Semiconductor ESD Protection Structure with Segmented Diffusion Layers
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Solution Overview
Problem
The miniaturization of semiconductor integrated circuits narrows the operating range of ESD protection elements, making it difficult to achieve desired breakdown voltage and high ESD resistance, while high-concentration diffusion layers near the gate electrode reduce breakdown voltage and increase the risk of thermal destruction.
Innovation Solution
A semiconductor device structure is implemented with a second conductivity-type low concentration diffusion layer, a first conductivity-type source and drain diffusion layers separated from the gate electrode, a first conductivity-type drain LDD diffusion layer, and a high-concentration diffusion layer with a controlled impurity concentration gradient to enhance breakdown voltage and ESD resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-concentration diffusion layer is disposed near the gate electrode to increase ESD resistance, then the ESD resistance is improved, but the breakdown voltage is reduced
Solution Approach 1:
The diffusion layer structure is segmented into multiple regions with different impurity concentrations: a first conductivity-type low concentration diffusion layer, a first conductivity-type high concentration diffusion layer, and a second conductivity-type low concentration diffusion layer. This segmentation allows each region to serve specific functions - the high concentration region provides ESD resistance while the low concentration regions maintain breakdown voltage, thereby resolving the contradiction between ESD resistance and breakdown voltage.
Solution Approach 2:
Different regions of the semiconductor device are assigned different impurity concentrations tailored to their specific functional requirements. The high concentration diffusion layer is positioned in the drain region where high ESD resistance is needed, while low concentration diffusion layers are positioned near the gate electrode and in the source region to maintain high breakdown voltage. This local quality differentiation resolves the contradiction by optimizing each region's properties for its specific function.
2Reliability
If the operating range of ESD protection element is set higher than maximum operating voltage to protect internal elements, then the protection capability is improved, but the operating range is narrowed due to miniaturization
Solution Approach 1:
The invention changes the impurity concentration parameters in different regions of the semiconductor device. By creating a multi-layer diffusion structure with varying concentrations (low concentration near gate, high concentration in drain region, low concentration in source region), the device achieves both high breakdown voltage for protection capability and maintains adequate operating range despite miniaturization. The parameter changes in impurity concentration allow the device to meet both protection and operational requirements.
3Strength
If a multiple diffusion structure is used to adjust breakdown voltage, then the breakdown voltage can be tuned, but the manufacturing precision is reduced due to structure and process variations
Solution Approach 1:
The diffusion structure is segmented into distinct layers with clearly defined concentration gradients. The first conductivity-type low concentration diffusion layer, first conductivity-type high concentration diffusion layer, and second conductivity-type low concentration diffusion layer are formed as separate segments. This segmentation makes the manufacturing process more controllable and reduces variability, thereby improving manufacturing precision while maintaining the ability to tune breakdown voltage.
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 structure effectively alleviates electric field stress near the gate electrode, increases ESD resistance, and allows for easier adjustment of breakdown voltage by separating the high-concentration diffusion layer from the gate, thereby suppressing deterioration and thermal destruction.
Implementation Method 1
a second conductivity-type low concentration diffusion layer provided inwardly from a surface of a semiconductor substrate, a first conductivity-type source diffusion layer and a first conductivity-type drain diffusion layer provided on a surface of the semiconductor substrate
Implementation Method 2
a gate electrode provided on a surface of the second conductivity-type low concentration diffusion layer with an interposition of a gate oxide film
Data Source
AI summary
In the semiconductor device, a high-concentration diffusion layer and a low-concentration diffusion layer are disposed around a drain diffusion layer of an ESD protection element. The high-concentration diffusion layer is separated from a gate electrode, and a medium concentration LDD diffusion layer is disposed in a separation gap. Variations in characteristics are suppressed by reducing thermal treatment on the high-concentration diffusion layer and a medium concentration diffusion layer.