High Voltage Transistor Source Segmentation for Rdson Reduction

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Solution Overview

Problem

High voltage transistors in integrated circuits typically have high resistance in the 'on' mode (Rdson), leading to energy losses during switching, and reducing Rdson values to improve efficiency also reduces breakdown voltage and reliability.

Innovation Solution

The design includes a substrate with a gate extension that divides the source into multiple sections, reducing the drain distance while maintaining reliability by using shallow trench isolation structures and specific dopant distributions to control conductivity and resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the drain distance is increased to reduce substrate current and increase current capacity, then reliability is improved, but Rdson increases leading to higher energy losses

Engineering Contradiction:

Improvebreakdown voltageVSAvoidenergy losses during switching

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The source region is divided into multiple source sections (first source section, second source section, etc.) separated by shallow trench isolation structures. This segmentation allows the transistor to achieve lower Rdson through increased effective source width while maintaining acceptable breakdown voltage through the isolated structure arrangement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the transistor are given different dopant concentrations - the source sections have higher dopant levels to reduce resistance, while the drift region maintains lower dopant levels to preserve breakdown voltage. The shallow trench isolation structures are strategically placed to provide electrical isolation where needed.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If the dopant level in the drift region is increased to reduce resistance, then Rdson is reduced, but breakdown voltage decreases reducing reliability

Engineering Contradiction:

Improveenergy losses during switchingVSAvoidbreakdown voltage

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The drift region is designed with a specific dopant concentration that balances resistance and breakdown voltage. The source sections are given higher dopant levels to reduce resistance locally, while the drift region maintains lower dopant levels to preserve breakdown voltage, creating local quality variations that optimize overall performance.

Inventive Principle:

Principle #3Local quality

3Loss of energy

If the drain distance is reduced to lower Rdson, then energy losses are reduced, but current capacity decreases and reliability is compromised

Engineering Contradiction:

Improveenergy losses during switchingVSAvoidbreakdown voltage

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The source is divided into multiple sections separated by shallow trench isolation structures, which allows the drain distance to be reduced while maintaining reliability through the isolated structure arrangement that manages substrate current and electric field distribution.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10032905B1Integrated circuits with high voltage transistors and methods for producing the same

Publication Date: 2018.07.24 GLOBALFOUNDRIES SINGAPORE PTE LTD

AI summary

Integrated circuits and methods of producing integrated circuits are provided. In an exemplary embodiment, an integrated circuit includes a substrate and a gate overlying the substrate. A drain is defined within the substrate, where the drain and the gate are separated by a drain distance. A source is defined within the substrate adjacent to the gate, wherein the source is divided into two or more source sections.