Lateral High-Voltage Transistor Stripe Diffusion Leakage
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Solution Overview
Problem
Conventional lateral high-voltage transistors experience reduced drain current and deteriorated breakdown voltage characteristics due to insufficient depletion of the drift region and leakage current when high voltage is applied, as the current flowing through the channel leaks to the substrate.
Innovation Solution
A lateral high-voltage transistor design featuring a semiconductor substrate with a stripe-shaped diffusion layer in the drift region, where double diffusion occurs, reducing the likelihood of impact ionization by concentrating the drain current on a surface region with high impurity concentration and distributing the electric field evenly, thereby minimizing leakage current without compromising breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high voltage is applied between drain and source in OFF state, then breakdown voltage characteristics are required, but depletion of drift region is insufficient causing deteriorated breakdown voltage characteristics
Solution Approach 1:
The drift region is segmented into multiple stripe-shaped diffusion regions arranged in parallel, creating multiple depletion zones that collectively provide sufficient depletion across the drift region when high voltage is applied, resolving the insufficient depletion problem while maintaining high breakdown voltage characteristics
Solution Approach 2:
The drift region is designed with non-uniform impurity concentration distribution through selective stripe-shaped diffusion, creating local high-concentration regions that enhance depletion efficiency in critical areas while maintaining overall high breakdown voltage characteristics
2Power
If a voltage equal to or higher than threshold voltage is applied to gate to put transistor into ON state, then drain current flows, but current leaks to substrate reducing drain current
Solution Approach 1:
The channel region is segmented into multiple isolated stripe-shaped conduction paths through the stripe-shaped diffusion regions, confining the drain current to specific channels and preventing lateral leakage to the substrate, thereby maintaining high drain current while reducing leakage
Solution Approach 2:
The stripe-shaped diffusion regions act as intermediaries that guide and confine the drain current through defined paths, preventing direct leakage to the substrate while maintaining efficient current flow between source and drain
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 effectively reduces leakage current while maintaining high breakdown voltage characteristics, as confirmed by experiments showing minimal substrate current even at high drain-source voltages, and allows for efficient signal transmission between high and low potential circuit parts.
Implementation Method 1
double diffusion occurs in a portion where stripe-shaped diffusion regions are adjacent to each other
Implementation Method 2
impact ionization is unlikely to occur in each of the linear diffusion layers included in the stripe-shaped diffusion layer
Implementation Method 3
a gate electrode provided on a part of the semiconductor layer between the source region and the drain region with interposition of a gate insulating film
Data Source
AI summary
A lateral high-voltage transistor includes: a semiconductor substrate; a semiconductor layer being provided on one main surface of the semiconductor substrate; a source region being provided selectively in a surface of the semiconductor layer; a drain region being provided selectively in the surface of the semiconductor layer; a gate electrode provided on a part of the semiconductor layer between the source region and the drain region with interposition of the gate insulating film; and a drift region being provided selectively in the surface of the semiconductor layer. The drift region includes a stripe-shaped diffusion layer extending in parallel with a direction from the drain region toward the source region. The stripe-shaped diffusion layer includes linear diffusion layers each including stripe-shaped diffusion regions that are adjacent to each other such that double diffusion occurs in a portion where the stripe-shaped diffusion regions are adjacent to each other.