High-Trigger Current SCR for ESD Protection
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Solution Overview
Problem
Conventional silicon-controlled rectifiers (SCRs) have low trigger current, leading to unintended triggering and potential damage to internal circuitry during electrostatic discharge (ESD) events.
Innovation Solution
The development of SCRs with higher trigger currents, achieved through specific doping concentrations and structures, including lightly doped p-type regions, n-wells, p-wells, P+ regions, and N+ regions, with adjustable spacing to enhance trigger and breakdown voltages, preventing false triggering during ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SCR designs are used, then the device structure is simple, but the trigger current is low causing inadvertent triggering and damage to internal circuitry
Solution Approach 1:
The patent applies local quality by creating distinct doped regions (n-well, p-well, P+ regions, N+ regions) with different doping concentrations and types at specific locations within the SCR structure. Each region serves a specific function: the lightly doped p-type region provides high breakdown voltage, while the heavily doped P+ and N+ regions provide low-impedance current paths. This localized differentiation of material properties enables the SCR to achieve high trigger current and reliable ESD protection without requiring complex external circuitry.
Solution Approach 2:
The patent employs parameter changes by systematically varying doping concentrations, well depths, and region spacing to optimize SCR performance. Specifically, the lightly doped p-type region (1×10^14 to 1×10^15 atoms/cm³) provides high breakdown voltage, while the n-well and p-well are doped at intermediate concentrations (1×10^16 to 1×10^17 atoms/cm³), and the P+ and N+ regions are heavily doped (1×10^20 to 1×10^22 atoms/cm³). These parameter variations enable precise control over trigger current and breakdown voltage characteristics, achieving reliable ESD protection.
2Reliability
If higher trigger current is achieved through specific doping structures, then false triggering is prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the SCR structure into distinct functional zones: a lightly doped p-type region for high breakdown voltage, an n-well region, a p-well region, P+ doped regions, and N+ doped regions. Each segment is formed through separate doping processes with specific concentration ranges and spatial configurations. This segmentation allows independent optimization of each region's properties to achieve the desired high trigger current while maintaining compatibility with standard semiconductor fabrication processes.
Solution Approach 2:
The patent employs parameter changes by systematically varying doping concentrations, well depths, and region spacing to optimize SCR performance. Specifically, the lightly doped p-type region (1×10^14 to 1×10^15 atoms/cm³) provides high breakdown voltage, while the n-well and p-well are doped at intermediate concentrations (1×10^16 to 1×10^17 atoms/cm³), and the P+ and N+ regions are heavily doped (1×10^20 to 1×10^22 atoms/cm³). These parameter variations enable precise control over trigger current and breakdown voltage characteristics, achieving reliable ESD protection.
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 improved SCRs provide enhanced protection against ESD by maintaining high trigger currents and adjustable voltage settings, preventing damage to internal circuitry and ensuring reliable operation.
Implementation Method 1
A lightly doped p-type region is formed over a semiconductor substrate. A first well of a first type is formed in a first upper area of the first doped region of the first type. A first well of a second type is formed in a second upper area of the first doped region of the first type
Implementation Method 2
The first well of the second type is laterally spaced from the first well of the first type by a non-zero distance. A second doped region of the first type is formed in a first upper area of the first well of the second type. The second doped region of the first type forms an anode of the silicon-controlled rectifier
Data Source
AI summary
An SCR includes a first doped region of a first type having a first doping concentration. A first well of the first type and a first well of a second type are disposed in upper areas of the first doped region of the first type such that the first well of the second type is laterally spaced from the first well of the first type by a non-zero distance. A second doped region of the first type has a second doping concentration that is greater than the first doping concentration and is disposed in the first well of the second type to form an anode of the SCR. A first doped region of the second type is disposed in the first well of the first type and forms a cathode of the SCR.