Nitrogen-Modified Gate Dielectric for Threshold Voltage Control
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Solution Overview
Problem
Existing semiconductor devices face challenges in controlling threshold voltage while using high-k dielectric layers as gate dielectric materials, particularly due to the complexity and time required for fabricating transistors with different electrical characteristics, and the need to manage leakage current and interface layer growth.
Innovation Solution
The implementation of nitrogen-incorporated active regions and high-k dielectric layers with a nitrogen-containing capping layer, allowing for the formation of gate dielectric layers with the same thickness across different regions, which suppresses interface layer growth and adjusts threshold voltage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-k dielectric layers are used as gate dielectric material to suppress leakage current, then leakage current is reduced, but threshold voltage control becomes difficult
Solution Approach 1:
The patent introduces a nitrogen-containing capping layer specifically on the high-k dielectric layer in regions where threshold voltage reduction is needed. This local modification allows different electrical characteristics in different regions while maintaining the overall high-k dielectric structure, enabling threshold voltage control without sacrificing leakage current suppression.
Solution Approach 2:
The patent modifies the chemical composition parameter of the gate dielectric layer by incorporating nitrogen into the capping layer. This parameter change (adding nitrogen) alters the electrical characteristics locally, enabling threshold voltage control while the bulk high-k dielectric material continues to provide leakage current suppression.
2Adaptability or versatility
If different gate dielectric layers are formed for transistors requiring different electrical characteristics, then electrical characteristics are optimized, but fabrication process complexity increases
Solution Approach 1:
The patent segments the gate dielectric layer into a bulk high-k dielectric layer and a nitrogen-containing capping layer. This segmentation allows the bulk layer to provide leakage suppression while the capping layer provides threshold voltage control, enabling different electrical characteristics without forming completely different dielectric structures.
Solution Approach 2:
The nitrogen-containing capping layer serves multiple functions: it acts as part of the gate dielectric structure, provides threshold voltage control through nitrogen concentration variation, and maintains interface quality. This multi-functionality reduces the need for separate specialized layers for each transistor type.
3Adaptability or versatility
If different gate dielectric layers are formed for transistors requiring different electrical characteristics, then electrical characteristics are optimized, but fabrication time increases
Solution Approach 1:
The patent merges the threshold voltage control function with the gate dielectric layer formation process by incorporating nitrogen into the capping layer during a single deposition process. This combines what would otherwise be separate process steps (forming different dielectric layers) into one unified process, reducing fabrication time.
Solution Approach 2:
The nitrogen-containing capping layer is formed preliminarily as part of the gate dielectric structure before transistor fabrication proceeds. This preliminary incorporation of threshold voltage control capability into the dielectric layer itself eliminates the need for subsequent separate processing steps to achieve different electrical characteristics.
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 enables the control of threshold voltage while maintaining low leakage current and simplifying the fabrication process, allowing for transistors with consistent electrical characteristics and reduced fabrication time.
Implementation Method 1
A nitrogen ion incorporated layer may be formed on the surface of the silicon substrate prior to the formation of the high-k dielectric layer. Accordingly, the growth of the interface layer may be suppressed.
Implementation Method 2
high-k dielectric layers having a dielectric constant higher than that of the silicon oxide layer may be used as the film-forming material of the gate dielectric layer instead of the silicone oxide layer
Data Source
AI summary
A semiconductor device may include a semiconductor substrate having a first region and a second region. The nitrogen-incorporated active region may be formed within the first region. A first gate electrode may be formed on the nitrogen-incorporated active region. A first gate dielectric layer may be interposed between the nitrogen-incorporated active region and the first gate electrode. The first gate dielectric layer may include a first dielectric layer and a second dielectric layer. The second dielectric layer may be a nitrogen contained dielectric layer. A second gate electrode may be formed on the second region. A second gate dielectric layer may be interposed between the second region and the second gate electrode. The first gate dielectric layer may have the same or substantially the same thickness as the second gate dielectric layer, and the nitrogen contained dielectric layer may contact with the nitrogen-incorporated active region.