GAA Gate Formation Using Cladding Layers for CD Uniformity
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Solution Overview
Problem
Semiconductor fabrication processes face challenges in achieving critical dimension uniformity, particularly as devices shrink in size, leading to inconsistencies and performance issues in gate structures.
Innovation Solution
The use of a cladding layer, formed either before or after filling a recess in the active channel structure with dielectric material, provides consistent and larger process windows for forming gate structures by ensuring uniformity in gate dimensions through selective placement around the active channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device size is decreased to improve integration density, then productivity and compactness are improved, but manufacturing precision deteriorates due to challenges in achieving critical dimension uniformity
Solution Approach 1:
A cladding layer is introduced as an intermediary structure between the gate electrode and the active channel. This cladding layer serves as a mediator that defines the gate width through its top surface alignment with the active channel top surface, thereby enabling precise critical dimension control at smaller node sizes. The cladding layer acts as a template that ensures uniform gate formation across the semiconductor device.
2Device complexity
If conventional gate formation processes are used without cladding layer, then process simplicity is maintained, but manufacturing precision deteriorates leading to gate width inconsistencies and overlap shift
Solution Approach 1:
The cladding layer is formed in advance before the gate electrode deposition step. By preparing the cladding layer with its top surface aligned with the active channel top surface prior to gate formation, the process establishes a predetermined reference plane that guides subsequent gate electrode formation. This preliminary action ensures that the gate width is precisely controlled without requiring complex real-time adjustments during gate formation.
3Manufacturing precision
If cladding layer is added to improve gate width uniformity, then manufacturing precision is improved, but device complexity increases due to additional fabrication steps
Solution Approach 1:
The formation of the cladding layer is merged with existing fabrication process steps. The cladding layer is formed using the same deposition and etching processes that are already employed for other device structures, rather than introducing entirely new process equipment or methods. This merging approach adds the necessary precision control while minimizing the increase in overall device complexity.
Data Source
AI summary
A method of fabricating a semiconductor structure includes selective use of a cladding layer during the fabrication process to provide critical dimension uniformity. The cladding layer can be formed before forming a recess in an active channel structure or can be formed after filling a recess in an active channel structure with dielectric material. These techniques can be used in semiconductor structures such as gate-all-around (GAA) transistor structures implemented in an integrated circuit.