After the wafer has gone through the previous process, the chip preparation is completed, and it needs to be cut to separate the chips on the wafer, and finally packaged. The wafer cutting process selected for wafers of different thicknesses is also different:
▪ Wafers with a thickness of more than 100um are generally cut with blades;
▪ Wafers with a thickness of less than 100um are generally cut with lasers. Laser cutting can reduce the problems of peeling and cracking, but when it is above 100um, the production efficiency will be greatly reduced;
▪ Wafers with a thickness of less than 30um are cut with plasma. Plasma cutting is fast and will not damage the surface of the wafer, thereby improving the yield, but its process is more complicated;
During the wafer cutting process, a film will be applied to the wafer in advance to ensure safer “singling”. Its main functions are as follows.
Fix and protect the wafer
During the dicing operation, the wafer needs to be cut accurately. Wafers are usually thin and brittle. UV tape can firmly stick the wafer to the frame or the wafer stage to prevent the wafer from shifting and shaking during the cutting process, ensuring the precision and accuracy of the cutting.
It can provide good physical protection for the wafer, avoid damage to the wafer caused by external force impact and friction that may occur during the cutting process, such as cracks, edge collapse and other defects, and protect the chip structure and circuit on the surface of the wafer.
Convenient cutting operation
UV tape has appropriate elasticity and flexibility, and can deform moderately when the cutting blade cuts in, making the cutting process smoother, reducing the adverse effects of cutting resistance on the blade and wafer, and helping to improve the cutting quality and the service life of the blade. Its surface characteristics enable the debris generated by cutting to adhere to the tape better without splashing around, which is convenient for subsequent cleaning of the cutting area, keeping the working environment relatively clean, and avoiding debris from contaminating or interfering with the wafer and other equipment.
Easy to handle later
After the wafer is cut, the UV tape can be quickly reduced in viscosity or even completely lost by irradiating it with ultraviolet light of a specific wavelength and intensity, so that the cut chip can be easily separated from the tape, which is convenient for subsequent chip packaging, testing and other process flows, and this separation process has a very low risk of damaging the chip.
Post time: Dec-16-2024