Package Wafer Groove Formation via Laser Ablation

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Solution Overview

Problem

Existing methods for processing semiconductor wafers into package devices often result in inconsistent groove intervals due to cutting blade bending and positioning inaccuracies, leading to issues with mold resin coverage on side surfaces, especially when low-dielectric-constant insulator films are involved.

Innovation Solution

A processing method that includes steps for mold resin removal, orientation adjustment, coordinate registration, and dividing groove formation, ensuring accurate placement of dividing grooves along pre-formed grooves filled with mold resin, using either a cutting blade or laser beam, to maintain resin coverage on side surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If grooves are formed by a cutting blade, then grooves can be formed in the semiconductor wafer, but the interval of the grooves varies due to bending of the cutting blade and expansion/contraction of the shaft

Engineering Contradiction:

Improvegroove formationVSAvoidgroove interval consistency

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical cutting blade system with a laser beam system for forming grooves. The laser beam forms grooves through ablation without physical contact, eliminating the bending and thermal expansion issues of mechanical cutting blades. This is achieved by irradiating the wafer surface with a laser beam that moves along the planned dividing lines to form grooves with consistent intervals.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the method of groove formation from mechanical cutting to laser ablation. By changing the physical parameter of the cutting mechanism (from mechanical blade to electromagnetic laser beam), the system achieves both ease of manufacture and high precision in groove interval consistency, resolving the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the width of the planned dividing lines is set small to increase the number of package devices, then productivity increases, but the possibility that mold resin is not left on the side surface becomes high due to groove interval variation

Engineering Contradiction:

Improvenumber of package devices per waferVSAvoidmold resin coverage on side surface

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

By replacing the mechanical cutting blade with a laser beam system, the patent achieves precise control over groove formation. This allows for smaller dividing line widths with consistent groove intervals, enabling higher productivity while maintaining reliable mold resin coverage on side surfaces through the precision of laser ablation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If laser ablation is used to remove the low-dielectric-constant insulator film, then the film can be removed, but the vicinity of the grooves becomes hard due to heat influence, causing cutting blade bending

Engineering Contradiction:

Improveinsulator film removalVSAvoidhardness of groove vicinity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent replaces the mechanical cutting blade with a laser beam system for groove formation. This eliminates the problem of cutting blade bending caused by heat-induced hardening, as the laser directly ablates the material without requiring mechanical contact. The laser forms grooves through controlled ablation even in the heat-affected zones created by previous laser ablation of the insulator film.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method ensures consistent mold resin coverage on side surfaces of package devices, improving the accuracy of groove formation and reducing the likelihood of resin being left off the devices, thereby enhancing the reliability of the package wafer processing.

Implementation Method 1

a mold resin removal step of removing the mold resin along a peripheral edge of the package wafer and exposing the grooves filled with the mold resin in the peripheral surplus region

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

when a low-dielectric-constant insulator film (Low-k film) is formed on a surface of the semiconductor wafer and the low-dielectric-constant insulator film is removed by laser ablation

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS10211104B2Processing method of package wafer

Publication Date: 2019.02.19 DISCO CORP

AI summary

A processing method of a package wafer includes a mold resin removal step of exposing grooves filled with a mold resin of the package wafer in a peripheral surplus region, a holding step of holding the package wafer in such a manner that the grooves are exposed, an orientation adjustment step of causing the grooves to be parallel to a processing-feed direction in which processing feeding of a chuck table is carried out when dividing grooves are formed, a coordinate registration step of imaging both ends of the plural grooves exposed at a peripheral edge and registering coordinate information of both ends or a single side of the grooves from taken images, and a dividing groove forming step of calculating the positions of the dividing grooves to be formed along the grooves based on the registered coordinate information of the grooves and forming the dividing grooves along the grooves.