Vertical TVS with Asymmetric Doping for Symmetric Breakdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional vertical transient voltage suppressors (TVS) face issues with asymmetric breakdown voltages and I-V characteristics, leading to unequal ESD protection under positive and negative stresses, and significant variation in breakdown voltage due to out-diffusion effects during processing.
Innovation Solution
A vertical TVS design featuring a conductivity type substrate with highly doping concentration, multiple lightly and heavily doped regions of opposite and same types, and deep heavily doped regions to form low resistance paths and symmetric I-V characteristics, allowing for effective bi-directional or uni-directional ESD protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional vertical TVS structure is used, then manufacturing process is simple, but breakdown voltage is not symmetric and I-V characteristics are asymmetric
Solution Approach 1:
The patent applies asymmetry principle by intentionally designing asymmetric doping concentrations and region configurations to achieve symmetric breakdown voltages. Specifically, the first and second lightly doped regions have different doping concentrations (Na and Nb), and the heavily doped regions are positioned asymmetrically, which compensates for process variations and achieves symmetric I-V characteristics despite the asymmetric structure
Solution Approach 2:
The patent applies local quality principle by creating regions with different doping concentrations and types in specific locations. The first and second lightly doped regions have different doping concentrations (Na < Nb), and the heavily doped regions are strategically positioned to create localized electrical properties that collectively achieve symmetric breakdown behavior
2Reliability
If traditional vertical TVS structure is used, then device structure is simple, but ESD protection ability under positive and negative stresses is not equal
Solution Approach 1:
The patent creates different local electrical properties by implementing first and second lightly doped regions with different doping concentrations (Na and Nb), and positioning heavily doped regions asymmetrically. This local differentiation enables the device to provide equal ESD protection under both positive and negative voltage stresses by balancing the breakdown characteristics in both directions
3Manufacturing precision
If traditional vertical TVS structure is used, then manufacturing process is straightforward, but breakdown voltage variation is large due to out-diffusion effect
Solution Approach 1:
The patent applies parameter changes principle by carefully controlling and optimizing doping concentrations (Na and Nb for lightly doped regions, and heavily doped regions) to compensate for out-diffusion effects during manufacturing. By adjusting these parameters, the patent achieves consistent breakdown voltages across production batches despite the complexity of the multi-region structure
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 design achieves symmetric breakdown voltages and improved ESD protection efficiency under both positive and negative stresses, reducing variation and enhancing protection within limited layout areas by discharging ESD current through both lateral and vertical transistors.
Implementation Method 1
The working principle of TVS is shown in FIG. 1. In FIG. 1, the TVS devices 10 are connected in parallel with the protected circuits 12 on the PCB (Printed Circuit Board). These TVS devices 10 would be triggered immediately when the ESD event is occurred. In that way, each TVS device 10 can provide a superiorly low resistance path for discharging the transient ESD current
Implementation Method 2
a first type heavily doped region and a second type heavily doped region, arranged in the first type lightly doped region, wherein the first and second type heavily doped regions and the conductivity type substrate belong to same types
Implementation Method 3
a first type lightly doped region, arranged on the conductivity type substrate, wherein the conductivity type substrate and the first type lightly doped region respectively belong to opposite types
Data Source
AI summary
A vertical transient voltage suppressor for protecting an electronic device is disclosed. The vertical transient voltage includes a conductivity type substrate having highly doping concentration; a first type lightly doped region is arranged on the conductivity type substrate, wherein the conductivity type substrate and the first type lightly doped region respectively belong to opposite types; a first type heavily doped region and a second type heavily doped region are arranged in the first type lightly doped region, wherein the first and second type heavily doped regions and the conductivity type substrate belong to same types; and a deep first type heavily doped region is arranged on the conductivity type substrate and neighbors the first type lightly doped region, wherein the deep first type heavily doped region and the first type lightly doped region respectively belong to opposite types, and wherein the deep first type heavily doped region is coupled to the first type heavily doped region.