through preliminary mandrel placement. This preliminary action enables precise control over fin positions and dimensions while simplifying the overall fabrication process
3Manufacturing precision
If simple mask and spacer processes are used, then manufacturing ease is maintained, but fin structure precision is insufficient
Solution Approach 1:
Multiple spacer layers act as intermediary structures that transfer the pattern from the mandrels to the final fin configuration. Each spacer layer is deposited with precise thickness control and patterned to create intermediate structures that progressively define the final fin geometry. This intermediary approach enables high manufacturing precision through controlled deposition and patterning steps while maintaining compatibility with conventional semiconductor manufacturing processes
Data Source
AI summary
A first mask layer is formed on top of a semiconductor substrate. A mandrel material is formed perpendicular to the first mask layer. A second mask layer is formed on one or more exposed surfaces of the mandrel material. The mandrel material is removed. A pattern of the first mask layer and the second mask layer is transferred into the semiconductor substrate.