Wafer Division Method Preventing Blade Clogging and Burr Formation

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Solution Overview

Problem

Existing wafer processing methods face issues such as clogging of cutting blades, generation of whisker-shaped burrs, and die shift during the division of small chips, which lead to processing failures and increased processing time.

Innovation Solution

A method involving the use of a front surface protective member, cut groove formation with a cutting blade, laser-assisted wafer division, and application of a liquid die bonding agent on the back surface after cut groove formation to prevent die shift and clogging, ensuring precise and efficient chip separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a tape with adhesive layer is adhered to the back surface of the wafer before division, then chips can be kept from being dispersed, but clogging occurs in the cutting blade and whisker-shaped burr is generated in the adhesive layer

Engineering Contradiction:

Improvechip dispersion preventionVSAvoidcutting blade clogging and burr generation

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The wafer is divided into individual chips before the adhesive layer is applied. The sequence is reversed from conventional methods: cutting grooves are formed first, then the adhesive layer is applied to the back surface. This preliminary division prevents the adhesive from interfering with the cutting process, eliminating clogging and burr generation while still preventing chip dispersion.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The wafer is segmented into individual chips through cut grooves before adhesive application. By dividing the wafer first and then applying adhesive to each separated chip or to the substrate holding the chips, the adhesive does not come into contact with the cutting blade, thus preventing clogging and burr formation.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If adhesive film is adhered to the wafer divided into individual chips, then chips are secured, but die shift occurs when adhesive is applied

Engineering Contradiction:

Improvechip securingVSAvoidchip position accuracy

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The wafer is divided into individual chips before adhesive application, and the chips are held in position by the cut grooves and holding table. The adhesive is then applied without requiring precise position detection, as the physical structure already secures the chips. This preliminary positioning eliminates die shift while maintaining securing effectiveness.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If laser processing is used to split adhesive layer, then wafer can be divided into individual chips, but processing time is long for chips with small size

Engineering Contradiction:

Improvewafer division capabilityVSAvoidprocessing speed

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The wafer division process is segmented into two stages: first forming cut grooves with a cutting blade, then using laser only for final separation along the grooves. This segmentation allows the majority of the division work to be done by the mechanical cutter at high speed, while the laser provides precise final separation, significantly reducing total processing time for small chips.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mechanical cutting process and laser processing are merged in a sequential workflow where the cutting blade creates grooves that guide and accelerate the subsequent laser separation. This combination leverages the speed of mechanical cutting with the precision of laser processing, achieving both efficiency and accuracy.

Inventive Principle:

Principle #5Merging (Combining)

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

Prevents die shift and clogging, allows for easy application of die bonding layers, and enhances the processing efficiency of small chips without generating burrs, thereby improving the overall wafer division process and reducing processing time.

Implementation Method 1

irradiating the wafer with a laser beam with such a wavelength as to be absorbed by the wafer along the cut grooves and dividing the wafer into individual chips

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

applying a liquid die bonding agent on the back surface of the wafer and curing the liquid die bonding agent applied on the back surface of the wafer to form the chips on which die bonding layers are disposed

Methodology Applied

Scientific EffectCuring:

Data Source

PatentUS10707129B2Processing method of wafer

Publication Date: 2020.07.07 DISCO CORP

AI summary

A processing method of a wafer includes a cut groove forming step of carrying out cutting with a cutting blade along streets from the back surface of the wafer to form cut grooves, a wafer dividing step of irradiating the wafer with a laser beam along the cut grooves and dividing the wafer into individual chips after the cut groove forming step is carried out, and a die bonding layer disposing step of applying a liquid die bonding agent on the back surface of the wafer and curing it to form the chips on which die bonding layers are formed on the back surface. According to the processing method of the present invention, the occurrence of clogging in the cutting blade and generation of a burr or the like in the die bonding layers can be prevented.