Semiconductor Package Retreating Metal Layers for Stress-Free Singulation

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Solution Overview

Problem

During the manufacturing of semiconductor packages, the sawing process through metal layers positioned vertically near the mold compound-substrate interface causes significant stress, leading to delamination and reduced yield due to the metal layers being cut through.

Innovation Solution

The implementation of retreating metal layers, where the first metal layer is set back from the lateral surface by at least 100 microns, with a dielectric segment between the metal layers and the lateral surface, preventing the sawing tool from cutting through the first metal layer and mitigating stress-related damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the sawing process cuts through metal layers positioned vertically near the mold compound-substrate interface, then complete singulation is achieved, but significant stress and delamination occur

Engineering Contradiction:

Improvesingulation completenessVSAvoidpackage integrity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The first metal layer is extracted or removed from the region near the saw street, creating a gap between the metal layer and the lateral surface. This prevents the sawing tool from cutting through the metal layer, thereby avoiding stress concentration and delamination while still achieving complete singulation through the dielectric material.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The metal layer is retreated from the lateral surface before the sawing process, creating a stress-free zone. This preliminary structural modification ensures that when the sawing tool passes through, it does not encounter metal layers that could cause delamination, thus protecting package integrity before the harmful action occurs.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If metal layers are positioned close to the lateral surface, then electrical connectivity is optimized, but stress during sawing causes delamination

Engineering Contradiction:

Improveelectrical connectivityVSAvoidsawing stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The substrate structure is segmented into distinct regions: a first region containing the retreated metal layer and a second region containing the dielectric material extending to the lateral surface. This segmentation allows the metal layer to maintain its electrical connectivity function while being isolated from the high-stress sawing zone, thus resolving the conflict between connectivity and stress resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dielectric material acts as an intermediary between the retreated metal layer and the lateral surface. It provides mechanical support and stress distribution in the region where the metal layer is absent, allowing the sawing process to proceed without causing delamination while maintaining the electrical connectivity of the metal layer to the circuitry.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the sawing tool cuts through all layers including metal layers, then singulation is complete, but yield is reduced due to delamination

Engineering Contradiction:

Improvesingulation efficiencyVSAvoidpackage yield

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The design converts the potential harm of the sawing tool encountering metal layers into a benefit by intentionally retreating the metal layer from the cut path. This structural modification transforms what would be a harmful interaction (saw cutting through metal causing stress) into a beneficial outcome (stress-free cutting through dielectric only), thereby improving package yield while maintaining singulation efficiency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 reduces stress and delamination during the singulation process, enhancing the yield and integrity of the semiconductor packages by ensuring the sawing tool only cuts through the mold compound and dielectric material, not the metal layers.

Implementation Method 1

The substrate includes a dielectric contacting part of the first and second metal layers and the via

Methodology Applied

Scientific EffectDielectric insulation: Dielectric

Implementation Method 2

the first metal layer positioned closer to the device side than the second metal layer and coupled to the second metal layer by way of a via

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20250006607A1Semiconductor package with retreating metal layers

Publication Date: 2025.01.02 TEXAS INSTRUMENTS INC

AI summary

A package comprises a die having a device side including circuitry. The package also comprises a substrate facing and coupled to the device side. The substrate includes first and second metal layers, the first metal layer positioned closer to the device side than the second metal layer and coupled to the second metal layer by way of a via. The substrate includes a dielectric contacting part of the first and second metal layers and the via. The package comprises a mold compound covering the semiconductor die and the substrate. The package includes a lateral surface perpendicular to the first and second metal layers of the substrate. The mold compound, the dielectric, and the second metal layer are exposed to the lateral surface, a segment of the dielectric positioned between the first metal layer and the lateral surface, the segment of the dielectric contacting the mold compound at the lateral surface.