Laser Wafer Dicing with Thermoreflectance Splash Defect Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing GAL process for laser dicing in wafers faces challenges with splash damage due to laser light scattering, which cannot be directly detected during processing, leading to reliability issues and a long-term verification period.

Innovation Solution

A laser processing apparatus equipped with a thermoreflectance measurement portion that irradiates a detection light onto an adjacent region and detects light reflected from that region to determine the location of splash defects in real time, allowing for immediate measurement of laser light scattering damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a metal film is coated on the opposite surface to indirectly detect splash defects, then measurement capability is provided, but test reliability deteriorates due to sample deviation and long-term verification is required

Engineering Contradiction:

Improvesplash defect detection capabilityVSAvoidtest reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention extracts the detection function from the indirect metal film method and implements it directly on the wafer surface. The splash defect detection is performed by directly measuring the wafer surface topology changes caused by laser scattering, eliminating the need for metal film coating and indirect measurement, thereby improving reliability while maintaining measurement capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces an optical interferometry-based measurement system as an intermediary to directly detect splash defects on the wafer surface. This intermediary measurement system enables real-time detection of surface topology changes without requiring metal film coating, resolving the contradiction between measurement capability and test reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If indirect detection method using metal film is used, then splash defects can be measured, but verification period becomes long and test yield is reduced

Engineering Contradiction:

Improvesplash defect measurement capabilityVSAvoidverification period

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The invention performs preliminary detection of splash defects during the laser dicing process itself rather than requiring a separate long-term verification period. By integrating real-time optical measurement during processing, splash defects are identified immediately, eliminating the time loss associated with post-processing verification while maintaining measurement precision

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If laser beam is focused inside substrate to form laser damage layer, then cutting is achieved, but splash damage occurs due to laser light scattering

Engineering Contradiction:

Improvesubstrate cutting capabilityVSAvoidsplash damage to circuit patterns

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention implements a feedback mechanism where an optical measurement system continuously monitors the wafer surface during laser dicing to detect splash defects in real-time. When splash damage is detected, the system provides feedback to adjust laser parameters or processing conditions, thereby maintaining cutting effectiveness while reducing harmful splash damage to adjacent circuit patterns

Inventive Principle:

Principle #23Feedback

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 solution enables real-time detection of splash defects, improving test reliability and yield by eliminating the need for indirect measurements and reducing the verification period.

Implementation Method 1

a thermoreflectance measurement portion configured to irradiate a detection light onto an adjacent region and to detect light reflected from the adjacent region to determine a location of splash defect

Methodology Applied

Scientific EffectThermoreflectance: Reflection

Implementation Method 2

a laser irradiation portion configured to focus a laser beam inside the substrate such that a laser damage layer is formed inside the substrate along a cutting line

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS20250162081A1Laser processing apparatus, laser processing method and substrate dicing method using the same

Publication Date: 2025.05.22 SAMSUNG ELECTRONICS CO LTD

AI summary

A laser processing apparatus includes a stage configured to support a substrate that is a processing object, a laser irradiation portion configured to focus a laser beam inside the substrate to form a laser damage layer inside the substrate along a cutting line, and a thermoreflectance measurement portion configured to irradiate a detection light onto an adjacent region near a region where the laser beam is focused and detect light reflected from the adjacent region to determine a location of splash defect in the adjacent region generated by the laser beam.