Multi-Threshold Gate Dielectric Tuning via Metal Ion Diffusion
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Solution Overview
Problem
Conventional methods for fabricating multi-threshold voltage semiconductor devices are costly and inconsistent due to the need for multiple layers of deposition and etching processes.
Innovation Solution
A method involving a substrate with gate trenches, where a first metal material layer is formed on exposed dielectric layers and undergoes annealing to diffuse metal ions into the dielectric layer, reducing the number of photolithography and etching processes required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple layers of lanthanum oxide and titanium nitride are deposited and stacked with multiple etching processes, then different threshold voltages can be achieved, but fabrication cost increases and consistency deteriorates
Solution Approach 1:
The patent changes the physical-chemical parameters of the dielectric layer by controlling metal ion diffusion through annealing processes. By adjusting annealing temperature, time, and metal material composition, different threshold voltages are achieved without requiring multiple deposition and etching layers, thus simplifying the fabrication process while maintaining consistency.
Solution Approach 2:
The patent extracts the threshold voltage differentiation function from the complex multi-layer deposition and etching process. Instead of creating different threshold voltages through structural complexity (multiple layers), the invention extracts the essential function by modifying the dielectric layer properties through controlled metal ion diffusion, thereby reducing fabrication process complexity.
2Manufacturing precision
If multiple layers of lanthanum oxide and titanium nitride are deposited and stacked with multiple etching processes, then different threshold voltages can be achieved, but fabrication cost increases
Solution Approach 1:
The patent achieves threshold voltage differentiation by changing the parameters of the dielectric layer through controlled metal ion diffusion. By adjusting annealing conditions (temperature, time, atmosphere) and metal material composition, the dielectric properties are modified to produce different threshold voltages, eliminating the need for expensive multi-layer deposition and etching processes.
Solution Approach 2:
The patent uses a temporary metal material layer that is diffused into the dielectric layer and then removed. This disposable metal layer serves its purpose during the diffusion process to modify threshold voltage and is subsequently eliminated, avoiding the need for permanent complex multi-layer structures and reducing fabrication cost.
3Ease of manufacture
If fewer photolithography and etching processes are used, then fabrication cost decreases and consistency improves, but achieving multiple threshold voltages becomes more difficult
Solution Approach 1:
The patent compensates for the reduced number of photolithography and etching processes by introducing precise control over metal ion diffusion parameters. By carefully adjusting annealing temperature, time, and metal material composition, the dielectric layer properties are precisely controlled to achieve the required threshold voltage differentiation, maintaining manufacturing precision while simplifying the overall process.
Solution Approach 2:
The patent replaces the mechanical/chemical processes of multiple deposition and etching steps with a thermal diffusion process. The annealing treatment enables metal ions to diffuse into the dielectric layer, creating the desired electrical properties through thermal energy rather than mechanical layering, thereby reducing process complexity while maintaining control precision.
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 achievement of two or more different threshold voltages with reduced fabrication costs and improved consistency, as fewer photolithography and etching processes are involved.
Implementation Method 1
performing an annealing process to cause diffusion of metal ions from the first metal material layer into at least one corresponding portion of the dielectric layer
Data Source
AI summary
A multi-threshold voltage semiconductor device and a method for fabricating the device are disclosed, in which a first metal material layer is formed on exposed dielectric layer in a part of gate trenches, and an annealing process is then carried out to cause diffusion of metal ions from the first metal material layer into the corresponding portion(s) of the high-k dielectric layer. In this way, two different threshold voltages can be achieved simply with one photolithography process and one etching process. More different threshold voltages can be achieved by adding photolithography processes. As fewer photolithography and etching processes are involved, the multi-threshold voltage semiconductor device can be fabricated at lower cost and exhibits improved consistency.