Bipolar ESD Protection Device Using Segmented P-Well Architecture
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Solution Overview
Problem
Conventional ESD clamp circuits face challenges in designing narrow design windows for high voltage protection, requiring tradeoffs between on-state resistance, triggering threshold voltage, and circuit size, which can lead to degradation of protected circuits and increased costs.
Innovation Solution
A compact bipolar-based ESD protection device with a low stage and top stage arrangement in semiconductor regions, utilizing npn and pnp transistors to provide low impedance discharging and optimized for single polarity protection, achieving high ESD performance with low on-state resistance and compact footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of the ESD protection circuit is increased to achieve low on-state resistance, then the on-state resistance decreases, but the chip cost increases
Solution Approach 1:
The ESD protection circuit is divided into multiple functional regions: a first ESD protection circuit region with an n-type semiconductor substrate and p-type well, and a second ESD protection circuit region with a p-type semiconductor substrate and n-type well. This segmentation allows each region to be optimized for specific polarity protection, achieving low on-state resistance without requiring a single large circuit area.
Solution Approach 2:
Different regions of the semiconductor substrate are doped with different conductivity types and concentrations to create locally optimized protection characteristics. The n-type substrate region provides optimal protection for one polarity while the p-type substrate region provides optimal protection for the opposite polarity, allowing each local region to operate at its best performance point.
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 solution provides robust ESD protection with low on-state resistance and compact design, enhancing current capability and immunity to voltage fluctuations without compromising other device properties, thus addressing the limitations of conventional ESD protection circuits.
Implementation Method 1
as the voltage applied to the terminals is increased, very little current flows through the ESD clamp circuit until the triggering threshold voltage Vt is reached, at which point the ESD clamp circuit begins conducting current
Data Source
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AI summary
An area-efficient, high voltage, single polarity ESD protection device (300) is provided which includes an p-type substrate (303); a first p-well (308-1) formed in the substrate and sized to contain n+ and p+ contact regions (310, 312) that are connected to a cathode terminal; a second, separate p-well (308-2) formed in the substrate and sized to contain only a p+ contact region (311) that is connected to an anode terminal; and an electrically floating n-type isolation structure (304, 306, 307-2) formed in the substrate to surround and separate the first and second semiconductor regions. When a positive voltage exceeding a triggering voltage level is applied to the cathode and anode terminals, the ESD protection device triggers an inherent thyristor into a snap-back mode to provide a low impedance path through the structure for discharging the ESD current.