Backside Chip Identification in Organic Laminate Packaging

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Solution Overview

Problem

Existing methods for backside chip identification in organic laminate packaging mechanically weaken the chip, making it prone to failure due to thermal expansion and contraction stresses, as the coefficient of thermal expansion (CTE) differences between the chip and the organic substrate cause tension that can lead to chip failure at the scribe mark.

Innovation Solution

The method involves depositing a thin metal layer on the wafer backside, patterning it, and using laser scribing or etching to create unique identification marks without weakening the underlying silicon layer, or using remote sensing technologies like X-ray to identify chips without physical marking, thereby minimizing mechanical stress on the chip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If a backside chip scribe is used for identification, then chip identification is provided, but the chip is mechanically weakened and more likely to fail under thermal warpage stresses

Engineering Contradiction:

Improvechip identificationVSAvoidchip mechanical strength

Core Design Contradiction:

Loss of informationVSStrength

Solution Approach 1:

The patent replaces the mechanical scribing process with laser-based marking or remote sensing technologies. The laser marks the chip backside without physically removing material that would create stress concentration points, thereby maintaining chip structural integrity while providing identification. Remote sensing methods eliminate physical contact entirely, using electromagnetic radiation to read identification marks without mechanical intervention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the parameters of the identification process by using laser energy rather than mechanical force. The laser parameters (power, pulse duration, wavelength) are controlled to mark the chip surface without creating deep scratches or weakening the substrate. This parameter change allows identification while preserving mechanical strength.

Inventive Principle:

Principle #35Parameter changes

2Loss of information

If laser marking is used for chip identification, then identification is provided, but the breaking strength of the chip decreases

Engineering Contradiction:

Improvechip identificationVSAvoidchip breaking strength

Core Design Contradiction:

Loss of informationVSStrength

Solution Approach 1:

The patent applies partial action by using controlled laser marking that affects only the surface layer of the chip without penetrating deep into the substrate. The laser energy is calibrated to create visible marks for identification while leaving the bulk material properties unchanged, thus maintaining breaking strength.

Inventive Principle:

Principle #16Partial or excessive action

3Adaptability or versatility

If CTE difference between chip and organic substrate is large, then organic laminate packaging is used, but chip breaking risk increases during thermal excursion

Engineering Contradiction:

Improveorganic laminate packaging compatibilityVSAvoidchip reliability during thermal stress

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the identification process from the mechanical structure modification. By using laser marking or remote sensing, the identification function is separated from any structural changes that would affect thermal stress distribution. This allows the chip to maintain its integrity under thermal excursion while still providing identification capability.

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

This approach provides a strong and reliable method for chip identification that does not compromise the mechanical integrity of the chip, reducing the likelihood of cracking during thermal stressing and enabling clear, readable identification without damaging the chip.

Implementation Method 1

utilizing a laser to scribe, etch, or fuse the deposited material on the backside of the wafer to provide the identification

Methodology Applied

Scientific EffectLaser heating and ablation: Laser Ablation

Implementation Method 2

utilizing a laser to scribe, etch, or fuse the deposited material on the backside of the wafer

Methodology Applied

Scientific EffectLight absorption and heating: Absorption (EM radiation)

Data Source

PatentUS8835229B2Chip identification for organic laminate packaging and methods of manufacture

Publication Date: 2014.09.16 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A chip identification for organic laminate packaging and methods of manufacture is provided. The method includes forming a material on a wafer which comprises a plurality of chips. The method further includes modifying the material to provide a unique identification for each of the plurality of chips on the wafer. The organic laminate structure includes a chip with a device and a material placed on the chip which is modified to have a unique identification mark for the chip.