Oxygen-Scavenging Source/Drain Layout for Stable Threshold Voltage
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Solution Overview
Problem
Existing methods to increase oxygen vacancies in source/drain regions of transistors for improved current density and reduced contact resistance lead to undesirable reductions in threshold voltage, complicating the manufacturing process and increasing costs.
Innovation Solution
A transistor design with varying concentrations of oxygen vacancies localized to the source/drain regions using materials with low oxide formation energy, forming oxide layers that pull oxygen from these regions during annealing, thereby increasing oxygen vacancies without affecting the channel's threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen vacancies are increased in source/drain regions to improve current density and reduce contact resistance, then current density increases and contact resistance decreases, but threshold voltage is reduced which is undesirable
Solution Approach 1:
The patent applies local quality by creating different oxygen vacancy concentrations in different regions of the semiconductor structure. Specifically, the source/drain regions are engineered to have high oxygen vacancy concentrations to improve conductivity, while the channel region maintains low oxygen vacancy concentrations to preserve threshold voltage. This is achieved through selective annealing processes and targeted oxygen removal methods that affect only specific regions, allowing each part to have the optimal properties for its function.
2Reliability
If oxygen vacancies are increased in source/drain regions, then contact resistance decreases, but the manufacturing process becomes more complex and costs increase
Solution Approach 1:
The patent merges multiple functions into the annealing process. The annealing step simultaneously serves to: (1) remove oxygen from source/drain regions to create oxygen vacancies and improve conductivity, (2) form metal silicide contacts, and (3) activate dopants. By combining these previously separate process steps into a single annealing operation, the manufacturing complexity is reduced while achieving the desired low contact resistance.
Solution Approach 2:
The patent employs self-service mechanisms where the annealing process automatically creates the desired oxygen vacancy distribution without requiring additional specialized equipment or steps. The thermal energy from annealing naturally drives oxygen diffusion and removal from the source/drain regions, and the process self-regulates to achieve the optimal oxygen vacancy concentration based on the material properties and processing conditions.
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 current density while maintaining a desirable threshold voltage, simplifying the manufacturing process and reducing costs by localizing the oxygen vacancy increase to the source/drain regions.
Implementation Method 1
forming oxide layers that pull oxygen from these regions during annealing
Implementation Method 2
forming oxide layers that pull oxygen from these regions during annealing
Data Source
AI summary
Some embodiments relate to an integrated device, including: a semiconductor layer comprising a semiconductor channel; a gate on the semiconductor channel; a first source/drain region on a first side of the semiconductor channel; and a second source/drain region on a second side of the semiconductor channel opposite the first side; where the first source/drain region and the second source/drain region have a first concentration of oxygen vacancies, and the semiconductor channel has a second concentration of oxygen vacancies that is less than the first concentration of oxygen vacancies.