FinFET Isolation Structure for Precise Self-Aligned Gate Patterning
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Solution Overview
Problem
The manufacturing process of FinFETs faces challenges in achieving precise control over the formation of semiconductor fins and gate structures, which affects the electrical control and performance of the devices, particularly in scaling down semiconductor devices.
Innovation Solution
The process involves forming semiconductor fins on a substrate using photolithography and self-aligned processes, followed by the formation of dummy gate structures, strained layers, and replacing them with metal gate stacks, along with the use of insulating and dielectric layers to achieve precise control over the channel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography and self-aligned processes are used to form semiconductor fins, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by forming dummy gate structures before the actual gate structures. These dummy gates serve as placeholders that define the channel region boundaries in advance, enabling subsequent self-aligned processes to precisely form the semiconductor fins and actual gates without requiring complex real-time alignment. This preliminary structuring simplifies the overall manufacturing sequence while maintaining high patterning precision.
Solution Approach 2:
The patent uses dummy gate structures as intermediary elements that mediate between the substrate and the final gate structures. These intermediary dummy gates facilitate the self-aligned formation process by providing reference structures for subsequent etching and deposition steps, thereby improving manufacturing precision without significantly increasing the complexity of the final device structure.
2Reliability
If gate wrapping structure is used to control the channel, then electrical control is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements self-service through self-aligned processes where the dummy gate structures automatically define the positioning for subsequent fin formation and gate deposition. The dummy gates serve their own purpose of defining channel boundaries while simultaneously serving as alignment references for all subsequent steps, eliminating the need for separate alignment operations and reducing precision requirements for manual alignment.
Solution Approach 2:
By forming dummy gate structures in advance, the patent establishes the channel region boundaries before actual device fabrication. This preliminary action creates a self-aligned reference system that guides subsequent processing steps, ensuring proper gate wrapping around fins without requiring high-precision alignment operations during critical gate formation steps.
3Manufacturing precision
If dummy gate structures are formed before metal gate stacks, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent merges multiple functions into the dummy gate structures: they serve as channel boundary definers, alignment references for fin formation, and templates for actual gate positioning. By combining these functions into a single preliminary structure, the patent avoids multiple separate alignment and patterning operations, thereby reducing overall process time while maintaining high manufacturing precision.
Solution Approach 2:
The dummy gate structures exhibit multi-functionality by simultaneously performing channel region definition, alignment reference provision, and gate positioning template functions. This universal role of the dummy gates eliminates the need for multiple specialized structures and alignment operations, reducing process time while achieving precise patterning of all subsequent device features.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables improved electrical control and performance of FinFETs by allowing for precise patterning and replacement of gate structures, enhancing the scalability and efficiency of semiconductor devices.
Implementation Method 1
forming semiconductor fins on a substrate using photolithography and self-aligned processes
Data Source
AI summary
A FinFET includes a semiconductor substrate, a semiconductor fin, a gate structure, and an isolation structure. The semiconductor fin protrudes from the semiconductor substrate. The gate structure is disposed across a first segment of the semiconductor fin. The isolation structure interrupts a continuity of a second segment of the semiconductor fin. The isolation structure has a first portion and a second portion stacked on the first portion. Sidewalls of the first portion are inclined and sidewalls of the second portion are straight. A top surface of the first portion is coplanar with a top surface of the gate structure.