Deep Trench Insulation Structure for Compact High-Voltage Isolation

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Solution Overview

Problem

Current deep trench insulation (DTI) technologies for high voltage semiconductor devices face challenges in manufacturing variability, leading to increased costs and reduced voltage breakdown risks due to variations in trench dimensions, necessitating separate integration steps and higher manufacturing costs for achieving different isolation capabilities.

Innovation Solution

The solution involves manufacturing both a first and a second deep trench insulation (DTI) in the same process steps, with the second DTI being smaller and filled with a solid insulating region, allowing for reduced dimensions and area while maintaining voltage capabilities, and enabling a 40% to 70% reduction in rail area without increasing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple DTIs with different dimensions are manufactured using current technology, then different isolation capabilities are achieved, but manufacturing costs increase and variability risks increase due to separate integration steps

Engineering Contradiction:
Improveisolation capabilitiesVSAvoidmanufacturing costs
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent divides the single DIT structure into multiple segmented DTI structures with different dimensions (first DTI with larger dimensions, second DTI with smaller dimensions) that can provide different isolation capabilities. This segmentation allows each DTI to be optimized for specific voltage requirements while being manufactured together in the same process steps, reducing manufacturing costs and variability risks.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a multi-functional insulation system where multiple DTI structures serve different isolation purposes within the same device. The first DTI provides isolation for higher voltage regions while the second DTI provides isolation for lower voltage regions, enabling a single insulation system to handle multiple voltage levels and device functions simultaneously.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If DTI dimensions are increased to ensure voltage breakdown protection, then voltage capabilities are maintained, but device area increases

Engineering Contradiction:
Improvevoltage breakdown protectionVSAvoiddevice area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent applies different DTI dimensions at different locations within the device based on local voltage requirements. The first DTI has larger dimensions for regions requiring higher voltage isolation, while the second DTI has smaller dimensions for regions with lower voltage requirements. This local quality approach ensures adequate voltage breakdown protection only where needed, minimizing overall device area.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent utilizes vertical dimension variations in DTI structures to provide different isolation capabilities. By creating DTIs with different depths and widths, the patent achieves multiple isolation levels without proportionally increasing the horizontal device area, effectively using the third dimension (depth) to solve the isolation vs. area trade-off.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 allows for a significant reduction in device dimensions while maintaining voltage capabilities, reducing manufacturing costs and variability-related risks, and enabling the integration of multiple DTIs with different functions on a single chip.

Implementation Method 1

the second deep insulation structure comprises a solid insulating region filling the second trench

Methodology Applied
Scientific EffectDielectric insulation: Dielectric

Implementation Method 2

the first deep insulation region comprises insulation walls surrounding a conductive filling portion

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4379785A1High voltage semiconductor device having a deep trench insulation and manufacturing process
Publication Date: 2024.06.05 STMICROELECTRONICS SRL
  • EP4379785A1 patent drawingFigure 1~2
  • EP4379785A1 patent drawingFigure 3~4
  • EP4379785A1 patent drawingFigure 5~6

AI summary

A high-voltage semiconductor device (100, 200) formed in a body (102) of semiconductor material having a surface (102A) and accommodating an active area (116); conductive regions (120-123); a first deep insulation structure (140) extending in the active area from the surface of the body in a first trench (111); and a second deep insulation structure (140) extending in the active area from the surface of the body in a second trench (141) and surrounding the conductive regions (120-123). The first deep insulation structure (140) has insulation walls (112) surrounding a conductive filling portion (113); the second deep insulation structure (140) is formed by a solid insulating region (142; 221) filling the second trench (141; 216'). The first deep insulation region has a first width (CD1) and a first depth (P1) and the second deep insulation structure has a second width (CD2) and a second depth (P2), the second width (CD2) being smaller than the first width (CD1) and the second depth (P2) being smaller than the first depth (P1).