Wafer Coat Layers with UV Absorbers and OSP for Laser Scribing

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Solution Overview

Problem

Low-k interlayer dielectrics in semiconductor processing are mechanically weak, leading to damage during saw singulation and yield/reliability issues, and the use of lasers for scribing creates debris that can impact device performance, while existing wafer coat layers increase manufacturing cycle time and interfere with laser ablation.

Innovation Solution

Incorporating an organic surface protectant (OSP) and ultraviolet absorber into the wafer coat layer formulation to protect die bumps from oxidation and enhance laser ablation, respectively, and using a conformal wafer coat layer deposited via vacuum deposition to reduce thickness variations and refraction effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a wafer coat layer is deposited to protect bumps from laser debris, then debris-related defects are reduced, but manufacturing cycle time increases and laser ablation efficiency decreases

Engineering Contradiction:

Improvedebris-related defectsVSAvoidmanufacturing cycle time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameters of the wafer coat layer by incorporating OSP and UV absorbers, transforming it from a passive protective coating to an active participant in the laser scribing process that enables simultaneous protection and efficient ablation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The wafer coat layer is formulated as a composite material combining OSP (for oxidation protection) and UV absorber (for laser energy absorption), creating a multi-functional coating that resolves the contradiction between protection and ablation efficiency

Inventive Principle:

Principle #40Composite materials

2Reliability

If a wafer coat layer is deposited to protect bumps from laser debris, then debris-related defects are reduced, but laser ablation efficiency decreases due to refraction and scattering

Engineering Contradiction:

Improvedebris-related defectsVSAvoidlaser ablation efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent converts the harmful effect of laser energy refraction and scattering by the wafer coat layer into a beneficial effect by incorporating UV absorbers that deliberately absorb laser energy to heat and ablate the wafer coat material, turning the coating from an obstacle into a facilitator of the scribing process

Inventive Principle:

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

Solution Approach 2:

The optical parameters of the wafer coat layer are modified by adding UV absorbers, changing its interaction with laser light from refraction/scattering to controlled absorption and ablation

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

The OSP layer reduces oxidation and debris-related defects, while the UV absorber improves laser ablation efficiency, and the conformal layer minimizes refraction and scattering, enhancing yield and reliability by reducing defects and cycle time.

Implementation Method 1

Incorporating an organic surface protectant (OSP) and ultraviolet absorber into the wafer coat layer formulation to protect die bumps from oxidation

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Implementation Method 2

Incorporating an organic surface protectant (OSP) and ultraviolet absorber into the wafer coat layer formulation to protect die bumps from oxidation and enhance laser ablation

Methodology Applied

Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Implementation Method 3

the laser beam 108 ablates and thereby removes from the scribe line region 110 the various device layers 104

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 4

to the extent that the wafer coat layer 207 optically refracts, diffracts, and/or scatter the laser's beam

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 5

to the extent that the wafer coat layer 207 optically refracts, diffracts, and/or scatter the laser's beam

Methodology Applied

Scientific EffectScattering: Scattering

Data Source

PatentUS7897486B2Semiconductor wafer coat layers and methods therefor

Publication Date: 2011.03.01 INTEL CORP

AI summary

Formulations and processes for forming wafer coat layers are disclosed. In one embodiment, an organic surface protectant is incorporated into a wafer coat formulation deposited onto a semiconductor wafer prior to the laser scribe operation. Upon removal of the wafer coat layer, the organic surface protectant remains on the bumps and thereby prevents oxidation of the bumps between die prep and chip and attach. In an alternative embodiment, an ultraviolet light absorber is added to the wafer coat formulation to enhance the wafer coat layer's energy absorption and thereby improve the laser's ability to ablate the wafer coat layer. In an alternative embodiment, a conformal wafer coat layer is deposited on the wafer and die bumps, thereby reducing wafer coat layer thickness variations that can impact the laser scribing ability.