PNPN Transistor ESD Protection via Parasitic SCR
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Solution Overview
Problem
Ultra-high voltage semiconductor transistors are susceptible to damage from electrostatic discharge (ESD), with existing ESD protection schemes providing insufficient protection beyond 1.5 kilovolts, which can lead to device failure and disruption of connected circuitry.
Innovation Solution
A semiconductor transistor device with a PNPN structure that includes p-type and n-type regions forming a drain-to-gate ESD current path, utilizing a silicon-controlled rectifier (SCR) to safely discharge ESD voltage, providing protection against high ESD current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing ESD protection schemes are used, then protection up to about 1.5 kV is provided, but protection against higher ESD voltages (2 kV or higher) is insufficient
Solution Approach 1:
The patent converts the harmful ESD voltage into a beneficial protective mechanism by utilizing the parasitic SCR structure inherent in the CMOS transistor. When ESD voltage exceeds a threshold, the SCR triggers and creates a low-impedance discharge path from drain to gate, safely dissipating the ESD energy through controlled breakdown rather than allowing it to damage critical transistor regions.
Solution Approach 2:
The patent introduces an intermediary n-type region that couples the drain and gate regions to form the parasitic SCR structure. This intermediary region enables the ESD current path while maintaining normal transistor operation, acting as a mediator that allows safe ESD discharge without interfering with standard device functionality.
2Reliability
If ESD protection structures are added to UHV transistors, then ESD resistance improves, but device complexity increases
Solution Approach 1:
The patent achieves multi-functionality by designing the parasitic SCR structure to serve dual purposes: it enables high-voltage operation (UHV capability) while simultaneously providing ESD protection. The same n-type region and SCR mechanism that allow the transistor to block high voltages also create the ESD discharge path, eliminating the need for separate protection structures.
Solution Approach 2:
The transistor structure is designed to be self-protecting through its inherent parasitic SCR formation. The ESD protection capability arises naturally from the device's own structure rather than requiring external protection circuits. The parasitic elements that normally represent potential failure modes are instead harnessed to provide automatic ESD clamping and discharge functionality.
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 PNPN structure effectively protects transistors from ESD damage by establishing a drain-to-gate ESD current path, reducing breakdown overshoot and enabling safe discharge of high ESD voltages, such as 2 kV or higher, compared to existing protection techniques.
Implementation Method 1
Electrostatic discharge (ESD) is a common difficulty in the manufacture and use of semiconductor transistors and related devices
Implementation Method 2
utilizing a silicon-controlled rectifier (SCR) to safely discharge ESD voltage
Data Source
AI summary
A semiconductor transistor device includes a source region, a gate region having a p-type gate region and an n-type gate region, and a drain region having a p-type drain region and an n-type drain region. The p-type gate region, the n-type gate region, the p-type drain region, and the n-type drain region are positioned to provide, in response to an electrostatic discharge (ESD) voltage, a drain-to-gate ESD current path to at least partially discharge the ESD voltage.