Semiconductor Device P-Type Isolation Surge Protection
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Solution Overview
Problem
Conventional high-voltage ICs are prone to breakdown due to negative voltage surges, which can cause parasitic pnp bipolar transistors to switch on, leading to excessive current flow and potential device failure, especially when external bypass capacitors cannot be used or are not effectively positioned.
Innovation Solution
The semiconductor device incorporates a p-type isolation diffusion region that electrically isolates the first and second semiconductor regions, preventing parasitic pnp bipolar transistor operation by maintaining depletion layers that connect when the second potential is higher than the third potential, thus preventing current flow between the VS and GND terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external bypass capacitors are added to prevent negative voltage surge breakdown, then device reliability improves, but device complexity and cost increase
Solution Approach 1:
A p-type isolation diffusion region is introduced as an intermediary structure between the first and second semiconductor regions. This isolation region contains a parasitic pnp bipolar transistor that acts as a protective mechanism, automatically activating during negative voltage surges to prevent breakdown without requiring external bypass capacitors.
Solution Approach 2:
The semiconductor device incorporates self-protection functionality through the isolation region's inherent parasitic pnp bipolar transistor. During negative voltage surges, the transistor automatically switches on to clamp the voltage and prevent breakdown, eliminating the need for external protective components.
2Reliability
If external bypass capacitors are positioned close to the high-voltage IC, then surge protection effectiveness improves, but layout complexity and manufacturing difficulty increase
Solution Approach 1:
The protection mechanism is integrated directly into the IC structure through the isolation region, eliminating the need for external bypass capacitors and their associated layout constraints. The self-protecting structure simplifies manufacturing while maintaining effective surge protection.
3Ease of manufacture
If self-isolation technology is used instead of external bypass capacitors, then device cost decreases, but protection against negative voltage surges may be insufficient
Solution Approach 1:
The p-type isolation diffusion region serves as an intermediary protective structure that enhances the basic self-isolation technology. The isolation region contains a parasitic pnp bipolar transistor that automatically activates during negative voltage surges, providing robust protection without requiring expensive external bypass capacitors.
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 solution effectively suppresses parasitic operation during negative voltage surges without the need for external components, preventing device breakdown and ensuring the high-voltage IC's reliability and cost-effectiveness through self-isolation technology.
Implementation Method 1
maintaining depletion layers that connect when the second potential is higher than the third potential, thus preventing current flow between the VS and GND terminals
Data Source
AI summary
In a high-side region, a first n-diffusion region, in which a PMOS constituting a gate drive circuit is formed, and a second n-diffusion region, in which a p-diffusion region is formed, are provided on a surface layer of a pāā substrate. An NMOS constituting a gate drive circuit is formed in the p-diffusion region. A p-type isolation diffusion region at ground potential is provided between the first n-diffusion region and the second n-diffusion region, and the first re-diffusion region and the second n-diffusion region are electrically isolated. The first n-diffusion region is connected to a VB terminal at a power source potential. The second n-diffusion region is connected to a terminal at a reference or floating potential. The p-diffusion region is connected to a VS terminal at a reference potential. Accordingly, it is possible to suppress parasitic operation due to a surge, without using external components, and without element breakdown.