GAA Fin Spacer Structure for Complete Source/Drain Recess Etching
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Solution Overview
Problem
The integration of gate-all-around (GAA) transistor features around silicon nanowires in semiconductor manufacturing is challenging due to complexity and inefficiencies in current methods, requiring improved processes for fin spacer formation and source/drain recess etching to enhance manufacturing yield and device performance.
Innovation Solution
The semiconductor structure employs shorter first fin spacers and taller second fin spacers to facilitate complete removal of dielectric material from source/drain recesses, allowing for improved epitaxial growth and reducing parasitic capacitance, thereby enhancing manufacturing yield and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used for fin spacer formation and source/drain recess etching, then the manufacturing process can be maintained with standard complexity, but complete removal of dielectric material from source/drain recesses cannot be achieved, reducing manufacturing yield
Solution Approach 1:
The fin spacer formation process is divided into two distinct stages: first fin spacers with a first height are formed, then second fin spacers with a second height (greater than the first height) are formed. This segmentation allows each spacer type to perform its specific function optimally, with the taller second fin spacers enabling complete dielectric removal while the shorter first fin spacers provide initial structure definition.
Solution Approach 2:
Different regions of the device are assigned different fin spacer heights based on local requirements. The first fin spacers are shorter and suitable for regions where moderate protection is needed, while the second fin spacers are taller and specifically designed for regions requiring complete dielectric removal. This local differentiation optimizes both manufacturing precision and process complexity.
2Reliability
If taller fin spacers are used to ensure complete dielectric removal, then manufacturing yield improves, but parasitic capacitance increases, reducing device performance
Solution Approach 1:
The fin spacer system is segmented into two height levels: shorter first fin spacers that minimize parasitic capacitance in regions where complete dielectric removal is less critical, and taller second fin spacers that ensure complete dielectric removal in regions where manufacturing yield is paramount. This segmentation allows the device to achieve both high yield and low parasitic capacitance simultaneously.
Solution Approach 2:
Different fin spacer heights are applied to different locations based on local device requirements. Areas requiring robust dielectric removal receive taller second fin spacers, while other areas use shorter first fin spacers to minimize parasitic effects. This localized approach optimizes the trade-off between manufacturing yield and device performance.
3Ease of manufacture
If standard fin spacer heights are used, then the fabrication process remains simple, but source/drain recess etching cannot completely remove dielectric material, affecting device performance
Solution Approach 1:
The fabrication process is segmented into two spacer formation steps rather than using a single standard height. This segmentation adds a controlled level of complexity that directly enables complete dielectric removal, transforming the etching process from incomplete to thorough while maintaining overall process manageability.
Solution Approach 2:
The first fin spacers are formed as a preliminary structure that defines the initial geometry, followed by the formation of second fin spacers that extend further to ensure complete dielectric removal. This preliminary action approach allows each step to build upon the previous one, achieving complete removal without requiring excessively complex single-step processes.
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 improves the manufacturing yield by ensuring complete dielectric removal and reduces parasitic capacitance, leading to better performance and speed of the resulting semiconductor devices.
Implementation Method 1
The fin structure includes shorter first fin spacers and taller second fin spacers. The shorter first fin spacers facilitate complete removal of a dielectric material for inner spacers from a source/drain recess
Implementation Method 2
reducing parasitic capacitance, thereby enhancing manufacturing yield and device performance
Data Source
AI summary
A method for forming a semiconductor structure is provided. The method includes forming a spacer layer along a first fin structure and a second fin structure, etching a first portion of the spacer layer and the first fin structure to form first fin spacers and a first recess between the first fin spacers, etching a second portion of the spacer layer and the second fin structure to form second fin spacers and a second recess between the second fin spacers, and forming a first source/drain feature in the first recess and a second source/drain feature in the second recess. The second fin structure is wider than the first fin structure. The first fin spacers have a first height, and the second fin spacers have a second height that is greater than the first height.