High-Voltage Isolation Structure Depletion Control

Solution Overview

Problem

The partial breakdown phenomenon in high-voltage isolation structures due to incomplete depletion of P-type junction isolation regions away from the high-voltage region reduces the withstand voltage, affecting the reliability of high-voltage integrated circuits.

Innovation Solution

Incorporating a N-type well region with varying implantation windows in the P-type junction isolation region, allowing the concentration of the second P-type well region to decrease gradually from the high-voltage to the low-voltage region, ensuring complete depletion and preventing partial breakdown.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a P-type junction isolation structure is used to isolate high-voltage LDMOS from other circuit parts, then isolation effectiveness is improved, but partial breakdown occurs in regions away from the high-voltage region due to incomplete depletion, reducing withstand voltage

Engineering Contradiction:

Improveisolation effectivenessVSAvoidwithstand voltage

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by introducing an N-type well region specifically in the P-type junction isolation region away from the high-voltage region. This creates a localized modification where the isolation structure has different doping characteristics in different areas: the P-type well provides isolation near the high-voltage region, while the added N-type well enhances depletion and prevents partial breakdown in regions farther away. This local modification resolves the contradiction by maintaining isolation effectiveness while improving withstand voltage in previously vulnerable areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the doping parameters of the isolation structure by adding an N-type well region with specific doping concentration and depth. This parameter change transforms the isolation region from a simple P-type structure to a more complex P-N junction structure, which alters the depletion characteristics and electrical field distribution. The parameter modification enables complete depletion of the isolation region, preventing partial breakdown while maintaining effective isolation, thus resolving the contradiction between isolation effectiveness and withstand voltage.

Inventive Principle:

Principle #35Parameter changes

2Strength

If the P-type junction isolation region is designed to completely deplete under high voltage, then breakdown voltage increases, but the region away from high-voltage cannot be depleted completely, causing partial breakdown

Engineering Contradiction:

Improvebreakdown voltageVSAvoiddepletion completeness

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies local quality by introducing an N-type well region specifically in the P-type junction isolation region away from the high-voltage region. This creates a localized modification where the isolation structure has different doping characteristics in different areas: the P-type well provides isolation near the high-voltage region, while the added N-type well enhances depletion and prevents partial breakdown in regions farther away. This local modification resolves the contradiction by maintaining isolation effectiveness while improving withstand voltage in previously vulnerable areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the doping parameters of the isolation structure by adding an N-type well region with specific doping concentration and depth. This parameter change transforms the isolation region from a simple P-type structure to a more complex P-N junction structure, which alters the depletion characteristics and electrical field distribution. The parameter modification enables complete depletion of the isolation region, preventing partial breakdown while maintaining effective isolation, thus resolving the contradiction between isolation effectiveness and withstand voltage.

Inventive Principle:

Principle #35Parameter changes

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 approach increases the breakdown voltage of the isolation structure, effectively isolating the high-voltage region from surrounding parts and enhancing the overall reliability of the high-voltage driving circuit.

Implementation Method 1

Incorporating a N-type well region with varying implantation windows in the P-type junction isolation region

Methodology Applied

Scientific EffectIon Implantation: Ion Implantation

Implementation Method 2

the P-type junction isolation region near the isolation part of high-voltage region can be depleted completely, while the P-type junction isolation region away from the isolation part of high-voltage region can't be depleted completely

Methodology Applied

Scientific EffectJunction Depletion: Electric Field

Data Source

PatentUS8933534B2Isolation structure of high-voltage driving circuit

Publication Date: 2015.01.13 SOUTHEAST UNIV

AI summary

An isolation structure of a high-voltage driving circuit includes a P-type substrate and a P-type epitaxial layer; a high voltage area, a low voltage area and a high and low voltage junction terminal area are arranged on the P-type epitaxial layer; a first P-type junction isolation area is arranged between the high and low voltage junction terminal area and the low voltage area, and a high-voltage insulated gate field effect tube is arranged between the high voltage area and the low voltage area; two sides of the high-voltage insulated gate field effect tube and an isolation structure between the high-voltage insulated gate field effect tube and a high side area are formed as a second P-type junction isolation area.