Wafer refers to the silicon wafer used in the production of silicon semiconductor circuits, and its original material is silicon. Due to its round shape, it is often referred to as a "wafer".
A wafer is like the foundation of the entire semiconductor structure. The foundation is good or not, directly determines the stability of the whole building, the same, complex electronic device process realization, are to be built on the basis of the structure of a smooth wafer.
Chip manufacturing is one of the current national key scientific research projects. With the chip to the direction of precision micro and highly integrated development, the density of integrated circuits continues to increase, the fab in the manufacture of semiconductor equipment also continues to face challenges.
In the micron scale, the traditional processing methods generally become bound, difficult to perform. Silicon wafers are already fragile and brittle, and as the thickness thins, the wafers become even more fragile, and when the diamond tip comes into contact with the wafers, it is very easy to produce cracks, faults, and broken wafers.
The chip industry is characterized by high net value and high cost. Individual wafers are expensive, and for mechanical scribing, an increase in breakage rates will have a serious impact on profitability, which is difficult for manufacturers to bear. Especially after the finished wafer is covered with a thin layer of metal, the metal debris will be wrapped around the diamond blade, which will seriously affect the cutting ability.
All factors, the laser as a modern industrial support tools, to "invisible cutting" way to realize the chip manufacturing process subversive enhancement.
The principle of invisible cutting, and commonly used in glass and other materials laser engraving is very similar. Through optical control will focus on the formation of multi-photon absorption within the wafer nonlinear absorption effect, making the material modified to form cracks. This process is only in the lower part of the wafer accounted for 1 / 3-1 / 4 of the part, does not affect the surface of the wafer. Due to the existence of UV film bearing under the wafer, when the internal modification layer is fully formed, the wafer can be separated along the cut seam by stretching the bearing layer or expanding the film.
Laser invisible scribing technology was initially used to cut ultra-thin semiconductor wafers, but it has performed well on silicon wafers of various thicknesses as well as specialty wafers. The following advantages exist for this technology:
Laser invisible scribing creates a small kerf, which allows fewer cut channels to be reserved in the chip design. In other words, the same wafer, the use of laser invisible scribing may be able to produce a greater number of chips, less waste material, can play a role in saving valuable semiconductor materials.
Laser invisible scribing is carried out inside the wafer, no scratches on the surface, no dust pollution, minimal material loss, and no subsequent cleaning process. As there is no silicon residue on the wafer surface, it will not affect the next step of processing, especially suitable for expensive materials, pollution-sensitive materials.
In the case of a certain chip area, the use of ortho-hexagonal dense rows of the shortest circumference. Through the laser invisible scribing can be realized irregularly shaped chip assembly synthesis wafer processing, can be processed hexagonal, octagonal and other shapes of the chip, independent of the cutting channel continuous or not, can be achieved to maximize the use of materials.
In recent years, thanks to the end market demand lift, global wafer shipments are still in a steady growth phase. According to EMI data, in 2022, the global semiconductor silicon wafer shipments area, revenue are record high, respectively, reached 14.7.13 billion square inches, 13.8 billion U.S. dollars. Based on the expansion of the market scale, in recent years, China's laser invisible cutting related technology localization has already started. 2020, Zhengzhou Railway Academy and Henan General joint, after a year of successful development of China's first semiconductor laser invisible wafer cutting machine, opened the prelude to the development of China's laser wafer cutting industry.
