Selective Spacer Formation via Hydrogen-Terminated Gate Sidewalls
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Solution Overview
Problem
In finFET device fabrication, the anisotropic etching process for forming spacers along sacrificial gate sidewalls often results in incomplete removal of spacer material, leading to undesirable spacer arrangements that obscure active regions and reduce device performance due to non-perfect directionality and increased gate height, which affects the pitch and performance of the resultant finFET devices.
Innovation Solution
A method involving the formation of a hydrogen-terminated surface on the sacrificial gate sidewalls, followed by selective deposition of spacer material using atomic layer deposition, ensuring spacers are formed only along the sidewalls and not on the fin surfaces, and subsequent removal of the sacrificial gate to expose the channel region for a gate stack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If anisotropic etching process is used to form spacers along sacrificial gate sidewalls, then spacers can be formed to define source/drain regions, but incomplete removal of spacer material occurs leading to undesirable spacer arrangements that obscure active regions
Solution Approach 1:
The patent applies local quality by creating a hydrogen-terminated surface specifically on the sacrificial gate sidewalls through plasma treatment, which then selectively attracts spacer material only to those sidewalls. This localized surface modification ensures spacers form precisely where needed (on gate sidewalls) while preventing deposition on fin surfaces, thereby resolving the contradiction between achieving accurate spacer placement and avoiding unwanted spacer material.
Solution Approach 2:
The hydrogen-terminated surface acts as an intermediary that mediates between the spacer deposition process and the sacrificial gate sidewalls. This intermediate layer with specific surface chemistry properties selectively binds spacer material, enabling precise spacer formation on gate sidewalls while preventing deposition on adjacent fin surfaces, thus resolving the technical contradiction.
2Manufacturing precision
If spacer material is deposited to form spacers along sacrificial gate sidewalls, then source/drain regions can be defined, but spacer material obscures active regions reducing device performance
Solution Approach 1:
By modifying only the local surface properties of the sacrificial gate sidewalls through hydrogen termination, the patent enables selective spacer deposition precisely where needed for source/drain region definition, while preventing spacer material from depositing on fin surfaces that would otherwise be obscured. This localized approach maintains both precise source/drain definition and device performance.
3Manufacturing precision
If conventional spacer formation is used, then spacers can be formed along gate sidewalls, but increased gate height affects pitch and performance of finFET devices
Solution Approach 1:
The patent changes the surface chemistry parameter of the sacrificial gate sidewalls by creating a hydrogen-terminated surface. This parameter change enables selective spacer deposition with precise thickness control, forming spacers that accurately define source/drain regions without excessive height that would affect device pitch and performance.
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 allows for the precise formation of spacers along the sacrificial gate sidewalls without obscuring active regions, enhancing the performance and pitch of finFET devices by ensuring accurate spacer placement and reducing unwanted spacer material on the fin surfaces.
Implementation Method 1
A hydrogen terminated surface is formed on sidewalls of the sacrificial gate
Implementation Method 2
a spacer is deposited on the hydrogen terminated surface of the sacrificial gate
Data Source
AI summary
A method for forming a semiconductor device comprises forming a fin on a substrate and forming a sacrificial gate over a channel region of the fin. A hydrogen terminated surface is formed on sidewalls of the sacrificial gate, and a spacer is deposited on the hydrogen terminated surface of the sacrificial gate. An insulator layer is formed over portions of the fin. The sacrificial gate is removed to expose the channel region of the fin, and a gate stack is formed over the channel region of the fin.