FinFET Gate Stack Treatment for Oxygen-Resistant Work Function Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in achieving high integration density and reducing feature sizes while minimizing defects and oxidation-related issues in the manufacturing of FinFETs, particularly in forming effective gate dielectric layers and work function tuning layers.
Innovation Solution
The process involves forming a fin field effect transistor (FinFET) using a gate-last process, with the introduction of active element dopants through a chemical soak to reduce oxygen diffusion and enhance the properties of the work function tuning layer, and subsequent post-treatment to eliminate dangling bonds, thereby improving the gate dielectric and work function layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gate dielectric layer and work function layer are made thinner to achieve higher integration density, then the integration density is improved, but oxygen diffusion and oxidation-related defects increase
Solution Approach 1:
A chromium oxide barrier layer is introduced as an intermediary between the gate dielectric layer and the work function layer. This barrier layer prevents oxygen diffusion from the work function layer into the gate dielectric layer, thereby resolving the contradiction by enabling thinner gate stacks without increasing oxidation-related defects.
Solution Approach 2:
The gate stack is constructed as a composite structure consisting of multiple layers: gate dielectric layer, chromium oxide barrier layer, and work function layer. This composite material approach allows each layer to perform its specific function, with the chromium oxide layer specifically designed to block oxygen while maintaining electrical properties.
2Reliability
If the work function layer is made thinner to reduce oxygen diffusion, then oxygen penetration is reduced, but the work function tuning capability is diminished
Solution Approach 1:
The chromium oxide barrier layer is strategically positioned only at the interface between the gate dielectric and work function layer, where oxygen diffusion is most problematic. This localized barrier allows the work function layer to maintain its tuning capability while preventing oxygen penetration at the critical interface region.
Solution Approach 2:
The chromium oxide barrier layer acts as an intermediary that selectively blocks oxygen diffusion while permitting electrical functionality. This mediator layer enables the work function layer to be thinner without compromising work function tuning, as the barrier handles the oxygen blocking function.
3Reliability
If a barrier layer is added to prevent oxygen diffusion, then oxygen penetration is reduced, but the gate stack complexity increases
Solution Approach 1:
The chromium oxide barrier layer is deposited with a specific thickness parameter (typically 1-10 nm) that is optimized to provide sufficient oxygen blocking while minimizing additional complexity. By controlling this critical parameter, the barrier layer achieves its function without excessively increasing gate stack complexity.
Solution Approach 2:
The barrier layer is applied locally at the critical interface region rather than throughout the entire gate stack. This localized approach prevents oxygen diffusion at the most vulnerable point while keeping the overall gate stack structure relatively simple and manageable.
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 enhances the integration density, reduces defects, and allows for thinner, more effective gate stacks, improving the performance and reliability of FinFETs by controlling oxygen penetration and optimizing the work function tuning layer.
Implementation Method 1
modifying a surface of the work function layer, wherein the modifying the surface is performed at least in part with a chemical soak that implants an active element
Implementation Method 2
reacting the active element with oxygen
Implementation Method 3
subsequent post-treatment to eliminate dangling bonds
Data Source
AI summary
A semiconductor device and method of manufacture are provided. In some embodiments a treatment process is utilized to treat a work function layer. The treatment prevents excessive oxidation of the work function layer during subsequent processing steps, such as application of a subsequent photoresist material, thereby allowing the work function layer to be thinner than otherwise.