Stepped Passivation Layout for Rugged Semiconductor Dies

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Solution Overview

Problem

Conventional semiconductor dies face delamination issues in humid environments and high temperatures, leading to moisture ingress and device failure due to electric fields at the passivation termination edges.

Innovation Solution

The implementation of multiple passivation layers with varying termination edges and a charge redistribution path to prevent moisture ingress and reduce electric fields, enhancing the ruggedness of semiconductor dies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single passivation layer is used to isolate semiconductor devices, then the structure is simple and manufacturing is easy, but the layer may delaminate in humid environments and high temperatures, allowing moisture to penetrate into the active area

Engineering Contradiction:
Improvepassivation layer structureVSAvoidpassivation layer adhesion
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the passivation structure into multiple layers (first passivation layer, second passivation layer, and third passivation layer) with different termination edges. Each layer terminates at a different distance from the substrate termination edge, creating a stepped configuration. This segmentation allows each layer to provide independent protection and prevents delamination by distributing stress across multiple interfaces rather than a single critical interface.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs multiple passivation layers with potentially different material compositions and properties. The first passivation layer, second passivation layer, and third passivation layer can be made from different dielectric materials, creating a composite passivation structure that combines the advantages of each material to resist delamination and moisture ingress under various environmental conditions.

Inventive Principle:
Principle #40Composite materials

2Area of stationary object

If the passivation termination edge is close to the substrate termination edge, then the device area is maximized, but the electric field at the termination edge becomes very high, drawing moisture towards the active area

Engineering Contradiction:
Improveactive areaVSAvoidmoisture ingress
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent transitions from a single-planar passivation termination to a multi-level stepped structure. By extending passivation layers to different distances from the substrate termination edge (first passivation termination edge, second passivation termination edge, third passivation termination edge), the solution adds a dimensional aspect to the passivation design. This allows the structure to maintain compact footprint while providing extended protection zones that gradually reduce electric field strength and prevent moisture concentration at any single critical edge.

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

3Reliability

If multiple passivation layers with different termination edges are implemented, then delamination and moisture ingress are prevented, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveresistance to delamination and moisture ingressVSAvoidpassivation layer structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the passivation structure into multiple layers (first passivation layer, second passivation layer, and third passivation layer) with different termination edges. Each layer terminates at a different distance from the substrate termination edge, creating a stepped configuration. This segmentation allows each layer to provide independent protection and prevents delamination by distributing stress across multiple interfaces rather than a single critical interface.

Inventive Principle:
Principle #1Segmentation

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 solution effectively prevents delamination and moisture ingress, increasing the ruggedness and reliability of semiconductor dies across a wide range of environmental conditions.

Implementation Method 1

This problem is exacerbated by an electric field created by operating one or more semiconductor devices in the active area 24, which may be quite high at the passivation termination edge 30

Methodology Applied
Scientific EffectElectric field: Electric Field

Data Source

PatentEP3718135B1Semiconductor die with improved ruggedness
Publication Date: 2024.04.24 WOLFSPEED INC
  • EP3718135B1 patent drawingFigure 1
  • EP3718135B1 patent drawingFigure 2
  • EP3718135B1 patent drawingFigure 3

AI summary

A semiconductor die includes a substrate, a first passivation layer over the substrate, and a second passivation layer over the first passivation layer and the substrate. The substrate has boundaries defined by a substrate termination edge. The first passivation layer is over the substrate such that it terminates at a first passivation termination edge that is inset from the substrate termination edge by a first distance. The second passivation layer is over the first passivation layer and the substrate such that it terminates at a second passivation termination edge that is inset from the substrate termination edge by a second distance. The second distance is less than the first distance such that the second passivation layer overlaps the first passivation layer.