SCR ESD Protection Device With Alternating PN Junctions
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Solution Overview
Problem
The miniaturization of high voltage electrostatic discharge (ESD) devices is hindered by their size, which is increased due to high latch-up free and immunity specifications, making them less competitive, and existing ESD protection circuits with silicon controller rectifier (SCR) structures struggle to maintain effective ESD protection without increasing device size.
Innovation Solution
The implementation of a semiconductor substrate with a PNPN or NPNP structure silicon controller rectifier (SCR) device and diode devices, alternately disposed to form PN junctions, which reduces base resistance and increases holding voltage, allowing for smaller device sizes while maintaining latch-up free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of ESD device is increased to meet high latch-up free and immunity specifications, then ESD protection performance is improved, but device area increases making miniaturization difficult
Solution Approach 1:
The patent embeds diode structures within the SCR device structure by sharing common diffusion areas (N+ and P+ regions). The diodes are formed by adding impurity areas to the existing SCR structure, creating a nested configuration where the diode is integrated inside the SCR footprint, thereby providing enhanced ESD protection without increasing device area.
Solution Approach 2:
The patent creates a composite structure combining SCR and diode elements in a single integrated device. The SCR provides voltage breakdown and current discharge functionality while the integrated diodes provide additional protection pathways. This composite structure achieves superior ESD immunity (4kV HBM level) while maintaining compact size by synergistically combining multiple protection mechanisms within a unified device architecture.
2Reliability
If SCR structure is used for ESD protection, then ESD current discharge capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the diode protection function with the SCR structure by sharing common diffusion areas (N+ area 154, P+ area 152). The diodes are formed by extending impurity doping into the existing SCR regions rather than adding separate discrete components. This merging reduces structural complexity while maintaining enhanced ESD discharge capability through multiple parallel protection pathways.
3Reliability
If base resistance is reduced to increase holding voltage, then ESD protection effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating specifically doped impurity areas (P-type first impurity area 161, N-type second impurity area 162) at precise locations around the SCR structure. These localized doped regions form the diode structures that provide additional protection pathways. The local doping approach allows control of base resistance and holding voltage characteristics while maintaining manufacturability through focused impurity implantation in defined areas.
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 configuration enhances ESD protection by increasing breakdown voltage and reducing base resistance, enabling smaller device sizes while ensuring stable operation and compliance with high voltage designs exceeding human body model (HBM) 4 kV immunity levels.
Implementation Method 1
a PN junction structure formed by the first and second impurity areas and the SCR device, wherein the PN junction structure is alternately disposed when a substrate is viewed from above
Data Source
AI summary
An electrostatic discharge protection device is provided. The electrostatic discharge protection device can include a semiconductor substrate having a first well and a second well, a silicon controller rectifier (SCR) device, and first and second impurity areas disposed on the first and second wells to form a PN junction. The SCR can have a PNPN structure or an NPNP structure, and the PN junction structure and the SCR device can be alternately disposed when the substrate is viewed from above.