① High cutting efficiency. The high cutting efficiency mainly comes from its technical characteristics: First, the diamond wire is fixed in a fixed way to combine with the diamond. Compared with the abrasive in the free state of the mortar wire, not only more diamonds are involved in grinding and cutting (less leakage), but also the mutual wear between the abrasives is reduced. Second, the diamond has high hardness and strong wear resistance, so the cutting and service life are longer. Third, the running speed of the diamond fixed to the diamond wire is consistent with the cutting wire, while the running speed of the free mortar is lower than that of the cutting wire.
② Less material loss and high yield rate. The larger the wire diameter of the cutting wire, the larger the knife gap during cutting, which leads to more material loss, and the wire diameter of the cutting wire is the sum of the bare wire diameter and the abrasive/blade material diameter. Because of its strong cutting ability, the diamond wire has a thinner coating than the mortar formed by the mixture of cutting fluid and silicon carbide, resulting in less knife gap loss. In addition, the damage layer caused by diamond wire cutting is smaller than that of mortar wire cutting, which is conducive to cutting thinner silicon wafers. Thinner wire diameters and thinner slices are conducive to reducing material loss and increasing the yield rate of silicon wafers. In 2015, the thickness of silicon wafers was mostly 180μm. The knife gap loss of mortar cutting was about 150μm, and the knife gap loss of diamond wire cutting was about 125μm. Therefore, diamond wire cutting can significantly increase the wafer yield.
③ Less environmental pollution. Mortar cutting will produce a large amount of waste mortar for crystalline silicon cutting. The waste mortar contains silicon carbide, polyethylene glycol, silicon powder and metal powder, which poses a greater threat to the environment. Some silicon powder with a particle size of less than 0.15μm will react quickly and release flammable gas H2 (hydrogen) and heat when in contact with water or humid air. If it is not properly utilized and disposed of, it will cause serious pollution. Diamond wire uses water-based grinding fluid (mainly water), which is conducive to improving the working environment and simplifying post-processing procedures such as cleaning.
④ Improved product quality. Diamond wire cutting reduces the processing damage layer (deteriorated layer), and the accuracy remains stable, resulting in a small TTV (total thickness change, the difference between the maximum and minimum values of a specific measurement point on the silicon wafer surface).
⑤ Reduced operating costs. The capital, space, manpower and electricity occupied by diamond wire cutting equipment have all decreased, and the entire production process has been simplified, thereby reducing operating costs.
