Dicing by Laser (Laser Dicing)

Dicing by laser

Laser dicing

Overview of Laser Dicing

“Laser” is an abbreviated expression of Light Amplification by Stimulated Emission of Radiation. There are primarily two types of laser oscillation for processing: continuous wave (CW) oscillation and pulse oscillation. The pulse oscillation process can minimize the thermal effect and is mainly used for laser dicing in semiconductor manufacturing.

DISCO has two laser dicing processes:
・ Ablation
・ Stealth dicing

Ablation process

Ablation process

Ablation is a processing method that sublimes, vaporizes and removes a workpiece by irradiating a very strong laser on the surface. This method is not affected by the hardness of the workpiece, allowing it to process various materials. Also, unlike mechanical processing methods, ablation can achieve high quality without chipping or cracking since it does not require contact with the workpiece.

Laser processing particles (debris) generated during the ablation process cannot be removed by deionized water cleaning once attached to the wafer surface. Debris causes device defects such as bonding defects. Therefore, it is common to spin coat a water-soluble resin onto the surface before laser processing. This water-soluble protective film can prevent the adhesion of debris on the workpiece surface and it can be washed away with debris using only deionized water after the ablation process.

Comparison of debris adhesion with and without water-soluble protective film
Comparison of debris adhesion with and without water-soluble protective film

Stealth Dicing

Stealth Dicing

Stealth dicing is a processing method that forms a modified layer (decomposed crystalline) in the workpiece by focusing a laser inside the workpiece before separating the die using a tape expander. Because stealth dicing modifies the internal part of the workpiece, it is possible to leave no scratches on the surface of the workpiece and suppress processing waste.

tape expansion

Stealth dicing is a completely dry process that requires no water, making it suitable for workpieces that are vulnerable to loading such as MEMS. Stealth dicing can make an extremely thin kerf width, greatly contributing to street reduction.

Applied Processing Equipment

Fully-automatic laser saw

Fully-Automatic Laser saw

The laser saws currently available have various automatic functions. In particular, the machines are equipped with wafer handling, auto alignment, and cleaning functions so that the machine can process the workpieces as a cassette.

Applied Processing Tool

Ablation process: laser head, water-soluble protective film
Stealth dicing:laser head (SD engine)

Main Workpieces for Laser Dicing

・ Dicing of semiconductor wafers
・ Dicing of semiconductor packages
・ Processing of devices for electric components and optical components