SCR ESD Well Structure for Decoupled Breakdown and Holding Voltage
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Solution Overview
Problem
Existing electrostatic discharge (ESD) devices, particularly semiconductor-controlled rectifier (SCR) structures, have limitations such as low holding voltages and fixed DC breakdown voltages, which hinder their use in applications requiring higher performance, like automotive systems, and limit their platform implementation due to manufacturing costs and substrate integration issues.
Innovation Solution
The development of semiconductor device structures with a multiple-well design and doped regions that decouple DC breakdown voltage and holding voltage control, allowing for adjustable performance and substrate isolation, enabling higher voltage handling and flexible integration through stacked configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional SCR structures are used for ESD protection, then device size is reduced, but holding voltage becomes too low and DC breakdown voltage becomes fixed and non-adjustable
Solution Approach 1:
The patent segments the single SCR structure into multiple SCR units connected in series. Each SCR unit has its own cathode and anode regions, allowing independent control of breakdown voltage for each unit. The total DC breakdown voltage becomes the sum of individual SCR breakdown voltages, enabling adjustable and higher breakdown voltage levels while maintaining compact size.
Solution Approach 2:
The patent introduces adjustable resistive elements connected to the cathode regions of the SCR units. By varying the resistance values, the DC breakdown voltage of each SCR unit can be dynamically adjusted, thereby tuning the overall breakdown voltage of the stacked ESD device to match different application requirements.
2Volume of moving object
If traditional SCR structures are used for ESD protection, then device size is reduced, but holding voltage performance deteriorates
Solution Approach 1:
By stacking multiple SCR units in series, the total holding voltage of the ESD device becomes the sum of the holding voltages of individual SCR units. This segmentation approach enables achieving higher holding voltage (e.g., >10V) while keeping each individual SCR unit compact, thus maintaining small overall device size.
3Ease of manufacture
If ESD devices are integrated closely with substrate, then manufacturing cost is reduced, but electrical performance deteriorates due to substrate interference
Solution Approach 1:
The patent extracts the active SCR regions from direct contact with the substrate by introducing isolation structures (such as deep trench isolations or pinned layers) between the SCR cathode regions and the substrate. This extraction eliminates substrate interference and parasitic effects, improving electrical performance while maintaining cost-effective integration.
Solution Approach 2:
The patent introduces intermediate isolation layers or pinned layers between the SCR structures and the substrate. These intermediary elements act as electrical barriers that prevent substrate interference and parasitic conduction paths, thereby improving the electrical performance of the ESD device without increasing manufacturing complexity.
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 ESD device performance by achieving higher holding voltages and adjustable DC breakdown voltages, improving electrical performance and supporting broader platform implementation while reducing manufacturing costs and substrate dependency.
Implementation Method 1
a doped region at the anode side, which modulates electric field build-up
Data Source
AI summary
In an example, a semiconductor device includes a region of semiconductor material with a buried doped region of a first conductivity type. A first well region of the first conductivity type is in the region of semiconductor material and is electrically coupled to the buried doped region. A second well region of a second conductivity type is in the region of semiconductor material and has a first peak dopant concentration. A third well region of the second conductivity type abuts edges of the second well region. The third well region is interposed between the first well region and the second well region and has a second peak dopant concentration that is different than the first peak dopant concentration. A doped anode region of the second conductivity type is in the first well region, a doped cathode region of the first conductivity type is in the second well region, and a doped contact region of the second conductivity type is in the second well region. The semiconductor device can be configured as a semiconductor-controlled rectifier (SCR) ESD device where the controlling mechanisms for DC breakdown voltage and holding voltage are decoupled. Other related examples and methods are disclosed herein.