UV dicing tape for wafer sawing
UV dicing tape holds the wafer securely during blade or laser dicing, then sharply reduces its adhesion when exposed to UV light so that pick-up machines can remove chips easily, without chipping, cracking or adhesive residue.
Wafer dicing is the step that divides a silicon wafer into hundreds to thousands of individual chips. During dicing, the blade spins at tens of thousands of revolutions per minute while coolant water is sprayed continuously. Small chips must be held absolutely still. But afterward, that same strong holding force hinders chip pick-up. UV tape resolves this conflict.
The trend toward thin wafers and small chips in sensors, power chips and RF components is making requirements for dicing tape increasingly stringent.
How UV reduces adhesion
The tape's acrylic adhesive layer contains groups that react under UV light. When UV is applied from the back of the tape, the adhesive crosslinks, becoming harder and losing its tack. Peel strength can drop from 5–10 N/25 mm to below 0.2 N/25 mm.
UV tape versus standard tape
| Criterion | UV tape | Non-UV tape |
|---|---|---|
| Adhesion during dicing | High | Medium |
| Adhesion during chip pick-up | Very low after UV | Unchanged |
| Suitable chips | Small chips, thin wafers | Large chips, thick wafers |
| Adhesive residue on chips | Very little | May occur |
| Cost | Higher | Lower |
Selecting tape parameters
Backing
The polyolefin or PVC backing must transmit UV well and stretch evenly when the expander pulls the tape to separate the chips. Thickness is typically 80–150 microns.
Initial adhesion
The smaller the chip, the higher the initial adhesion needed to prevent chips from flying off during dicing. For chips under 1 mm, choose a high-adhesion grade.
UV sensitivity
The exposure dose is typically 150–500 mJ/cm². The UV lamp must be uniform across the entire wafer frame area.
Chips flying off during dicing or chips that cannot be picked up usually stem from uncontrolled time between tape mounting and UV exposure. The adhesive's tack changes with waiting time. — Semiconductor Process Engineer, AMS Vietnam
- Store tape away from light at temperatures below 25°C.
- Mount tape without air bubbles and visually inspect after mounting.
- Apply UV within the recommended time after dicing.
For wafers thinner than 100 microns, combine dicing tape with a soft backing and lower-speed dicing parameters to limit backside chipping at the chip edges.
AMS supplies UV dicing tapes and wafer back grinding tapes. Contact AMS Vietnam to receive trial samples.
