High-k Dielectric Interface Stack for Low-Leakage Semiconductor Capacitors
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Solution Overview
Problem
As the degree of integration of semiconductor devices increases, the thickness of the dielectric layer decreases, leading to increased leakage current. Increasing the thickness of the dielectric layer to reduce leakage current results in an increase in the equivalent oxide layer thickness (EOT), limiting the increase in capacitance and potentially lowering the quality of the dielectric layer due to oxygen loss in a strong reducing atmosphere during top electrode formation.
Innovation Solution
A semiconductor layer stack is introduced, including a first conductive layer, a dielectric layer with a high-k material, a second conductive layer, and an interface control layer. The interface control layer comprises a leakage blocking material, a dopant material, a high bandgap material, and a high work function material, which are sequentially stacked to prevent reduction of the dielectric layer and enhance the dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of the dielectric layer is decreased to increase integration density, then the integration density is improved, but the leakage current increases
Solution Approach 1:
The patent employs a composite dielectric layer structure consisting of multiple materials with different properties (high-k material, leakage blocking material, high bandgap material). This composite structure allows the system to achieve both low leakage current and high capacitance density, resolving the contradiction between integration density and leakage current by combining materials that individually address different aspects of the problem.
Solution Approach 2:
The dielectric layer is segmented into multiple functional sub-layers: a high-k material layer for capacitance, a leakage blocking material layer for preventing leakage, and a high bandgap material layer for additional leakage suppression. This segmentation allows each layer to optimize its specific function while working together to achieve both high integration density and low leakage current.
2Object-generated harmful factors
If the thickness of the dielectric layer is increased to reduce leakage current, then the leakage current is reduced, but the equivalent oxide layer thickness (EOT) increases
Solution Approach 1:
By using high-k materials with dielectric constants significantly higher than silicon oxide, the patent achieves the same leakage current suppression as a thick oxide layer but with a much smaller physical thickness. The high-k material layer provides equivalent electrical insulation to a much thicker low-k layer, thereby reducing EOT while maintaining low leakage current.
Solution Approach 2:
The patent changes the dielectric constant parameter by introducing high-k materials (with k values of 20 or higher) to replace or supplement traditional silicon oxide. This parameter change allows the system to achieve the same electrical performance (leakage current suppression) with reduced physical thickness, thereby reducing EOT while maintaining low leakage.
3Ease of manufacture
If a strong reducing atmosphere is used during top electrode formation, then the electrode formation is improved, but the quality of the dielectric layer deteriorates due to oxygen loss
Solution Approach 1:
The patent introduces a leakage blocking material layer and/or high bandgap material layer as a protective barrier between the dielectric layer and the top electrode. This preliminary protective structure prevents oxygen loss from the dielectric layer during subsequent reducing atmosphere processing, thereby protecting dielectric quality while allowing effective electrode formation.
Solution Approach 2:
The leakage blocking material and high bandgap material serve as intermediary layers between the dielectric layer and the top electrode. These intermediary layers act as oxygen barriers that prevent direct interaction between the reducing atmosphere (used for electrode formation) and the dielectric layer, thereby allowing both good electrode formation and maintenance of dielectric quality.
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
The proposed solution effectively reduces leakage current, maintains a high dielectric constant, and prevents the reduction of the dielectric layer, thereby minimizing the equivalent oxide layer thickness (EOT) and enhancing capacitance while maintaining the quality of the dielectric layer.
Implementation Method 1
a dielectric layer including a high-k material
Implementation Method 2
including a leakage blocking material, a dopant material and a high bandgap material
Implementation Method 3
The interface control layer may further include a high work function material formed between the high bandgap material and the second conductive layer
Data Source
AI summary
A semiconductor layer stack includes a first conductive layer, a dielectric layer including a high-k material, which is formed on the first conductive layer, a second conductive layer formed on the dielectric layer, and an interface control layer formed between the dielectric layer and the second conductive layer and including a leakage blocking material, a dopant material, a high bandgap material and a high work function material.