In recent years, with the increase of device integration, the chip size and cutting channel width are shrinking accordingly. The thickness of the wafer and chip is getting thinner and thinner. However, due to the brittleness of semiconductor materials, the traditional cutting method will produce mechanical stress on the front and back of the wafer, and the high-speed water flow will also bring deformation pressure to the wafer. As a result, stress damage is generated in the crystal of the chip, which is easy to produce edge collapse, debris pollution and reduce the mechanical strength of the chip, The initial chip edge cracks will further diffuse in the subsequent packaging process or in the use of products, which may cause chip fracture and electrical performance failure.
Because the wavelength of ultraviolet light is 0.4 μ M, and the focus can be as small as submicron, so that when the UV laser cuts the chip, the notch of the UV laser process (the part of material loss during cutting) is narrower than that of other technologies, and the notch width is less than 3 μ m. And the incision is tighter, the edge of the incision is straighter, finer and smoother. UV laser can process extremely small parts because of its good focusing performance and cold treatment characteristics; Moreover, it can be used to process materials that can not be processed by infrared and visible lasers. Thus, UV laser has higher flexibility and wider applications.
Due to the advantages of UV laser cutting technology in semiconductor chip cutting, this technology has been widely used abroad, especially in some high-end chips (such as thin chips and GaAs wafers) and mass-produced chips (such as blue LED manufacturing). At present, UV laser technology still has great potential to be developed. It will further develop in the number of bare chips per unit wafer and shorten the investment payback period. It will open up a new prospect for semiconductor chip cutting.